In this study, the usability of pumice powder and lime in concrete production as a binding additive for rigid superstructure concrete road pavement was investigated. Following the determination of the optimum binder ratio, these new binder ratios were used in crushed limestone concrete production. The concrete thus formed was named concrete containing cement, pumice powder and lime (PPCC). The normally produced concrete, without pumice powder and lime binder was selected as reference concrete (RC). Regarding the total binder amount of the most appropriate binder ratio 50% was found to be cement, 30% pumice powder and 20% lime in the result of the study. In consequence of the study, the 20 ± 2 °C and 7–28 days compressive strengths of the reference concrete were found to be 33.8 MPa and 38.2 MPa and its bending strengths were 4.2 MPa and 4.7 MPa. The 20 ± 2 °C and 7–28 days compressive strengths of PPCC were found to be 25.1 MPa and 28.3 MPa and its bending strengths were 3.2 MPa and 3.5 MPa. The results of the study showed the usability of PPCC in concrete pavement. Pumice 3 . Especiavailable ,7. As thvailable . Pumice vailable . Small cvailable . Pumice When processing pumice extracted from quarries, a significant amount of pumice sand is produced. Waste materials should be evaluated for their possible uses. Pumice is a pyroclastic rock type . Pumice 6 within a 20-year period and airports with more than 5000 departures of large passenger airplanes yearly, are constructed as rigid pavements. In the specifications for the proportioning of concrete pavement, a few of the criteria considered are maximum w/c ratio being 0.40–0.45, minimum compressive strength being 280 kg/cm2 and minimum amount of cement being 270–335 kg/m3 [Considering the increasing number of commercial vehicles in the world with each passing day, the use of concrete pavements as road superstructures is expected to become widespread in the future . Overall35 kg/m3 . In buil35 kg/m3 . MateriaThe use of these materials dates back to ancient times. The most commonly used binders are oily lime, cement and gypsum. Before cement was found in the 19th century, soil and limestone mixtures, different limes and gypsums, baked clay and other binders  were used as binding materials . The matSince the compressive strength of pumice, which has a significant amount of pores in macro and micro dimensions is very low, its areas of usage in the construction sector have remained limited and it has mainly been used in wall and plaster construction aimed at insulation, in filter material production in water treatment units, in grinding and polishing jobs in the textile industry, in torching material production in match factories and in similar sectors. Pumice aggregate is finitely used for insulation purposes in concrete production sector, but it cannot be used as building concrete in the carrier parts of the structure since the compressive strength of the aggregate is very low. This study was prepared with the aim of providing the widespread use of concrete elements that will be formed with pumice powder in the construction sector. It is possible to use other materials with a binding property such as pozzolanic rock powders in certain ratios together with cement in order to reduce the cost in concrete production . In thei3 in production. In this study, cement, crushed stone (gravel-sand) and water containing normal concrete production, which are generally used in construction sector, were prepared for the purpose of comparison and the samples to be formed were selected as reference concrete.In this study, pumice powder and lime were found to have a significant binding effect on concrete when mixed with cement. In this study, a new type of concrete production was developed by using pumice powder (PP) and lime (L) together with cement. The compressive and bending strengths of the concrete samples produced in this way were found to be high and the concrete production cost was reduced by reducing the amount of cement per mIn this study, the usability of pumice powder and lime in concrete production as a binding additive for concrete road pavement was investigated. Pumice powder with dimensions of 0–0.04 mm was used in the study. Seventy-two types of concrete samples were formed in different mixing ratios, with pumice powder. The optimum ratios of pumice powder and lime as the binding additive were determined in consequence of all the experiments. Following the determination of the optimum binder ratio, these new binder ratios were used in crushed limestone concrete production. Compressive and bending strength tests of the new concrete produced were performed. The concrete thus formed was named concrete containing cement, pumice powder and lime (PPCC). The concrete produced without pumice powder and lime binder, only with cement binder was selected as reference concrete (RC). RC and PPCC concrete were cured with standard water curing of 7 and 28 days. Following water curing, compressive and bending strength tests were performed on all concrete samples. The results of the study showed the usability of PPCC in concrete pavement.CEM I 42.5 R type cement, which complies with TS EN 197-1 EN 197-1:2011) (2012) standard, was used in all experiments [11 (2012)The cement appearance is given in Potable Bitlis city water was used in the experiments. Pumice powder is shown in 3 (Miner Mining Transportation Trade Limited Company) [Pumice powder grain diameter was between 0–0.04 mm. Specific gravity of slacked lime was 2.2 g/cmCompany)  and compCompany) . The limThe chemical properties of pumice and lime are shown in 2 + Al2O3 + Fe2O3 total should at least have the ratio of 70% [2 + Al2O3 + Fe2O3 was 86.5% in total. This ratio indicates that pumice powder can be used as binder. For comparison purposes, physical and mechanical properties of pumice, cement, and lime are shown in The pumice powder used as cement additive must comply with TS 25 (TS 25/T1) (2008) Trass Standard. It was indicated in the TS 25 (TS 25/T1) (2008) Trass Standard prepared by TSE (Turkish Standardization Institute) that the SiOOne of the highest cost items in concrete production is the amount of cement used in production. In this study, the compressive strengths of samples formed by using pumice powder (PP) and lime (L) together with cement (C) were calculated in order to reduce the amount of cement. Seventy-two different mixture types were formed for the determination of the optimum binder ratio. With all the mixtures formed to determine the appropriate binder ratio, the water/binder ratio was considered as 0.60. Consistency and workability were not influenced by the substitution. Three samples from each type of mixture were taken, and the average of these three values was calculated. The prepared mixtures are shown in Type-1 mixing ratios are shown in Six different types of mixture were formed by taking 0%, 20%, 40%, 60%, 80% and 100% of the cement amount.As shown in As shown in Type-2 mixing ratios are shown in Six different types of mixture were formed by taking 0%, 20%, 40%, 60%, 80% and 100% of the pumice powder amount as lime amount.As shown in Type-3 mixing ratios are shown in Six different types of mixture were formed by taking 0%, 20%, 40%, 60%, 80% and 100% of the cement amount as lime amount.Type-4 mixtures included cement, pumice powder, lime and water. The mixing ratio of each type was different. Nine different types of mixtures were produced from Type-4 mixtures.Type 4-1 mixing ratios are shown in In the mixture ratio with the highest compressive strength, six different types of mixture were formed by considering the amount of lime as 0%, 20%, 40%, 60%, 80% and 100% of the cement amount.Type-4-2 mixing ratios are shown in In the mixture ratio with the highest compressive strength, six different types of mixture were formed by considering the amount of lime as 0%, 20%, 40%, 60%, 80% and 100% of the pumice powder amount.Type-4-3 mixing ratios are shown in In the mixture ratio with the highest compressive strength, six different types of mixture were formed by considering the amount of lime as 0%, 20%, 40%, 60%, 80% and 100% of the (cement + pumice powder) amount.Type-4-4 mixing ratios are shown in In the mixture ratio with the highest compressive strength, six different types of mixture were formed by considering the amount of cement as 0%, 20%, 40%, 60%, 80% and 100% of the pumice powder amount.Type-4-5 mixing ratios are given in In the mixture ratio with the highest compressive strength, six different types of mixture were formed by considering the amount of cement as 0%, 20%, 40%, 60%, 80% and 100% of the lime amount.Type-4-6 mixing ratios are presented in In the mixture ratio with the highest compressive strength, six different types of mixture were formed by considering the amount of cement as 0%, 20%, 40%, 60%, 80% and 100% of the (pumice powder + lime) amount.Type-4-7 mixing ratios are given in In the mixture ratio with the highest compressive strength, six different types of mixture were formed by considering the amount of pumice powder as 0%, 20%, 40%, 60%, 80% and 100% of the cement amount.Type-4-8 mixing ratios are shown in In the mixture ratio with the highest compressive strength, six different types of mixture were formed by considering the amount of pumice powder as 0%, 20%, 40%, 60%, 80% and 100% of the lime amount.Type-4-9 mixing ratios are shown in In the mixture ratio with the highest compressive strength, six different types of mixture were formed by considering the amount of pumice powder as 0%, 20%, 40%, 60%, 80% and 100% of the (cement + lime) amount.Samples prepared for optimum binder fixation were prepared for 7-day compressive strength determination and each mixture was prepared as three pieces in total, with dimensions of 150 × 150 × 150 mm. Samples were cured for 7 days at 20 ± 2 °C by standard water curing. Samples taken into the curing pool are shown in In reference concrete production, CEM I 42.5 R type cement, which complied with TS EN 197-1 (EN 197-1:2011) standards, crushed limestone as aggregate and Bitlis city water qualifying as drinking water for concrete mixing water were used. Reference concrete class was taken as C30/37. In the study, reference concrete samples were prepared for 7 and 28 days of daily compressive strength determination, in dimensions of 150 × 150 × 150 mm. being three each and six in total. Three samples were cured with a 20 ± 2 °C standard water curing of 7 days, and the other three samples were cured with a 20 ± 2 °C standard water curing of 28 days. The curing pool is shown in Six pieces of samples with dimensions of 100 × 100 × 400 mm were prepared for bending strength. three samples were treated with a 20 ± 2 °C standard water curing of 7 days, and the other three samples were treated with a 20 ± 2 °C standard water curing of 28 days. The curing pool is shown in In the production of PPCC, CEM I 42.5 R type cement, 0–0.04 mm pumice powder and lime were used as binders in accordance with TS EN 197-1 standards (EN 197-1:2011). Potable Bitlis city water was used as aggregate for crushed limestone and concrete mixed water. C30/37 concrete class was considered in PPCC concrete production. Three samples from each type of mixture were taken, and the average of these three values was calculated. The material mixing ratios obtained at the optimum binder ratio are shown in The water/binder ratio of the concrete (PPCC) prepared in the ratio of reference concrete (RC) and optimum binder were taken as 0.42 as shown in The recommended slump value for pavement concrete is 3 cm according to 3 and the approximate water amount according to the w/c ratio as 189 kg/m3. The mix design target strength for 0.42 w/c ratio was found to be 380 kg/cm2 (38 MPa) [For 3 cm slump, the Water/Cement (W/C) value of which is 0.42, the cement amount was considered as 450 kg/m(38 MPa) . Table 1(38 MPa) ,30.In accordance with The amount of aggregate required for sieve analysis is given in Reference concrete (RC) and optimum binder concrete (PPCC) sieve analysis were performed according to the TS EN 933-1 (2012) (EN 933-1:2012) standard . As statSamples prepared for compressive strength tests are shown in The appearance of the samples in the compressive strength tester is shown in The results are presented for the 7-day period Type-1 mixture quantity, unit volume weight (BHA) and compressive strength test results are shown in Pumice powder was taken as 0%, 20%, 40%, 60%, 80% and 100% of the cement amount. The mixture 1-1 was the reference mortar of the binder paste. Only cement was used as binder in the reference mortar. According to the reference mortar, the mixture with the highest strength was the 1-2 mixture and its compressive strength was found to be 17.3 MPa.Type-2 mixture quantity, unit volume weight and compressive strength test results are shown in As can be seen in Type-3 mixture quantity, unit volume weight and compressive strength test results are shown in As shown in Compressive strength tests of the nine different types of mixture obtained from Type-4 mixtures were performed and the strengths of binder pastes were calculated.Type-4-1 mixture quantity, weight per unit of volume and compressive strength test results are shown in Accordingly, in the mixing ratio with the highest compressive strength, the amount of lime were taken as 0%, 20%, 40%, 60%, 80% and 100% of the cement amount. As shown in Type-4-2 mixture quantity, weight per unit of volume and compression test results are shown in In the mixing ratio, the compressive strength of which was found to be the highest, the amounts of lime were taken as 0%, 20%, 40%, 60%, 80% and 100% of the pumice powder amount. As shown in Type-4-3 mixture quantity, weight per unit of volume and compression test results are shown in In the mixing ratio with the highest compressive strength, the amounts of lime were taken as 0%, 20%, 40%, 60%, 80% and 100% of the (cement + pumice powder) amount, respectively. As shown in Type-4-4 mixture quantity, weight per unit of volume and compression test results are shown in In the mixing ratio, the compressive strength of which was found to be the highest, the amounts of cement were taken as 0%, 20%, 40%, 60%, 80% and 100% of the pumice powder amount. As shown in Type-4-5 mixture quantity, weight per unit of volume and compression test results are shown in In the mixing ratio, the compressive strength of which was found to be the highest, the amounts of cement were taken as 0%, 20%, 40%, 60%, 80% and 100% of the lime amount. As seen in Type-4-6 mixture quantity, weight per unit of volume and compression test results are shown in In the mixing ratio, the compressive strength of which was found to be the highest, the amounts of cement were taken as 0%, 20%, 40%, 60%, 80% and 100% of the (pumice powder + lime) amount. As seen in Type-4-7 mixture quantity, weight per unit of volume and compression test results are shown in In the mixing ratio, the compressive strength of which was found to be the highest, the amounts of pumice powder were taken as 0%, 20%, 40%, 60%, 80% and 100% of the cement amount. As shown in Type-4-8 mixture quantity, weight per unit of volume and compression test results are shown in In the mixing ratio, the compressive strength of which was found to be the highest, the amounts of pumice powder were taken as 0%, 20%, 40%, 60%, 80% and 100% of the lime amount. As shown in Type-4-9 mixture quantity, weight per unit of volume and compression test results are shown in In the mixing ratio, the compressive strength of which was found to be the highest, the amounts of pumice powder were taken as 0%, 20%, 40%, 60%, 80% and 100% of the (cement + lime) amount. As shown in As can be seen in The compressive strength test results of all mixture types are shown in As shown in Reference concrete (RC) and optimum binder concrete (PPCC) sieve analysis is shown in The reference concrete (RC) and optimum binder concrete (PPCC) sieve analysis graph is shown in As shown in The average compressive strength test results of reference concrete (RC) and optimum binder concrete (PPCC) are shown in The average bending strength test results of reference concrete (RC) and optimum binder concrete (PPCC) are shown in As a result of the study, regarding the total binder amount of the most appropriate binder ratio, 50% was found to be cement, 30% pumice powder and 20% lime;In consequence of the study, the 20 ± 2 °C and 7–28 days average compressive strengths of reference concrete were found to be 33.8 MPa and 38.2 MPa, and the average bending strengths 4.2 MPa and 4.7 MPa;The 20 ± 2 °C and 7–28 days daily average compressive strengths of the concrete formed by optimum binding ratio were found to be 25.1 MPa and 28.3 MPa and the average bending strengths 3.2 MPa and 3.5 MPa. The results of the study showed the usability of PPCC in rigid pavement;Subsequent studies may conduct fatigue and impact tests on the samples produced in this work.Pumice powder is a waste material that contributes to environmental pollution and waste landfills. The presence of pores in coarse pumice gives the extremely low compressive and bending strengths, and therefore, such materials cannot be used as aggregates in concrete production. On this basis, coarse pumice has limited applicability in the construction sector. In this study, the usability of pumice powder and lime in concrete production as a binding additive for concrete road pavement was investigated. A total of 72 types of concrete samples were composed with different mixing ratios, which were formed with cement, pumice powder and lime mixtures. The most appropriate ratios of cement, pumice powder and lime as the binding additive were determined in consequence of all the experiments. Following the determination of the optimum binder ratio, these new binder ratios were used in crushed limestone concrete production. Compressive and bending strength tests of the new concrete produced were performed. The concrete thus formed was named concrete containing cement, pumice powder and lime (PPCC). The normally produced concrete, without pumice powder and lime binder was selected as reference concrete (RC). The reference concrete and PPCC concrete were cured with standard water curing of 7 and 28 days. The following results were obtained in the study:


Concrete creep has become one of the major problems that threatens concrete structural development and construction. However, a reasonable and accurate calculation model for numerical analysis is the key to control and solve the creep deformation of concrete. To better describe the concrete nonlinear creep damage evolution rule, the visco-elasticity Plasticity Rheological Theory, Riemann Liouville Theory and Combined Model Theory are quoted, and the Able dashpot is used to reconstruct fractional-order soft-body composite elements to propose the expression of the stress-strain relationship of the elastomer, visco-elasticity plasticity body, and Viscoplasticity body, considering the evolution of the concrete compression damage process. A nonlinear creep damage constitutive model of concrete, based on fractional calculus theory, is conducted, and the parameters of the specific calculation method of the model are given. The influence of stress level σ, fractional order n and material parameter α on the concrete creep process is determined by a sensitivity analysis of the model parameters. The creep process and deformation amount of concrete in practical engineering can be effectively controlled by the results of the proposed sensitivity analysis. The research results can be used to provide guidance and reference for the safe construction of concrete engineering in actual practice. Concrete creep refers to the phenomenon in which concrete deformation increases with time under long-term external load . Creep dCreep strain has a linear relationship with applied stress in the case of low stress levels (less than 30% compressive strength). However, creep presents an unstable phenomenon as time and stress increase in the case of high stress levels (between 30% and 80% compressive strength); that is, it presents a nonlinear relationship, which is found in concrete creep theories and experimental research ,5,6,7. AThe nonlinear creep process of reinforced concrete columns was simulated considering the high stress conditions by Bažant and Tsubaki . A simplSome strain in creep is related to the corresponding instantaneous stress state, and also to the previous stress state, which is illustrated by a large number of concrete creep phenomena. The fractional derivative, based on time parameters, is an arbitrary order time differential operator, which can fully reflect the course of the function change over time ,23. FracTo better describe the concrete nonlinear creep damage evolution rule, Fractional Calculus Theory and Rheological Model Theory have been quoted to propose a non-linear creep damage constitutive model of concrete using Able dashpot to replace Newton dashpot and the concrete damage evolution rule. The rationality and applicability of the conducted constitutive work was verified. Finally, the calculation method and sensitivity analysis of the conducted model parameters provide a reference for safe construction and the long-term stable operation of concrete engineering.t > 0, Re(n) > 0.There are many fractional order calculus definitions, among which the creep characteristics of concrete are defined and described by Riemann Liouville theory ,30. Thisn (n > 0) is the fractional order, n, and d is a differential operator. The ideal solid stress-strain relationship follows Hooke’s law.The Riemann Liouville fractional order differential form is defined as.The ideal fluid stress-strain relationship follows Newton’s viscous law.Ideal solids and ideal fluids are idealized models, which can only be used for approximate calculations in practical engineering. Concrete is a material between an ideal solid and an ideal fluid, and a software element  can be uThe constitutive equation based on the fractional derivative  is estabIn current research, the basic rheological mechanics models include elastomers, the viscoelastic body, the visco-elasticity plasticity body, the viscous body and the viscoplastic body. The rheological properties of materials can be described by the combination of strings and parallelism among them. The combined model has been widely used in the creep simulation research of asphalt, rock, polymer materials, concrete, and other materials because of its visualization and intuition capabilities ,34,35.The typical concrete compression and creep process consists of three stages: deceleration creep, steady creep, and accelerated creep. In the current study, the elastic-visco-elasticity plasticity-viscoplastic creep model  is used to describe the instantaneous and isovelocity creep of concrete. However, when concrete reaches the yield limit, the creep curve will exhibit accelerated unsteady characteristics. At this time, the MSSB model cannot describe the nonlinear creep characteristics of concrete, and it can only be studied by nonlinear theory. In this paper, the creep constitutive Equation based on the fractional derivative is constructed by using the Able dashpot, instead of the Newton dashpot in the MSSB model to accurately describe the three stages of deceleration creep, steady creep and accelerated creep. The constitutive model combination is shown in The small damage produced is neglected during the deceleration creep and steady creep stages, and only the damage caused by the accelerated creep stage is considered in the concrete indoor creep test.The concrete damage evolution in the accelerated creep process is consistent with the change in the exponential function.To derive the constitutive equation, the main hypothesis conditions are given.Stress-strain relationship of elastomer.Stress-strain relationship of visco-elasticity plasticity body.The visco-elasticity plasticity body is represented in parallel with the elastomer element, the Able dashpot and the friction element. The stress on the friction element is expressed by Based on the above constitutive models and assumptions, the stress-strain relationship between elastomers, the visco-elasticity plasticity body, and the viscoplastic body are derived as follows.The total stress on the visco-elasticity plasticity body can be obtained from the combined model theory.When Equation (11) can also be expressed as follows.Laplace transformation of Equation (12).Laplace inverse transformation of Equation (13).(3) Stress-strain relationship of viscoplastic body. The viscoplastic body is expressed in parallel with the friction element by the Able dashpot. The stress When According to the theory of fractional calculus ,36, the During the creep test process, especially in the accelerated creep stage, the creep rate of the concrete specimens increases continuously until failure, which is caused by the expansion of internal damage and crack development in the concrete. Therefore, the viscosity coefficient is no longer a fixed value, but rather is a variable that decreases with the increase in the degree of damage. The damage variable is a negative exponential function  that conCombining the above three parts, the strain and nonlinear creep damage constitutive model of concrete, based on fractional calculus theory, is obtained asThe parameter t is the creep time t, where When the creep curve has an unloading curve, the three parameters nloading . The exp, and A nonlinear regression analysis method  can be uThe parameters 3. The experimental curves are shown in Uniaxial compressive nonlinear non-linear creep and residual strain tests of normal concrete with deep storage nuclear waste were carried out by Narintsoa Ranaivomanana, et al. . The speAs shown in et al.’s  experimeNarintsoa Ranaivomanana et al.’s  experimeCompressive nonlinear creep and residual strain tests on C40 concrete specimens under different stresses were carried out by Can Tang et al. . The conUnder stress of 16.9 MPa and 25.7 MPa, the instantaneous creep occurred first and then the isometric creep, and the creep was velocity first increased and then decreased, as shown in Can Tang et al.’s  test curσ, n, and α are the main factors affecting the concrete creep in the concrete creep damage constitutive model; these parameters are obtained by analyzing the experimental data curve and the theoretical curve. Therefore, the sensitivity analysis of the model parameters will be carried out by the control variable method in this section to study the influence of the above model parameters on concrete creep. The model parameters are as follows: Parameters Parameters The concrete creep deformation is greatly affected by the stress level, and the creep deformation will be increased as the stress level increases. However, stress has no obvious effect on the creep velocity. The higher the stress level, the greater the instantaneous deformation in the elastic stage, and the shorter the time required to enter steady state creep at a constant velocity. In addition, the form of the concrete creep curves is gradually changed to the exponential type as the stress level increased. When the stress level exceeds a certain level, a sudden change will occur. At this point, micro-cracks will occur, eventually causing macro-crack penetration failure. This is consistent with Narintsoa Ranaivomanana et al.’s test  of how hIn order to analyze the sensitivity of the fractional order, the control variable method is used to ensure that other parameters remain unchanged. The fractional order is gradually increased from 0.1 to 0.6, and a series of creep curves with different orders are obtained, as shown in From α, as shown in α increases, the sooner the accelerated creep phase begins, and the greater the creep velocity will be. The power index is the main factor that influences creep velocity. The larger the power exponential value, the more prone the concrete will be to accelerated creep.Considering the change in the damage variable in a viscoplastic body, the control variable method is used to obtain the creep curves under different α, by changing the value of The classical rheological model and the Fractional order theory are introduced to inform the concrete nonlinear creep damage constitutive model after the results of the above research. The conducted constitutive model is a viscoelastic-plastic model. It is assumed that the damage in the deceleration creep stage and in the stable creep stage is neglected, and only the damage in the accelerated creep stage is considered. Also, the accelerated creep rate conforms with changes in the exponential function charge in the indoor concrete creep tests. In practice, the above two assumptions may not be agreed with each other. Therefore, the concrete fractional nonlinear creep damage constitutive model derived from this assumption differs from the actual situation. However, the concrete specimen damage data contributes little to the constitutive equation in either the initial stage or the stable creep stage in the actual uniaxial compression creep tests. The constructed concrete creep damage model is more able to meet the needs of actual working conditions and tests that consider accelerated creep stage damage as the main research object. In addition, the constructed concrete creep damage model parameters have specific physical significance in this paper, and the entire concrete creep process in practical engineering can be reflected and described by the proposed model, which has certain engineering practical and reference values.To better describe the concrete non-linear creep damage evolution rule, and better solve the concrete creep in concrete engineering, Fractional Calculus Theory is introduced to inform a concrete nonlinear creep damage constitutive model. The conducted constitutive model is verified and analyzed for sensitivity by means of the concrete creep test. The following conclusions may be drawn:The Visco-elasticity Plasticity Rheological Theory, the Riemann Liouville Theory and the Combined Model Theory are quoted to propose the stress-strain relationship expressions of the elastomer body, the visco-elasticity plasticity body, and the viscoplastic body. The nonlinear creep damage evolution equation of the concrete fractional order is conducted with consideration of damage evolution, and the parameter specific calculation method in the constructed model is given.The constructed concrete creep damage constitutive model in this paper is validated in high stress and different stress situations that involve uniaxial compression creep; data from the residual strain tests of Narintsoa Ranaivomanana et al.  and Can σ, material parameter α, and fractional order n, are analyzed. The results show that σ and n are positively correlated with the concrete creep deformation and rate. The creep deformation and rate will increase as σ and n increase. α is related to the time at which the concrete enters the accelerated creep stage, and the larger the value of material parameter α, the earlier the concrete will enter the accelerated creep stage.To determine the influence degree of the model parameters, the sensitivity analysis of the main influence parameters in the concrete creep damage constitutive model, including


This paper presents the results of the behavior of end zone of post-tensioned (PT) beams made of fiber reinforced concrete (FRC). The principal aim of using FRC was to enhance the ductility and post-cracking behavior of end-zone of post-tensioned beams. A stronger and tougher end-zone of PT-beams is necessary when it is subjected to dynamic loading. Post-tensioned (PT) beams are typically used for the construction of bridges and industrial buildings, which are often subjected to vibrations and cyclic loading. Pre-mature cracking of the end zone (EZ) of a PT-beam is considered the type of problem that may cause the structural collapse. In this research program, polyvinyl alcohol (PVA) and copper-coated steel (CCS) fibers were used in concrete for improving the EZ performance of PT-beams. The use of FRC caused a 50% reduction in the shear reinforcement within the end zone of the PT-beam, which also avoided the congestion of steel in the end zone. Hence, the concrete was placed homogeneously, and smooth finished surfaces of the beams were obtained. FRC controlled the bursting of the end zone during the transfer of the full pre-stress force, and approximately 25% increment in the strain energy of the end zone was observed, which was also found efficient in strain diminution along the length of the beam. For the past several years, the advances made in the field of prestressed-concrete have widened the freedom of architectural setting of floor-framing in a building structure. Architectural freedom allows achieving high loading capacity with the adoption of longer-span and smaller cross-section dimensions. Post-tensioning technique of prestressing is the most commonly adopted method by the industry due to many advantages. The post-tensioned bar in a concrete member constitutes concentrated force applied under compression mode to the concrete cross-section. It has been experienced that the application of high magnitude focused force to the immature concrete section is always a big challenge. In the early development stage from the 1950s to 1980s, many infrastructures made of pre-stressed girders suffered pre-mature failures. For example, Stone & Breen  and duriIn many cases, to avoid such types of failure; heavy shear reinforcement is usually introduced within the end anchorage zone to stop the crack propagation. It is observed that the cracks form a passage within the concrete that allows aggressive agents present in the vicinity of the structure to ingress in the concrete that can cause corrosion to the embedded steel reinforcement . Once ruBreen et al.  have claThere are several factors responsible for the unusual behavior of anchorage zone; the most dominating factors are section dimension, eccentricity, loading area, external influence, reinforcement, anchorage device, inclination, and the number of tendons and properties of concrete. Cracks develop along with the longitudinal edge to form a link between inside reinforcement and the ambient environmental conditions. The mode of longitudinal edge tensile stresses are changed to compressive stress at a farther distance from the end , but thiIn earlier studies, high strength concrete (HSC) was introduced in dealing with the issues and challenges faced regarding the performance of end anchorage zone of post-tensioned beams, the aim of using HSC was to resist the high compression stresses. Whereas, additional shear reinforcement was added to the conventional shear reinforcement to withstand the tensile stresses AASHTO, 2002). Addition of low elastic modulus fiber reinforced polymer tendon reduces losses and increases prestressing level . Some re02. AdditThe principal aim of this research study was to investigate the performance of the end zone (EZ) of PT-beams made of FRC; two type of fibers; copper-coated micro steel (CCS) and PVA fibers were used. The concrete mixes were developed using 100% cement as well as 80% cement + 20% fly ash. The first phase of the research program focused on investigating the effects of fiber content on the workability and mechanical properties of concrete, whereas the second phase of the research was to evaluate the contribution of PVA and CCS fibers in resolving performance concerns of the end-zone of PT beams. The results discussed in this experimental investigation are significant for improving the performance of the anchorage end zone of post-tensioned concrete beams, which usually face challenges of avoiding the premature cracks and failure. Therefore, the enhancement of the performance of the anchorage end zone by increasing the ductility of concrete using PVA or CCS fibers results in avoiding cracks at the early stage of the beam, which can improve the durability of the beam because of the resistance of ingress of the aggressive agent. Ordinary Portland cement (OPC) type-1 and fly ash (FA) Class-F conforming to ASTM C150 and ASTM C618-15 respectively were used in this study. Well-graded coarse aggregates (4.75 mm to 20 mm) and river sand were acquired from a local query in Perak, Malaysia. Superplasticizer Sika Viscocrete 2044 was used to improve the workability of fresh concrete. Two types of fibers, PVA fibers 18 mm length and 200 μm diameter (aspect ratio 90) and CCS fibers of 20 mm length and 200 μm diameter (aspect ratio 100), were bought from off the shelf. A total of six different mixes was prepared; three mixes were made of 100% OPC, and the other three were made of 20% FA + 80% OPC. 100% OPC mix with no fiber is called the control mix (CM), and the mix with 20%FA without fiber is called the control mix (CF). All samples were cast and cured according to requirements of ASTM C192/C192M-16a. 100 mm size cubes were made for compressive strength test and 100 mm diameter and 300 mm high cylinders were made for split tensile and elastic modulus tests, whereas 100 mm × 100 mm size and 500 mm long prism were cast for the flexural strength test. Dimensions of PT-Beams were designed as 130 mm wide, 250 mm high, and 2000 mm long. Ducts for insertion of PT-Tendon was placed in the formwork before concreting for beam; two unbonded tendons comprising of seven wire strands passing through black anti-UV treated HDPE were used. Tendon nominal diameter was selected as 15.3 mm, and tensile strength was 1860 MPa, which complied with the requirements of EN 10138 and BS 5896. For improving the bursting and spalling stresses, one tendon was inserted at the center, and the other was placed at an eccentricity of 80 mm. Both tendons were coupled with a bearing plate and spiral reinforcement at the end. Eight shear links were placed within the anchorage block of normal concrete (CM & CF) beams while FRC beams contained only four shear links (50% reduction). Four strain gauges were installed within the end region for monitoring the performance of the anchorage zone for measuring the variation in the magnitude of the prestressing force. Two strain gauges were glued on the stirrups, and the other two were attached to the concrete surface at the distance of 160 mm and 250 mm from the end of the beam. A total number of six beams were cast; three of them were made of fly ash concrete, and the other three were cast using 100% OPC concrete. When prestressing was applied, fly ash concrete beams suffered cracks before reaching the pre-decided value of the prestressing force of 200 kN. The reason could be the low early strength of fly ash concrete. The pozzolanic effects of fly ash appear after 28 days. It was obtained that at the early age fly ash concrete beams resist lower initial force than the 100% OPC concrete. Therefore, the fly ash based beams were prestressed until the hairline cracks appeared on the surface, Cube compressive strength test was done at the age of 3, 7, 28, and 56 days; the test was performed according to BS EN 12390-3:2009. Split-tensile, flexure, and elastic modulus tests were conducted at the age of 28 days only. Post-tensioning of beams was done at the 7th-day of concrete casting, using prestressing bed available in the concrete technology laboratory, Universiti Teknologi PETRONAS. The details are illustrated in Experimental test results of compressive strength of all concrete mix are given in A total of six beams were cast, at the age of seven days. A post-tensioning operation was performed for each of the beams using the pre-stressing bed located in the concrete laboratory at UTP. This is schematically drawn in Consequently, the fly ash concrete beam without fiber, PSCFY-2 was stressed until the hairline cracks appeared at the surface. The beam was stressed until 125 kN force, which was 37.5% lower than the designed pre-stress force. The fly ash concrete beam PSCFyPVA-0.3 containing 0.3% PVA fibers and 50% end zone reinforcement content was also stressed until hairline cracks appeared. It sustained 150 kN PT force, which indicates that the addition of PVA fiber enhanced the capacity of prestressing force by 20%. The other three beams were made of 100% OPC; one control beam and one beam each containing PVA and CCS fibers. All three beams were stressed until the full design pre-stress force (200 kN); in such beams, no hairline cracks appeared until the entire design load transferred. From the observations made on six beams during the transfer of prestressing force and the related discussion, it can be generalized that concrete beams containing fly ash can sustain 67% to 75% of the design post-tensioned force as compared to 100% cement concrete beams. Thomas  discusseStructural Response of End-Anchorage Zone at applied load (service condition).Structural response of anchorage end can be described as the variation in strain in the embedded steel stirrups and surface concrete. The following section discusses the anchorage end zone response of six beams made of fly ash and 100% cement concrete.Overall, it is observed that the addition of fly ash as a partial substitute of cement enhances tensile stresses in the end region that become a cause of cracks. RDP reduced the peak tensile value but increased the area under the influence of tensile stresses. Reduction in the amount of end zone reinforcement encourages bearing compression stresses, tensile bursting stresses, and transmission length. Addition of PVA fibers managed the effects of modification of end zone reinforcement. In contrast, the anchorage zone of CCS FRC trapped in the compression stresses and expanded the stress distribution area far beyond the anchorage zone. Anchorage zone behavior of post-tension beams can be linked with the elastic modulus of the specimen. Strain energy shows the energy needed for failure or to bring some strain. It is estimated as the area under the curve. Usually, high energy dissipated material is required in critical structures to resist the high impact and dynamic load. Therefore, fiber is used to increase the ductility and energy absorption capacity of concrete . The strForm the results and discussion on the experimental investigation and the analysis performed, the following conclusion can be drawn: Both types of fibers (0.3% by the volume fraction of PVA and CCS) in the fiber reinforced concrete used in the study have enhanced the ductility and mechanical properties of concrete. PVA fibers caused much higher effects on the elastic modulus of concrete, particularly in 100% OPC concrete, while PVA fibers significantly increased the elastic modulus to 47 GPa. Pozzolanic reactivity of fly ash usually starts after 28 days of curing. Since PT transfer was made at the age of 7 days, at that age fly ash was found unreacted in concrete. Therefore, the design prestressing force for fly ash concrete beams was reduced to about 38%.From the analysis of the end zone strain of all PT beams, it is observed that the inclusion of fly ash increased the tensile stresses, which caused cracks to appear. Therefore, decreasing the design prestress level reduced the induction of tensile stresses, but it raised the tensile stress distribution area. Reduction in the end zone reinforcement caused an increase in compression stresses, tensile stresses, and stress distribution area. PVA FRC beams managed to withstand the high intensity of stresses and restrained the drastic changes to occur in the end zone behavior. On the other hand, copper coated micro steel FRC even did not handle well the compression stresses and allowed to exceed beyond the local zone.PVA and copper coated steel fibers in FRC resulted in the reduction of the end zone reinforcement and avoided the congestion that caused a smooth transmission of prestressing force. This research can be extended by involving the loading area, the eccentricity of the tendon, and percentage of the end zone reinforcement as a variable and generate a guideline for the FRC PT-beam on both experimental and analytical levels.


The effect of the anchoring group on the detailed polymerization kinetics was investigated using monomethacryloxy-heptaisobutyl POSS (1M-POSS). This compound was copolymerized with lauryl methacrylate (LM) as the base monomer, at various molar ratios. The process was initiated photochemically. The polymerization kinetics were followed by photo-DSC and photorheology while the polymers were characterized by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). For comparison, a methacrylate containing the branched siloxy-silane group (TSM) was also studied. It was found that the modifiers with a bulky substituent have a dual effect on the termination process: (i) At low concentrations, they increase the molecular mobility by increasing the free volume fraction, which leads to an acceleration of the termination and slows the polymerization; while (ii) at higher concentrations, they retard molecular motions due to the “anchor effect” that suppresses the termination, leading to acceleration of the polymerization. The anchor effect can also be considered from a different point of view: The possibility of anchoring a monomer with a long substituent (LM) around the POSS cage, which can further enhance propagation. These conclusions were derived based on kinetic results, determination of polymerization rate coefficients, and copolymer analysis. This results in the POSS molecule having a unique shape: the inorganic core is surrounded by an organic outer layer. The size of the POSS cage is ~1.5 nm propyl methacrylate (TSM) . This prTSM (purity 98%) and LM (purity 96%) were delivered by Sigma-Aldrich; they were purified by column chromatography  before use and were stored over molecular sieves. The photoinitiator, 2,2-dimethoxy-2-phenylacetophenone, was also supplied by Sigma-Aldrich and was used in conc. 1 wt %.1H, 13C, 29Si NMR spectra were recorded on Bruker Avance 300 MHz and 400 MHz  in CDCl3.1M-POSS pentacyclo- octasiloxane) was prepared in a two-step procedure, i.e., condensation of 1,3,5,7,9,11,14-heptaisobutyltricyclo  heptasiloxane-endo-3,7,14-triol with trichlorosilane, resulting in 1-hydro-3,5,7,9,11,13,15-hepta(isobutyl)pentacyclo  octasiloxane and its subsequent hydrosilylation with allyl methylacrylate using a Karstedt catalyst . All sol1H NMR : 0.59–62 , 0.95 , 1.73–1.79 , 1.81–1.89 , 1.95 , 4.11 , 5.55, 6.11 .13C NMR : 8.88 (SiCH2), 18.79 (CH2CH2), 22.98 (CH2CH(CH3)2), 24.33 (CH2CH(CH3)2), 26.16 (CH2CH(CH3)2), 67.07 (CH2O), 125.63 (=CH2), 137.01 (=CCH3), 167.94 (C=O). 29Si NMR : −67.70, −68.56, −68.85 (SiO3).The viscosity of the photocurable systems was measured with a DV-II+ PRO Brookfield Digital Viscometer  at the polymerization temperature.gT, was measured with a Mettler Toledo DSC1 instrument  under a nitrogen atmosphere at a heating rate of 20 °C/min in the temperature range from −80 °C to 180 °C. The gT value was determined from the second run of the DSC measurement and was taken as an average value from three measurements. The reproducibility of the results was about ±4%.Glass transition temperature, 1H and 13C NMR spectra were performed on Bruker Ultra Shield 400 and 300 spectrometers  using toluene-d8 and CDCl3 as solvents. Chemical shifts are reported in ppm with reference to the residual solvents’  peaks for 1H and 13C NMR.2). The polymerization was initiated by the UV light  from the LED lamp . All photopolymerization experiments were conducted at least in triplicate. The reproducibility of the kinetic results was about ±3%. For computations, the heat of the polymerization of the methacrylate group, 56 kJ·mol−1, was taken [Reaction rate profiles were monitored by DSC using a Pyris 6 instrument  equipped with a lid especially designed for photochemical measurements. The 15 mg samples were polymerized in open aluminum pans (diameter 6.6 mm) under isothermal conditions (40 °C) in high-purity argon atmosphere (<0.0005% of Oas taken .pk) and bimolecular termination rate coefficient (tbk) in the expression for the polymerization rate (Equation (1)) [M] is the double bond concentration, ϕ denotes the quantum yield of initiation, and aI is intensity of the light absorbed, and were obtained from postpolymerization processes (non-steady-state measurements), which were registered after stopping the irradiation at various degrees of the double bond conversion. The calculations were performed over the first 10 s of the dark reaction. The rate coefficients were determined according to the bimolecular termination model t and [M]0 are the concentrations of double bonds after the time, t, of the dark reaction and at the moment of breaking the irradiation. Equation (2) allows the determination of the tb/kpk ratio. Using Equation (2) (non-stationary conditions) and Equation (3) (from steady-state measurements):F = aϕ·I, we can determine the polymerization rate coefficients in the form of p × Fk and tb × Fk. It was assumed that F is constant in the range of the conversions studied. A detailed procedure of the calculations was described in [The experimental data for the calculations of the polymerization rate coefficients: Propagation rate coefficient (ion (1)) :(1)Rp=kpon model :(2)[M]t projected via a waveguide into the sample through the bottom quartz window. During the measurements, the change in the normal force along with the storage modulus, G’, and loss modulus, G”, were recorded. The measurement for each sample was run for 2400 s.Real-time photorheology experiments were performed on an Anton Paar MCR 301 rheometer  using parallel plate geometry of a quartz plate and metallic plate  with a diameter of 25 mm and a gap thickness of 0.2 mm. The measurements were carried out at 40 °C (in the heating chamber); the rheometer operated at a frequency of 10 Hz (oscillatory mode). Polymerization was initiated 30 s after starting the measurement by switching on the UV light  and polydispersity index (PDI) values were calculated based on the calibration curve using polystyrene standards (Shodex) in a range of 1000–3,500,000, using Agilent Software GPC/SEC – 1260 GPC set.GPC analyses were performed using Agilent 1260 Infinity system  equipped with RI detector and Phenogel 10 μm Linear(2) 300 × 7.8 mm column. THF was used as a mobile phase in a flow rate of 1.0 mL·minTEM images were recorded on a JEM-1400 microscope made by JEOL . The accelerating voltage was 120 kV. A small amount of the samples was applied on a copper grid .The photopolymerization kinetics of the LM/1M-POSS and LM/TSM systems were followed at 40 °C in a wide range of the comonomer ratios. The kinetics were investigated both in general terms (kinetic curves) as well as by determination of the polymerization rate coefficients. Due to the fact that the effects of two different monomers with bulky substituents were compared, the concentrations of the formulation components were set in mole percent. 1M-POSS showed a limited solubility with LM (up to 12 mol %), whereas TSM was soluble in every ratio; therefore, the range of the investigated (base monomer)/modifier compositions was determined by the limits of miscibility. The composition of the investigated formulations (given in mol % and wt %) is given tb~η−1k). Thus, it is necessary to consider its changes when the ratio of the comonomers is changed.The initial viscosity of a polymerizable composition  is the important factor influencing the termination rate coefficient  is given in ƞ40 = 2.7 mPa·s, TSM: ƞ40 = 2.49 mPa·s). This proves changes in viscosity due to changes in the monomer ratio will practically not affect the polymerization.On the other hand, the viscosity of the LM/TSM system is low and changes very slightly (LM: 1H and 13C NMR spectra of the monomers and (co)polymers containing 8 mol % of 1M-POSS or 50 mol % of TSM are shown in 1H NMR stacked spectra disclose the correlations between the 1H NMR spectra of LM, 1M-POSS, and their copolymer (2- (polymer chain) at 1.63 ppm (wide resonance line) and 1.35 ppm, along with the changes in the region between 4.10–4.00 ppm that is assigned to the -OCH2- groups deriving from the copolymer and monomers. The surrounding -OCH2- chemical is slightly changed in the fragments derived from LM and 1M-POSS. This region is the most susceptible to changes and they are obviously more noticeable with the rising 1M-POSS content in the copolymer. In the case of the TSM-containing copolymer, there is a resemblance in the matter of the -OCH2- moiety and new signals arising from the -CH2- fragments.In opolymer a and LM,opolymer b. The re13C NMR spectra confirm the appearance of new resonance lines at ca. 177.3 ppm that can be attributed to the carbonyl moiety (C=O) in the newly formed copolymer and this region is shifted towards higher values of ppm when compared to the LM monomer and 1M-POSS (166.7 ppm)  (The 6.7 ppm) a. In add(TSM 50) b.2- moiety, i.e., the presence of new peaks at 67.75 and 65.53 ppm from the poly-LM/(TSM 50) copolymer together with residual signals at 67.15 and 65.11 ppm assigned to the LM and TSM monomers.There is a similarity with regard to the new resonance lines at about 177.49 ppm derived from carbonyl groups (C=O), as well as the region corresponding to the -OCH1H NMR spectra of the copolymers reveal the presence of chemical shifts  of the methylene protons at 6.11 and 5.21 ppm derived from the double bonds of the monomers.The From the spectra of the (co)polymers with different modifier contents, the conversions of the monomers were calculated by an evaluation of the integration ratio of methylene protons with the rest of the protons’ contribution before and the after (co)polymerization. The results are given in pR, on the irradiation time, t, and on the degree of the double bond conversion, p, are shown in Polymerization traces of neat LM and LM/1M-POSS mixtures, expressed as the dependence of the polymerization rate, pmaxR, is defined as the highest reaction rate, not the rate at the maximum of the gel effect.The homopolymerization of neat LM (as other methacrylates with a longer ester group) occurs, with a poorly marked gel effect appearing at higher conversions ). Conseqp ~ 0.7 ÷ 0.8  due to the steric effect of the substituents, i.e., the mobility of the segment around the radical center [M is the concentration of radicals, and pk is a constant up to high conversions. Therefore, the corresponding changes in the radical concentrations during the polymerization can be expressed readily by the function p/(1−p) = f(p)R (p/(1−p)R value) as well as the maximum of the effect shift to lower conversions with an increasing modifier concentration, which can result to a high degree from the increase in the viscosity of the formulations.As mentioned above, the gel effect in LM-based formulations is poorly marked. We can observe it better on the plots showing the dependence of the concentration of radicals on the conversion degree. The polymerization rate is expressed by Equation (4):) = f(p) . As coulpR/(1 − p) function); the enhancement is observed above this concentration. An analogous phenomenon, even more pronounced, occurs in the case of the LM/TSM system. The weakening of the gel effect, which in this case is also associated with the decrease in the polymerization rate and decrease in the radical concentration in the steady-state region, occurs for compositions containing up to at least 12 mol %; above this concentration, an enhancement of the gel effect is observed.However, the addition of small amounts of 1M-POSS (<~4 mol %) at first weakens the gel effect , which results in the acceleration of termination and leads to the drop of pmax = f(modifier conc.)R and f = f(modifier conc.)p. The threshold concentration is higher for TSM due to the smaller “anchor group” and lower viscosity. However, it should be remembered that the anchor effect can only be one of the reasons for the increase in the polymerization rate.It has been suggested that introduction of methacryloxypropyl-heptaisobutyl POSS into the polymer chain can increase molecular mobility by increasing the free volume fraction through the bulky substituent and the plasticizing effect exerted by isobutyl groups ,28. We cPOSSr, is below 1 while the reactivity ratio of MMA, MMAr, is above 1. In the case of methacryloxypropyl-heptaisobutyl POSS, the reactivity ratios for POSS and MMA are 0.584 and 1.607, respectively. This means that MMA is preferentially incorporated into the copolymer and the amount of POSS introduced increases as the reaction progresses. The difference in the reactivity of the two comonomers can be explained by the significant difference in their molecular size and in the steric hindrance they exert [AdMAr = 1.25 and MMAr = 0.79 [An additional complicating, but important parameter is the reactivity ratio of the two comonomers. From the data provided by hybrid plastics ,31, in aey exert . Very reey exert . InteresA = 0.79 .However, in the case of LM/1M-POSS and LM/TSM pairs, the situation may be different. Re-inspection of G’ and G”, respectively, as a function of the irradiation time at 40 °C , are a measure of the final conversion [fG’ occurring as the modifiers’ content increases reflect both the effect of changes in the double bond conversions  and to a much greater extent the effect of the increasing amounts of pendant anchor groups .The second technique used to follow the polymerization kinetics was photorheology. The curing of the investigated formulations was monitored, with the rheometer registering the storage and loss modulus, at 40 °C . Becausenversion . For ourfG’ on the modifier concentration is shown in fη*  , corresponds to the maximum polymerization rate (at the inflection point of the curves in max(dG’/dt)  dependence on the 1M-POSS and TSM contents. The plot of the function, (max = f (modifier conc.)dG’/dt) , exactly corresponds to the behavior of the pmaxR values determined by the DSC method  and/or acceleration of the propagation (increase in pk), compared to Equation (1). The discussion presented above suggested the conclusion that the accelerating effect of 1M-POSS and TSM is associated with the anchor effect that inhibits termination. To find out whether our modifiers affect only the termination or also the propagation, the rate coefficients (in the form of p × Fk and tb × Fk) were calculated for the neat monomers (LM and TSM) and for compositions containing 10 mol % of 1M-POSS and 80 mol % of TSM. The compositions were selected to obtain large differences in the polymerization rates with respect to the neat LM. It is noteworthy that a similar increase in pmaxR, as with the addition of 10 mol % 1M-POSS, requires the addition of up to 50 mol % TSM.Any change in the polymerization rate reflects changes in the polymerization rate coefficients. As mentioned earlier, the accelerating effect of the additives may be caused by a suppression of termination (reduction of p × Fk), and termination, (tb × Fk), as functions of the double bond conversion, p, are shown in pk and tbk coefficients after adding modifiers with bulky substituents.Parameters related to the rate coefficients of propagation, ; their slight increase at medium conversions (in the region of the gel effect) results from the deficiency of the model used for calculations. Regarding the tb × Fk parameter, at the steady state region , its values show a plateau up to conversions of about 0.3 ÷ 0.4. When the gel effect begins , tb × Fk starts to decrease with the increase in conversion. The tbk behavior in different reaction stages is better visible on the tbk/pk = f(p) dependence (p ~ 0.7 ÷ 0.8). The practical lack of the reaction diffusion controlled termination region is probably associated with the fact that poly-LM is a highly viscous liquid even at room temperature.The nversion . The kp×pendence . Becausetbk coefficient. The reduction is moderate—for the LM/(1M-POSS 12 mol %) formulation by about 3.6% and in the case of LM/(TSM 80 mol %) by about 14%. The unexpected result is that pk of neat TSM is about 1.7 times higher than pk of LM. This clearly indicates that TSM reactivity is higher than that of LM. We can expect a similar result for the LM/1M-POSS pair. The p × Fk parameters in the two copolymerization processes are higher by 43% for TSM and by 26% for 1M-POSS compared to LM. Because the polymerization rate is inversely proportional to the square root of tbk and directly proportional to pk, the obtained results lead to the important conclusion that the accelerating effect of the modifiers (at concentrations higher than a few mol %) on LM polymerization results, to a greater extent, from the increase in the propagation rate rather than from suppression of termination.Concerning the effect of the modifiers, it is clear that—as expected—they reduce the tbk coefficient of branched tert-butyl methacrylate (tert-BMA) has been reported to be lower than that of linear n-butyl methacrylate (n-BMA), as attributed to the effects of chain mobility hindered to a greater extent in tert-BMA than in n-BMA polymerization [pk values of methacrylates with cyclic ester groups  are clearly higher than pk of LM [An explanation of this result is difficult. Both anchor groups cause high steric hindrance, which should impede the access of the reactive group to the growing macroradical. In the published literature, the rization . On the kp of LM . This iskp of LM , which inM, and weight average, wM, molecular weights, polydyspersity index, PDI, and fraction contents) of selected copolymerization products containing 4 and 8 mol % of 1M-POSS or 4, 8, and 50 mol % of TSM are given in The results of GPC analysis , which allows more monomer molecules to react.Again, the plots show the same feature: The existence of a minimum at low amounts of the introduced modifier. The difference in the TEM images presented in gT plots against the modifier content. The minimum on the curve for the LM/TSM system appears again, whereas for the LM/1M-POSS system, only a drop in gT values is observed; however, we cannot rule out that with higher POSS contents, there would be an increase in gT.The above-described effect of bulky substituents on the mobility of polymer chains should also be reflected in the values of glass temperature. gT of neat poly-MMA were observed in the entire range of comonomers ratios (as in our case). A similar effect was reported also for the copolymer of styrene and methacryloxystyrene-POSS functionalized with isobutyl groups [It was indicated that POSS copolymerized with a base monomer can induce modifications to cooperative molecular motions typical of the glass transition, leading to retardation or acceleration of the dynamics. Therefore, the change in the glass transition temperature relative to the base polymer can be negative or positive and it is not correlated with the molecular weight . In the l groups . Becausel groups .gT, which confirms the effect of the branched siloxy-silane group on the mobility of the polymer chains, as discussed above (gT) for copolymers of styrene and methacryloxystyrene-POSS containing cyclohexyl vertex groups was described in [gT values of the copolymers, with competition between the free volume and intermolecular interactions. We can assume a similar explanation for the behavior of our LM/TSM copolymers.For LM/TSM copolymers, we observed both a negative and a positive change in ed above . This inribed in . In thisThe effect of the anchoring group on the detailed polymerization kinetics was investigated by DSC and photorheology using photochemical initiation. The monomer with the bulky substituent was monomethacryloxy POSS (1M-POSS); for comparison, a methacrylate with a branched siloxy-silane group (TSM) was also applied. Both monomers were copolymerized with LM at various molar ratios.The addition of the comonomers containing “anchor objects” had a dual effect on termination in LM/modifier copolymerization:An increase of the molecular mobility by increasing the free volume fraction through the bulky substituent (and the plasticizing effect exerted by isobutyl groups in 1M-POSS), which results in an enhanced mobility of radical centers, leads to an acceleration of termination, a weakening of the gel effect, and a slowing down of the polymerization; these effects dominated at low concentrations of the modifiers.Retardation and slowdown of molecular motions due to the “anchor effect” suppress the termination, leading to the acceleration of the polymerization; these effects dominated at higher modifier contents.pmax, pfR , MW, and PDI on the modifier content showed the minima. The threshold concentration was higher for TSM due to the smaller “anchor group” and the lower viscosity of the TSM-containing formulations.As an effect, the dependencies of pk, and termination, tbk, rate coefficients led to the conclusion that the accelerating effect of the modifiers on LM polymerization results both from the suppression of termination as well as from the increase in propagation The increase in pk led to an additional interpretation of the anchor effect: Anchoring the monomer with a long substituent (LM) around the POSS cage; this additionally enhanced the propagation by a local increase in the concentration of double bonds.Determination of the propagation, TEM images suggest that during polymerization, some of the pendant POSS cages formed nanocrystals (on the order of 20 nm), and polymer chains wrap around them. This could partially confirm the above supposition.gT behavior of TSM-containing copolymers was similar to the behavior of the polymerization rate (a minimum in the plot of gT vs. the modifier content), resulting from the influence of TSM on polymer chain mobility. In the case of 1M-POSS, only a plasticizing effect was observed.The In conclusion, we can say that the anchoring effect in the polymerization kinetics (for the monomers used in this work) affects the termination and propagation steps. The direction of this influence on termination depends on the concentration of the monomer containing the anchor object.


Some patients with IgG4-related disease (IgG4-RD) exhibit elevated serum interleukin (IL)-6 with excessive inflammatory reactions or with repeating relapse. To date few reports pertaining to clinical implications of elevated serum IL-6 in IgG4-RD patients have been published. The aims of the current retrospective study were to investigate the clinical implications of elevated serum IL-6 in IgG4-RD patients, and to examine whether IL-6 can predict the activity and/or relapse of the disease.We examined the clinical picture at the onset of 43 patients who were diagnosed with IgG4-RD in our hospital and were able to measure serum IL-6 before steroid treatment.p = 0.008), hemoglobin level  and albumin level . When 43 patients were divided into two groups by using a cut-off IL-6 of 4 pg/mL, the high IL-6 group showed higher age, lower albumin, higher CRP and higher aspartate aminotransferase (AST) . Hepatic swelling and splenomegaly were significantly more prevalent in the high IL-6 group than it was in the low IL-6 group . Biliary tract involvement tended to admit more in the high IL-6 group (p = 0.060).The median level of serum IL-6 was 2.2 pg/mL. There was a significant correlation between IL-6 and C-reactive protein (CRP) level (r = 0.397, Serum IL-6 level at the onset of IgG4-RD may be significantly correlated with clinical inflammatory parameters and it may also be associated with involvement of the bile duct, liver, and spleen. IgG4-related disease (IgG4-RD) is a systemic condition that is histologically characterized by abundant infiltration of IgG4-positive cells and lymphocytes in conjunction with massive fibrosis, particularly storiform fibrosis. It evidently involves a wide range of organs including the pancreas, bile duct, lacrimal glands, salivary glands, central nervous system, thyroid, lungs, liver, gastrointestinal tract, kidneys, prostate, retroperitoneum, aorta/artery, lymph nodes, skin, and breasts -2]. The. The2]. The prognosis of IgG4-RD is considered favorable if substantial improvements in serological and radiological abnormalities are observed after steroid therapy; however, approximately 31%–57% of patients experience relapse of the disease during steroid tapering or after steroid cessation . PatientTo date few reports pertaining to clinical implications of elevated serum IL-6 in IgG4-RD patients have been published. The aims of the current retrospective study were to investigate the clinical implications of elevated serum IL-6 in IgG4-RD patients, and to examine whether IL-6 can predict the activity and/or relapse of the disease.The study was approved by the Ethics Committee of Kansai Medical University. Written informed consent from patients was obtained. Of all 129 IgG4-RD patients included in our database since 2002, we enrolled 38 patients diagnosed as definitive or probable cases of type 1 AIP according to the International Consensus Diagnostic Criteria for AIP and 5 patients diagnosed as cases of definitive, probable, or possible IgG4-RD according to the comprehensive diagnostic criteria for IgG4-RD . In. In13]. Previous studies suggest that baseline elevations in serum IgG4 are predictive of IgG4-RD relapse -15]. We. We15]. MCD is a polyclonal lymphoproliferative disorder caused by hyperproduction of IL-6 in affected lymphoid tissues. Patients commonly exhibit fever, night sweats, weight loss, lymphadenopathy, ascites, pleural effusion, and hepatosplenomegaly, primarily via the action of IL-6. Serologically, increased CRP and polyclonal increases in immunoglobulins are usually observed. Although the disease typically takes an aggressive course, the humanized IL-6 receptor antibody tocilizumab and a chimeric monoclonal antibody that binds to IL-6, siltuximab, are effective in MCD patients -17]..17].Some investigators have reported difficulty differentiating between MCD and IgG4-RD due to similar clinical and histopathological observations -19]. Pa. Pa19]. In addition to MCD, anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is also a disease that sometimes has difficulty in differential diagnosis of IgG4-RD because of similarity of clinical and pathological features. AAV is characterized by pauci-immune necrotizing vasculitis involving systemic or focal small vessels. In general, patients with AAV have fever, increase of inflammatory markers such as CRP and erythrocyte sedimentation rate, and symptoms resulting from the affected organ(s). AAV includes microscopic polyangiitis, granulomatosis polyangiitis , and eosinophilic GPA . Kawashima et al. reported some patients with AAV have similar features of IgG4-RD in elevation of serum IgG4 levels, distribution of organ involvement, response to steroid, and infiltration of IgG4-positive cells in the affected tissue . Indeed,In a previous systematic literature review the majority of patients with MCD exhibited hepatomegaly and/or splenomegaly (78%) , whereasIn the present study, despite no incidences of cirrhosis or extrahepatic obstruction of the portal vein, splenic enlargement was associated with higher serum IL-6. There are various potential causes of splenomegaly, including hematological, hepatic, infectious, congestive, and inflammatory conditions. The mechanism or mechanisms underlying splenic enlargement vary based on etiology . It has There were a few limitations in the current study. Firstly, the study was retrospectively conducted. Secondly, limited data about serum IL-6 levels after steroid therapy were available. Thirdly, due to small sample size, it was impossible to perform multivariate analysis for enhancement of the evidence for a link between elevated IL-6 levels and involvement of organs, such as the bile duct or liver. To resolve these limitations, a prospective well-designed multicenter study is needed.In conclusion, serum IL-6 level at the onset of IgG4-RD may be significantly correlated with clinical inflammatory parameters such as serum levels of CRP, hemoglobin, and albumin, and it may also be associated with involvement of the bile duct and liver. With regard to serum IL-6 levels, IgG4-RD diagnosed in accordance with the current diagnostic criteria may include heterogeneous groups characterized by different underlying pathogenic components. Further studies in IgG4-RD patients with elevated IL-6 levels are needed to elucidate the pathogenesis of IgG4-RD and to develop accurate diagnostic criteria enabling the identification of “true” IgG4-RD.


Background: Lower urinary tract infections (LUTIs) are amongst the most common community acquired infections with frequent antibiotic prescribing.Objectives: To assess empiric antibiotic choice in different types of lower urinary tract infections. We also aimed to identify determinants of fluoroquinolone prescribing, as well as to determine the rate of short antibiotic courses. The frequencies of executing laboratory tests and recommending analgesics/anti-inflammatory drugs were also assessed.Methods: A prospective observational study was performed in 19 different Hungarian primary care practices. Participating general practitioners (GPs) filled out data sheets for each patient with a suspected urinary tract infection. Details of drug use were evaluated. Comparison of different LUTI groups were made by descriptive statistics and univariate analysis. Possible determinants of fluoroquinolone prescribing were assessed by logistic regression.Results: Data sheets of 372 patients were analyzed. The majority of patients (68.82%) had acute uncomplicated cystitis. While antibiotics were prescribed for almost every patient , analgesics/anti-inflammatory drugs were recommended at a rate of 7.81% in uncomplicated, and 13.79% in complicated cystitis cases. Ciprofloxacin was the most commonly prescribed antibacterial agent in both types of cystitis. Short-term antibiotic therapy was prescribed in one third of relevant cases. Logistic regression found a weak association between fluoroquinolone use and patient’s age and presence of complicating factors.Conclusions: Many aspects of suboptimal cystitis management were identified . In this study, patient characteristics has weakly influenced fluoroquinolone prescribing. Based on these results there is considerable room for improvement in primary care antibiotic therapy of cystitis in Hungary. To combat antibiotic resistance by lowering selection pressure, rationalizing antibiotic use for the most frequent community infections should be the key target of any antibiotic stewardship programmes. Lower urinary tract infections (LUTIs) are among the most commonly encountered illnesses in the ambulatory care , with consequently high antibiotic prescribing .The classification of urinary tract infections is based on the affected anatomical site, and can be further stratified into uncomplicated or complicated types based on the presence or absence of complicating factors (e.g. diabetes mellitus) . CompareA prospective observational study was conducted. General practitioners (GPs) were invited and voluntarily participated, without any financial incentives. Twenty-five GPs accepted participation (response rate: 51%), and 19 GPs  contributed throughout the study. GPs were asked to fill in a data sheet for all consecutive patients who first presented with a suspected urinary tract infection. The following data were recorded: patient’s demography, drug allergy, presence of complicating factors, clinical signs, history of urinary tract infections in the previous year, performed lab tests and treatments. Doctors’ specialty and experience (number of practicing years) were derived from a public national database .All patients over 16 years of age were eligible for inclusion. Pregnant women, as well as cases with a suspected upper UTI (pyelonephritis), or genital or sexually transmitted infection  and cases where crucial data (e.g. prescribed/recommended therapy) were missing were excluded. Based on the recorded signs/complaints and comorbidities we classified each case as an uncomplicated or complicated lower urinary tract infection according to the guideline of the European Urological Association . The folPatient age, diagnostic measures and prescribed/recommended therapy was compared in complicated and uncomplicated cystitis by descriptive methods and univariate analysis (Fischer’s and Welch’s tests). Potential influencing factors of fluoroquinolone prescribing  were analyzed by logistic regression. Statistical analyses were performed with the R statistical software (version 3.5).The study protocol was approved by the Regional Human Medical Biology Research Ethical Board of the University of Szeged, Hungary. The ethical approval did not allowed the identification and follow-up of patients, hence the therapeutic outcomes could not be evaluated.Overall, 510 data sheets were collected. A total of 138 patients were excluded , thus data sheets of 372 patients were analyzed. Most patients were female , diagnosed with uncomplicated cystitis . Recurrent cystitis was present in one fifth of patients .The average age of those diagnosed with complicated cystitis was significantly higher (64.44 ± 16.30 years vs. 48.12 ± 19.56), and recurrent cystitis was also slightly more frequent in this patient group. Table 1.Diagnostic measures and details of prescribed/recommended therapies are summarized in The most frequently prescribed antibiotics are shown in age: 0.98 yearly; odds ratio complicating factors: 1.80). The frequency of fluoroquinolone prescribing varied substantially: some of the GPs did not prescribe these agents at all, while a single GP prescribed this antibiotic in 85.71% of cystitis cases diagnosed in her practice.Only evidence of a weak association was found between patient characteristics and fluoroquinolone prescribing Table 3:The burden of urinary tract infections is high worldwide . HoweverAs antibiotics are unambiguously superior to placebo for urinary tract infections , antibioThe use of analgesics/anti-inflammatory agents was found to be limited, which can be explained by the lack of such recommendations in national and international guidelines on urological infections . This isShort-course oral antibacterial treatment has been proven to be as effective as long courses of antibiotics in the ambulatory management of LUTIs . HoweverEnterobacteriaceae is present) its use can be justified.The GPs in this study performed urine analysis (i.e. a urine dipstick test) in the majority of cases in both types of cystitis. As dipstick analysis is considered to have little added value when typical urinary tract symptoms are present , unnecesMicrobiological confirmation of UTI is recommended in all cases of complicated infections and recurrent urinary tract symptoms . UnfortuThe pattern of antibiotic use was similar for both uncomplicated and complicated cystitis, and showed a high dominance of fluoroquinolones. The use of fluoroquinolones in UTI varies greatly in the literature, but none of the European countries (except for a non-recent publication from France) reportedE.coli already exceeds 20% in urine samples in Hungary , but considering that resistance surveillance systems may overestimate resistance patterns (Regarding sulphamethoxazol-trimethoprim (SMX-TMP), its first line use should be limited to uncomplicated cases, and only when local resistance patterns permit this choice. In Hungary, the prevalence of patterns , SMX-TMPThe strengths of our survey include the ability to exploit clinical data. Also, by applying common diagnostic and classification criteria, misclassification bias could be avoided, and the choice of antibiotic could be justified. A limitation of our study is the voluntary participation of GPs. As volunteering GPs may be more concerned about their rational antibiotic prescribing practices, the global prescribing patterns in Hungary might be more suboptimal than presented in this study.Our study has found similar patterns of antibiotic use in both types of cystitis (with high fluoroquinolone dominance), and identified suboptimal antibiotic use from various aspects. Patient characteristics has weakly influenced fluoroquinolone prescribing More prudent use of antibiotics in lower urinary tract infections is urgently needed.The datasets generated for this study are available on request to the corresponding author.The studies involving human participants were reviewed and approved by the Regional Human Medical Biology Research Ethical Board of the University of Szeged. The patients/participants provided their written informed consent to participate in this study.RBe, MM, ZJ, JB, EH, and ZP had the original idea for the manuscript. ZJ and EH organized data collection. RBo, MM, JB, GS, and ZP contributed to the analysis. RBo, MM, and JB drafted the manuscript, which was reviewed and approved by ZP, ZJ, GS, and EH.The study was funded by the University of Szeged.Author JB is employed at Grove Lodge One, though she was not at the time the study was conducted.The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


SLs) in roots in response to nitrogen or phosphate deficiency. To evaluate SL levels under other mineral deficiencies in rice, we cultivated rice seedlings in hydroponic media without nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, and iron. Tiller bud outgrowth was stimulated under calcium deficiency because of low SL levels. SL levels increased under sulfur deficiency, in addition to phosphate, and nitrogen deficiencies. To explore which genes are key regulators of SL production under sulfur deficiency, we analyzed the expression of SL‐related genes in sulfur‐sufficient and sulfur‐deficient conditions. An SL biosynthesis gene, DWARF27 (D27), was strongly expressed under sulfur deficiency, and its expression was decreased by sulfur supply. The levels of D10, D17, and MAX1Os transcripts did not differ between sulfur‐sufficient and sulfur‐deficient conditions. These results suggest that the increased SL levels under sulfur deficiency are due to a high expression of D27. A combination of nitrogen, phosphorus, and sulfur deficiencies had no additive synergistic effect on SL production. Under combined phosphorus and sulfur deficiency, the expression levels of most SL biosynthesis genes were elevated. The number of tiller buds in the d27 mutant was higher than in the wild type, but lower than in other d mutants. Under sulfur deficiency, the chlorophyll content of d27 was lower than those of other d mutants. These results indicate that D27 plays an important role in adaptation to sulfur deficiency in rice.Plants produce strigolactones ( The seedlings were then transferred to glass vials containing hydroponic culture medium  ethanesulfonic acid (MES) buffer adjusted to pH 5.7. Only tillers growing over 2 mm were counted  and loaded onto 1‐ml Sep‐Pak Silica cartridges , washed with ethyl acetate: n‐hexane (15:85) and then eluted with ethyl acetate: n‐hexane (35:65).To measure the amounts of 4DO released from roots, hydroponic media were extracted with ethyl acetate twice after adding d1‐labeled 4DO; the homogenates were filtered with Bond Elute reservoirs  and evaporated to dryness under nitrogen gas. The extracts were dissolved in water adjusted to pH 2–3 with 1 N HCl and extracted with ethyl acetate twice. The ethyl acetate phase was evaporated to dryness under nitrogen gas. The extracts were dissolved in 10% acetone, loaded onto Oasis HLB 3‐ml cartridges (Waters), washed with 10% acetone, and eluted with 60% acetone. The eluates were dissolved in ethyl acetate: n‐hexane (15:85), loaded onto Sep‐Pak Silica 1‐ml cartridges (Waters), washed with ethyl acetate: n‐hexane (15:85), and eluted with ethyl acetate: n‐hexane (35:65).To measure 4DO levels in roots, roots (ca. 650 mg) were homogenized in 10 ml acetone containing Purified 4DO‐containing fractions were dissolved in 50% acetonitrile and subjected to liquid chromatography–tandem mass spectrometry (LC‐MS/MS) analysis using a system consisting of a quadrupole tandem mass spectrometer  and a high‐performance liquid chromatograph  equipped with a reverse‐phase column . Data were analyzed in Analyst 1.5.1 and Multi Quant 2.0.2 .2.3Total RNA was extracted from roots using an RNeasy Maxi kit  and concentrated using an RNeasy Mini kit (Qiagen). A 3‐μg aliquot of total RNA was used for cDNA synthesis with a ReverTra Ace qPCR RT Master Mix with gDNA Remover . qRT‐PCR was performed on a StepOnePlus RT‐PCR system  using a Thunderbird Probe qPCR Mix , specific primers, and Taq‐Man probes listed in Table 2.4t test for pairwise comparisons, ANOVA and Tukey's honestly significant difference test (HSD) for multiple comparisons.Statistical analysis was performed in SPSS 23  using Student's 33.1To evaluate the effect of macronutrient deficiency on tiller bud outgrowth in rice, we cultivated WT seedlings in hydroponic media without N, P, K, S, Ca, Mg, or Fe for 1 week and counted the number of outgrowing tiller buds >2 mm). Interestingly, the second leaf tillers grew in the absence of Ca but not of other nutrients Figure . Tiller  mm. InteUnder –P conditions, the 4DO levels were highest among all experimental conditions tested . We grew WT seedlings in hydroponic medium without S for 1 week, transferred them to fresh +S or −S medium, and analyzed 4DO levels and gene expression levels at 0, 1, and 2 days after transfer Figures . 4DO lev Figures c and S3Cs Figure . mRNA le3.3To investigate the effects of combinations of N, P, and S deficiencies on 4DO levels, we grew WT seedlings under nutrient‐sufficient conditions (control), single macronutrient deficiency, or combined deficiencies. 4DO levels increased significantly in all the treatments in comparison with control . We grew WT seedlings in −PS medium for 1 week and then transferred them to fresh +PS or −PS medium Figure a. 4DO le Figures c and 5c.S Figure .3.4d10 and d27, and the SL signaling mutant d14 in hydroponic culture medium with or without S for 22 days after preculture  was highly expressed and thus contributed to SL production under −S  increases SL levels under −P (Umehara et al., D10 and D17 increase under −N, but that of D27 is not affected (Sun et al., D27 is highly expressed under −S, and its level is 10 times that under −P (Umehara et al., D27 decreased but that of the other SL biosynthetic genes increased compared with −S, resulting in increasing the flow of SL biosynthesis (Figures AtD27 in Arabidopsis roots increases under low S condition, but the expression of MAX1 and MAX3 do not (Iyer‐Pascuzzi et al., D27 expression is responsive to −S. Figures  and 5. T Figures . MicroarS‐adenosyl methionine, sulfolipids, and many secondary metabolites (Amtmann & Armengaud, d mutants still grew (Figure d10 and d14 were higher than that of WT under −S (Figure d mutants were smaller under −S than under +S, indicating that SLs only partially mediate the regulation of shoot branching and leaf senescence, and effect of nutrient deficiency are involved directly.Sulfur is a macro‐element required for plant growth because it is a component of biologically important compounds such as the amino acids Cys and Met, antioxidant tripeptide glutathione, w Figure a. The SPS Figure b. Thus, Medicago and rice (Liu et al., D27 expression is upregulated by NSP1 and NSP2 under −P and in rhizobium symbiotic signaling (Liu et al., NSP1 and NSP2 did not increase in the absence of N or P (Liu et al., D27 transcript increase in AM colonized roots compared with non‐AM colonized roots among SL biosynthetic genes (Kobae et al., D27 is involved in −S response, and D27 might play an important role in effective S absorption via AM fungi. To understand the interactions between SL production under −S condition and symbiosis with AM fungi, further research would be required in the future.In SL biosynthesis, the transcription factors NSP1 and NSP2 are indispensable in None declared.M.S. and M.U. performed the experiments and analyzed the data. K.S. and S.Y. contributed to the experimental design. M.U. directed the research and designed the experiments. M.S. and M.U. wrote the manuscript. Click here for additional data file. Click here for additional data file. Click here for additional data file.