Fiber-reinforced polymer (FRP) composites have been widely employed to design advanced structural columns such as the hybrid FRP–concrete–steel double-skin tubular column (hybrid DSTC) with potential benefits. To date, the safety and self-monitoring of the hybrid DSTCs are still a challenge to overcome due to the complex damage scenarios. This paper investigates the self-sensing performance of a newly developed smart double-skin tubular confined concrete column (smart BFST-DSTC) made of basalt FRP–steel composite with built-in optical fiber Bragg grating sensors (OFBGs). The design of the smart BFST-DSTC and sensing principle are firstly addressed, followed by an experimental investigation on the basic mechanical properties and strain-based sensing performance of ten scaled specimens under axial compression. The outcomes reveal the enhancement of the proposed column in terms of load-carrying capacity, confinement ratio, and axial stress-axial strain behavior, as well as failure and damage modes when compared with the hybrid DSTC. The self-sensing investigation demonstrates that the measurement range satisfies the requirement to monitor and evaluate the hoop strains of the FRP jackets and the health state of the inner tube. The smart BFST-DSTC can replace the hybrid DSTC with the ability to provide early failure warning and life cycle health monitoring. Fiber-reinforced polymer (FRP) composites have been widely used as civil infrastructure construction materials in the world due to their high strength-to-weight ratio, good corrosion resistance, and tailorable mechanical properties. FRP composites offer ample possibilities for advanced structural columns including concrete-filled FRP tube (CFFT) , FRP-conDifferent methods have been developed for the damage detection in FRP-based confined tubular columns. Li et al. used acoustic emission (AE) technology to analyze the damage of CFST . The sevOptical fiber sensors (OFS) are easy to integrate into complex materials due to their tiny dimensions, lightweight size, low cost, and immunity to electromagnetic interference. Researchers have demonstrated the excellent properties of OFS packaged into FRP materials for strain and temperature change detection in civil infrastructures ,17,18. BHowever, it is difficult to embed OFBGs in the inner steel tube of the hybrid DSTC. FRP-jacketed steel (FRP–steel composite) has been used in CFST to solve the corrosion issue and enhance the mechanical behavior of the column ,28,29. TThis paper investigates the self-sensing performance of a newly developed OFBG-based smart DSTC with basalt FRP–steel composite (smart BFST-DSTC) under axial compression. The smart BFST-DSTC consists of inner and outer basalt FRP–steel composite tubes with built-in OFBGs. The designed manufacturing process and self-sensing principle are first highlighted. A series of axial compression tests on ten scaled specimens were conducted to investigate the basic mechanical properties and the strain-based self-sensing performance. Parameter designs  that influence the strain-sensing properties were also studied briefly. The smart BFST-DSTC has potential mechanical benefits to overtake the hybrid DSTC as a modern form of structural column. The embedded OFBGs can monitor the strain developed in the column up to 70% of the strengthening load, which is wide enough to detect minor damage occurring in the BFST-DSTC. Finally, the wavelength shift (WS) from the inner FRP jacket allows us to evaluate damage beyond the ultimate load of the column. The smart BFST-DSTC consists of an inner and outer self-sensing basalt FRP–steel tube (BFSTs), and concrete in between. The BFSTs with built-in OFBGs are manufactured first, before the production of the smart BFST-DSTC. Similar to the hybrid DSTC, the inner BFST provides longitudinal reinforcement, and the outer BFST plays a role as lateral confinement. Thus, the inner BFST has a thicker steel layer than the outer BFST. The use of FRP jacket in the inner BFST delays the plastic deformation and even the buckling of the steel. The OFBG sensors’ layout design is based on the preliminary analysis of the stress distribution and the monitoring purpose. For the typical damage modes of the DSTC, such as cracking and buckling, the damage evolution process is always accompanied by the continuous increase of the hoop strain. However, the strain variation characteristic is not consistent for the vertical strain under damage. Therefore, the OFBGs are only embedded in the hoop direction for both the inner and outer FRP jackets. To be more sensitive to the damage or failure, the OFBGs are positioned at the middle height of the column. The BFST has two OFBGs positioned at the middle height in the circumference direction between the FRP layers , is expressed in Equation (1) [neff represents the effective refractive index and Λ is the grating period of the optical fiber. The Bragg gratings are formed by exposing the core of the optical fiber to the UV-laser light. The refractive index of the gratings section is different from that of the optical fiber. The formed grating only reflects a specified wavelength that is related to its grating period when a broadband source of light travels in the fiber. The reflected wavelength, known as the Bragg wavelength (tion (1) .(1)λB=2λB) varies when a load is applied to the fiber. A stretching or tension loading results in a positive wavelength shift (ΔλB), while a compression force produces a negative shift. However, the Bragg wavelength shifts (WS) are linearly proportional to the applied strain and temperature variation. The cross-sensitivity of the Bragg WS can be expressed in Equation (2) [αε and αT are the strain and temperature sensitivity coefficients of the OFBGs, respectively. The Bragg wavelength (tion (2) .(2)ΔλB.Ten specimens, including two hybrid DSTCs and eight BFST-DSTCs with different structural designs, were tested for comparison. The eight BFST-DSTCs included two normal BFST-DSTCs and six BFST-DSTCs with punched-in patterns. All of the test specimens were designed based on the guidelines in GB50608-2010 . The spefco) could be converted by the concrete cubic strength obtained from the test at 28 days. The fco were 20.02 MPa and 60.55 MPa for the normal strength concrete (NSC) and high-strength concrete (HSC), respectively. The steel used in the inner tube of all specimens consisted of galvanized Q275. The steel layer in the outer BFST consisted of a low-grade steel plate, where the radial punched-in patterns were manually formed. The tensile test samples were conducted by following the British standard BS18 [The experiment involved the use of self-compacted concrete, carbon steel, and unidirectional basalt fiber sheets. The concrete cylinder compressive strength  were installed on the FRP surface at midheight for all the tubes. The SGs were located at the same position as the OFBGs, but distant radially as they were mounted outside the FRP jacket instead of built-in like the OFBGs see . Two linGenerally, the failure mechanism of all the BFST-DSTC specimens includes the rupture of the outer FRP jackets. Steel-adhesive interfacial debonding occurred before the rupture of the outer jacket, characterized by several epoxy sounds. The BFST-DSTCs showed a progressive rupture of the outer FRP jacket b,c, charPy), load-carrying capacity (Pf), confinement ratio (εcc/εco), and confinement efficiency (fcc/fco). fco and εco are the compressive strength and corresponding strain of the unconfined concrete, respectively. fcc and εcc are the maximum compressive strength and corresponding strain of the confined concrete. The BFST-DSTC with punched-in pattern showed higher load capacity due to the additional confinement force from the outer punched-in steel layer and inner FRP jacket compared with the hybrid DSTC and the normal BFST-DSTC. The confinement efficiency and confinement ratio were enhanced for all the BFST-DSTC, except for BFST-DSTC1, which could be due to the low confinement efficiency of the two outer FRP layers. The cost-benefit of the proposed system was defined by the highly enhanced ratio of the confinement efficiency up to 40% when three layers of inner FRP jacket and a skinny punched-in steel layer were adopted in the design. The enhanced ratio in Py of the BFST-DSTC was also enhanced slightly.The load-carrying capacity and confinement ratio define the strength for FRP-based confined concrete column at the rupture of the FRP. fcc. The first segment (OM) ends at the yield point of the inner steel tube. The second linear segment (MN) starts from the full activation to the rupture of the FRP tube, since the strain reading from the OFBGs in the FRP tube is quite small and unstable at the OM part. The stress–strain behavior of the BFST-DSTC (fd) that is still superior to the yield point (fco) of the concrete inside the BFST-DSTC. A gradual descent of the loading capacity due to the slow attenuation of the FRP confinement is observed. At last, a residual section, (curve DF or DN’F) depending mainly on the parameters of the inner BFST, will be further explored in future works. A second ascending segment (DN’) with post-peak stress (f2c) and a degradation part (curve N’F) characterize the residual section for specimens with NSC. For specimens with HSC (curve DF), it decreases progressively until reaching stress equivalent to fc,rup. The corresponding strain for each specific stress is also plotted in The differences in the failure mechanisms of the hybrid DSTC and BFST-DSTC result in distinct changes in the stress–strain behavior. FST-DSTC b generalɛlim) for the confined concrete, which gave a lower value than the recommended value  in ACI 440.2R-08 [εlim_min = 3500 με) and maximum (εlim_max = 5400 με) defined the range of the usable strain limit for specimens with NSC, while the average of εlim was represented for the specimen with HSC. The nominal axial strain was the average axial shortening from LVDTs to the overall height. The self-sensing included only the piecewise linear segments of each respective specimen. The WS and the SG shared a tiny slope at the commencement with an axial load below 200 kN and 500 kN for the specimen with NSC and HSC, respectively. All specimens were healthy, and there was no micro-damage observed yet. Before the steel yielded, the slopes of the WS and SG curves for all specimens increased slowly with the hoop strain around 2000 με, except for BFST-DSTC3. According to εlim_min. The concrete core deformation accompanied with the outer steel layer confinement activation might have caused the increase of the WS slopes before the yielding point. The εlim for all specimens could be effectively monitored based on the relationship between the WS and the axial strain. The sharp changes of the WS curves were due to concrete expansion and the steel yielding. However, the WS curves were still reliable for assessing the strain developed in the outer FRP jacket. The increase in the gap between the SG and WS was considered as a warning sign of the full activation of the outer FRP jacket. The hoop strain values were below 4000 με, except for the BFST-DSTC3  and the yield load (Py). All the BFST-DSTCs have a minimum TMF of 71.5%. Within these values, the measured strain of the FRP jacket reached 8000 με to 10,000 με for specimens with NSC  of the confined concrete fell in the elastic stage for specimen BFST-DSTC2, BFST-DSTC3, and BFST-DSTC5 (εlim. In the transition part, the inner steel yielded, and the inner FRP jacket started to activate gradually. A sudden drop of the WS in specimens with HSC (εlim (see This section discusses the self-sensing performance of the built-in OFBGs in the inner tube to detect the deformation of the column with the increase of load. The WS curve for each specimen has been compared with the SG curve. ST-DSTC5 a–c. The εlim see d,e fell με. In the BFST-DSTC5 (In the strengthening stage, the self-sensing performance depended on the parameters of the inner BFST. Here, how far the inner BFST can provide data for its self-damage analysis is the focus. The measurement ranges of each specimen were analyzed based on the error between the readings of the built-in OFBGs and the SG. The WS for BFST-DSTC2 a ended aST-DSTC5 c, the WSThe WS of the built-in OFBGs from the inner tube could monitor the axial load history of each specimen. A relationship can be established to support the results from the built-in OFBGs of the outer tube if the latter is broken before reaching the maximum load. With the built-in concept, an innovative FRP-based confined concrete system with self-sensing ability is easy to develop and cost-effective. The proposed smart BFST-DSTC shows potential mechanical benefits to overtake the hybrid DSTC as a modern form of structural columns. The additional inner FRP layer and outer steel skin with punched-in patterns improve the loading capacity, the confinement ratio, and the confinement efficiency compared with the hybrid DSTC.The OFBGs embedded in the outer tube satisfied the self-monitoring requirements of the strain condition in the proposed smart BFST-DSTC and hybrid DSTC within their service limit. Specimens with punched-in outer steel had a SMR and TMF beyond 70% of the strengthening load. These outcomes are wide enough to detect minor and major deformations of the BFST-DSTC.The embedded OFBGs monitor the hoop strain of the inner and outer FRP jackets and provide early failure warning for the inner tube. The WS from the inner FRP jacket can help for further damage evaluation of the BFST-DSTC in the post-peak stage.The load and WS curves from the inner and outer tubes showed good linear relation at each piecewise segment. The WS of the built-in OFBGs in both tubes can monitor the axial load history of the FRP-confined concrete.This paper presents the experimental investigation of the self-sensing performance for a proposed smart BFST-DSTC with built-in OFBGs under axial compression. The conclusions of this paper are listed as follows:The findings in this paper would be a useful contribution to the R&D of smart civil infrastructures. However, further investigation and optimization design are still needed to improve the self-sensing performance of the smart BFST-DSTC developed in this study.


Birth cohort studies generate huge amounts of data, and as a consequence are a source of many peer reviewed publications. We have taken the list of publications from the Avon Longitudinal Study of Parents and Children UK birth cohort, filtered, de-duplicated and cleaned it to generate a bibliographic research data set. This dataset could be used for accurate reporting and monitoring of the impact of the study as well as bibliometric research. It is often the case that these studies keep track of the publications that have arisen from the data they have given to researchers for project monitoring purposes and to report back to the funder(s). The size of these lists of publications is sometimes used as a crude metric of the the research outputs or impact for the study.Birth cohort studies in the U.K. generate and distribute huge amounts of longitudinal data for medical, social and economic research. Data is generally applied for and given out to researchers once the relevant governance conditions have been metCrossRef holds over 100 million such records. These resolving services also host a wealth of metadata themselves. TheDOI data model outlines the format of DOI data. In addition to CrossRef there exists other resolving and metadata services that are domain-specific. These may have more in depth metadata about their domain than the generality that the DOI data model can offer. In this work we also make use of the persistent identifiers that the National Center for Biotechnology Information (NCBI) PubMed generates , and themetadata their resolving service provides2. This offers extra metadata over and above that available from CrossRef, but only on medical focused publications, i.e. a subset of all available publications in birth cohort studies.Most modern academic journals will assign a unique persistent identifier to new publications. This persistent identifier may be unique and resolvable by the journal, but may be meaningless outside of the journal’s ecosystem. The Digital Object Identifier (DOI) is the de facto persistent identifier which is used as an independent external reference to publications, posters, data, software etc. DOI resolving services exist to refer users (human and machine) to the journal web page for a given DOI,Avon Longitudinal Study of Parents and Children (ALSPAC). ALSPAC began in 1990 (see the cohort profiles for an overview4), and has publications within the biomedical research domain. ALSPAC reports to have over 1800 publications as of August 20185. Thestudy website contains details of all the data that is available through a fully searchable data dictionary and variable search tool.In this paper we describe how we created a cleaned, de-duplicated list of peer-reviewed publications arising from theThe ALSPAC master list of publications at the time this project started (2014), consisted of a large table in a Microsoft Word document. This table was imported into a spreadsheet containing a reference to the publication, a DOI and a PMID. Given the amount of time that has passed since the original master list was parsed we have merged this list with the list of publications on the ALSPAC website as at 12/9/18. One pertinent point is that there exists a small number of publications in the original Microsoft Word document that are not present on the website; we include these here for completeness.Ulrichs Web Global Serials Directory with a "refereed" status. Non-peer-reviewed articles were removed from the publications list. Examples of non-peer-reviewed publications included theses, book chapters, published abstracts, opinion articles, comments on other articles, working papers and technical reports.Each publication was audited manually to ensure it was a peer reviewed publication i.e. that the journal had a defined peer-review process and/or that it appeared inZotero. Zotero usesNCBI PubMed to resolve PMIDs andCrossRef to resolve DOIs.The DOI and PMID for each entry were also audited to validate the identifier and ensure they corresponded to the correct article. A common error was the truncation of a PMID, which due to the numerical nature of PMIDs was itself a valid PMID albeit referring to the wrong publication. If a DOI or PMID was missing from a publication, wherever possible this was sourced from the journal or PubMed directly. The DOI and PMID fields from the publications spreadsheet were used to import the publications lists into a bibliographic library inWe then further cleaned the list of publications by deduplicating the list using Zotero’s native de-duplicate feature. Duplicates often arose in the bibliography when a publication was accepted in one year and then appeared online the next, or when it was listed with a DOI in one case and a PMID in another. Another common source of duplicates was having both the pre-print and the final published paper marked as separate items. In this case we disregarded the pre-print.Given that publications are not necessarily reported to ALSPAC on acceptance to a journal, and some journals have a long turn around in publication time, we chose to have a cut-off of the end of 2015 for this data set. Given the misclassification of years of some publications, we added all publications up to the end of 2016 (as defined by the list on the ALSPAC website), but disregarded any that had a publication date after the end of 2015. This criteria left us with 1300 peer reviewed publications claimed by ALSPAC to the end of 2015.Zotero v5.0.56 was used to export the data.To make this list of publications available to others in as useful way as possible we exported it from our Zotero library in two different formats: BibTeX format to be able to import into any reference manager and comma separated variable (CSV) to allow import into analysis tools to do bibliometric analysis with. Both of these formats are described inZenodo. DOI:https://doi.org/10.5281/zenodo.22767856.The cleaned BibTeX and CSV data described here are available atCreative Commons Attribution 4.0 International license (CC-BY 4.0).Data are available under the terms of theALSPAC website and the individual publications’ metadata from their respective publishers. PubMed and CrossRef have additional terms and conditions2 on their aggregated metadata, but these are permissive and allow fair use.All of the metadata presented here is publicly available in its raw form—the list of publications is available from the Thank you for the opportunity of reviewing this data note. I think that this represents really exciting work and a huge effort in documenting studies using the data and cleaning these.I think the rationale around collating this information could be strengthened a little. In particular, I think the rationale should better make the case that understanding the scientific impact of these cohort studies is key in supporting the continuation of this study and funding future studies.The source data are drawn from records held by the ALSPAC team, which has been keeping track of publications. These formed a ‘master list’ of publications which was then extensively cleaned and refined to form the dataset. However, the processes used to keep track of publications need to be better described – how are studies identified and to what extent do the researchers feel that these records represent the full range of peer-reviewed studies published using ALSPAC data?The authors described that these are publications arising from ALSPAC data. Were any criteria imposed on what this ‘usage’ should look like? For example would a commentary that makes reference to the ALSPAC data  be included as a publication; would secondary analyses of studies using ALSPAC data be included ? While the PMID and DOIs were cleaned, were the studies checked for their usage of these data? This seems important to clarify. While this data note describes a dataset of ALSPAC publications, I’m not clear if this is exclusively a dataset of primary studies using ALSPAC data in novel analyses, or if it also includes other publication types. If the dataset does include other publication types, does this have implications for the way in which the dataset should be used by future researchers?As a minor suggestion, it may be interesting to have an addition to Table 1 that includes a breakdown of publications by year.  The suggestions made above are mainly for clarification to help understand the parameters of the data set. I would like to again emphasise that this data note does represent a huge task undertaken and has resulted in a very worthwhile output. There are some aspects that I think could be better described to help support other similar exercises in the future:I have read this submission. I believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard. The manuscript reports on creating a complete bibliography of publications associated with the ALSPAC longitudinal study. Collecting such data is not trivial given the duplication via preprints, PMIDs, and variable metadata associated with articles. This work is important for understanding the impacts of the study, as well as potential future meta-analyses.I have read this submission. I believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.


Variations in both chemistry and bacterial communities were observed in groundwater, but T-RFLP analysis did not allow to uncover a pesticide-specific effect on endogenous bacterial communities. To circumvent issues of hydrogeochemical and seasonal variations in situ, groundwater samples from two monitoring wells of the Ariège aquifer with contrasting records of pesticide contamination were exposed to different levels of MET in laboratory experiments. The standard Microtox® acute toxicity assay did not indicate toxic effects of MET, even at 5 mg L-1 . Analysis of MET transformation products and compound-specific isotope analysis (CSIA) in laboratory experiments demonstrated MET biodegradation but did not correlate with MET exposure. High-throughput sequencing analysis (Illumina MiSeq) of bacterial communities based on amplicons of the 16S rRNA gene revealed that bacterial community differed mainly by groundwater origin rather than by its response to MET exposure. OTUs correlating with MET addition ranged between 0.4 to 3.6% of the total. Predictive analysis of bacterial functions impacted by pesticides using PICRUSt suggested only minor changes in bacterial functions with increasing MET exposure. Taken together, results highlight MET biodegradation in groundwater, and the potential use of bacterial communities as sensitive indicators of herbicide contamination in aquifers. Although detected effects of MET on groundwater bacterial communities were modest, this study illustrates the potential of integrating DNA- and isotopic analysis-based approaches to improve ecotoxicological assessment of pesticide-contaminated aquifers.Common herbicides such as metolachlor (MET), and their transformation products, are frequently detected in groundwater worldwide. Little is known about the response of groundwater bacterial communities to herbicide exposure, and its potential use for ecotoxicological assessment. The response of bacterial communities exposed to different levels of MET from the Ariège alluvial aquifer (Southwest of France) was investigated  Ongoing intensive use of pesticides leads to accumulation of pesticide mixtures and their transformation products (TP) in groundwater ecosystems . While p-1) and herbicides (>0.03 μg L-1) in an oxic aquifer (-1) were not detected . It was subsequently replaced in the 2000s by S-MET, which is enriched (approximately 86%) in the herbicidally more active 1′S-enantiomer , and the bacterial community response was evaluated by 16S rRNA amplicon sequencing.In this context, the purpose of this study was to evaluate the response of groundwater bacterial community to exposure to MET and its transformation products, as well as MET degradation potential. Issues of field hydrogeochemical heterogeneity in the response of bacterial community in the Ariège alluvial plain (Southwest France) were circumvented by laboratory microcosm experiments of MET exposure. Groundwater samples from two monitoring wells with contrasting records of pesticide contamination were exposed to different levels of MET 15H22ClNO2, (S)-2-Chloro-N-(2-ethyl-6-methyl-phenyl)-N-(1-methoxypropan-2-yl)acetamide) was purchased from Sigma-Aldrich (>99% purity). Stock solutions for spiking were prepared at 1 g L-1 in acetonitrile (ACN).Racemic metolachlor (C2) covers the alluvial domain of the Ariège river . The alluvial plain lies above Aquitanian (Miocene) and Stampian (Oligocene) molasse deposits. Alluvium transported by the Ariège deposited as silt on the molasse, in five terrace levels with similar physicochemical composition. Terrace levels differ in their degree of pebble weathering and pedological evolution. The sand-and-gravel alluvium of the lower terrace and the lower plain defined a continuous unconfined aquifer feeding rivers Ariège and Hers-Vif. The thickness of the unsaturated zone varies between a few meters and up to 10 m locally. The study area features mostly cultivated farmland, including corn.The study area  define a decreasing concentration gradient of MET and its transformation products (TP), and present contrasted hydrochemical composition (Supplementary Section C). Samples were collected after pumping and discarding three purge volumes, to ensure pH and electrical conductivity stabilization. Temperature, pH, electrical conductivity , redox potential (Eh) and dissolved oxygen (O2) were measured on-site using a WTW multi 340i meter equipped with a Sentrix 81 WTW pH electrode and a Tetra Con 325 WTW EC electrode . For analyses of anions and major cations, samples were separately collected in 100 mL PE bottles after filtration through a 0.45 μm PVDF filter. Samples for major cations analyses were acidified to pH 2 with ultrapure HNO3. For MET and TP analysis, groundwater (1 L) was collected in a glass bottle. All samples were placed on ice for transportation to the laboratory and stored at 4°C until chemical analysis.Groundwater sampling was conducted in May, July, September and December 2012, and February and May 2013. The five sampled monitoring wells 151, 60, 117, 230, 224 (Supplementary Section D) were collected in February 2014. Well 151 has a history of chronical exposure to MET . In contrast, MET had not been detected in well 224 (Supplementary Section D). Hydrochemical and bacterial composition of initial groundwater used for preparing the exposure experiments was analyzed for comparison with spiked and incubated groundwater.Groundwater samples (10 L) from monitoring wells 151 and 224 with contrasting records of contamination , and added MET at either 0.1 mg L-1  or 5 mg L-1 . An experimental repetition  was prepared from each of the two selected wells and for each of the three exposition doses.To compare the response of bacterial communities exposed to MET, groundwater subsamples  originating from initial 10 L groundwater samples collected in each well, were incubated -1 in can) was dissolved in distilled water, and ACN was evaporated after 6 h stirring under a fume hood. MET aqueous solutions were filter-sterilized through a 0.2 μm syringe filter  before spiking. To ensure initial homogeneisation following spiking with MET, laboratory microcosms were shaken at 100 rpm for 1 h before incubation at the same temperature of 20°C. In experiments without MET addition, the same procedure was followed using pure ACN evaporated in distilled water to account for possible effects of ACN traces. ACN was never detected in the headspace of MET aqueous solutions (data not shown). Control experiments (performed in duplicate) consisted in filter-sterilized water spiked with MET to evaluate abiotic MET dissipation. To maintain aerobic conditions while limiting water loss and avoiding contamination, a 0.22 μm syringe filter was mounted on a syringe tip stuck through the vial cap.The MET standard stock solution (1 g L-1 confirmed oxic conditions throughout the experiment (Supplementary Section C). Laboratory experiments with or without addition of MET were incubated for 21 days, a duration typical of reported MET half-life values  fixed to the inner face of the bottles before autoclaving. Oxygen concentrations from 5 to 8 mg Le values . Mean gre values . Experime values , and (ii® assay (2 × 15 mL) (see below). Remaining groundwater of each repetition experiment (2 × 670 mL) was filtered through a unique sterile 0.2 μm cellulose membrane  to obtain DNA in sufficient and representative quantities for Illumina sequencing  and the Microtoxquencing . Each me2+, Na+, K+, Mg2+ with 5% uncertainty), ion chromatography  and potentiometric methods according to N EN ISO 9963-1 . Total organic carbon (TOC) and dissolved organic carbon (DOC) were quantified according to NF EN 1484 (1997) procedures.Groundwater samples were analyzed at BRGM Orleans using ICP-AES (Ca-1. Water samples (1 L) were loaded at a flow rate of 5 mL min-1. After drying by flushing with pure N2 (30 min), analytes were eluted twice successively with 4 mL ACN at a rate of 1 mL min-1. Sample extracts were concentrated down to 1 mL under a gentle stream of nitrogen at ambient temperature. For extraction of ionic compounds, cartridges were conditioned at a flow rate of 1 mL min-1 with MeOH (5 mL), followed by ACN (5 mL) with 0.2% v/v acetic acid. The water sample , was loaded at a flow rate of 5 mL min-1. After 30 min of drying, analytes were eluted twice successively with MeOH (4 mL) at 1 mL min-1, and eluates concentrated to 1 mL as described above.Pesticides in groundwater, including MET and its neutral TP, were extracted using a Gilson GX 274 ASPEC solid phase extraction (SPE) system, with Oasis HLB (6 mL - 500 mg) cartridges (Waters) and quantified as described elsewhere . Briefly-1. Limits of quantification were 5 ng L-1 for MET, 10 ng L-1 for MESA and MOXA, and between 5 and 20 ng L-1 for neutral TP.Quantification of pesticides and TP was carried out by a Waters Ultra Performance Liquid Chromatography (UPLC) system coupled to a Waters micromass MSMS (Waters Quattro-Premier XE/Q). Chromatographic separation for neutral and ionic compounds was achieved with a Waters Acquity UPLC BEH C18 column . The mobile phase consisted of a gradient of (A) water/0.05% formic acid and (B) acetonitrile/0.05% formic acid for neutral molecules, and (A) water/0.007% formic acid and (B) methanol/0.007% formic acid for ionic molecules, established at a flow rate of 0.4 mL minSupplementary Section A for the detailed protocol). Briefly, the GC-C-IRMS system consisted of a TRACETM Ultra Gas Chromatograph (Thermo Fisher Scientific) coupled to an isotope ratio mass spectrometer  via a GC IsoLink/Conflow IV interface. Reproducibility of triplicate measurements was ≤0.2‰ (1 σ). Carbon isotope ratios were reported in δ notation in parts per thousand [‰], relative to the international carbon isotope standard Vienna Pee Dee Belemnite (V-PDB).The carbon isotope composition of MET in the laboratory exposure experiment was analyzed by adapting a previously described protocol   following a standard protocol  after incubation at 20°C for 48 h. Toxicity of MET in laboratory exposure experiments was assessed by the standard Microtoxprotocol . All mat® DNA Isolation Kit  following manufacturer’s instructions. Concentrations of DNA were determined using the Quant-it PicoGreen dsDNA Assay Kit .Total DNA was extracted from filters with the PowerWater1  were PCR-amplified using 5-carboxyfluorescein (6-FAM) labeled 27 f and 927 r primers as described previously . T-RFLP 1 . Peak he® , and a pool of equimolar amounts of each amplicon was prepared. A final gel purification step ensured elimination of non-specific products. The combined library was loaded onto the Illumina MiSeq Platform using a standard MiSeq paired end (2 × 250 bp) flow cell and reagent cartridge. Denoising, chimera checking, generation of operating taxonomic units (OTUs) and taxonomic classification were performed using Mothur software package v.1.33.2 (2. The detailed protocol is provided in Supplementary Section B. Obtained sequences were deposited in the NCBI BioProject database (BioProject ID: PRJNA393085).Sequencing of laboratory exposure experiment samples was performed at INRA-UR0050-LBE  using Illumina MiSeq. The 16S rRNA gene spanning hypervariable region V4 and V5 was amplified in a two-step process including a set of multiplex indexed primers (U515F 5′-GTGYCAGCMGCCGCGGTA-3′ and U909R 5′-CCCCGYCAATTCMTTTRAGT-3′) . Individv.1.33.2  by folloObtained sequences analyzed using Mothur were clustered to define OTUs at 98% sequence identity. A subsample of sequences was randomly selected to obtain equally sized datasets according to the standard operating procedure . The res3 for pre-processing, the output file was analyzed using STAMP   by classng STAMP , and retSupplementary Sections D) was investigated by fitting environmental vectors a posteriori onto the NMDS, and their significance was assessed with a Monte-Carlo permutation test (1000 permutation steps). Analysis of similarities (ANOSIM) based on Bray–Curtis dissimilarities were used to infer statistical differences between groups of community profiles.Multivariate analyses were carried out within R Development . To visuIllumina MiSeq sequencing data and PICRUSt profiles were classified separately by cluster analysis to investigate the relationship between bacterial communities exposed to different levels of MET. Hierarchical cluster analysis was carried out to identify robust groupings of sequence data and PICRUSt profiles based on the distances supplied in a hierarchical manner. For both analyses, distance between Hellinger-transformed datasets was computed based on the Hellinger distance. A hierarchical cluster analysis was performed on the resulting dissimilarity matrix using Ward’s method . The optFigure 2). A posteriori fitting of physicochemical and pesticide variables revealed that changes in bacterial community composition correlated significantly only with redox potential (p < 0.05).T-RFLP fingerprints of PCR-amplified 16S rRNA gene fragments were used to follow dominant community members and compare their variation in samples collected from different origins and time points from the Ariège aquifer. Compared to DGGE, TGGE or SSCP, T-RFLP was used for its resolving power and because T-RFs can be used for cross-referencing with other studies . Strong in situ, unlike the effect of acute and punctual contamination by industrial solvents for example  and higher  concentrations of both MET and transformation products (TP). The two clusters of bacterial assemblages did not differ , suggesting little effect of MET and its TP on groundwater communities. This also supports the notion that the response of bacterial groundwater communities to MET in situ cannot easily be teased apart from the effects of variations of hydrogeological conditions using T-RFLP. Worthy of note, T-RFLP of 16S rRNA genes, as other fingerprinting techniques, may suffer not only from a dependence of the data obtained on the protocol used for extraction of nucleic acids from groundwater samples, which may limit reproducibility between groundwater wells, but also from the high differential required to reliably detect a dose-dependent response at environmentally relevant concentrations. Thus, an in labo microcosm approach under controlled conditions was subsequently used in order to characterize MET degradation potential and composition of bacterial communities from contaminated groundwater as a function of MET exposure.These results are consistent with previous data from a related study of the Ariège aquifer that suggested that bacterial communities were influenced by hydrogeological conditions and triazines . In this example . We focuVariations in physicochemical conditions and heterogeneity of aquifer structure may not only affect the composition of bacterial communities, but also its metabolic activity . We thusTable 1). No MET dissipation was observed in the abiotic control (data not shown). Change in carbon isotope composition after 50% MET dissipation during this experiment (Table 1) highlight MET biodegradation, and are consistent with previous studies (13C (>1‰) in the 5 mg L-1 experiments compared to initially spiked MET. Historical MET exposure also correlated with a more limited extent of MET dissipation in groundwater from well 151 exposed to 0.1 mg L-1 MET. Since hydrochemical conditions were the same in the different microcosms, it is likely that they do not affect degradation (Table 1 and Supplementary Section E). Extent of MET degradation did not change significantly across experiments, including at high MET concentrations. This suggests a lack of community sensitivity to MET exposure levels, or alternatively, fast recovery or adaptation of groundwater functions to degrade MET at high MET exposure levels. This phenomenon was observed previously for different pesticides in soil (The extent of MET dissipation in exposure experiments with groundwater from wells 151 (chronic exposure to MET) and 224  ranged from 20 to 51% after 21 days ( studies . Specifi in soil .Table 1). This corresponded to TP patterns in the initial groundwater wells. ESA and OXA formation was suggested to be mediated by glutathione-S-transferases (GSTs) (Supplementary Section D). MET may also be degraded to ESA and OXA via other yet unknown enzymatic pathways (-1 MET (Table 1). The detected TP suggested that degradation pathways involving 4-(2-ethyl-6-methylphenyl)-5-methyl-3-morpholinone, a major photolysis product (The spectrum of known polar MET transformation products (TP) was analyzed to evaluate production and dissipation of MET TP  in labors (GSTs) , but no s (GSTs)  is unlikpathways . Neverth product , or hydr product , were op product  and at t product .-1 MET, but remained below 3% in the other experiments. This suggests that TP were rapidly degraded, since accumulation of TP resulted in apparent reduction of MET dissipation rates in some experiments (Table 2). Alternatively, it is possible that other unknown but relevant TP of MET were not detected.Worthy of note, the TP/MET ratio was highest (about 9%) in the experiment with 151 groundwater  at 0.1 mg LSupplementary Section F), suggesting that toxic effects of MET on the bacterial compartment were minor. Potential effects of MET and its degradates produced in microcosms on bacterial metabolic activity were further probed using the standard Microtox® bacterial assay, which relies on disruption of luminescence production by a tester bacterial strain. The standard Microtox® test was chosen as it is routinely used, standardized and cost-effective. Previously reported EC50 values ranging from 15.3 to 19.1 mg L-1 (-1 MET in pure water), with an EC20 for MET higher than 40 μM . In addition, microcosm groundwater samples after 21 days of incubation did not produce detectable effects (Supplementary Section G). This confirms that as MET itself, transformation products of MET in microcosms, be them identified or not, did not affect metabolism of the Microtox® tester strain. Altogether, our data confirm that the Microtox® is of poor value for ecotoxicity assessment of MET, and that cultivation-dependent approaches may often be less sensitive than cultivation-independent approaches to detect potential bacterial toxicity in groundwater.Viable cell counts on solid medium were very similar in all microcosms experiments irrespectively of MET exposure level , with diversity indices reaching asymptotes (Supplementary Section I), indicative of sufficient sampling depth. The effect of MET exposure on groundwater bacterial communities from the eight groundwater experiments was assessed based on (i) diversity indices, (ii) relative distribution of abundant and rare OTUs, and (iii) cluster analysis of Illumina MiSeq sequencing data to evaluate changes in bacterial composition. Overall, Shannon and inverse Simpson diversity indices, but not the Schao1 estimator, were higher in experiments with well 151 groundwater than with well 224 groundwater (Table 2). This mainly reflects the relative distribution of abundant and rare OTUs in the two wells. Over 70% of OTUs in well 224 experiments had high, greater than 1% abundance (Table 2). By contrast, 34–42% of OTUs in experiments with well 151 groundwater were either rare (<1% abundance) or very rare (<0.1% abundance). In the latter microcosms, very rare OTUs slightly increased with increasing addition of MET, whereas they tended to decrease in experiments with well 224 groundwater (Table 2). As previously reported for soils (Table 2).A total of 19 545 OTUs were obtained from the eight groundwater experiments. OTUs covered 26 phyla, 179 families and 346 genera. Sequencing depth allowed to retrieve a representative portion of total bacterial diversity , represented over 60% of sequences in initial groundwater and in experiments with well 224 groundwater involving MET addition, whereas they accounted for less than 45% of sequences in well 151 groundwater experiments . In all groundwater experiments, the 8 most abundant families (80% clustering) represented 55% of sequences, with Comamonadaceae the most abundant (>25%) , while at 98% clustering, the 25 most abundant OTUs made up 90% of total sequences. Comamonadaceae increased with MET addition in experiments with groundwater from well 224 (>45%), compared to the experiment without MET addition (<37%). Rhodobacteraceae became very rare (<0.1%) at 5 mg L-1 exposure in experiments with groundwater from both wells. Microbial diversity of MET-contaminated environments and enzymes and pathways for MET degradation, in particular in groundwater, are still unknown, preventing comparison with other studies.Analyzing bacterial composition patterns in more detail, Figure 4A). Bacterial communities of the initial groundwater clearly differed from samples obtained following laboratory incubation, suggesting differentiation into distinct communities in the different experiments. Samples were mainly discriminated by well, i.e., well 151 samples differed from well 224 samples irrespectively of MET addition. Bacterial composition in the different microcosms did not converge with time, making it unlikely that storage and incubation had a significant influence.Cluster analysis was performed to better understand the potential origin of the observed variations in bacterial composition between microcosms, revealing four distinct clusters . As for bacterial community composition, different microcosms were mainly discriminated by groundwater origin. Compared to bacterial composition profiles , however, the relative height of cluster separation was an order of magnitude lower for functional predictions , confirming that changes in minor changes in predicted functions were likely minor.Changes in community functional profiles suggested by PICRUSt were evaluated by cluster analysis, revealing two distinct clusters (n = 8) of functional counts, respectively (Supplementary Section K). Functions for xenobiotics biodegradation and metabolic pathways featured prominently, ranging from 2.2% (experiments with well 224 groundwater exposed to MET) to 2.5% (experiments with well 151 groundwater) of functional counts (Supplementary Section L). Predicted pathways for glutathione metabolism, predicted to be associated with chloroacetanilide transformation (Supplementary Section L). In contrast, predicted metabolic pathways for atrazine had very low (≤0.03%) abundances, in agreement with very minor concentrations of atrazine in groundwater samples (Supplementary Section L).Interestingly, the three major predicted types of functions in all microcosms were metabolism, genetic information processing and environmental information processing, accounting for 47.1 ± 1.2%, 16.6 ± 0.5%, and 16.3 ± 1.4% . Relative abundance of sequences exclusively found at highest MET amendment (>3.5%) was largest in experiments with well 224 groundwater. In contrast, sequences uniquely found with MET addition in experiments with well 151 represented only 0.4% (0.1 mg L-1 MET) and 2.1% (5 mg L-1 MET) of total sequences. This suggests that exposure to higher MET levels in groundwater with a history of chronical (well 151) or very low (well 224) exposure to MET was associated with a slight increase of specific taxa. Strikingly, however, OTUs exclusively associated with either unamended or MET-amended conditions were essentially well-specific (Supplementary Section J). In other words, generally applicable MET-responding OTUs are likely to be very limited.PICRUSt-based predictions suggest the occurrence of only slightly distinct gene complements in the bacterial compartment of the two tested groundwater wells, despite markedly different contamination histories. This contrasts with previous work on diverse environments contaminated with hydrocarbons, where specific functional modules were identified that then served as biomarkers to distinguish between different oil contaminated sites . Thus, a-1) and common to well 151 and well 224 yielded only 2 OTUs  affiliated to Clostridia sp., the unclassified OTU00544 and Fastidiosipila sp. OTU00881. Conversely, OTU01317 (affiliated to Gammaproteobacteria) was the only OTU common to both wells and found exclusively in microcosms to which no MET was added. The association between these two OTUs and MET exposure is still unknown.MET-responding OTUs exclusively found in microcosms with MET addition , e.g., by way of shotgun sequencing of microcosm metagenomes and assembly and analysis of associated contigs , may helin situ and in labo experiments, including CSIA and a culture-independent 16S rRNA survey. The response of bacterial communities exposed to chloroacetanilide herbicides could not be teased apart from effects of hydrogeochemical conditions and other pesticides in situ. Therefore, microcosm investigations on groundwater samples under controlled conditions in labo were used to filter out environmental in situ variations. Degradation of MET did not correlate with MET exposure level, even at very high MET exposure levels or in groundwater with no records of MET contamination. Moreover, no relationship between bacterial community composition as assessed by 16S rRNA amplicon sequencing and extent of MET degradation was apparent. In other words, detrimental toxic effects of metolachlor on the bacterial compartment of groundwater were not apparent, as also found by the standard Microtox® ecotoxicological assay. Further, functional profiles of bacterial communities as predicted from 16S rRNA by PICRUSt indicated only minor differences in the gene complement of bacterial communities in association with differences in pesticide contamination. Nevertheless, a small number of OTUs whose abundance correlated with levels of MET exposure were identified. This suggests that alterations of groundwater communities exposed to pesticides can be sensitively probed using high-throughput sequencing. In conclusion, this study provides a possible analysis framework to explore the potential of using bacteria as biomarkers of pesticide contamination in aquifers.This study evaluated the response of groundwater bacterial communities exposed to MET and its degradates by coupling GI and SV designed the work and critically revised the article. GI, NB, BM, and SD collected and analyzed the samples. GI drafted the article with contributions from LB, NB, and SV. All co-authors analyzed and interpreted the data and approved the final submitted version of the manuscript.The 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.


At the same fineness (3800 cm2/g), the initial and final setting times of HSPC were 92 and 98 min less than OPC. Early mortar compressive strength was approximately 176% higher after 24 h. After curing for 15 h, 18 h, and 24 h, the maturity of HSPC concrete  and early compressive strength  were higher than measured for OPC concrete. HSPC fineness was 111.8% higher than OPC, leading to early activation of the hydration reaction. By X-ray fluorescence analysis, the SO3 content of HSPC was 107.9% that of OPC. The applicable time for HSPC concrete form removal was shorter than that for OPC concrete. The relationships y = −10.57 ln(x) + 47.30 and y = −9.84 ln(x) + 44.05 were estimated for predicting the early-age strength OPC and HSPC concrete. Therefore, applying HSPC concrete to an actual construction site is expected to shorten the construction period and reduce the heating curing cost in winter compared to OPC concrete.In this study, the influences of chemical composition and fineness on the development of concrete strength by curing conditions were investigated through performance evaluation of high SO AfterThe contribution of cement particles to the strength of the concrete is closely related to their size ,13. SpecSuperplasticizers are also applied to cementitious materials and concrete fabrication to realize significant improvements in machinability, mechanical properties, porosity, and durability. They can provide excellent workability while substantially reducing the water/binder ratio ,20,21,224) but, owing to instability, rarely as the hemihydrate (CaSO4∙1/2H2O). Gypsum is present in cement as calcium sulfate dihydrate (CaSO4∙2H2O) and is expressed in terms of trioxide sulfate (SO3) levels [3 content should be less than 4% according to European standard EN 197-1 [3 content cannot guarantee sufficient condensation delay, whereas high SO3 content has a significant effect on the cement strength and dimensional stability. Optimal SO3 content ensures maximum strength and minimum shrinkage of the matrix without excessive expansion in water [Portland cement CEM I is a powdered material made of clinker and gypsum . Gypsum ) levels . The SO3EN 197-1  because,in water ,30,31.3 content (%) can be calculated using one of the following formulas:According to Kurdowski , the opt3 content is approximately 3.0%–3.2%.However, as reported by Mohammed and Safiullah , and sho3 to 3.1% and improving fineness by 111.8% (400 cm2/g on 3400 cm2/g). In this study, the new HSPC was evaluated against OPC by setting time and early compressive strength according to cement fineness and type in a mortar test (Series I), and slump and air content according to cement fineness and type in a concrete test (Series II). Early compressive strength and maturity were evaluated in the Series II testing. The strength prediction of concrete and the possibility of removing the vertical formwork according to the heat of hydration were applied to the in-place curing of concrete samples in a field test structure.To maximize early compressive strength and apply the findings to construction sites, the research team added gypsum to OPC clinker, increasing SO2/g) was prepared by adding gypsum to a level of 3.1% SO3 content to ensure the development of early compressive strength. Washed sea sand (40%) and crushed sand (60%) were mixed for use as the fine aggregate. Crushed granite aggregate was used as the coarse aggregate. Polycarboxylic superplasticizer was applied to both OPC and HSPC, as the only admixture used.Ordinary type 1 Portland cement and type 2 fly ash (FA) that met the KS L 5201 standard (Portland cement)  were use3 content (3.13%) and loss on ignition (L.O.I.) than OPC. The particle size distributions, obtained using a Mastersizer 2000 , are shown in 3, which corresponded to the compressive strength most commonly used for a typical apartment floor (24 MPa). The ready-mixed concrete was produced by Remicon S companies , which delivered the concrete to the construction sites. Ten percent of the total binder quantity was replaced with fly ash to improve durability and long-term strength, by increasing cement mix fluidity, and a polycarboxylic superplasticizer-based admixture was used.Two series of setting time and early compressive strength tests were carried out: Series I (mortar test); Series II (concrete tests). The tests, fineness level settings, and concrete curing conditions for the two types of cement are shown in In Series I, the mortar flow test was performed according to ASTM C1437 , and the0 is the datum temperature , and t is the elapsed time (h).Equation (5), a functional formula proposed by Nurse–Saul, was used to calculate the sample maturity according to ASTM C1074 ,44,45. Mc is the compressive strength (MPa), M is the maturity index (°C∙h), and a and b are regression constants.Equation (6) was used to predict the early-age strength. It is a functional formula proposed by Plowman in 1956, based on the hypothesis that the compressive strength of concrete is close to linear when expressed as a logarithmic function of maturity using the Nurse–Saul equation . As this2/g, and the final setting time was reduced by 4 min 38 s. At the same fineness (3800 cm2/g), HSPC initial and final setting times were less than those of OPC by 92 and 98 min, respectively.2/g), the compressive strength of HSPC was higher by 146%, 159%, and 176% after 15 h, 18 h, and 24 h, respectively. 2/g increase in fineness.3 and SO3/Al2O3 and the hydraulic moduli of OPC and HSPC were reviewed (3 ratio was lower (93.7%), the SO3/Al2O3 ratio was higher (116.1%), and the hydraulic modulus (CaO/(SIO2 + Al2O3 + Fe2O3)) was also higher (104.4%). These differences have implied correspondence with the faster setting time and higher early compressive strength of HSPC at the same fineness.Taken together, the results of reviewed . For HSPFresh OPC and HSPC were produced from the batchers at Remicon S. The initial air content and slump values after production were compared with those obtained one hour after production. The test results revealed that both OPC and HSPC met the target slump and air content values of 180 ± 25 mm and 4.5 ± 1.5%, respectively .3 content (107.9%) as measured by X-ray fluorescence analysis 2/g), the initial and final setting times of HSPC were 92 and 98 min less than OPC, and the early compressive strength was approximately 176% higher after 24 h curing.According to the Series I (mortar) test, increasing the fineness of OPC resulted in faster setting time and early compressive strength. At the same fineness (3800 cm(2)3 molar ratio was lower (93.7%), SO3/Al2O3 was higher (116.1%), and the hydraulic modulus was 104.4% higher than OPC.HSPC CaO/SO(3)According to the Series II (concrete) test, the maturity at elapsed time 24 h was HSPC > Air > OPC, regardless of the curing method. At elapsed times of 15 h, 18 h, and 24 h, the maturity of HSPC concrete was 107.4%, 109.6%, and 111.7% higher than OPC concrete, and the early compressive strengths were 146.4%, 170.7%, and 154.5% higher.(4)2/g increase) greater than OPC, leading to early activation of the hydration reaction, and by the results of X-ray fluorescence analysis, HSPC had 107.9% higher SO3 content. The heat of hydration and maturity of HSPC were higher than that of OPC under the same mixing and curing conditions.The reasons for the improvement were that the fineness of HSPC was approximately 111.8% (400 cm(5)The applicable time of form removal was estimated according to the average temperature history of the field molds. Relationships of y = −10.57 ln(x) + 47.30 and y = −9.84 ln(x) + 44.05 were estimated for OPC and HSPC concrete, respectively. The average curing temperature must be 15.8 °C or higher for OPC and 14 °C or higher for HSPC to ensure 5 MPa within 18 h after concrete pouring.In this study, the influences of chemical composition and fineness on the development of concrete strength by curing conditions were investigated through the performance evaluation of HSPC and OPC. The early compressive strength of HSPC was predicted, and its application to actual construction sites was examined. The main conclusions are as follows.Based on the monthly average temperatures in Busan, Korea, for the last five years, heat curing would not be required from early April to the end of October (approximately 6.8 months). During the remaining months, measures, such as heat curing, would be required to maintain average curing temperatures of 14 °C or higher for HSPC.In future studies, the performance impact of HSPC according to mineralogical composition would be investigated, and the effects of the construction period and cost reduction effects would be examined when HSPC is applied to actual construction sites.


In this study, we propose a simple approach to the optimal design of the fly ash and slag mixture in blended concrete that considers the carbon pricing, material cost, strength, workability, and carbonation durability. Firstly, the carbon pricing and the material cost are calculated based on the concrete mixture and unit prices. The total cost equals the sum of the material cost and the carbon pricing, and is set as the optimization’s objective function. Secondly, 25 various mixtures are used as a database of optimization. The database covered a wide range of strengths between 25 MPa and 55 MPa and a wide range of workability between 5 and 25 cm in slump. Gene expression programming is used to predict the concrete’s strength and slump. The ternary blended concrete’s carbonation depth is calculated using the efficiency factors of fly ash and slag. Thirdly, the genetic algorithm is used to find the optimal mixture under various constraints. We provide examples to illustrate the design of ternary blended concrete with different strength levels and environmental CO2 concentrations. The results show that, for a suburban region, carbonation durability is the controlling factor in terms of the design of the mixture when the design strength is less than 40.49 MPa, and the compressive strength is the controlling factor in the design of the mixture when the design strength is greater than 40.49 MPa. For an urban region, the critical strength for distinguishing carbonation durability control and strength control is 45.93 MPa. The total cost, material cost, and carbon pricing increase as the concrete’s strength increases.Concrete producers and construction companies are interested in improving the sustainability of concrete, including reducing its CO However, the addition of fly ash and slag to concrete reduces its carbonation resistance. To rationally use fly ash and slag to achieve sustainable concrete use, a careful examination of their positive and negative effects should be carried out [Fly ash and slag are industrial byproducts and are widely used as mineral admixtures in the concrete industry. Fly ash and slag have many advantages, such as reducing COried out ,2.2 emissions. Rivera et al. [3 of concrete containing 728 kg of fly ash has a strength greater than 30 MPa, higher chloride penetration resistance, and a lower environmental impact. Tait and Cheung [Many studies have evaluated the sustainability of blended concrete. Celik et al.  found tha et al.  showed td Cheung  found th2 emissions that considers the mixing stage, the transportation stage, and the manufacturing stage. Sebaaly et al. [2 concentrations will affect the carbonation rate and have an impact on blended concrete mixtures. For example, the CO2 concentration in a suburban region and the CO2 concentration in an urban region can be different. Therefore, the strengths and mixtures that are required to produce carbonation durability in the two regions may be different. In summary, with respect to the design of blended concrete mixtures, the strength, carbonation durability, and workability requirements should be met while the material cost and the carbon pricing should be kept as low as possible.Compared with studies that evaluate sustainability ,5,6,7,8,y et al.  proposedy et al.  presentey et al. ,11,12,13y et al. , Lee andy et al. , Kim et To overcome the limitations of the models ,11,12,13To optimize the proportions of fly ash and slag in the blended ternary concrete, the object function and constraint conditions need to be established. In this study, we set the object function as the sum of the material cost and carbon pricing. The constraint conditions include the desired strength, workability, component contents, component ratios, absolute volume, and carbonation durability ,15.The optimization’s object function is written as follows:2 emissions content and the unit price of CO2 as follows:2, 2 emissions content, and 2 emissions of cement, slag, fly ash, water, coarse aggregate, fine aggregate, and superplasticizer, respectively [2 emissions are shown in 2’s unit price to 0.4817 NT dollar/kg [2 emissions are taken from the life–cycle inventory (LCI) of Korea. LCI offers straight–forward accounting of everything involved in the “system” of interest. The data of LCI relates to all the flows in and out of the product system. For example, emissions of CO2 from Portland cement production include direct emissions and indirect emissions. Direct CO2 emissions mainly come from carbonate decomposition from raw material and the burning of cement kiln fuel. Indirect CO2 emissions mainly come from electricity consumption. Considering both direct and indirect CO2 emissions, according to the life–cycle inventory (LCI) of Korea, the CO2 emission of 1 kg cement is set as 0.93 kg (direct CO2 0.78 kg and indirect CO2 0.15 kg) [The carbon pricing can be calculated based on the COectively . The conollar/kg . The conThe object function  is subject to various constraints. Examples are concrete strength, workability, component contents, component ratios, absolute volume, and carbonation durability . Since tThe strength constraint is that the designed strength should be higher than the required strength. The formula for the strength constraint is as follows :(4)real Equation (5) shows the workability constraint for fresh concrete :(5)real Equation (6) shows the carbonation durability constraint for a fly ash and slag concrete blend :(6)carboThe range of component contents is as follows:The component ratio constraint is as follows:3, 3150 kg/m3, 2850 kg/m3, 2220 kg/m3, 2660 kg/m3, 2540 kg/m3, and 1220 kg/m3, respectively. The specific gravity equals the ratio of the density of a material to the density of water. Equation (9) implies that the sum of each concrete component should equal 1 m3 [The absolute volume constraint is as follows:ual 1 m3 .Yeh  conducteGene expression programming (GEP) was used to mathematically model strength and slump. GEP is a data–mining technology, proposed by Ferreira , based oBased on the experimental results on compressive strength  and the As shown in 2/kg. A total of 84% fly ash particles are finer than 45 μm [Based on the experimental results on slump  and the ×−.674)−×−.674)−) , and RH 0.5×FA)) . In the 2 diffusivity can be viewed as complying with the Arrhenius law, as follows [2 diffusivity at the reference temperature Tref (20 °C), 2 diffusivity at temperature T, and 2 D(T)In this section, we determine the object function of and the constraints on the concrete mixture’s proportions. The object function is the concrete’s total cost, which is equal to the sum of the material cost and the carbon pricing. The constraints include various types of mechanical and constructability performance. These constraints are shown in The genetic algorithm is used to solve the object function under constraints ,21. The The basic steps of the genetic algorithm are: Step 1, generate a random population; Step 2, determine the fitness of the individual and make a selection according to the fitness; Step 3, generate new individuals based on a crossover and mutation operation; and Step 4, check whether the termination criteria are satisfied; if the termination criteria are not satisfied, return to Step 2.We used the MATLAB global optimization toolbox to solve the objective function under constraints ,21. The air in the concrete mixture is assumed to be 2%.In this section, we provide examples to illustrate the design of a fly ash and slag concrete blend mixture with various strength levels . The strengths of these concrete mixes are used to show the necessity of constraining the carbonation durability in the mixture design. The required slump is assumed to be 70 mm, the exposure temperature is assumed to be 20 °C, the carbon dioxide concentration is assumed to be 0.041% (for a suburban region), and the relative humidity is assumed to be 0.65. The exposure temperature and relative humidity correspond to a temperate exposure condition ,23. We a2/kg, 323 m2/kg, and 601 m2/kg, respectively. Cement is American Society for Testing and Materials (ASTM) type I cement. Cement consists of lime (63.6%), silica (20.2%), alumina (4.3%), ferrite (3.08%), and a small number of other oxides. Fly ash is a by–product of a fossil power plant. Fly ash consists of silica (49.7%), alumina (27.8%), lime (6.3%), ferrite (5.2%), and a small number of other oxides. Slag is a by–product of the iron and steel industry. Slag consists of lime (41.4%), silica (31.6%), alumina (13.8%), magnesium (7.5%), and a small number of other oxides.Particle size distributions of fine aggregate and coarse aggregate are shown in 3, which is equal to the fly ash’s upper limit. This is due to the fact that fly ash’s price and CO2 emissions are much lower than those of cement and slag. In addition, in 3.In this section, we design a fly ash and slag blended concrete without considering carbonation. Based on the Genetic algorithm and under various constraints, such as strength, slump, the concrete component’s range, the component ratio’s range, and absolute volume, the optimal mixtures for different strength levels were determined and are shown in We calculated the carbonation depths of Mix1, Mix2, and Mix3 using the carbonation model. Hence, when designing a fly ash and slag concrete blend with a moderate strength, such as 30 MPa or 40 MPa, the carbonation durability requirement cannot be met over the entire service life. When designing a fly ash and slag concrete blend with high strength, such as 50 MPa, the carbonation durability requirement can be met.In this section, we design a fly ash and slag concrete blend mixture while taking carbonation into consideration. We aim at a strength of 30 MPa. In Based on the genetic algorithm and under various constraints, the concrete mixture was calculated and is shown in As shown in 2 concentration was assumed to be 0.041%, which corresponds to the CO2 concentration in a suburban region. In an urban region, due to the large amount of CO2 emissions from transportation, industrial factories, and residential activities, the CO2 concentration is much higher than that in a suburban region. In this section, we consider the effect of a high environmental CO2 concentration on the design of a ternary blended concrete mixture. The CO2 concentration in an urban region is assumed to be 0.053% (30% higher than that in a suburban region) [In  region) . The aim2 concentration increases from 0.041% to 0.053%, and the critical strength for distinguishing carbonation durability control and strength control increases from 40.49 MPa to 45.93 MPa. As shown in Based on the genetic algorithm and under various constraints, the concrete mixture was calculated and is denoted as Mix5. As shown in 2 concentration region) and an urban region (high CO2 concentration region), the critical strengths to meet the requirement of carbonation durability are 40.49 MPa and 45.93 MPa, respectively. An increase in the service life means a strengthening of the constraint of carbonation durability, which is akin to changing exposure conditions from a low CO2 concentration region to a high CO2 concentration region. Hence, if the aimed service life is higher than 50 years, the critical strengths to meet the requirement of carbonation durability will be higher. In other words, to meet the requirement of a longer service life, the binder content of the optimal critical mixture should be increased.In this study, we consider the constraints of both strength and carbonation durability. The time of exposure relates to the constraint of carbonation durability. This study assumed that the service life is 50 years. We find that for a suburban region  study . The newDifferences in optimal mixtures: (1) The regression equations of strength from various databases are different. (2) For strength control cases , the optimal mixtures from various databases are different. This is because the strength equation for various databases are different. (3) The critical strengths for differentiating carbonation control and strength control from various databases are different.Similarities in the optimal mixtures are as follows: (1) For carbonation durability control cases (Mix4 and Mix5), the optimal mixtures from various databases are the same. This is because the calculation equation of the carbonation depth is the same for various databases. (2) For low–strength blended concrete, carbonation is a control factor of optimal mixture design. While for high–strength blended concrete, strength is a control factor of optimal mixture design. For various databases, this trend is the same. (3) As the strength of the concrete increases, carbon pricing, cost of concrete material, and the total cost of concrete increase. For various databases, this trend is the same.2 blended concrete. To use the proposed method, firstly, we collected the available mixtures and performed regressions on the strength and workability of the concrete using GEP. Secondly, we selected the object function and performed an optimization using GA. For different countries, the strength and slump equations may be different from the equations that were used in this study. Although these equations may differ, the design procedure will remain very similar.The method proposed in this study can be regarded as a general method for the design of low–cost and low–CO2 emissions and the material cost of a fly ash and slag concrete blend considering constraints with respect to workability, mechanical properties, and carbonation durability.In this study, we proposed a simple approach to the optimization of the CO2 emissions and the CO2 unit price. The total cost is equal to the sum of the material cost and the carbon pricing and was set as the optimization’s object function.Firstly, we calculated the material cost based on the concrete mixture and the component’s unit price. We calculated the carbon pricing based on the levels of COSecondly, gene expression programming was used to predict the concrete’s strength and slump. The GEP results were found to be in general agreement with the experimental results. With regard to the concrete’s strength and slump, the correlation coefficients between the calculation results and the experimental results were found to be 0.99 and 0.96, respectively. The ternary blended concrete’s carbonation depth was calculated using the efficiency factors of fly ash and slag. Furthermore, the genetic algorithm was used to find the optimal mixture, considering the object function and various constraints.2 concentration is higher than that in a suburban region, the critical strength was found to be 45.93 MPa, which is higher than that for a suburban region. As the concrete’s strength increases, the carbon pricing, the concrete material cost, and the total cost increase.Thirdly, we provided examples to illustrate the design of ternary blended concrete with different strength levels. The influence of carbonation on the optimal mixture was clarified. For a suburban region, the critical strength for distinguishing carbonation durability control and strength control was found to be 40.49 MPa. When the designed strength is less than 40.49 MPa, carbonation durability is the controlling factor in the mixture’s design. When the designed strength is greater than 40.49 MPa, strength is the controlling factor in the mixture’s design. Given that, in an urban region, the COIn conclusion, the proposed approach can be used as a general tool for designing sustainable concrete. For different countries, the strength and slump equations may differ from the equations that were used in this study; however, the design procedure will be very similar.


This paper carried out burst tests on the carbon and polyvinyl alcohol (PVA) fiber high-strength concrete specimens to investigate the effects of fiber type, fiber content, water content, heating rate and test specimen size on the burst, and the whole burst process of fiber-high concrete was photographed and recorded. The results indicated that fiber addition will improve the high temperature burst behavior of the high-strength concrete, and the performance of PVA is greatly different from that of carbon fiber. The water content and heating rate have little influence on the burst of the PVA test specimen, but they will greatly affect the carbon fiber test specimen. The size of the test specimen has a great influence on the burst. For the PVA concrete test specimen, the large size test specimen bursts on the surface; as for the carbon fiber test specimen, the large size test specimen delays the initial burst time, but the burst becomes fiercer. High-strength concrete possesses superb mechanical properties ,2,3,4,5 As a matter of fact, there are fibers with superior properties other than steel fiber and PP fiber, which can be used to improve the property of high-strength concrete; for instance, carbon fiber and polyvinyl alcohol (PVA) fiber have better mechanical properties than steel fiber and PP fiber. The tensile strength of carbon fiber can be as high as 4200 MPa; moreover, it has excellent thermal conductivity, but its diameter and length are far lower than those of steel fiber. In addition, PVA also has superior mechanical properties to PP fiber but with a lower diameter, which also belongs to the low-melting-point plastic fiber. However, whether the addition of these two fibers into the high-strength concrete can exert a similar burst suppression effect to that of steel fiber and PP fiber remains unclear. It was only pointed out in the research by Han  that a 02/g; the specific surface area of the silica fume was 207800 cm2/g, the ignition loss quantity was 0.31%; the specific surface area of the ultrafine fly ash was 10600 cm2/g, the ignition loss quantity was 7.2%; the fineness modulus of the river sands was 2.45; The scope of the diabase’particle size was 5–10 mm; the crushing index was 4.6%; the polycarboxylate super plasticizer had a water-reducing rate of 30%; and the dry matter content was 50%. By adjusting the amount of water reducing agent, the slump of concrete was maintained at 200–220 mm. The mixture ratio is presented in The major materials of the concrete were as follows: The Ordinary Portland cement  had minimal compressive and rupture strengths of 42.5 MPa and 6.5 MPa, respectively; the specific surface area of the mineral powder was 4750 cmThe materials were precisely weighed according to the mixture ratio in The high-temperature test furnace adopted for heating the concrete was a self-processed electric furnace high-temperature chamber furnace . The rated power was 18 kW, the maximum operating temperature was 1200 °C, and the hearth size was 800 mm × 500 mm × 500 mm; in addition, it was equipped with an automatic temperature control box , which could set the target temperature and heating rate and could automatically change to a constant temperature after reaching the target temperature. The furnace door was made of aluminate cement and had set up the refractory glass a, which Previous studies had indicated that the fiber type and content ,27, the Ordinary concrete has an excellent fire-resistance performance, which will not burst under high temperatures. Denmark scholar Hertz  had firsAs could be seen from It could be observed from As could be observed from It could be seen from Photos were taken at an interval of 30 min to record the change status of the high-strength concrete test specimens under high temperature, and photos of the change status of test specimens within the high-temperature furnace were taken at an interval of 10 min at the presented burst intensive time zone. At the same time, the burst sounds were also recorded. In the burst statistical charts , the greater polygons indicated greater bursts, while the smaller polygons suggested smaller bursts, and the ellipses indicated non-explosion.The burst test results are displayed in The test specimen with a 0.2% carbon fiber content had spalling once only, the upper part of this test specimen as well as half of the lateral part burst, but no burst occurred thereafter a. At theThe initial burst of the test specimen with a 0.6% carbon fiber content occurred in the side back to the observational glass, the seamed edges and planes of the test specimen were exploded and the furnace temperature at this time was 378 °C; subsequently, a huge burst sound was heard at 119 min, the test specimen had completely burst, the burst fragments could be seen around and the furnace temperature at this time was 419 °C c. High-sIn this experiment, the addition of PVA fiber, regardless of whether the carbon fiber was mixed, did not burst, but there were numerous cracks on the surface, as presented in It could be discovered based on the abovementioned experiments that, when compared with the initial burst time of the reference concrete, the presence of carbon fiber would advance the initial burst time of the concrete and that the addition of carbon fiber would change the sudden complete burst into a continuous and gradual burst. The addition of a small amount of carbon fiber would alleviate the burst, but the burst degree would be aggravated with the increase in carbon fiber content; typically, carbon fiber test specimens with 0.4% and above volume contents would finally completely burst. However, no great difference was observed in the initial burst time of the carbon fiber test specimens, which occurred at around 100 min, and the furnace temperature at this time was about 350 °C. By contrast, the PVA and C + P test specimens had not burst. The possible reason was that carbon fiber possessed an excellent tensile strength; with the increase in temperature, the concrete would remarkably expand under heat treatment, while the thermal expansion coefficient of carbon fiber was quite small, which finally manifested as almost unchanged. This, together with the steam pressure, would lead to the increase of the bond stress enven surface slip occure on the contact surface, and bursting would emerge when the stress was greater than the concrete tensile stress. The PVA melting point was 230 °C; with the increase in temperature, the heat would be transferred gradually from the outer surface to the interior, while PVA would be melted from outside in, and the site where PVA used to exist would be melted to form the small pores. On the other hand, the water in the concrete would absorb the heat to become steam, which would thereby fill these pores and be circulated; at the same time, the pores could also accumulate more energy to alleviate the steam pressure, thus avoiding the occurrence of burst. The burst statistics of the test specimens with various water contents are shown in It could be observed when comparing the burst status of carbon fiber test specimens with two water contents that the test specimen with a low water content could delay the burst time and could elevate the initial burst temperature, but its burst was a single and more fierce failure, which could be ascribed to the effect of water within the concrete. With the increase in temperature, the water in the test specimen would be gradually transformed into steam and aggregate continuously to the internal part with a lower temperature, and the concrete developed a spalling burst when the steam pressure was greater than the concrete tensile strength. The test specimen with a high water content had contained sufficient water, and the large amount of water in the interior would make it impossible for the water to move from the exterior with a higher temperature towards the interior with a lower temperature; as a result, steam would be formed near the test specimen surface, and the exterior would first suffer from spalling when the steam pressure was excessively high. However, there was a low water content within the test specimen with a low water content, which could leave enough space for the internal migration of external water; the internal water had continuously aggregated, the steam pressure was continuously increased and no steam pressure-induced spalling was observed near the surface, since there was no water, but it fiercely burst when the internal steam pressure was large enough. This was consistent with the steam pressure theory. The burst statistics are shown in By contrast, the carbon fiber 100-mm test specimen under the same conditions had developed sparse bursts at 108 min, followed by a continuous burst until a complete burst at 137 min b. The PVA 100-mm test specimen did not burst, while the PVA 150-mm test specimen had spalling on the surface at 105 min, as presented in The burst statistics of the test specimens at two heating rates are displayed in The PVA test specimen did not burst, but intense cracks could be observed on the surface, as presented in The test results suggested that, compared with the heating rate of 3 °C/min, the heating rate of 5 °C/min could advance the burst time of the test specimen while shortening the burst duration, indicating that the steam pressure within the concrete would be increased at a faster rate in the presence of a higher heating rate and that the initial burst time would be advanced. However, the excessive heating rate would render a sudden increase in the thermal radiation on the concrete; as a result, the external heat could not be timely and effectively transferred into the interior due to the limited thermal conductance of the concrete and the fiber. In this way, there was a great difference between the internal and external temperatures along with a thermal expansion of the concrete to various degrees in different regions; after reaching a certain difference, the internal stress produced by thermal expansion was greater than the interaction between the concrete materials, finally giving rise to a burst . As shown in Fiber addition will improve the high-temperature burst behavior of the high-strength concrete, and the performance of PVA is greatly different from that of carbon fiber.Carbon fiber can markedly improve the strength of the high-strength concrete but cannot suppress the incidence of bursting; instead, it can only change the sudden burst into a continuous weak burst. In this experiment, 0.2% carbon fiber is the optimal addition amount, but the addition of carbon fiber will reduce the burst temperature of the concrete, and the reduction is related to the amount of addition of carbon fiber in the high-strength concrete. Generally, the temperature will be 42–73 °C lower than that of the basic mix proportion.PVA fiber has a superb burst-suppression property; its addition can enhance the flexural strength and splitting strength of the concrete, and it has little influence on the axial compressive strength but will reduce the compressive strength of the concrete. PVA fibers will develop vaporization under high temperatures, and holes will be formed in the concrete, which can effectively release the concrete vapor pressure and suppress the incidence of concrete burst. The influence of the mixed addition of fiber on the concrete is the same as that on the PVA test specimen.The water content and heating rate have little influence on the burst of the PVA test specimen, but they will greatly affect the carbon fiber test specimen. A low water content will delay the initial burst time of the carbon fiber test specimen, but the burst will become fiercer. Similarly, a faster heating rate will advance the initial burst time of the carbon fiber concrete and accelerate the burst degree.The size of the test specimen has a great influence on the burst. For the PVA concrete test specimen, the large size test specimen burst on the surface; as for the carbon fiber test specimen, the large size test specimen delayed the initial burst time, but the burst became fiercer.From the observation and the records of the experiments, some useful results were obtained and are given below: