The paper deals with the effectiveness of various types of polymers  as superplasticizers of concrete mixtures based on low-clinker slag Portland cement. Using the mathematical planning experimental method and statistical models of water demand of concrete mixtures with polymer superplasticizers, as well as concrete strength at different ages and under different curing conditions  were obtained. According to the models, the superplasticizer’s water-reducing effect and relative change in concrete strength were obtained. The proposed criterion for evaluating the effectiveness and compatibility of superplasticizers with cement takes into account the water-reducing effect of the superplasticizer and the corresponding relative change in concrete strength. The results demonstrate that the use of the investigated superplasticizer types and low-clinker slag Portland cement allows for achieving a significant increase in concrete strength. The effective contents of various polymer types, which allow the achieving of concrete strengths from 50 MPa to 80 Mpa, has been found. Superplasticizers (SPs) are used in concrete production since the early 1970s. Using them has allowed significant improvement of concrete properties without increasing cement consumption. Superplasticizers enable obtaining cast and self-compacting mixtures with cone slump of 20 cm and 26 cm, respectively, with a moderate water demand as well as producing high-strength concrete based on ordinary Portland cement and aggregate with low permeability, high corrosion resistance, etc. . Adding Most superplasticizers are polymeric substances of various structures . As knowSome of the first SPs were additives that belonged to the joint naphthalene–formaldehyde (NF)-type group. At an additive content of 0.5–1% by cement weight, they allow increasing the concrete mixture cone slump from 2–4 cm to 20–22 cm. Under conditions of equal mixtures workability, as a result of a decrease in W/C, the strength of the concrete with NF SP at 28 days is up to 30–40% higher compared to that without additives. At the same time, the concrete density and water resistance significantly increase, and a number of other properties improve [Using P-type SP, based on polyacrylates and polycarboxylates, reduces the concrete mixtures water demand by more than 30% . If concThe cheapest plasticizers are surfactants based on lignosulfonates. Hydrolysis production wastes—technical lignosulfonates (LST) added into concrete mixtures, usually in an amount of 0.15–0.25% by cement weight, are widely used in concrete technology. Adding 0.8–1% of LST, approximately the same liquefaction can be achieved as with conventional SP content; however, the concrete strength decreases by 1.5 times or more .adsorption of mono- or polymolecular surfactants on the surface of mainly hydrate neoplasms;colloidal–chemical phenomena at the phases border.The SP effect is due to a complex of physicochemical processes in the cement paste-additive system . It is dThe predominant effect of NF, MF, and LST-type SP  is the eModern cements have different chemical and mineralogical compositions. The practice of recent decades has shown that adding the same SP in concrete mixtures based on different cements or using the same cement with different superplasticizers has a different character ,10.3S and C3A minerals [Many studies have been carried out to determine the mineralogical and material composition of cement in assessing the effectiveness of using SP . The claminerals ; howeverGranular blast-furnace slags are the most widely used in cement technology as active mineral admixtures. The addition of SP improves the rheological properties of slags, especially if their dispersion is high . With a In research and practice, cement systems, including active mineral additives, like slag, in an amount of 10 to 70% by cement weight, became popular. It was shown in  that it Based on available research results ,19,20, iIt was proposed to use three categories of cement–additive compatibility factors: chemical and mineral composition of cement; superplasticizer characteristics: molecular weight, molecular chains structure, and branching, polycondensation degree, as well as such technological parameters as the concentration of additives, temperature, sequence of introduction, mixing mode, etc. . This apAnother way to assess compatibility was proposed in ,23. BaseIn studies directly related to the compatibility of cements and superplasticizers ,19,21, icmf) to the value of the water-reducing effect (WRE):-water-reducing effect :0 and WSP are the concrete mixture water content before and after SP addition, respectively.In most studies , the com-relative change in compressive strength . The cement-specific surface area was 4534 cm2/g and the standard cement strength was 48 MPa. Locally available granulated blast furnace slag attributed to the main slags (Mo = 1.09) [3S = 57.1%, C2S = 21.27%, C3A = 6.87%, and C4AF = 12.19%), which according to its mineralogical composition can be attributed to typical medium aluminate clinkers produced by cement plants of Ukraine. Phosphogypsum dihydrate (FG) was used as a sulfate component of low-clinker slag Portland cement (LCSPC). Chemical composition of the materials is given in f = 1.9 were used as aggregates for concrete.The present research was performed for concrete based on cement with the following composition: clinker—11.2%, slag—81.8%, phosphogypsum—7.0% ;bX1, X2 are the investigated factors (variables).0 corresponds to the arithmetic mean value of the investigated property, obtained in the experiment; b1, b2 display the linear influence of the investigated factors . In this way, mathematical models of water consumption of concrete mixture and compressive strength of concrete were obtained . EquatioGraphical dependences that illustrate the influence of technological factors on the concrete mixture water demand and compressive strength of concrete after steaming and 28 days of normal hardening after steaming are shown in W/C. Increasing the content of P admixture to the value of 0.6% by cement weight allows maximal W/C reduction and, accordingly, doubles the magnitude of the concrete strength. At the same time, the concrete strength is about 40 MPa at 7 days and more than 60 MPa at 28 days. When using P and LS SP it is about 30 MPa at 7 days and more than 45 MPa at 28 days; for NF SP it is 30 MPa and 40 MPa at 7 and 28 days, respectively.The concrete strength at 7 and 28 days increases with an increase in binder content and SP content, which leads to a corresponding decrease in The relatively high strength of concrete based on low-clinker slag Portland cement can be explained by high binder reactivity, which has an increased grinding fineness, contributing to a higher activating effect of the binder cement and sulfate components on the blast furnace slag. Achieving low water-cement ratio values due to the use of plasticizing admixtures contributes to cement hydration in “compressed conditions”, which leads to faster formation of a supersaturated solution, with such a supersaturation degree, at which hydrate neoplasms and hardening structure formation occurs most rapidly .An even more significant effect of using finely ground low-clinker slag Portland cement is observed during heat-moist processing . A charaTo evaluate the effectiveness and compatibility of various superplasticizers with an LCSPC according to the mathematical models (Equations (4)–(18)), a comparison of the admixtures’ water-reducing effect and the relative increase in strength at 7 and 28 days was carried out. A graphic comparison of these indicators is shown in W/C to the maximum possible values with a simultaneous increase in cement hydration degree. According to Powers [According to theoretical concepts , the higo Powers , the comA is a constant characterizing the cement gel strength (A ≈ 240 MPa), n is a coefficient determined by cement characteristics (n = 2.6–3),X is a structural criterion.X in Equation (19) characterizes the cement hydration products concentration in the space available for these substances and is proportional to the relative cement stone density:Structural criterion HK = 2.09–2.2 is the hydration products’ (gel) volume growth coefficient; PCV is the specific volume of cement ; α is part of the cement that has undergone hydration (hydration degree). W/C values and a relatively small increase in the hydration degree [W/C = 0.2 with an increase in α from 0.1 to 0.2, the cement stone compressive strength increases from 30 to 55 MPa, and already at W/C = 0.3—only from 15 to 25 MPa [Known experimental data also shows a higher increase in the strength of cement paste with low n degree . For exao 25 MPa .cmf and the SP water-reducing effect under different hardening and duration conditions of LCSPC concrete. This criterion uniquely characterizes the efficiency and compatibility of the investigated superplasticizer types and cement.cK criterion for polycarboxylate SP additive were 1.82–3.11, the NF-type SP was slightly less effective (cK = 1.32–2.12). Naphthalene–formaldehyde-type SP was quite effective when used with LCSPC, especially at an early age (on 7th day cK = 2.12). SP, consisting of polycarboxylate and lignosulfonate, showed high efficiency at 28 days of normal hardening (cK = 1.58). It is because polycarboxylate superplasticizers have a significantly higher water-reducing effect due to the steric liquefaction mechanism. This allowed the significant reduction of the concrete mixture water demand and W/C, improving the concrete strength and a number of other properties.According to the experimental data , the maxExperimental and statistical models for water demand and compressive strength of LCSPC concrete with a clinker consumption of 12% at 7 and 28 days were obtained for cases of normal hardening and steaming and using superplasticizers based on naphthalene formaldehyde, polycarboxylate, and lignosulfonate polymers.It was found that polycarboxylate SP is characterized by the maximum water-reducing effect (27 ... 52%) of LCSPC concrete, the complex polycarboxylate and lignosulfonate SP is somewhat less effective (19–41%), and the lowest effect (10–17%) was found for naphthalene formaldehyde SP. At the same time, polycarboxylate SP demonstrated an increase in concrete strength by two times (more than 60 MPa at 28 days). For polycarboxylate and lignosulfonate superplasticizers, the strength was more than 45 MPa, and for naphthalene–sulformaldehyde—about 40 MPa.The use of the investigated SP types and LCSPC allows for achieving a significant increase in concrete strength, even after heat and moisture processing. The effectiveness of various SP types, allowing to achieve concrete strength from 50 MPa to 80 MPa has been found.cK), is proposed. The values of the criterion indicate cement and SP compatibility and indicate the additional effect that SP have on structure formation and, as a result, on concrete strength.A criterion for evaluating the compatibility and effectiveness of the investigated superplasticizers with cements, considering the SP water-reducing effect and the corresponding relative change in strength (


Two pre-treatment methods, mechanical pre-processing (MPCCA) and accelerated carbonation (CO2CCA), are investigated for quality improvements in CCA. The resulting aggregates show an increased density, contributing to an increase in the concrete’s compressive strength. The novelty of this paper is the superposition of the effects of the composite parts of concrete, the aggregate and the cement mortar, and their contributions to concrete fracture. Investigations are directed toward the influence of fine aggregates on mortar samples and the influence of the combination of coarse and fine aggregates on concrete samples. The physical and mechanical properties of the aggregates are correlated with mortar and concrete fracture properties. The results show that CCA concrete achieves 70% of the fracture energy values of concrete containing natural aggregates, and this value increases to 80% for GGBS mixes. At lower w/c ratios, MPCCA and CO2CCA concretes show similar fracture energies. CO2CCA fine aggregates are the most effective at strengthening the mortar phase, showing ductile concrete behavior at a w/c ratio of 0.48. MPCCA aggregates contribute to higher compressive strengths for w/c ratios of 0.42 and 0.48. Thus, mechanical pre-processing can be improved to produce CCA, which contributes to more ductile concrete behavior.This paper investigates the fracture mechanical properties of concrete, using crushed concrete aggregates (CCA) and granulated blast furnace slag (GGBS) for partial cement replacement. CCAs made from prefabricated concrete replace 100% of the fine and coarse fractions in concrete recipes with  The aggregates used in concrete are a finite resource. In Sweden, natural sand of fluvial origin is a critical resource which is necessary for the preservation of drinking water reservoirs. Therefore, Swedish law has placed restrictions on the volume of sand that can be extracted for concrete and road applications . Alterna2 footprint associated with its production. This arises mainly from the manufacture of cement, which accounts for 5% of global anthropogenic CO2 emissions contributing to climate change [2 footprint of concrete. Concrete with a lowered CO2 footprint is climate-reduced concrete. The use of GGBS is shown to favor the development of strength in concrete at high CCA replacement percentages [Another important aim with respect to concrete is the reduction of the COe change ,4. The uThe CCA is a composite of aggregate and adhered cement mortar, unlike stone-based aggregates that are homogeneous . Figure 2 from CO2 sources such as flue gas [In most cases, CCAs show reduced densities compared to natural aggregates except for CCAs derived from high-strength concrete ,7. The uflue gas .The reduced mechanical performance of CCA concrete is claimed to be due to the weaker interface formed between the cement paste and aggregate which is caused by adhered mortar . Studies2 gas at a concentration of 10%, corresponding to the concentration of CO2 in flue gas from local incineration plants. A sealed incubator is prepared to maintain an exposure duration of 5 h at a relative humidity of 50%. The parameters for the carbonation setup are designed to maximize CO2 uptake and are based on previous research [Concrete rubble undergoes three crushing and sieving steps, resulting in fine and coarse CCA fractions. Mechanical pre-processing involves tumbling the CCA at 50 RPM for 15 min in a rotating ribbed drum to dislodge adhered mortar. The adhered mortar is removed by washing the aggregates on sieves . The accF is one such parameter for measuring tensile toughness [F through a Mode I failure based on the opening of a crack [F measurements using three-point bending tests on notched concrete specimens are most commonly seen in the literature related to recycled aggregate concrete [F can be made on notched cylindrical and cubic specimens of CCA concrete, as seen in [The toughness of concrete in tensile failure needs to be investigated to ascertain the concrete’s resistance to crack propagation. The fracture energy Goughness . The foc a crack . GF measconcrete ,17,18,19 seen in . The opeThe fracture mechanical properties of concrete are influenced by the aggregate and cement mortar phases . Coarse w/c ratio or with SCMs such as silica fume or GGBS [w/c ratio [The cement mortar phase responds first under loading to produce microcracks. The strengthening of the cement mortar phase inhibits the initiation of cracks, thereby increasing the concrete’s fracture energy. This is achieved either via a reduction in the  or GGBS ,23,24,26/c ratio . The ang/c ratio ,28. Aggr/c ratio . The gra/c ratio .Fracture energy tests show a large variation in the results for replicates of the same concrete . Tests oSo far in the literature, only chemical-based pre-treatment methods have been investigated for their influence on the fracture properties of concrete containing CCAs ,33,34. Tw/c ratio of the concrete mixes. Two w/c ratios are: investigated 0.48 for normal-strength concrete and 0.42 for a high-strength concrete. A 30% replacement of cement with GGBS for a w/c equivalent 0.42 is also investigated. A reference concrete mix containing natural coarse and fine aggregates is made for all three recipes. The experimental scheme consists of tests on the physical, mechanical and fracture mechanical properties of the aggregates, cement mortar. and concrete. The number of test samples are aimed at understanding the dependence of concrete’s mechanical properties on aggregate and mortar strength. For a regular statistical assessment, more test samples are required. This study does not include any microscopic analyses.This study focuses on the 100% replacement of coarse and fine aggregates with a CCA. The aggregate’s influence is investigated using two CCA pre-treatment methods which produce fine and coarse CCAs of different qualities. Both pre-treatment methods result in concrete with a compressive strength comparable to natural-aggregate concrete. The influence of cement mortar is investigated by varying the 2CCA, respectively.The concrete waste was sourced from rejected prefabricated elements from an industrial facility. The crushed concrete aggregates (CCAs) were prepared by crushing concrete in a jaw crusher, followed by sieving the particles to obtain coarse and fine aggregate fractions. The aggregates were pre-treated via mechanical pre-processing and accelerated carbonation techniques according to the procedures in The physical and mechanical properties of the coarse and fine aggregates were investigated. The particle size distribution of the coarse and fine aggregates was tested according to SS-EN 933-1:2012 . The flaThe aggregate crushing value (ACV) was determined according to the standard BS-812-110:1990 . The ACV2CCA mixes had two fine fractions, 0/4 and 0.5/4 mm, to match the grading of the reference mix. The grading curves of the fine aggregates are shown in The Charpy test shows the energy required to break a prism specimen using dynamic loading created by a swinging hammer connected to a pendulum, as shown in w/c ratio of 0.48.The Charpy test has a dynamic loading character in comparison to the static three-point bending tests used to determine fracture energy on concrete specimens. Therefore, the Charpy test provides an over-estimated value for the mortar compared to the fracture energy of concrete. Compressive strength was tested on mortar samples measuring 40 × 40 × 160 mm, and the elastic modulus was tested using 100 × 200 mm cylinders, using the standards SS-EN 1015-11  and SS-Ew/c equivalent to 0.42 is denoted 0.42 SLAG. The GGBS influences the workability of the concrete, as seen via the increased slump values which may influence the hardened concrete’s properties [The cement used was CEM II/A-LL 42.5 R manufactured by CEMENTA, Sweden, and the superplasticizer was polycarboxylate-based with a dry content of 24% by weight; the proportions are shown in operties . No specThe compressive strength, elastic modulus and splitting tensile strength at 28 days were measured using three sets of 100 × 200 mm cylinders, according to SS-EN 12390-3 , SS-EN 1F was calculated according to the method proposed by the RILEM technical committee 50, given by the formula 0 represents the area under the load–deformation curve (N/m), δ0 is the deformation at the final fracture (m), m is the sum of the weight of the beam between the supports and the loading arrangement (kg), g is acceleration due to gravity 9.81 m/s2 and Alig (m2) is the cross-sectional area of the beam above the notch.The fracture energy Gg in N/m . W0 reprThe mechanical performance of the aggregates, reported using the elastic modulus;The properties of the fine aggregates, with the mortar’s mechanical and Charpy energy properties;The properties of the coarse aggregates, with the mechanical properties and fracture energy of the concrete.To understand the aggregate’s influence on the mechanical properties of mortar and concrete, the following results are reported in this chapter:Tests of physical properties—the apparent density, flakiness index and unit weight—were conducted for both the coarse and fine fractions. The coarse and fine aggregates’ properties are presented separately in 2CCA aggregate was densified via the strengthening of the adhered mortar. The densities of the aggregates are reported in 2CCA aggregates are shown along with flakiness index values in The removal of adhered mortar manifested as a reduction in the flakiness index for the MPCCA aggregate. From the point of view of the aggregates’ shapes, this positions the MPCCA aggregate between CCA and natural coarse gravel. The MPCCA aggregate was densified via the removal of adhered mortar, while the COaggregate is the elastic modulus of the aggregate, and aggregate results are shown in The aggregate elastic modulus is related to the density of the aggregate. This is given by the Müller-Rochholz  relation2CCA aggregates should bring improvements to the s elastic modulus values. An aggregate’s elastic modulus has a strong influence on the stiffness of concrete and thus on the fracture mechanical properties of the concrete. In this way, improvements in the aggregate density can bring about improvements in the fracture mechanical properties of concrete.The improved densities of the MPCCA and COIn this study, the aggregate elastic modulus was determined experimentally via the confined axial loading of a constant volume of aggregates during an ACV test. The test results confirm that improvements in aggregate density result in an increase in the aggregates’ elastic modulus. The experimental and calculated elastic modulus are plotted against each other for coarse aggregate fractions of 8/10 and 8/11.2 in 2CCA aggregate, although there was an increase in density; values are provided in The experimental elastic modulus shows a reasonable correlation with the elastic modulus calculated using aggregate density values for each of the investigated aggregate types. The best correlation is seen for NAs, followed by MPCCA aggregates. The natural aggregates with the highest density values also show the highest elastic modulus values during testing. The mechanically pre-processed aggregates show the most similar behavior to the natural aggregates (correlation factor: 0.9). The lowest in elastic modulus correlation is seen in the case of the COThe properties of the fine aggregate fractions used in both the mortar and concrete mixes are shown in 2CCA fraction manifested as an increase in the unit weight, bringing it closer to the NA fraction.The density and unit weight of the fine recycled aggregate fraction of 0/4 mm improved markedly via accelerated carbonation compared to mechanical pre-processing. This effect is not seen for the 0.5/4 mm fraction as the fraction lacks fines which show the highest tendency for carbonation. For the MPCCA, the process of sieving and washing resulted in the loss of high-density fines. The increase in particle density of the COc) and elastic modulus (Emortar), for mixes with a w/c ratio of 0.48 are shown in The results of the mechanical properties of the mortar, such as its compressive strength , static elastic modulus (Econcrete) and splitting tensile strength (ft) were tested for the concrete mixes 0.48, 0.42 and 0.42 SLAG; the values are presented in F), peak load and maximum deflection results are shown in The compressive strength .The experimental and calculated elastic modulus values correspond well, particularly for the MPCCA-based mixes. The EF, was calculated as the area under the load–deflection curve resulting from a three-point bending test on concrete beams. High GF values can result either from high peak load values or gradual and wide descending branches of the load–deflection curve. The GF values were analyzed against the corresponding peak loads and time to failure. The fracture energy shows a better correlation with the corresponding peak loads compared to the time to failure; the peak loads are plotted against GF in The fracture energy, GThe best correlation is seen for the concrete mix containing GGBS which behaved almost like a high-strength concrete, and the second-best correlation is shown by the 0.42 mix. The GGBS mix resulted in the highest peak load with the lowest time to failure, indicating more brittle behavior compared to the other mixes. This is also confirmed by the Charpy energy values in F is shown in F values that were lower than the reference concrete, independent of the pre-treatment method used. This is a conclusive finding for concrete comprised of 100% recycled aggregates.The aggregate’s effect on Gw/c, 2CCA aggregates. A higher compressive strength does not imply a higher fracture energy, as pointed out in [2CCA concrete samples show lower GF values than the reference concrete, including brittle failure at lower w/c ratios, while achieving the reference concrete’s compressive strength. This is unlike the CCA concrete, which does not meet the compressive strength of the reference concrete yet shows a higher fracture energy value than the MPCCA and CO2CCA concrete samples. Aggregates which received accelerated carbonation pre-treatment (CO2CCA) produce mixes that demonstrate ductile behavior at higher w/c ratios.Concrete’s compressive strength is an outcome of the strengths of both the aggregate and cement paste phases . From thd out in ,24. The 2CCA, respectively. Two w/c ratios were investigated, 0.42 and 0.48, including a climate-reduced concrete with GGBS with a w/c equivalent 0.42. Recommendations for normal and high-strength recycled aggregate concrete are made using the results of fracture mechanical investigations. This was achieved through a combined analysis of the aggregates’ properties, Charpy test results on mortar and mechanical properties and the fracture mechanical properties of the concrete. The conclusions of this study are as follows:This study is an assessment of the contributions of aggregates and cement mortar to the fracture mechanical properties of concrete. CCA replaced 100% of the aggregates in the investigated concrete recipes. Two quality improvement methods were investigated for the recycled aggregates: mechanical pre-processing and accelerated carbonation. The resulting aggregates are denoted MPCCA and COw/c ratio, and this value increases to 80% for mixes with the addition of GGBS.The CCA concrete achieves 70% of the fracture energy value of the reference concrete independent of the 2CCA showed high compressive strength values, low Charpy energy values and ductile behavior. Concrete mixes containing CO2CCA aggregates showed lower fracture energy values than the reference concrete. Thus, CO2CCA aggregates fit concrete with high w/c ratios.Mortar mixes containing aggregates treated with accelerated carbonation, COThe MPCCA concrete showed a lower fracture energy than the reference concrete due to the loss of the aggregate’s flakiness following mechanical pre-processing. Mixes containing mechanically pre-processed aggregates show more brittle behavior and higher compressive strength values which fit normal–high-strength concrete.


Studying the rheological behavior of concrete, especially self-compacting concrete is vital in the design and structural integrity of concrete structures for design, construction, and structural material sustainability. Both analytical and numerical techniques have been applied in the previous research works to study precisely the behavior of the yield stress and plastic viscosity of the fresh self-compacting concrete with the associated flow properties and these results have not been systematically presented in a critical review, which will allow researchers, designers and filed operators the opportunity to be technically guided in their design and model techniques selection in order to achieve a more sustainable concrete model for sustainable concrete buildings. Also, the reported analytical and numerical techniques have played down on the effect of the shear strain rate behavior and as to reveal the viscosity changes of the Bingham material with respect to the strain rate. In this review paper, a critical study has been conducted to present the available methods from various research contributions and exposed the inability of these contributions to revealing the effect of the shear strain rate on the rheological behavior of the self-compacting concrete. With this, decisions related to the rheology and flow of the self-compacting concrete would have been made with apt and more exact considerations. This concept includes the study of the stresses (yield stress), viscosity, and flow characteristics which are the physical outcome of the stress inputs5 as depicted in Fig. 8. These properties are studied both in the laboratory using experimental methods and also by the application of mathematical models to represent the field and laboratory conditions under the influence of established boundary conditions9. In the laboratory/field studies, the V-funnel, L-box, J-ring, Orimet, etc. apparatuses have been developed to study the rheological behavior of the self-compacting concrete (SCC) and this has been done with very wide applications according to the EFNARC requirements10. Also, various analytical and numerical techniques have been developed to represent these rheological behaviors of the self-compacting concrete for the purposes of design and construction of sustainable building structures. Most of the analytical and numerical methods in use today have been identified as follows: analytical techniques: Krieger–Dougherty model (KDM), modified Krieger–Dougherty model (MKDM), Chateau–Ovarlez–Trung model (COTM), modified Chateau–Ovarlez–Trung model (MCOTM), Elastic–plastic damage model, Navier–Stokes (NS), Robertson–Stiff Model (RSM), Casson model (CM), De Kee model (DKM), Yahia and Khayat model (YKM), Quemada model (QM), Vom Berg model (VBM), and numerical techniques: Finite Element Method (FEM), Discrete Element Method (DEM), Material Point Method (MPM), Smoothed Particle Hydrodynamics (SPH), etc. as presented in Fig. 11. In this research paper, a critically systematic review has been conducted on the constitutive relations applied in modeling the flow of self-compacting concrete (SCC). This is to further explore the inputs made by various researchers and the applied techniques in the research cause with a view to presenting a synthesized idea of this subject to the research world for ease of application and flexibility in the choice of methods to apply both in their future research efforts and in the field.The concept of rheology is an important one in the production and handling of fresh concrete for the sustainability of the building industry12 used a homogenous approach integrated into the finite element numerical method to model the flow of the self-compacting concrete considering the Lagrangian integration point (LIP). The material behavior types under time and space motion were observed in this model considering non-linear and time-dependent properties. Also, the interfaces for the material based on the Bingham behavior were monitored. The rheology characteristics of three different concrete materials from experiments were used to compare the results of the LIP-FEM model outcomes. The properties observed and reported in that work were the yield stress, the slump flow spread and the L-box flow of the studied self-compacting concrete. The results show strong agreement between laboratory and model values. It can be observed further that the shear strain rate behavior of the modeled material was not reported as to reveal the viscosity changes of the Bingham material. Hoornahad and Koenders13 investigated the grain-paste-grain interaction response in a fresh self-compacting concrete mix slump flow by using the discrete element method (DEM). The explicit description of the interaction of the materials in the mix as a 2-phase paste bridge-system in a mutual interaction influenced by the mix composition with the excess paste theory indulgence was further considered in that research report. The results of the DEM model agreed with the experimental values from the slump flow test. In a following research report, Zhang et al.14 investigated the effect of the irregular shaped coarse aggregates on the rheological characteristics of fresh self-compacting concrete. That research paper reported that the shape of aggregates is polytropic as the shapes are not controlled by any known environmental factor except, they are manufactured, hence the particles of a spherical shape are not however engineering in nature and analysis. Further, the slump and L-box flow configurations were adopted in thatstudy and both experimental and simulated situations were used to compare the results. Also, the Bingham material law was observed to study the behavior of the yield stress and the plastic viscosity of the studied models. Finally, the results of the models and the experiments agreed by an insignificant margin. In that paper, a nearly full investigative study was conducted to study the yield stress, viscosity, passing ability, and workability, however, the filling ability and the resistance to segregation of the modeled concrete material were not covered in that report. Again, the DEM has been applied by Mechtcherine et al.15 to study the theory and applications in the flow of the self-compacting concrete. The focus of that study15 was to show the ability of the DEM interface to model the flow of the concrete. The results showed a strong correlation between model values and standard conditions. In an extended study following the previous work on the theory and application, Mechtcherine et al.16 further studied the fresh concrete simulation by using the DEM. The filling ability, passing ability, and workability considering the geometrical conditions of the mixes were observed in that study. The results of the extended DEM model showed strong agreement with the values of the experimental studies. Li et al.17 also appliedthe DEM to study the flow of the self-compacting concrete by adopting the slump cone and the J-ring configurations. In that report, a lot of micro-level parameters of the DEM concrete model based on particle–particle and particle-geometry interface were measured, which included the coefficient of restitution, coefficient of rolling friction, coefficient of static friction, and the energy of the surface. High-precision glass spheres were used in place of aggregates to overcome the effect of aggregateshape and sizes on the models. The results of the model showed consistent agreement between the initial stage, rapid stage, and slow stage models of the concrete flow and experimental values. Cui et al.18 investigated the influence of coarse aggregate shape on the flowability of the self-compacting concrete by using the constitutive abilities of the DEM. The shape descriptors of needle-shaped coarse aggregates were used to establish the shape of the added material in the model mixes. The flow process through the L-box experimental configuration for the flowing concrete was adopted in this model. The material addition procedure was adopted for continuous incorporation of the aggregate with needle-shapes and the effect on the concrete flow was monitored and recorded. The results of the model showed a consistent correlation with laboratory values and espoused the relevance of aggregate selection during design and infrastructure field operations. Meanwhile, the study reported in that research paper failed to present extensive models based on the flow through other concrete geometries especially the slump and V-funnel so as to study the rheological characteristics of the modeled concrete. In the following research paper by Williams et al.19, the descriptors of the aggregate particle shape have been assessed by a digital image segmentation technique and the DEM has been deployed to model the flow effect considering the particle shape parameters. Once more the effect of the aggregate particle shape on the rheological behavior of the self-compacting concrete has been observed and presented in a DEM model outcome, which agrees with experimental records.Dufour and Pijaudier-Cabot20 studied the modeling of the self-compacting concrete slump flow by making use of the Lagrangian particle-based technique known as the smoothed particle hydrodynamics (SPH). That research was made of with or without the short steel bars technique. The incompressible flow nature of the non-Newtonian concrete materials explained by the Bingham material model was simulated to study the flow of the concrete by using the shear stress to shear strain rate approach and smoothening out the material behavior kink. The aggregates and the steel bars were treated in this model execution as rigid bodies and slender rigid fibers respectively to measure the viscosity of the concrete material through a micromechanical model. The mass conversion incompressibility and the Navier–Stokes were the fundamental equations solved by the SPH interface in this modeling operation. The procedure to securing the solution of this model applied the fractional steps of the prediction-correction technique without pushing the incompressibility state in the runs of the prediction which was satisfied with a divergence free-space. The model results agreed strongly with the allowable slump flow values from literature and standard design requirements and this supported the capability of the SPH to model the rheology and flowability of the self-compacting concrete in the fresh state. However, the yield stress was not studied and reported in that research paper. Deeb et al.21 applied the configuration of the L-box in a 3D SPH modeling of the self-compacting concrete flow in a with or without steel fibers’ structure. The simulation emphasis on the without fibers was on the aggregate sizes’ distribution throughout the flow time and domain while the orientation and distribution of the steel fibers were considered the major focus in the with fibers structure. To validate the model, the results were matched with laboratory results from the blocking ratio experiments. The results of the model were consistent with the laboratory values thereby confirming the capability of the SPH to model the passing ratio as the concrete passing ability through reinforced structural members during handling and placement. The model further presented the best orientation for the cut fibers for a more sustainable passing ability of the studied self-compacting concrete. However, the rheology and the filling ability of the fresh concrete were not studied in the research work, which would have presented more comprehensive data for designers and constructors. Deeb et al.22 went further to apply the configuration of the Slump cone in a 3D SPH modeling of the self-compacting concrete slump flow in a “with or without” steel fibers’ structure. The simulation emphasis on the “without” fibers was on the aggregates larger than or equal to 8 mm sizes’ distribution throughout the flow time and domain while the orientation and distribution of the steel fibers were considered the major focus in the with fibers structure. To validate the model, the results were compared with laboratory results from the slump flow experiments. The results of the model were consistent with the laboratory values thereby confirming again the capability of the SPH to model the slump flow as the concrete workability and dynamic stability through reinforced structural members throughout the handling and placement. The model further presented the best orientation for the cut fibers for a more sustainable resistance to segregation and workability of the studied self-compacting concrete. However, the rheology based on viscosity and yield and the filling and passing abilities of the fresh concrete were not studied in the research work, which would have further presented more comprehensive data for designers and constructors during field application. Alyhya et al.23 applied a 3D SPH technique on the V-funnel configuration in the flow time modeling considering the Bingham-type material model for a non-Newtonian concrete fluid flow. The results of this model agreed favorably with those from the experimental exercise and confirm the capability of the 3D SPH to model the discharge time or the filling ability of self-compacting concrete. Al-Rubaye et al.24 also applied the 3D Lagrangian particle-based modeling technique on the L-box configuration to optimize the passing ability of the self-compacting concrete of the Bingham-type behavior, which was coupled with the momentum and the equations of continuity to predict the flow. The focus of the model execution was on the profile of the free surface, flow times, and the “bigger than or equal to 8 mm” aggregates distribution throughout the flow. The experimental results of the actual tests conducted in the laboratory were compared with the model responses in the results were consistent with the allowable values and the model methodology was confirmed suitable to model the passing ability and the aggregate distribution during the concrete handling and placement. Dhaheer et al.25 reported the flow behavior modeling in a J-ring concrete configuration using the mesh-free smoothed particle hydrodynamics. The model was simulated from the time the ring was removed to the time the flow stopped. The continuity and the Lagrangian momentum expressions were incorporated in this simulation of the concrete flow through the gaps between the reinforcements also considering aggregate distribution throughout the flow. The results revealed that the simulated passing ability of the mixes conforms to allowable values for the self-compacting concrete and confirms the ability of the SPH methodology to model the passing ability and homogeneity of aggregates during concrete handling. Badry et al.26 presented the yield stress and flow behavior through a Slump cone configuration for a self-compacting concrete by using the SPH modeling tool. The simulation was executed for between lifting the cone and stopping of the flow spread. The model work in that research work was focused on observing the ability to forecast the yield stress of the concrete from measured flow times; T-500 and T-stop considering a known plastic viscosity value and also the uniform spread of the 8 mm and larger aggregates at the end of the flow. Results of the model show that the yield stress at the measured times and the aggregate distribution at the end of the flow were consistent with measured values from the laboratory and this confirms also the capability of the SPH to model the slump flow and aggregate distribution throughout the flow situation in self-compacting concrete. Lashkarbolouk et al.27 investigated the self-compacting concrete flow simulation through the L-box configuration to study the passing ability of the mix for a non-Newtonian Bingham behavior considering a linear shear to strain rate ratio embodied with the material’s yield stress and plastic viscosity. The results showed values consistent with available literature and laboratory results. It further posited that the allowable viscosity to be considered for self-compacting concrete works lies between 50 and 270 Pa s. These results again confirm the capability of the SPH to model flow and rheologysituations of the fresh self-compacting concrete. Lashkarbolouk et al.28 has again applied the V-funnel self-compacting concrete configuration in the modeling of the flow and the rheological behavior of the concrete based on the 2D SPH technique. A homogenous Bingham fluid flow consistency was considered in this time of discharge model exercise. Yield stresses and viscosities were predefined in this model based on the requirements of the EFNARC standard for the self-compacting concrete. The filling ability SPH model through the V-funnel values compared well with the standard values and this result showed the SPH capability to model the flowability of the self-compacting concrete for a sustainable concrete placement and handling operation. However, this was executed based on predetermined rheological values of the fresh concrete flow condition. Further, reinforced concrete structures are mainly the reason for the development of the self-compacting concrete for ease of passing through the blocking effects of the bar under different orientations and that research would have been stronger with the incorporation of the passing ability model through the L-box. Wu et al.29 have investigated the capabilities of the enhanced Lagrangian particle-based SPH (eSPH) in the modeling of the flow by using the L-box and slump flow configurations of the self-compacting concrete considering surface deformation, convergence, and fragmentation problems. The results of the 2D eSPH showed great matching results with values from available literature and standard requirements. It further showed satisfactory convergence behavior with the material model execution. However, the viscosity and the filling ability behavior of the studied concrete were not observed or reported in that research paper. Furthermore, Tran-Duc et al.30 investigated the effect of coarse aggregate on the flowrate of the self-compacting concrete by using the 2-phase smoothed particle hydrodynamics (SPH) technique considering four different coarse aggregate sizes between 8 and 20 mm with a common density of 2800 kg/m3. The coarse aggregates were varied to about 0.3 by vol% fraction of the mix. It was reported in that research paper that coarse aggregate alters the homogeneity and rheology response of the self-compacting concrete in its fresh state. The results reported that the increased coarse aggregate up to 24 wt% increased the yield stress and viscosity and this outcome affects the overall flow behavior of the self-compacting concrete due to its mixes’ resistance to flow due to increased viscosity with increased coarse proportion. The model further showed that upon the addition of bigger coarse aggregates greater than 20 mm, the effective yield stress reduced exponentially confirming the average influence of the bigger averaged contact space in the concrete mixes. This outcome seems to be at variance with the available data. Generally, the summary of the studied numerical techniques yet applied in the self-compacting concrete modeling has been presented in Table Kulasegaram et al.31 studied the application of the Herschel–Bulkley model (H–BM) and the modified Bingham model (MBM) in the evaluation of the rheological characteristics of a fresh rubberized self-compacting concrete at a fixed water-to-binder ratio of 0.35 and total binder density of 520 kg/m3. Meanwhile, 30 wt% of fly ash belonging to class F was included by wt% of the total binder in the mixes used for the model exercise with a rubber percentage of 5–25 wt% as the added component. A rheometer of the ICAR specification was used to monitor the rheological properties related to the workability of the self-compacting concrete mixes. The results showed that the increase in the rubber produced a shear thickening, higher exponent (ή) of the H–BM, and higher coefficients (c/μ) of the MBM. However, the flowability potentials of the self-compacting concrete mixes were not modeled to determine their passing and filling abilities, which is prominent in the working of the flowing concrete structures. In yet another study, Güneyisi et al.32 utilized nano silica (NS) and fly ash (FA) as high-range water reducers (HRWR) and viscosity modifiers in the production of the self-compacting concrete and once again further applied the Herschel–Bulkley model (H–BM) and the modified Bingham model (MBM) to model the rheological behavior of the concrete produced at a fixed water-to-binder ratio of 0.33 and density of 570 kg/m3. FA was used up to 75 wt% by wt% of the total binder to replace the ordinary cement in this exercise. The experimental configurations utilized in the protocol were the slump flow spread, slump flow time at 50 mm, V-funnel flow time, and the L-box blocking ratio. These apparatuses measured the workability, yield stress, passing and filling abilities, and segregation resistance. The shear rate from this model was observed with the increase in the values of the exponents and the coefficients of the H–BM and MBM respectively. The models and the experimental values were compared afterwards and the results agreed within an acceptable margin as the increase in the FA and NS improved the rheology of the studied concrete in line with design requirements. Feys et al.33 applied a time-independent approach to model the fresh behavior of the self-compacting concrete by using the Herschel–Bulkley model (H–BM) and the Bingham model (BM), modified Bingham model (MBM). Whereas the BM produced negative yield stresses and the H–BM suffered mathematical restrictions in terms of the models’ execution, the MBM showed superior performance in modeling the rheological properties of the studied concrete with appropriate indices to define the concrete model shear thickening in terms of the shear rate coefficients (c/μ). In that work, the MBM has proven to be more accurate and appropriate in handling the rheology and flow of the self-compacting concrete considering the conditions and assumptions of the present research work.Güneyisi et al.34 investigated the application of the LBM in the simulation of the slump flow of self-compacting concrete using the slump cone configuration for five different groups of fresh concrete mixes. The rheological characteristics in that research work were optimized with the Herschel–Bulkley (H–B) and the Bingham material models. The fitting approaches of the linear and nonlinear derivation of equations and the rheometer measurements were applied in the determination of the microparameters of the fresh concrete and their optimization. The H–B model showed its superior accuracy in the rheological behavior estimation and optimization of the concrete. The results further revealed a higher degree of errors in the Bingham model than in the Herschel–Bulkley (H–B) model. Also, the influence of the rheological response on the concrete flow time, velocity, shear strain rate, flow rate, and concrete placement contour appearance was revealed in the models. However, the study did not observe the viscosity changes as a non-Newtonian fluid model of the Bingham type at different rates of shear strain. This further would have given a clearer understanding of the micro-behavior of the strain stresses during the flow model of the self-compacting concrete under gravitational flow and plastic deformation along the flow path. A multiple relaxation time optimized LBM has been applied by Qui and Han35 in the flow of self-compacting concrete based on the 3D format and the model of discrete velocity and a constitutive mode of the H–B was adopted in the model execution as the modifier. The slump flow and the L-box passing configurations were used in the study and the modeled numerical values were matched with the values from the available literature. The model proved its capability to forecast the flow behavior of the self-compacting concrete as it compared well with the measured experimental values from the literature. Once more the rheological characteristics of the studied concrete of this model operation have been avoided in the report. Mu et al.36 investigated the flow of the self-compacting concrete through a U-box configuration by using the LBM combined with the H–B model framework. The yield stress, power law index, and consistency index were studied with the combined LBM–H–B model framework. The simulation results though with a 7% average error showed high accuracy. The LBM–H–B model further reported that the yield stress was the determinant factor towards the efficient flow and passing ability of the studied self-compacting concrete and that its increase resulted in the weaker passing ability in the concrete flow regime. The results also reported that the indices of the power law and the consistency did not present any significant effect on the studied concrete passing ability and that the total increase in the values of yield stress, power law index, and consistency index reduced the shear velocity in a shear-thickening consistency. Meanwhile, Kabagire et al.37 adequately applied the Krieger–Dougherty (KD) and Chateau–Ovarlez–Trung (COT) models in evaluating the plastic viscosity and the static yield stress of the self-compacting concrete mixes at water-to-powder (w/p) ratios of 0.30 and 0.35. Also, the rheological characteristics’ responses to the incorporation of the solid fractions and particle configurations were observed during the experimental phase. The results showed the adequacy of the KD and the COT models in predicting the concrete rheology for effective placement during the pumping and concreting of concrete structures. In an attempt to present more efficient model versions of the Krieger–Dougherty (KD) and Chateau–Ovarlez–Trung (COT) models, Kabagire et al.38 presented the modified Krieger–Dougherty (MKD) and modified Chateau–Ovarlez–Trung (MCOT) models in the predictions of the flow and rheological characteristics of the self-compacting concrete considering the incorporation of manufactured sand, volume of paste (VP), volume of sand (VS), paste-to-sand ratio (VP:VS), w/b ratio and the content and type of coarse aggregates. The results showed that the MKD and the MCOT showed the most satisfying outcome in the prediction of the rheology of the fresh concrete, which further reported that the VP:VS and the w/b influence the model’s performance more than the other parameters incorporated into the exercise. Huang et al.39 investigated the shear thickening behavior of the self-compacting concrete made from high volume superplasticizer (SP) and air-entraining agent (AEA) by using the modified Bingham model (MBM). The results showed that at intensified shear thickening of the modeled concrete, the yield stress and the plastic viscosity significantly decreased, which resulted in the increase in the wt% of the SP while at increased AEA, the YS increased with a decrease in PV whereas high air content weakened the shear thickening, which reduced to zero leading to shear thinning behavior of the model at the air proportion reached up to 8.7%. This model showed that air-entraining is an effective means of improving the performance of the rheological characteristics of the self-compacting concrete and of course a sustaining concrete placement. Meanwhile, the passing and filling abilities of the concrete were not modeled in the MBM protocol. In a more comprehensive model exercise to study the behavior of the shear rate of the self-compacting concrete, Campos and Maciel40 applied the Bingham model (BM), modified Bingham model (MBM), and the Herschel–Bulkley model (H–BM) considering water-to-cement mass ratios of 0.40 and 0.65 under the influence of the shear rates of 50/s and 100/s and single- and multiple-staged distinct shearing techniques. Further on, experimental data were used to fit the model values. The results showed that models and test methodology exert effects on the evaluation of the rheological parameters of the self-compacting concrete. Meanwhile, the H–BM showed superior performance in the prediction of the rheology of the studied concrete. It further reports that more reliable and applicable results were achieved with the multiple-staged distinct shearing method at the shear rate of 100/s. Rehman et al.41 equally conducted another comprehensive model exercise using the Bingham model (BM), modified Bingham model (MBM) and the Herschel–Bulkley model (H–BM), and the Casson model (CM) to predict the yield stress and the plastic viscosity of the self-compacting concrete under different shear rates of 300, 200 and 100/s. Graphene was incorporated in the wt% of 0.03, 0.05 and 0.10 wt% of cement in the concrete mixes. Also, the flow curves trend was observed under the influence of SP. While graphene increase increased the YS and the PV, the effect of the SP was different. The YS increased and the PV decreased with an increase in the shear rates on the concrete model. Finally, the H–BM, which produced the lowest computation error outclassed the BM, MBM, and CM thereby proving to be the best framework to predict the rheological behavior and flow trend of the self-compacting concrete mixed with graphene and SP and subjected to shear rates between 300 and 100/s. Once more the passing and filling ability of the model concrete mixes were not studied in this exercise leaving much to be done to evaluate the flowability potential of the concrete. In an effort to pursue the net-zero protocol of the UNSDGs and COP27 for the year 2050 towards carbon neutrality in engineering design and infrastructural development, Taleb et al.42 investigated the effect of natural pozzolana (NP) as a partial replacement for Portland cement in self-compacting concrete mixes. This procedure was modeled with MBM and H–BM techniques considering a slump test configuration to study the YS and PV of the mixes. Both models (MBM and H–BM) showed a satisfactory shear thinning behavior of the mixes with natural pozzolana (NP) addition to the mix. But in terms of the rheological properties, the MBM seemed to perform better this time. It further reported that at 30 wt% replacement of cement with NP, the YS and PV values showed acceptable ranges required by standard design conditions and further reduced carbon emission by 40%. Meanwhile, the flowability characters were not considered in the model execution leaving yet another vacuum for further research studies to evaluate the flowability indices of the natural pozzolana-based self-compacting concrete. The YS and PV have been evaluated in another work by Petersson et al.43 by using the basic Bingham model considering different fillers, viscosity enhancers, and superplasticizers. The slump flow and the L-box configurations were adopted in that work to model the rheological behavior and the passing ability and workability. With the strong agreement between the model values and the experimental values, the model has shown to be appropriate in predicting the rheological behavior of the self-compacting concrete with different fillers, VMA, HRWR, etc. incorporated. Furthermore, Zhaidarbek et al.44 conducted a complex model transition from the Khatib-Khayat model (KKM) to the H–BM and MBM in the evaluation of the flow rate to pressure drop relationship in self-compacting concrete pumping considering the oiling layer and the shear thickening characteristics of the studied fresh concrete. In this process, a new method was developed to determine the flow rate-to-pressure drop relationship based on the Hagen–Poiseuille flow incompressible concrete fluid state conditions. The shear rate and velocity distributions based on the H–BM and MBM were observed to graphically produce the volumetric flow rate-loss of pressure behaviors. The results showed an innovative approach of hybridization of the Khatib–Khayat model (KKM) into the H–BM and MBM for a more appropriate and efficient prediction of the flow rate of the self-compacting concrete during design and concrete placement. However, the filling and passing abilities as well as the yield stress and viscosity of the studied concrete were not put into consideration in that research report. Also, the response of the concrete behavior with respect to the addition of different fillers, VMA, HRWR, etc. was not considered. Further on, an entirely new approach known as the volume of fluid model (VFM) was used by Shin et al.45 to predict the flow behavior and the yield stress of the self-compacting concrete based on the single-fluid simulation, which accommodated the partial instability or consolidation of the coarse aggregates in the modeled mixes. The L-box configuration was adopted in this model for passing ability flow simulation. In the end, the results were used to update the rheograph, which was used to study the rheological characteristics of the self-compacting concrete for the purposes of efficient design and sustainable construction. Hosseinpoor et al.46 sufficiently applied the computational fluid dynamics (CFD) based on the Dam Break Theory (DBT) in a seemingly different analytical approach to model and simulate the flow profile for a self-compacting concrete using a modified L-box configuration set-up. The influence of gravity on the flow conditions of this flowing concrete model set-up into the horizontal section was observed by filing the vertical section of the modified L-box set-up at 50 and 110 cm heights with concrete mixes of low-to-high segregation resistance levels. Also, three stop times of 1, 5, and 15 min were used to evaluate the effect of the static segregation on the flow conditions of the modeled self-compacting concrete. The studied concrete was assumed to have linear and nonlinear flow characteristics, which were described by adopting the rheological models of Bingham (linear) and Herschel–Bulkley (nonlinear) considering the relationship coefficients and exponents, respectively. The results of the analytical models based on the DBT showed accurate predictions which agreed with the values of the modified L-box experimental results. It was further reported that the Herschel–Bulkley (nonlinear) model led to better analytical predictions than the linear Bingham model. However, the yield stress and the shear rate conditions were not determined in that work. Furthermore, on the analytical models’ application in the prediction of the flowability characteristics of the self-compacting concrete, Onyelowe et al.47 and48, respectively applied the L-box and V-funnel concrete experimental set-up configurations in the forecast of the blocking ratio and the flow time of the studied concrete. These models were responsible for the modeling of the passing ability and the filling ability respectively of the studied concrete by making use of Bernoulli’s and the flow continuity theories (BT and CT). The geometry of the two configurations was basic in these analytical models. For the L-box blocking ratio model reported by Onyelowe et al.47, embedded steel bars were considered under shear stress and pressure conditions of the self-compacting concrete. Sixty seconds (60 s) elapse-time was used before opening the shutter between the vertical and horizontal compartments of the L-box and the sum of the forces between the upstream and downstream was evaluated under the continuity theory (CT). The vertical stress with respect to the friction stress between the concrete particles and the walls was determined and incorporated into the flow mechanism of the analytical model. The yield stress distribution on the flow path was graphically presented and the passing which fell within an acceptable range according to the standard requirements provided by EFNARC was obtained. With this flow output, the L-box model according to the BT and CT proved to be appropriate in the prediction of the passing ability of the self-compacting concrete for industry use and application in infrastructure designs. For the V-funnel flow time (filling ability) model reported by Onyelowe et al.48, The BT and CT were applied on the V-funnel with an outlet duct of 75 × 65 mm and effective dimension of 515 × 600 mm according to EFNARC standard. The principle of flow convergence was merged in the V-funnel flow model continuity behavior. The time taken for the studied self-compacting concrete to flow through an elemental height dh of the funnel configuration was considered for the weight of the concrete, the downward acceleration due to gravity, and the upward friction force which accounted for the dynamic viscosity of the mix. The model results showed acceptable flow time limits between 5 and 25 s agreeable with the requirements of the EFNARC. Again, the BT and CT showed their coupled capability to predict the filling ability conditions of the self-compacting concrete through the V-funnel set-up. A similar method of model called the new rheological model cell method (NRM-CM) has been applied by Mahmoodzadeh and Chidiac49 to predict the yield stress and the plastic viscosity of self-compacting concrete. Benaicha et al.50, developed a v-funnel innovative device applied to quantify the rheological behaviors of the self-compacting concrete (SCC), which are basically yield stress and plastic viscosity, which determines the micro-behavior of the SCC flow. Tests were conducted to model/caliberate the system using the provisions of EFNARC and the recommendations of AFGC. Comparative results from this study show that the SCC characterization can successfully be carried out using the method from this research case and its empirical suggestions. Benaicha51 also applied empirical correlation method based on abacus to develop concrete flow characterization techniques for the self-compacting concrete plastic viscosity and yield stress independent of field operators influences on site. In this case, the v-funnel, l-box and slump cone models were successfully correlated with empirical results based on EFNARC guidlines. Table 57. However the research study investigated the workability, strength, water absorption, freeze–thaw resistance and permeable voids of the concrete and did not delve deep into the concrete rheological behavior. Finally, the summary of the constitutive analytical modeling of the rheological states of the self-compacting concrete is presented in Table Li et al.The slump cone, V-funnel, and L-box have been prominently used in the estimation of the self-compacting concrete rheological behavior over the other apparatuses due to their relationship with flow shearing.The coarse aggregates were found to increase the yield stress and viscosity when used with sizes greater than 20 mm, which reduces the flow efficiency of the fresh concrete.The analytical modeling techniques were found to exhibit limitations in the computation of yield stress, viscosity, and the flow properties of concrete due to the inability to handle complex concrete state conditions.However, the numerical modeling techniques perform optimally in coupled mathematical computations like the LBM–H–B and SPH model framework for the fresh concrete (SCC) rheology, which showed the highest accuracy so far.It is recommended that Orimet flow model be studied by applying novel numerical and analytical methods as a supplimmentary method to the V-funnel, L-box and the slump cone techniques.A critical review of rheological models in self-compacting concrete for sustainable structures has been conducted, which has extensively presented the application of the analytical and numerical techniques previously applied in modeling the yield stress, plastic viscosity, and flow characteristics of the studied concrete. Several techniques were presented with superior outputs. In this research also, the effect of the aggregate proportioning, particle friction, viscosity modifying agent (VMA), superplasticizers, and water-cement ratio on the concrete rheology and flow was also explored.Furthermore, the flows through the slump cone, L-box, V-funnel, Orimet, J-ring, and U-tube apparatuses with respect to the yield stress and viscosity of the fresh self-compacting concrete were reviewed in connection to numerical and analytical models. The following are the conclusions from the critical review of the rheological models.Future research works in this area should be directed at studying the application different hybrids of the smoothed particle hydrodynamics, which has presented a potential to adapt other techniques in its computational framework in solving this concrete structural problem.


MET amplification as a resistance driver in a ROS1-rearranged lung adenocarcinoma after sequential treatment with ROS1 inhibitors. Subsequent combination therapy with lorlatinib plus capmatinib, a MET-selective inhibitor, induced intracranial and extracranial tumor response. At relapse, sequencing of the resistant tumor revealed a MET D1246N mutation and loss of MET amplification. We performed integrated molecular analyses of serial tumor and plasma samples, unveiling dynamic alterations in the ROS1 fusion driver and MET bypass axis at genomic and protein levels and the emergence of polyclonal resistance. This case illustrates the complexity of longitudinal tumor evolution with sequential targeted therapies, highlighting challenges embedded in the current precision oncology paradigm and the importance of developing approaches that prevent resistance.Acquired drug resistance remains a major problem across oncogene-addicted cancers. Elucidation of mechanisms of resistance can inform rational treatment strategies for patients relapsing on targeted therapies while offering insights into tumor evolution. Here, we report acquired  ROS1) gene are potent oncogenic drivers identified across multiple tumor types including in 1–2% of non-small cell lung cancer (NSCLC)2. ROS1 rearrangements result in the expression of the ROS1 fusion oncoprotein, constitutive ROS1 kinase activity, and aberrant downstream signaling activation, ultimately leading to dysregulated tumor survival and proliferation3. Patients with metastatic ROS1-rearranged lung cancers typically derive substantial benefit from ROS1-targeted tyrosine kinase inhibitors (TKIs) such as crizotinib and entrectinib, often with marked initial tumor responses5. However, the durability of response is inevitably limited in most patients due to acquired drug resistance. Prior studies have elucidated mechanisms of on-target resistance mediated by a spectrum of ROS1 kinase domain mutations 9, motivating the clinical development of next-generation ROS1 inhibitors13. In contrast, insights into mechanisms of off-target resistance have remained limited.Chromosomal rearrangements involving the ROS proto-oncogene 1 (MET) gene—which encodes a receptor tyrosine kinase involved in promoting mitosis, motility, and survival14—represents one potentially actionable mechanism of off-target resistance to ROS1 inhibitors that has been identified using ROS1-rearranged cell lines and biopsies from patients relapsing on therapy (including after entrectinib and lorlatinib)16. In EGFR-mutated lung cancers harboring MET amplification-mediated resistance to EGFR TKIs (which occurs in 10–15% of patients relapsing on first-line third-generation EGFR inhibitors)18, various combinations of EGFR and MET TKIs have demonstrated clinical activity and tolerability in phase I/II clinical trials20, attesting to the actionability on this resistance driver. Similarly, combinations with MET inhibitors have induced tumor responses in ALK- and RET-rearranged lung cancers with MET-driven resistance to TKIs targeting the original oncogene drivers22. In ROS1-rearranged disease with MET-mediated resistance, the optimal clinical strategy for co-targeting ROS1 and MET is unknown. One case report described the efficacy of crizotinib monotherapy (a multitargeted ROS1/MET/ALK TKI) in a patient relapsing on entrectinib with MET polysomy23. Crizotinib is a first-generation multikinase inhibitor with limited selectivity, suboptimal coverage of on-target resistance mutations that can emerge on therapy, and poor blood-brain barrier penetrance24, all of which can limit clinical benefit. Therefore, a rationale exists for exploring combination strategies that exploit potent, CNS-penetrant next-generation ROS1 TKIs and selective MET TKIs such as capmatinib or tepotinib.Amplification of the mesenchymal-epithelial transition 31.Of note, across treatment-naïve and -resistant cancers, upregulation of MET signaling occurs through an array of molecular events ranging from protein overexpression to genomic alterations, including amplification, mutations , or chromosomal rearrangementsROS1-rearranged lung cancer overexpressing MET protein at baseline, which then acquired genomic amplification of MET as an off-target mechanism of resistance to ROS1 inhibitors. To our knowledge, this is the first documented case of extracranial and intracranial disease response to a ROS1/MET co-inhibition strategy using lorlatinib plus capmatinib in MET-amplified, ROS1-rearranged NSCLC. The subsequent emergence of an on-target MET resistance mutation and loss of MET amplification highlights the temporal evolution of multi-faceted MET signaling axis activation and complex overall molecular landscape longitudinally as tumor cells acquire resistance to sequential targeted therapies.Here, we report a case of SLC34A2-ROS1 gene rearrangement and CDKN2A H83Y and TP53 V173fs mutations detected on NGS , PMS2 E518K (VUS), ERCC2 N92S (VUS) (Supplementary Table A 34-year-old woman with no smoking history presented with persistent dry cough and was found to have a 2.2 cm FDG-avid left lingular lung nodule on chest computed tomography (CT) and positron emission tomography (PET) imaging without evidence of metastatic disease. A biopsy of the lung nodule demonstrated primary lung adenocarcinoma. She underwent left upper lobe segmentectomy but was noted intraoperatively to have pleural and pericardial nodules. Cytology evaluation demonstrated malignant pleural effusion, and pathologic staging was pT2 pNx pM1a. Genotyping via next-generation sequencing (NGS) and ROS1 fluorescence in situ hybridization (FISH) on the resected lung tumor sample revealed a SLC34A2-ROS1 rearrangement and CDKN2A H83Y and TP53 V173fs mutations  which was confirmed by MET FISH testing with a MET:CEP7 ratio of 6.1  . In contrast, genomic MET amplification (as tested using MET FISH) was absent in all previously biopsied tumors.After an initial response to chemotherapy plus lorlatinib, the patient presented with intracranial and extracranial progressive disease after 5.5 months Fig. , includient Fig. . Howeverent Fig. . Additio6.1 Fig. . Of noteMET amplification, and in view of active disease in the central nervous system (CNS), combination therapy of lorlatinib (dose reduced to 50 mg daily) and capmatinib (400 mg twice daily), an ATP-competitive, potent, and CNS-penetrant type Ib MET TKI28, was pursued. She experienced rapid clinical improvement with palpable shrinkage of left axillary fullness and improvement of fatigue and shortness of breath within 2 weeks. Repeat scans performed 10 weeks after initiation of combination therapy demonstrated partial response per RECIST v1.1 criteria with a 69% reduction in the target tumor lesions  as well as shrinkage of non-target lesions, including the left pleural thickening and chest wall soft tissue disease . Liquid biopsy with Guardant360 cell-free DNA (cfDNA) assay demonstrated a SLC34A2-ROS1 rearrangement [variant allele fraction (VAF) 55.6%] and heterogeneous genomic alterations, including MET D1246N (VAF 7.8%) and TP53 V173fd (VAF 45.7%), as well as BRCA2 loss, EGFR amplification , and FGFR1 amplification  which had not been identified through tissue NGS or EGFR FISH testing  in order to maximize CNS penetration and activity in the context of actively progressing brain metastases. Indeed, the patient experienced both intracranial and extracranial responses to therapy.This report represents, to the best of our knowledge, the first description of a dramatic—albeit brief—clinical and radiographic tumor response to combined selective inhibition of ROS1 and MET using lorlatinib plus capmatinib in the setting of acquired resistance to sequential ROS1 inhibitor therapy (crizotinib followed by lorlatinib) due to ROS1-rearranged cancer confirms MET amplification as the driver of resistance that is, importantly, actionable. Collective evidence continues to buttress MET amplification as a shared genomic mechanism of off-target resistance and biomarker for subsequent rational combination strategy across oncogene-addicted lung cancers22, and underscores the clinical value of re-biopsy and comprehensive molecular profiling in therapy-resistant cancers. In addition, here, the combination of half-dose lorlatinib and full-dose capmatinib was tolerated without grade 2 or higher treatment-related AEs or the requirement for further dose modifications. It is impossible to generalize regarding the efficacy or tolerability of lorlatinib plus capmatinib in patients with MET-amplified, ROS1-rearranged lung cancers on the basis of this single case. However, it will not be pragmatically feasible to perform phase Ib/II clinical trials of discrete combination regimens for each individual therapy-resistant, rare molecular subset of lung cancer  and for each distinct genomic mechanism of resistance. Therefore, creative basket trial designs in parallel with added knowledge from smaller case series and extrapolation from the available data in relatively larger molecular subsets of NSCLC (such as EGFR-mutant disease) will be pivotal to effectively inform clinical practice and advance viable treatment strategies. For instance, the field may benefit from shifting the way basket trials are structured to be centered around mechanisms of resistance rather than each original oncogenic driver.The activity of lorlatinib plus capmatinib in this patient with 37. Indeed, at the time of disease progression on lorlatinib plus capmatinib therapy, a subset of the known metastatic foci of disease were continuing to respond, whereas others had developed resistance—demonstrating clearly discordant inter-metastatic tumor behavior. Furthermore, the serial cfDNA findings were supportive of genotypic polyclonal resistance, with identification in the lorlatinib/capmatinib-resistant sample of new BRCA2 loss, EGFR amplification, and FGFR1 amplification  on top of the known ROS1 rearrangement, TP53 variant, and MET D1246N resistance mutation that had been detected in the contemporaneous liver tumor biopsy. These findings highlight the complementary advantage of liquid biopsy in capturing heterogeneous resistance mechanisms that may exist across distinct metastatic sites within a patient and are missed in single-lession tumor biopsies. In addition, the complex evolution of resistance—as exemplified by (1) the stepwise acquisition of lorlatinib-refractory MET amplification followed then by capmatinib-refractory MET D1246N mutation with loss of MET amplification and (2) the emergence of polyclonal resistance-underscores that therapeutic strategies aimed at delaying or preventing resistance are ultimately more likely to be truly transformative than those aimed at overcoming resistance once it has already developed.The brief duration of benefit from the combination regimen herein is noteworthy and deemed to reflect the emergent tumor heterogeneity across disease sites under the selective pressure of sequential targeted therapies—a prominent recurring clinical problem within the evolving treatment paradigmMET, tumor cells were ROS1-dependent, as evidenced by the initial durable responses to ROS1 inhibitors crizotinib (14 months) and then lorlatinib (30 months). The subsequent MET amplification event likely served to engage MET signaling as a true bypass pathway, driving the resistance to ROS1-targeted therapy and conferring MET dependency. Thus, this case supports that high-level expression of MET alone without concomitant genomic lesions such as amplification is an insufficient oncogene or resistance driver. Moreover, the case illustrates that distinct mechanisms of MET activation are not functionally equivalent, emphasizing the importance of understanding the differences in various diagnostic methods used , to enable accurate interpretation and clinical application of the results.We have additionally uncovered multiple layers of MET axis activation in this case, differentially engaged throughout distinct therapy exposures. MET was overexpressed in the treatment-naïve tumor, and this persisted throughout the patient’s disease course. Despite the protein overexpression of MET, in the absence of additional genomic alterations in ROS1 rearrangement at the time of MET amplification-driven ROS1 TKI resistance. The loss of ROS1 expression in the resistant tumor—while concordant with phenotypic lack of sensitivity to ROS1 TKI—raises important questions about the continued molecular changes involving the original oncogenic driver during targeted therapy. Case reports have detailed the loss of fusion or mutant oncoprotein expression in lineage-transformed TKI-resistant lung cancers, including EGFR-mutant and ROS1-rearranged NSCLC39. Furthermore, studies in cell culture models have demonstrated that reduction of ROS1 protein expression or phosphorylation can also occur in the context of ROS1 TKI resistance and activation of off-target bypass pathways40. The genetic and epigenetic mechanisms mediating the downregulation or loss of the original oncoprotein expression remain to be elucidated.Intriguingly, we found that ROS1 protein expression was ‘lost’ despite retained genomic MET amplification is a bona fide driver of ROS1 TKI resistance in ROS1-rearranged lung cancer and that a combination of CNS-penetrant and selective MET and ROS1 inhibitors can induce intra- and extracranial responses. Our findings from the integrated clinical and molecular analyses leveraging multiple serial tumor and plasma samples highlight both the successes and salient challenges embedded in the current era of precision oncology, including the stepwise acquisition of distinct resistance mechanisms with sequential targeted therapies, dynamic and multi-faceted changes involving the original oncogenic driver and the bypass signaling axis, and the emergence of polyclonal resistance resulting in therapy-refractory tumor. Efforts for comprehensive molecular testing at the time of acquired drug resistance will continue to be clinically relevant and potentially guide subsequent therapy selection. Yet these efforts will need to be complemented by discovery efforts focused on developing avenues for fundamentally altering the natural course of cancer and circumventing the evolution of resistance upfront.In summary, this report confirms that The patient was treated with commercial supplies of lorlatinib plus capmatinib (off-label use) after a detailed discussion of the potential benefits and risks of the therapeutic regimen. The patient provided informed consent for the treatment. The patient signed written informed consent under an institutional review board (IRB)-approved protocol for electronic medical record review to extract relevant clinicopathologic data, including treatment history and outcomes, and for all indicated sample collections and analyses. The radiographic responses to therapy were assessed by an independent radiologist (S.R.D.) according to the RECIST version 1.1 criteria for extracranial disease and modified RECIST version 1.1 criteria for intracranial disease. AEs were graded according to the CTCAE version 5.0.ROS1 rearrangement and EGFR and MET copy number gains were assessed using FISH. Briefly, 5-micron sections of formalin-fixed paraffin-embedded tumor material were prepared, and an H&E section was reviewed to select regions for hybridization that contain a majority of tumor cells. A break-apart probe set targeting the 5′ upstream region of ROS1 (RP11-359J11) and the 3′ downstream region of ROS1 (RP11-1036C2) was hybridized, as previously described41. The number of cells containing break-apart signals or rearrangement was scored out of a total 50-cell count. A ROS1 rearrangement was reported if more than 15% of cells show split signals. For EGFR, we used a dual-color FISH assay using Bacteria Artificial Chromosome probe CTD-211A18 (chromosome 7p EGFR locus) and a copy number control , and for MET, we used a dual-color FISH assay using Bacterial Artificial Chromosome probe CTB-13N12 (chromosome 7q MET locus) and a copy number control . Signal quantitation was used to generate an EGFR or MET to centromere 7 ratio. For example, a ratio of MET:CEP7 of 1.8 to 2.2 is considered borderline for amplification. A ratio between 2.2 to 5.0 is considered low-level amplification. A ratio greater than 5.0 or clustered MET signals that are too numerous to count would be considered highly amplified43. ROS1 and MET IHC were performed with Automated Stainer Leica Bond III  using a ROS1 antibody  and a c-MET antibody , respectively. All procedures were performed in a CLIA-compliant environment.Tumor samples were obtained either by surgical resection, core needle biopsy, or thoracentesis. Formalin-fixed paraffin-embedded specimens derived from tumor samples were reviewed by an MGH pathologist (M.M.K.) to confirm the histopathological diagnosis and to ensure adequate tumor cellularity for analysis. All NGS testing was performed on a clinical basis using extracted DNA and amplicon sequencing with the UPMC Oncomine platform in Pittsburgh, PA. The Dana-Farber/Harvard Cancer Center Institutional Review Board (DFCI #13-416) approved this study.Further information on research design is available in the supp tableReporting Summary


Immunoglobulin G4-related disease (IgG4-RD) is an immunomediated disease that can virtually affect any organ. Despite the pancreas being known as the most frequently involved organ, pulmonary and pleural IgG4-RD is being increasingly reported. The authors present two cases of IgG4-RD diagnosed in the same year, with different presentations and outcomes, in which the lung and pleural involvement were essential for the diagnosis. Recognizing IgG4-RD as a possible cause of chronic pleural effusion and/or thickening and lung abnormalities is important for an early diagnosis and prognosis improvement. Immunoglobulin G4-related disease (IgG4-RD) is a recently recognized condition, with the first report dating two decades ago in Japan in a group of patients with autoimmune pancreatitis in which elevated serum Immunoglobulin G4 (IgG4) levels were identified . A few yCase 1A 78-year-old man presented to the emergency department with a 15-day history of worsening dyspnea, generalized weakness, and anorexia. He had cardiovascular and respiratory symptoms reported for over 10 years, with several admissions to the hospital. One of them was because of constrictive pericarditis, in which he was submitted to a partial pericardiectomy, with a histopathological exam that only revealed lymphoplasmacytic infiltrate, but no immunostaining for IgG4 plasma cells was performed at that time. The other admissions were related to chronic pleural effusion and pleural thickening, and the patient was submitted to multiple thoracocentesis and one pleural biopsy. The bacterial and mycological culturing were negative as well as polymerase chain reaction (PCR) and culturing for mycobacteria. Malignancy was excluded, and histopathological examination showed a polymorphic inflammatory infiltrate. During this period, he had numerous infectious intercurrences, having taken several antibiotics.On admission, the physical examination was remarkable for hypoxemia, decreased breath sounds at the left lung base, and symmetric peripheral edema. Electrocardiogram showed atrial multifocal rhythm. Laboratory blood tests showed C-reactive protein (CRP) of 22.7 mg/L, erythrocyte sedimentation rate (ESR) of 24 mm/h, positive antinuclear antibodies (ANAs) titers 1/1000) in a speckled pattern, consumption of serum complement proteins (C3c and C4), marked elevation of serum levels of total IgG , IgG4 , and IgE . Other autoantibodies tests were normal. A computed tomography (CT) scan of the thorax was performed, revealing stability of the chronic pleural effusion and pleural thickening on the left, with newly identified pleural effusion and pleural thickening on the right as well as the progression of extensive areas of ground-glass appearance on pulmonary parenchyma . An 18F-fluorodeoxyglucose-positron emission tomography (18F-FDG PET) showed increased uptake in some areas of the pulmonary parenchyma and in the pleura, with no uptake in other organs. After a transthoracic pulmonary biopsy, the histopathologic study revealed the presence of a moderate lymphoplasmacytic infiltrate and more than 20 IgG4 positive plasma cells per high power field (HPF) with an IgG4/IgG-positive cell ratio of 40%-45%  of prednisolone. A month later, he was evaluated in an outpatient setting: Chest radiography showed regression of the lung nodules and stable pleural effusion Figure , and bloCase 2A 78-year-old man was admitted to the hospital with a 10-day history of fever and inflammatory signs on the left foot. His past medical history was significant for type 2 diabetes mellitus, chronic arterial hypertension, and chronic renal disease on a current hemodialysis program. He was started on antibiotics for cellulitis, with good clinical improvement and fever resolution but sustained elevation of CRP (400 to 200 mg/L) and ESR (128 mm/h). Other laboratory blood tests were requested, showing normocytic normochromic anemia, positive ANA titers (1/100) in a speckled pattern with negativity for other autoantibodies, normal serum levels of complement proteins, normal serum levels of total IgG, and elevation of IgG4 serum levels . A whole-body CT scan showed two new pleural nodules and densification of the fat adjacent to the infrarenal aorta with a longitudinal extension of 47 mm on a circumferential pattern  of IgG4-RD, encountering patients with lung nodules and pleural effusions is common in clinical practice .The first case reports a 10-year evolution of unilateral pleural effusion and pleural thickening with later progression to both sides, associated with pulmonary nodules that were labeled as idiopathic for several years, underlying the challenge of the diagnosis of IgG4-RD. Although the diagnosis results from the integration of clinical, radiological, serological, and histopathological features, histology is rarely the key to the diagnosis. Comprehensive diagnostic criteria have been published in 2020 with the goal of helping clinicians make an accurate diagnosis, but tissue samples are usually necessary to exclude malignancy . In thisIn the second case, the diagnosis was possible after a transthoracic pleural biopsy. Aortitis and periaortitis are also reported manifestations of IgG4-RD and are associated with significant morbidity. Radiologically, they present as an arterial wall or periarterial tissue thickening in a circumferential or anterolateral pattern. Abdominal aorta periaortitis is the most commonly encountered manifestation. However, obtaining tissue samples, given the location, can be challenging .IgG4-RD usually responds well to treatment with glucocorticoids. Treatment is recommended in most patients, even when asymptomatic, as it is documented to induce remission and slow progression to fibrosis and organ dysfunction. A delay in treatment can cause irreversible sequelae . A good Raising awareness for IgG4-related lung and pleural disease is of major importance. It is an important differential diagnosis in patients with lung parenchyma abnormalities, pleural effusion, and/or thickening, particularly when there are elevated serum IgG4 levels. It can occur in isolation or in conjunction with other organ manifestations, but transthoracic pulmonary or pleural biopsy is the safest and easiest way to obtain tissue samples, and it is frequently available, enabling the exclusion of other diseases and the definite diagnosis. Given the risk of progressing to permanent fibrosis, it is crucial to provide timely treatment for these patients to improve overall survival.


Antimicrobial resistance is an ever-emerging global public health issue. In the healthcare setting, it is essential to use antimicrobials appropriately and manage infections effectively to help tackle antimicrobial resistance.To review local antibiotic resistance data, update the plastic surgery infection guidelines based on this data, implement interventions to facilitate compliance with the guidelines and re-audit to assess if these interventions have been effective.A review was undertaken of the previous 3 months of antibiotic susceptibility results for significant staphylococci and streptococci species isolated from blood cultures and wound swabs, and the microbiology results of all local cases of necrotizing fasciitis over a 5-year period. The plastic surgery infection guidelines were updated to reflect the changes in local antibiotic resistance rates. Following implementation of the new guideline, various interventions were undertaken including provision of departmental teaching sessions, ensuring availability of appropriate antibiotics in the burns and plastics theatres and redesigning the guideline to include all plastic surgery and infection guidelines within the one document (previously multiple specific guidelines). Between each intervention, compliance with the guideline was measured to establish if the intervention had made a difference.Changes to the guideline included using clindamycin rather than doxycycline for the treatment of cellulitis in penicillin allergic patients, as 44% of Group A Streptococcus isolates identified in wound swabs were resistant to doxycycline. Other changes included the introduction of linezolid if the patient had received a recent or failed course of clindamycin, and the use of cefazolin rather than clindamycin for patients with severe cellulitis with a penicillin allergy, due to the increase in rates of clindamycin resistance. After the three intervention cycles, prescriber compliance with the guideline increased from 50% to 71% demonstrating the need for ongoing intervention and re-evaluation.Co-amoxiclav and clindamycin were the most commonly prescribed antibiotics in those patients whose antibiotic prescriptions did not comply with the guidelines. The main reason for this is historical usage of these antibiotics within the specialty; this project demonstrates the challenges in changing established practices in individual clinicians. Interventions to ‘make it easy’ for prescribers to follow antibiotic guidelines , along with targeted education, can be effective but long-standing prescribing habits within specialist areas may be difficult to change.