In cold regions, concrete practitioners face challenges in achieving the target performance criteria of concrete produced under low temperatures. When concrete temperature drops to −2.8°C, the hydration development of cementitious binders nominally ceases due to the freezing of mixing water, which results in hydraulic and osmotic pressures, that exceed the tensile capacity of concrete, especially at early-age (immature stage). Subsequently, the hardening and strength gain rates of concrete are adversely affected, resulting in insufficient microstructural development and irreversible deterioration, which makes concrete applications challenging under cold weather. Therefore, multiple investigations have been conducted to develop efficient approaches to overcome the challenges of placing concrete under low temperatures. The current paper synthesizes code provisions in North America and Europe and state-of-the-art knowledge on cold weather concreting, in terms of mixtures components as well as new inventions and methods of concrete curing and protection under low temperatures. Hence, it should provide informative guidance for the construction industry in cold regions to improve cold weather concreting practices.
{"title":"Cold weather concreting: codes' provisions and research advances","authors":"A. M. Yasien, M. T. Bassuoni","doi":"10.1680/jcoma.23.00062","DOIUrl":"https://doi.org/10.1680/jcoma.23.00062","url":null,"abstract":"In cold regions, concrete practitioners face challenges in achieving the target performance criteria of concrete produced under low temperatures. When concrete temperature drops to −2.8°C, the hydration development of cementitious binders nominally ceases due to the freezing of mixing water, which results in hydraulic and osmotic pressures, that exceed the tensile capacity of concrete, especially at early-age (immature stage). Subsequently, the hardening and strength gain rates of concrete are adversely affected, resulting in insufficient microstructural development and irreversible deterioration, which makes concrete applications challenging under cold weather. Therefore, multiple investigations have been conducted to develop efficient approaches to overcome the challenges of placing concrete under low temperatures. The current paper synthesizes code provisions in North America and Europe and state-of-the-art knowledge on cold weather concreting, in terms of mixtures components as well as new inventions and methods of concrete curing and protection under low temperatures. Hence, it should provide informative guidance for the construction industry in cold regions to improve cold weather concreting practices.","PeriodicalId":51787,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Construction Materials","volume":" 14","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135241175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
3D concrete printing (3DCP) is a cutting-edge construction method that has recently received much attention. Most of the 3DCP research works focused on printer development, printable material mix design, and the complexity of the geometry shapes. This research primarily focuses on determining appropriate mix proportions and suitable 3D printable concrete (3DPC) mix design using a trial and error approach. The experimental tests are performed on 27 mix trials with different materials to determine the printable properties such as flowability, buildability, extrudability, and open time. Also, printed and cast samples were tested for compressive strength. The 3DPC mix with 19% OPC, 23% of fly ash, 7% of silica fume, 13% of GGBS, 4% limestone and 0.22% superplasticizer (% by mass of total binder) was found as identified mix proportion, which exhibits the required 3DPC characteristics such as good buildability, easy extrusion, less setting time, cohesiveness of mix, and reduction in deformation. The proposed mixing protocol and suggested 3DPC mix design were encouraging for large-scale 3DCP. To demonstrate the application of the 3DPC mix, the 3D printed concrete furniture was printed with a nozzle of size 30 mm, extrusion speed of 100mm/s and a printing speed of 60mm/s.
{"title":"Mix design, optimization and performance evaluation of extrusion-based 3D printable concrete","authors":"P.S. Ambily, Neeraja Rajendran, Senthil Kumar Kaliyavaradhan","doi":"10.1680/jcoma.23.00077","DOIUrl":"https://doi.org/10.1680/jcoma.23.00077","url":null,"abstract":"3D concrete printing (3DCP) is a cutting-edge construction method that has recently received much attention. Most of the 3DCP research works focused on printer development, printable material mix design, and the complexity of the geometry shapes. This research primarily focuses on determining appropriate mix proportions and suitable 3D printable concrete (3DPC) mix design using a trial and error approach. The experimental tests are performed on 27 mix trials with different materials to determine the printable properties such as flowability, buildability, extrudability, and open time. Also, printed and cast samples were tested for compressive strength. The 3DPC mix with 19% OPC, 23% of fly ash, 7% of silica fume, 13% of GGBS, 4% limestone and 0.22% superplasticizer (% by mass of total binder) was found as identified mix proportion, which exhibits the required 3DPC characteristics such as good buildability, easy extrusion, less setting time, cohesiveness of mix, and reduction in deformation. The proposed mixing protocol and suggested 3DPC mix design were encouraging for large-scale 3DCP. To demonstrate the application of the 3DPC mix, the 3D printed concrete furniture was printed with a nozzle of size 30 mm, extrusion speed of 100mm/s and a printing speed of 60mm/s.","PeriodicalId":51787,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Construction Materials","volume":"23 S1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135873486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Warm-mix asphalt (WMA) was produced using a two-phase mixing process without additives, with bitumen–emulsion-coated aggregates and with bitumen at different mixing temperatures (MTs). The asphalt samples were prepared with 8% ground granulated blast-furnace slag fillers determined from hot-mix asphalt (HMA) analysis, with different bitumen-to-emulsion ratios and different MTs. Using the factorial design technique, the effects of the selected factors on Marshall performance parameters were investigated using interaction plots and main effect plots. The analysis from contour plots revealed that WMA prepared at 120°C with a bitumen-to-emulsion ratio of 80:20 performed best, with indirect tensile strength, tensile strength ratio, retained stability, rutting tests and ravelling loss values all meeting the standard code limits. Compared with HMA, the chosen WMA had a 37% lower ravelling loss.
{"title":"Effects of two-phase mixing process on wma by factorial analysis and its performance","authors":"Hemanta Kumar Behera, Sudhanshu Sekhar Das, Debabrata Giri","doi":"10.1680/jcoma.23.00039","DOIUrl":"https://doi.org/10.1680/jcoma.23.00039","url":null,"abstract":"Warm-mix asphalt (WMA) was produced using a two-phase mixing process without additives, with bitumen–emulsion-coated aggregates and with bitumen at different mixing temperatures (MTs). The asphalt samples were prepared with 8% ground granulated blast-furnace slag fillers determined from hot-mix asphalt (HMA) analysis, with different bitumen-to-emulsion ratios and different MTs. Using the factorial design technique, the effects of the selected factors on Marshall performance parameters were investigated using interaction plots and main effect plots. The analysis from contour plots revealed that WMA prepared at 120°C with a bitumen-to-emulsion ratio of 80:20 performed best, with indirect tensile strength, tensile strength ratio, retained stability, rutting tests and ravelling loss values all meeting the standard code limits. Compared with HMA, the chosen WMA had a 37% lower ravelling loss.","PeriodicalId":51787,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Construction Materials","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135923566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The addition of fibres to concrete enhances several mechanical properties under tension and flexure. This paper discusses the benefits of adding two types of fibres, namely E-glass and basalt, to a concrete mixture. The mechanical properties of of conventional and fibre-reinforced concrete were assessed by subjecting cubes and cylinders to compressive strength, splitting tensile, impact and modulus of elasticity tests. A flexural beam set-up was also constructed with varying reinforcement and tested under two-point loading. The deflections under the loading were measured using a deflectometer. The strains in the reinforcement were also measured using strain gauges. It was found that the hybrid fibre-reinforced concrete (HFRC) containing 2% basalt fibre and 1% E-glass fibre exhibited higher compressive strength than various other mix proportions. It was also found that the HFRC exhibited less deflection and higher modulus of elasticity and stiffness compared with the conventional concrete specimen. In addition, the HFRC was observed to have a higher impact resistance.
{"title":"Effect of hybrid E-glass and basalt fibre on the flexural behaviour of concrete","authors":"Deendayal Rathod, S. Manikandaprabhu","doi":"10.1680/jcoma.20.00051","DOIUrl":"https://doi.org/10.1680/jcoma.20.00051","url":null,"abstract":"The addition of fibres to concrete enhances several mechanical properties under tension and flexure. This paper discusses the benefits of adding two types of fibres, namely E-glass and basalt, to a concrete mixture. The mechanical properties of of conventional and fibre-reinforced concrete were assessed by subjecting cubes and cylinders to compressive strength, splitting tensile, impact and modulus of elasticity tests. A flexural beam set-up was also constructed with varying reinforcement and tested under two-point loading. The deflections under the loading were measured using a deflectometer. The strains in the reinforcement were also measured using strain gauges. It was found that the hybrid fibre-reinforced concrete (HFRC) containing 2% basalt fibre and 1% E-glass fibre exhibited higher compressive strength than various other mix proportions. It was also found that the HFRC exhibited less deflection and higher modulus of elasticity and stiffness compared with the conventional concrete specimen. In addition, the HFRC was observed to have a higher impact resistance.","PeriodicalId":51787,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Construction Materials","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135685695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents the application of Artificial Neural Network (ANN) model for predicting the penetration depth under projectile impact in Ultra High Performance Concrete (UHPC) targets containing steel fibers. Despite the availability of a large number of existing empirical models, the prediction of penetration depth remained inconclusive, partly owing to the phenomenon's complexity and partly due to the limitation of statistical regression. From the results of this study, it is evident that the ANN model is capable of predicting the penetration depth of UHPC more accurately than the other machine learning models (Linear Regression (LR), Decision Tree Regression (DTR), and Random Forest Regression (RFR)) and empirical formulae. The ANN model achieved a lower Root Mean Square Error (RMSE) of 11.68 compared to other machine learning models (RMSE – 16.66 to 19.74) and empirical equations (RMSE – 25.17 to 53.42), when applied to the test dataset. The velocity, impact energy, diameter of the projectile, and thickness of the UHPC targets are the most significant parameters (p-value <5%) for predicting the penetration depth using ANN and MLR models.
{"title":"Ballistic impact: predicting penetration depth in UHPC targets with ML models","authors":"Nabodyuti Das, B. Darshan, Prakash Nanthagopalan","doi":"10.1680/jcoma.23.00006","DOIUrl":"https://doi.org/10.1680/jcoma.23.00006","url":null,"abstract":"This paper presents the application of Artificial Neural Network (ANN) model for predicting the penetration depth under projectile impact in Ultra High Performance Concrete (UHPC) targets containing steel fibers. Despite the availability of a large number of existing empirical models, the prediction of penetration depth remained inconclusive, partly owing to the phenomenon's complexity and partly due to the limitation of statistical regression. From the results of this study, it is evident that the ANN model is capable of predicting the penetration depth of UHPC more accurately than the other machine learning models (Linear Regression (LR), Decision Tree Regression (DTR), and Random Forest Regression (RFR)) and empirical formulae. The ANN model achieved a lower Root Mean Square Error (RMSE) of 11.68 compared to other machine learning models (RMSE – 16.66 to 19.74) and empirical equations (RMSE – 25.17 to 53.42), when applied to the test dataset. The velocity, impact energy, diameter of the projectile, and thickness of the UHPC targets are the most significant parameters (p-value <5%) for predicting the penetration depth using ANN and MLR models.","PeriodicalId":51787,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Construction Materials","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88403072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nabodyuti Das, Aparna Sai Surya Sree Nedunuri, Prakash Nanthagopalan
Ultra-high-performance concrete meets the demand of modern infrastructure due to its exceptional strength and durability. The effect on concrete strength of size and shape of fine aggregates, and binder content and type, were investigated. Particle packing concepts were adopted for fine aggregate optimisation, and shape of the fine aggregate was assessed using an aggregate image measurement system. Further, the effects of binder content, binder type and curing age were investigated through compressive strength, thermos-gravimetric analysis and quantitative X-ray diffraction. Mixtures with 2.36 mm nominal maximum size of aggregate and angular aggregates exhibited higher compressive strength. No significant increase in the compressive strength beyond the optimum binder content of 1000 kg/m3 was observed. The study also revealed that ultra-fine slag as a feasible alternative to silica fume. The thermos-gravimetric and X-ray results of concrete paste samples at different curing ages showed that the degree of hydration was relatively low (38.3%) with no further significant increase beyond seven days. This work contributes to the fundamental understanding of the effect of raw materials on ultra-high-performance concrete strength, which helps in rational selection of materials and mixture proportioning.
{"title":"Physio-chemical characterisation of ultra-fine-slag-based ultra-high-performance concrete","authors":"Nabodyuti Das, Aparna Sai Surya Sree Nedunuri, Prakash Nanthagopalan","doi":"10.1680/jcoma.23.00017","DOIUrl":"https://doi.org/10.1680/jcoma.23.00017","url":null,"abstract":"Ultra-high-performance concrete meets the demand of modern infrastructure due to its exceptional strength and durability. The effect on concrete strength of size and shape of fine aggregates, and binder content and type, were investigated. Particle packing concepts were adopted for fine aggregate optimisation, and shape of the fine aggregate was assessed using an aggregate image measurement system. Further, the effects of binder content, binder type and curing age were investigated through compressive strength, thermos-gravimetric analysis and quantitative X-ray diffraction. Mixtures with 2.36 mm nominal maximum size of aggregate and angular aggregates exhibited higher compressive strength. No significant increase in the compressive strength beyond the optimum binder content of 1000 kg/m3 was observed. The study also revealed that ultra-fine slag as a feasible alternative to silica fume. The thermos-gravimetric and X-ray results of concrete paste samples at different curing ages showed that the degree of hydration was relatively low (38.3%) with no further significant increase beyond seven days. This work contributes to the fundamental understanding of the effect of raw materials on ultra-high-performance concrete strength, which helps in rational selection of materials and mixture proportioning.","PeriodicalId":51787,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Construction Materials","volume":"12 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85504617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The performance of pavement structures is influenced by their dynamic responses, which are governed by factors such as traffic loads, temperature variations, and material properties. In this study, the dynamic behavior of asphalt pavement subjected to harmonic rectangular moving loads and varying boundary conditions and temperature profiles is investigated. The dynamic response of multi-layered asphalt pavements is analyzed using the third-order shear deformation plate theory (TSDPT). The governing equations of motion in the time domain are derived using Hamilton's principle, and solutions are obtained in the Laplace domain through the Fourier series. Durbin's transform is then applied to revert the equations back to the time domain. The accuracy of the proposed approach is validated through comparisons with literature data and finite element simulations. The results demonstrate that these factors significantly influence the response of the considered system to excitations. The study's key findings include: A higher dynamic response is observed in asphalt pavement under uniform temperature fields compared to linear and harmonic distributions. Harmonic temperature patterns result in larger deflections than linear profiles. Therefore, the non-uniformity of temperature fields, particularly those with harmonic patterns, should be considered in pavement design and construction.
{"title":"Effect of temperature profile on dynamic behavior of asphalt pavements under moving loads","authors":"Ehsan Tabasi, Behnam Jahangiri, Farhad Kooban","doi":"10.1680/jcoma.22.00116","DOIUrl":"https://doi.org/10.1680/jcoma.22.00116","url":null,"abstract":"The performance of pavement structures is influenced by their dynamic responses, which are governed by factors such as traffic loads, temperature variations, and material properties. In this study, the dynamic behavior of asphalt pavement subjected to harmonic rectangular moving loads and varying boundary conditions and temperature profiles is investigated. The dynamic response of multi-layered asphalt pavements is analyzed using the third-order shear deformation plate theory (TSDPT). The governing equations of motion in the time domain are derived using Hamilton's principle, and solutions are obtained in the Laplace domain through the Fourier series. Durbin's transform is then applied to revert the equations back to the time domain. The accuracy of the proposed approach is validated through comparisons with literature data and finite element simulations. The results demonstrate that these factors significantly influence the response of the considered system to excitations. The study's key findings include: A higher dynamic response is observed in asphalt pavement under uniform temperature fields compared to linear and harmonic distributions. Harmonic temperature patterns result in larger deflections than linear profiles. Therefore, the non-uniformity of temperature fields, particularly those with harmonic patterns, should be considered in pavement design and construction.","PeriodicalId":51787,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Construction Materials","volume":"30 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75147674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work a transducer based on spiral planar inter-digital capacitive structure is designed and implemented for timber moisture content measurement. The sensor capacitance measured at frequency 100 KHz is found to depend strongly on the material dielectric properties, which is found to increase with increasing moisture contents (MC). The moisture contents in the range from 0% to 82% for 5 different varieties of timber specimens are measured and the results presented. The measured capacitances increase with moisture contents with an exponential fitting, with a correlation coefficient better than 0.98 indicating good fit for all the timber varieties. The sensitivity of the technique varies with the specimen as well as its moisture content. The best sensitivity obtained is 0.01 pF/MC%. The performance of the technique in terms of relevant sensor parameters has been analysed and compared with existing techniques for the same measurement. Although several moisture measurement methods exist for timber, the present inter-digital capacitive technique has many advantages over them in terms of sensitivity, dynamic range, cost effectiveness, non-invasiveness, non-destructiveness and measurement speed.
{"title":"Timber moisture content evaluation using spiral capacitive structures","authors":"B. Oommen, J. Philip","doi":"10.1680/jcoma.22.00020","DOIUrl":"https://doi.org/10.1680/jcoma.22.00020","url":null,"abstract":"In this work a transducer based on spiral planar inter-digital capacitive structure is designed and implemented for timber moisture content measurement. The sensor capacitance measured at frequency 100 KHz is found to depend strongly on the material dielectric properties, which is found to increase with increasing moisture contents (MC). The moisture contents in the range from 0% to 82% for 5 different varieties of timber specimens are measured and the results presented. The measured capacitances increase with moisture contents with an exponential fitting, with a correlation coefficient better than 0.98 indicating good fit for all the timber varieties. The sensitivity of the technique varies with the specimen as well as its moisture content. The best sensitivity obtained is 0.01 pF/MC%. The performance of the technique in terms of relevant sensor parameters has been analysed and compared with existing techniques for the same measurement. Although several moisture measurement methods exist for timber, the present inter-digital capacitive technique has many advantages over them in terms of sensitivity, dynamic range, cost effectiveness, non-invasiveness, non-destructiveness and measurement speed.","PeriodicalId":51787,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Construction Materials","volume":"60 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77932146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the first part of this research, concretes with different dosage on Alfa fibers were formulated. At ambient temperature, the results show that the incorporation of 1% per volume of concrete of untreated Alfa fiber represents the highest mechanical values among the Alfa fiber concretes. Further, the addition of Alfa fibers induces an increase in ductility, compared to no fiber concrete. In the second part, specimens of ordinary concrete, concrete with polypropylene fibers, with treated and untreated Alfa fibers are heated to various temperature plateaus up to 800°C, with an average heating rate 7- 8°C/min, in steps of 100°C, maintained for 3 h. At the end of these heating parts, two cooling regimes are applied: air and water cooling regimes. The impact of these heating-cooling regimes has been valued through the study of the residual compressive strength. For both regimes and for all types of fiber concretes, compressive strength drastically reduces, up to 800°C with linear tendencies. More damage is noticed in the case of fiber concrete quenched in the water. Furthermore, for both cooling regimes, the use of Alfa fibers allowed an improvement in the residual compressive strength of ordinary concrete and more particularly in the temperature range [500-800°C].
{"title":"Effect of heating–cooling regimes on the compressive strength of Alfa fiber Concrete","authors":"Zied Ben Hammed, H. Sabeur, M. B. Ouezdou","doi":"10.1680/jcoma.23.00022","DOIUrl":"https://doi.org/10.1680/jcoma.23.00022","url":null,"abstract":"In the first part of this research, concretes with different dosage on Alfa fibers were formulated. At ambient temperature, the results show that the incorporation of 1% per volume of concrete of untreated Alfa fiber represents the highest mechanical values among the Alfa fiber concretes. Further, the addition of Alfa fibers induces an increase in ductility, compared to no fiber concrete. In the second part, specimens of ordinary concrete, concrete with polypropylene fibers, with treated and untreated Alfa fibers are heated to various temperature plateaus up to 800°C, with an average heating rate 7- 8°C/min, in steps of 100°C, maintained for 3 h. At the end of these heating parts, two cooling regimes are applied: air and water cooling regimes. The impact of these heating-cooling regimes has been valued through the study of the residual compressive strength. For both regimes and for all types of fiber concretes, compressive strength drastically reduces, up to 800°C with linear tendencies. More damage is noticed in the case of fiber concrete quenched in the water. Furthermore, for both cooling regimes, the use of Alfa fibers allowed an improvement in the residual compressive strength of ordinary concrete and more particularly in the temperature range [500-800°C].","PeriodicalId":51787,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Construction Materials","volume":"64 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77187824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The thermal conductivity of a material is a measure of its capacity to conduct heat and is a major factor influencing heat transfer in buildings. For better thermal insulation, construction materials should possess low thermal conductivity. The feasibility of expanded perlite aggregate as a thermal insulation material in foamed concrete was examined. Mechanical, thermo-mechanical and durability properties were assessed and compared. A base mix was designed to have 1100 kg/m 3 density, a water-to-solids ratio of 0.3 and a cement-to-sand ratio of 1:1. Expanded perlite aggregate was used as a substitute for fine aggregate in the foamed concrete mix at contents of 0, 10, 20 and 30% by volume. The work was extended by replacing cement with 60% by weight of fly ash to study an eco-friendly mix. The test results showed that the strength values increased with an increase in fly ash and decreased with an increase in perlite. The reverse trend was observed for thermal conductivity and durability, which was also affected by the addition of perlite. The test results showed that expanded perlite is an excellent replacement for sand as a thermal insulation material. The efficiency of the developed material was assessed by an analytical model using the Comsol Multiphysics software program.
{"title":"Thermo-mechanical and durability properties of expanded perlite aggregate foamed concrete","authors":"Sakir Sharook, Dhanya Sathyan, Mini K. Madhavan","doi":"10.1680/jcoma.20.00041","DOIUrl":"https://doi.org/10.1680/jcoma.20.00041","url":null,"abstract":"The thermal conductivity of a material is a measure of its capacity to conduct heat and is a major factor influencing heat transfer in buildings. For better thermal insulation, construction materials should possess low thermal conductivity. The feasibility of expanded perlite aggregate as a thermal insulation material in foamed concrete was examined. Mechanical, thermo-mechanical and durability properties were assessed and compared. A base mix was designed to have 1100 kg/m 3 density, a water-to-solids ratio of 0.3 and a cement-to-sand ratio of 1:1. Expanded perlite aggregate was used as a substitute for fine aggregate in the foamed concrete mix at contents of 0, 10, 20 and 30% by volume. The work was extended by replacing cement with 60% by weight of fly ash to study an eco-friendly mix. The test results showed that the strength values increased with an increase in fly ash and decreased with an increase in perlite. The reverse trend was observed for thermal conductivity and durability, which was also affected by the addition of perlite. The test results showed that expanded perlite is an excellent replacement for sand as a thermal insulation material. The efficiency of the developed material was assessed by an analytical model using the Comsol Multiphysics software program.","PeriodicalId":51787,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Construction Materials","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135845697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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