Waqas Latif Baloch, Hocine Siad, Mohamed Lachemi, Mustafa Sahmaran
This research examines the influence of various supplementary cementitious materials (SCMs) and fibers on the fire resistance of composite systems (CS) that combine engineered cementitious composites (ECC) in tension with self-compacting concrete (SCC) in compression. The study was designed to determine the ECC formulation ideally suitable for optimizing mechanical properties and bonding performance at ambient and elevated temperatures. The SCC and ECC were hot-joined without vibration or surface preparation, using a fresh-to-fresh casting method. Modifications to the chemical composition of ECC included the addition of Class-F fly ash (FAF), Class-C fly ash (FAC), or slag (SL), as well as polyvinyl alcohol (PVA) or steel reinforcing fibers. Subsequently, the samples were exposed to temperatures of 200 °C, 400 °C, 600 °C, and 800 °C, followed by comprehensive testing to evaluate their flexural strength, tensile strength, and interfacial properties. The results indicate that the incorporation of an ECC layer within the SCC system significantly improved mechanical strength, and thermal stability, both at ambient temperatures and under high-temperature conditions. Notably, the utilization of FAF in the ECC layer offered superior thermal stability and ensured the retention of desirable residual mechanical properties compared to FAC and SL. Moreover, steel fiber reinforcement greatly improved the bonding between SCC and ECC, outperforming PVA reinforcement at elevated temperatures.
{"title":"Impact of supplementary cementitious materials and fibers in ECC on the fire resistance of hot-jointed SCC/ECC composites","authors":"Waqas Latif Baloch, Hocine Siad, Mohamed Lachemi, Mustafa Sahmaran","doi":"10.1680/jmacr.23.00023","DOIUrl":"https://doi.org/10.1680/jmacr.23.00023","url":null,"abstract":"This research examines the influence of various supplementary cementitious materials (SCMs) and fibers on the fire resistance of composite systems (CS) that combine engineered cementitious composites (ECC) in tension with self-compacting concrete (SCC) in compression. The study was designed to determine the ECC formulation ideally suitable for optimizing mechanical properties and bonding performance at ambient and elevated temperatures. The SCC and ECC were hot-joined without vibration or surface preparation, using a fresh-to-fresh casting method. Modifications to the chemical composition of ECC included the addition of Class-F fly ash (FAF), Class-C fly ash (FAC), or slag (SL), as well as polyvinyl alcohol (PVA) or steel reinforcing fibers. Subsequently, the samples were exposed to temperatures of 200 °C, 400 °C, 600 °C, and 800 °C, followed by comprehensive testing to evaluate their flexural strength, tensile strength, and interfacial properties. The results indicate that the incorporation of an ECC layer within the SCC system significantly improved mechanical strength, and thermal stability, both at ambient temperatures and under high-temperature conditions. Notably, the utilization of FAF in the ECC layer offered superior thermal stability and ensured the retention of desirable residual mechanical properties compared to FAC and SL. Moreover, steel fiber reinforcement greatly improved the bonding between SCC and ECC, outperforming PVA reinforcement at elevated temperatures.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"16 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138517460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ali Dousti, Negar Saraei, Mohammad Shekarchi, Mohammad Nikookar
Microbiological attacks cause concrete structures used in wastewater collection and treatment facilities to deteriorate and degrade rapidly in short service lives. Hence, it is more cost-effective to produce concrete resistant to chemical and sulfuric acid corrosion. In the present study, a total of six concrete mixtures incorporating 7.5% silica fumes (SF) and 10% natural zeolite (ZE) were immersed in 0.5% and 1% sulfuric acid solutions with a maximum pH threshold of 2 and 1 respectively for 70 weeks to enhance concrete resistance to acid attack. The specimens were regularly monitored for surface deterioration, mass changes, and crushing load changes. To better understand the relationship between the pore structure of concrete mixtures and resistance to sulfuric acid, various durability tests such as rapid chloride penetration, water absorption, electrical resistivity, and chloride diffusion coefficient were performed. Based on the results obtained, it was concluded that converting calcium hydroxide (CH) into CSH gel through pozzolanic reactions and then refining the porosity of concrete with silica fume and natural zeolite was effective in enhancing the resistance of concrete to attack by sulfuric acid of relatively low concentration. As a result, using SF and ZE is a lower-cost method for reducing corrosion rates to extend the service life of facilities, particularly in lower concentrations.
{"title":"Increasing service life of concretes in sewage treatment plants using silica fume and natural zeolite","authors":"Ali Dousti, Negar Saraei, Mohammad Shekarchi, Mohammad Nikookar","doi":"10.1680/jmacr.23.00129","DOIUrl":"https://doi.org/10.1680/jmacr.23.00129","url":null,"abstract":"Microbiological attacks cause concrete structures used in wastewater collection and treatment facilities to deteriorate and degrade rapidly in short service lives. Hence, it is more cost-effective to produce concrete resistant to chemical and sulfuric acid corrosion. In the present study, a total of six concrete mixtures incorporating 7.5% silica fumes (SF) and 10% natural zeolite (ZE) were immersed in 0.5% and 1% sulfuric acid solutions with a maximum pH threshold of 2 and 1 respectively for 70 weeks to enhance concrete resistance to acid attack. The specimens were regularly monitored for surface deterioration, mass changes, and crushing load changes. To better understand the relationship between the pore structure of concrete mixtures and resistance to sulfuric acid, various durability tests such as rapid chloride penetration, water absorption, electrical resistivity, and chloride diffusion coefficient were performed. Based on the results obtained, it was concluded that converting calcium hydroxide (CH) into CSH gel through pozzolanic reactions and then refining the porosity of concrete with silica fume and natural zeolite was effective in enhancing the resistance of concrete to attack by sulfuric acid of relatively low concentration. As a result, using SF and ZE is a lower-cost method for reducing corrosion rates to extend the service life of facilities, particularly in lower concentrations.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"144 ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138504815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A novel lightweight aggregate concrete (LWAC) or lightweight concrete (LWC) is developed using the expanded perlite powder (EPP) and light-weight expanded clay aggregate (LECA) as a replacement for conventional fine and coarse aggregates respectively. Furthermore, the natural plant-based flax fiber in treated form was added to the LWC mix at three different volume fractions. The mechanical and thermal characterization of lightweight concrete was done using the compressive strength test, split tensile test, modulus of rupture, thermal conductivity and thermal resistance test. Moreover, the micro-structural and durability properties were obtained using scanning electron microscope/ energy dispersive X-ray spectrum analysis, rapid chloride penetration test, sorptivity and water absorption test. Test results reveal that the addition of 2.0% flax fiber resulted in improved mechanical, thermal and durability properties when compared to the LWC with no fibers. Moreover, the micro-structural analysis using SEM revealed the formation of Ettringite which is responsible for the strength development in the LWAC mix.
{"title":"Thermal and mechanical properties of a sustainable bio-flax fiber based light-weight aggregate concrete","authors":"M. Chellapandian, J. Maheswaran, N. Arunachelam","doi":"10.1680/jmacr.23.00080","DOIUrl":"https://doi.org/10.1680/jmacr.23.00080","url":null,"abstract":"A novel lightweight aggregate concrete (LWAC) or lightweight concrete (LWC) is developed using the expanded perlite powder (EPP) and light-weight expanded clay aggregate (LECA) as a replacement for conventional fine and coarse aggregates respectively. Furthermore, the natural plant-based flax fiber in treated form was added to the LWC mix at three different volume fractions. The mechanical and thermal characterization of lightweight concrete was done using the compressive strength test, split tensile test, modulus of rupture, thermal conductivity and thermal resistance test. Moreover, the micro-structural and durability properties were obtained using scanning electron microscope/ energy dispersive X-ray spectrum analysis, rapid chloride penetration test, sorptivity and water absorption test. Test results reveal that the addition of 2.0% flax fiber resulted in improved mechanical, thermal and durability properties when compared to the LWC with no fibers. Moreover, the micro-structural analysis using SEM revealed the formation of Ettringite which is responsible for the strength development in the LWAC mix.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"146 ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138504814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Luca Lavagna, Daniel Suarez-Riera, Nicoletta Mangani, Matteo Pavese
The use of waste plastic from Waste Electrical and Electronic Equipment (WEEE) as a substitute for natural aggregate in cementitious materials is an increasingly relevant issue. In fact, this would allow to recycle plastics destined for landfills and to decrease the use of new natural resources. However, replacing sand with plastic tends to reduce the mechanical properties of mortars due to the different mechanical properties between the natural aggregate and the waste plastic and the poor interfacial compatibility between the plastic and the cement paste. This work used several strategies to improve the mechanical properties of mortars containing waste plastic. The addition of 1 % of superplasticizer coupled with a lower w/c ratio succeeds in restoring the mechanical properties to values equal to a standard mortar prepared with the natural aggregate, thus obtaining a material that can be used in the construction field.
{"title":"Mortars containing waste plastic from WEEE as replacement of natural aggregate: different strategies to achieve good mechanical properties","authors":"Luca Lavagna, Daniel Suarez-Riera, Nicoletta Mangani, Matteo Pavese","doi":"10.1680/jmacr.23.00102","DOIUrl":"https://doi.org/10.1680/jmacr.23.00102","url":null,"abstract":"The use of waste plastic from Waste Electrical and Electronic Equipment (WEEE) as a substitute for natural aggregate in cementitious materials is an increasingly relevant issue. In fact, this would allow to recycle plastics destined for landfills and to decrease the use of new natural resources. However, replacing sand with plastic tends to reduce the mechanical properties of mortars due to the different mechanical properties between the natural aggregate and the waste plastic and the poor interfacial compatibility between the plastic and the cement paste. This work used several strategies to improve the mechanical properties of mortars containing waste plastic. The addition of 1 % of superplasticizer coupled with a lower w/c ratio succeeds in restoring the mechanical properties to values equal to a standard mortar prepared with the natural aggregate, thus obtaining a material that can be used in the construction field.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"147 ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138504813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dehui Wang, Qingnan Gong, Surong Luo, Zhengxian Yang
The application of seawater and sea sand concrete (SWSSC) can reduce the construction period and cost of island infrastructure, but it may also bring the risk of alkali-silica reaction (ASR) due to the presence of alkali ions in seawater and sea sand. To compare the characteristics of ASR between SWSSC and seawater and desalinated sea sand (DSS) concrete and investigate the effects of desalinated sea sand on the ASR of SWSSC, the properties and the ASR products of mortar-bars with different desalinated sea sand content were investigated. When the DSS proportion increased from 0% to 100%, the Na + , K + , and Ca + concentration contents and pH of the specimens decreased by 22.6, 2.0, 45.1 mg·L + and 0.05, and the expansion of mortar bars reduced by 0.16%. Desalination of sea sand could not eliminate the risk of ASR of SWSSC completely. The 14 days expansion of mortar bars with 100% DSS was 0.13%, and the precursors of ASR-P1 were observed by SEM. The experimental results of XRD, FTIR, Raman spectrometer, DTA, SEM, and EDX all showed that with the increase of DSS proportion, the content of Na-shlykovite and ASR-P1 were gradually reduced. A small amount of Mg element in both Na-shlykovite and ASR-P1 was detected by EDX, but the mechanism of Mg element in ASR of SWSSC needs further study. This study can provide a basis for the application of SWSSC in island infrastructure.
{"title":"Effects of desalinated sea sand on the alkali-silica reaction of seawater and sea sand concrete","authors":"Dehui Wang, Qingnan Gong, Surong Luo, Zhengxian Yang","doi":"10.1680/jmacr.22.00202","DOIUrl":"https://doi.org/10.1680/jmacr.22.00202","url":null,"abstract":"The application of seawater and sea sand concrete (SWSSC) can reduce the construction period and cost of island infrastructure, but it may also bring the risk of alkali-silica reaction (ASR) due to the presence of alkali ions in seawater and sea sand. To compare the characteristics of ASR between SWSSC and seawater and desalinated sea sand (DSS) concrete and investigate the effects of desalinated sea sand on the ASR of SWSSC, the properties and the ASR products of mortar-bars with different desalinated sea sand content were investigated. When the DSS proportion increased from 0% to 100%, the Na + , K + , and Ca + concentration contents and pH of the specimens decreased by 22.6, 2.0, 45.1 mg·L + and 0.05, and the expansion of mortar bars reduced by 0.16%. Desalination of sea sand could not eliminate the risk of ASR of SWSSC completely. The 14 days expansion of mortar bars with 100% DSS was 0.13%, and the precursors of ASR-P1 were observed by SEM. The experimental results of XRD, FTIR, Raman spectrometer, DTA, SEM, and EDX all showed that with the increase of DSS proportion, the content of Na-shlykovite and ASR-P1 were gradually reduced. A small amount of Mg element in both Na-shlykovite and ASR-P1 was detected by EDX, but the mechanism of Mg element in ASR of SWSSC needs further study. This study can provide a basis for the application of SWSSC in island infrastructure.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"9 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135042862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Water can cause a certain degree of damage to cement stabilized macadam. If cement stabilized macadam is immersed in water for a long time, the degree of damage will be greater. In order to study the damage of cement stabilized macadam with long-time water immersion, a discrete element model of cement stabilized macadam was established in this paper. The Weibull distribution function was used to simulate the heterogeneous contact between particles. The parallel bond model was to simulate the material constitutive relationship. The microscopic parameters of cement-stabilized macadam were obtained by trial-and-error method. The stress-strain curve was obtained by immersion test. The micromechanics behavior of cement stabilized macadam after immersion was analyzed. The results show that the contact area and strength of cement stabilized macadamia immersed for 30 days are 31.4 % and 46 % smaller than that of not immersed macadamia. The force chains between particles are evenly distributed. At the loading peak, the normal contact force between particles is much larger than the tangential force, and the vertical force chain is much larger than the transverse force chain. The distribution of cementation energy/friction energy/impact energy is not uniform in the middle/peak loading stage.
{"title":"Meso-damage behavior of cement stabilized macadam for a long-time immersion based on particle flow theory","authors":"Guofang Zhao, Chengcheng Luo, Xiaoyong Wu, Xinqiang Wang, Yongkang Yan, Zhanyou Yan","doi":"10.1680/jmacr.23.00012","DOIUrl":"https://doi.org/10.1680/jmacr.23.00012","url":null,"abstract":"Water can cause a certain degree of damage to cement stabilized macadam. If cement stabilized macadam is immersed in water for a long time, the degree of damage will be greater. In order to study the damage of cement stabilized macadam with long-time water immersion, a discrete element model of cement stabilized macadam was established in this paper. The Weibull distribution function was used to simulate the heterogeneous contact between particles. The parallel bond model was to simulate the material constitutive relationship. The microscopic parameters of cement-stabilized macadam were obtained by trial-and-error method. The stress-strain curve was obtained by immersion test. The micromechanics behavior of cement stabilized macadam after immersion was analyzed. The results show that the contact area and strength of cement stabilized macadamia immersed for 30 days are 31.4 % and 46 % smaller than that of not immersed macadamia. The force chains between particles are evenly distributed. At the loading peak, the normal contact force between particles is much larger than the tangential force, and the vertical force chain is much larger than the transverse force chain. The distribution of cementation energy/friction energy/impact energy is not uniform in the middle/peak loading stage.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" 887","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135186467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The objective of this study is to develop a simplified numerical model that can be used to accurately and quickly conduct collapse analysis of a reinforced concrete (RC) frame impacted by a vehicle obliquely at 45°. The simplified numerical model included introduces a simplified RC frame and a simplified vehicle. For the simplified RC frame, a mixed modelling technique was used, in which structural components that experienced serious damage were simulated using detailed elements, while the retained structural components were simulated by larger elements. A constraint algorithm of nodal rigid body in LS-DYNA was adopted to guarantee the displacement compatibility of two kinds of element. For the simplified vehicle model, the spring–mass system was improved on the basis of the energy conservation principle to represent the vehicle in a 45° impact. Combining the simplified RC frame model and vehicle model, the impact response of an RC frame subjected to vehicle impact was studied and compared with the results of a detailed RC frame model impacted by a detailed vehicle. The validation confirmed that these introduced simplifications could significantly improve the computational efficiency and ensure the computational accuracy for the collapse analysis of an RC frame subjected to vehicle impact.
{"title":"Simplified numerical model for the collapse analysis of RC frame under the oblique impact","authors":"Yujing Zhou, Xiaowei Cheng, Yi Li, Fangfang Liu","doi":"10.1680/jmacr.23.00046","DOIUrl":"https://doi.org/10.1680/jmacr.23.00046","url":null,"abstract":"The objective of this study is to develop a simplified numerical model that can be used to accurately and quickly conduct collapse analysis of a reinforced concrete (RC) frame impacted by a vehicle obliquely at 45°. The simplified numerical model included introduces a simplified RC frame and a simplified vehicle. For the simplified RC frame, a mixed modelling technique was used, in which structural components that experienced serious damage were simulated using detailed elements, while the retained structural components were simulated by larger elements. A constraint algorithm of nodal rigid body in LS-DYNA was adopted to guarantee the displacement compatibility of two kinds of element. For the simplified vehicle model, the spring–mass system was improved on the basis of the energy conservation principle to represent the vehicle in a 45° impact. Combining the simplified RC frame model and vehicle model, the impact response of an RC frame subjected to vehicle impact was studied and compared with the results of a detailed RC frame model impacted by a detailed vehicle. The validation confirmed that these introduced simplifications could significantly improve the computational efficiency and ensure the computational accuracy for the collapse analysis of an RC frame subjected to vehicle impact.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135293375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Aguilar Rosero, E.O. Soriano Somarriba, B. Farivar, C.D. Murray
Belitic calcium sulfoaluminate (BCSA) cement has well-established advantages such as a fast setting time, fast strength gain, long-term strength, shrinkage and sustainability. BCSA cement reaches an initial set in about 15 min at room temperature and can reach compressive strengths of over 27 MPa in about 2 h. While it can be mixed in a similar fashion to Portland cement (PC), a set retarder (such as citric acid) is usually required to achieve adequate working time and the design of mixtures differs slightly from PC designs. This paper provides guidance on establishing mix design criteria for BCSA cement. Slump and compressive strength studies measurements were taken for varying mixture proportions with strengths measured up to 1 year of hydration. For BCSA concrete mixtures, a relationship between water content and slump was established. Citric acid was found to increase the slump, especially at lower water contents. A relationship between setting time and citric acid dosage was proposed on the basis of mortar penetrometer and Vicat needle tests. X-ray diffraction analysis was also conducted on BCSA cement pastes with different water/cement (w/c) ratios. Crystalline structure growth was found to be directly related to the w/c ratio and inversely proportional to compressive strength.
{"title":"Effects of mixture design parameters on the properties of belitic calcium sulfoaluminate concrete","authors":"I. Aguilar Rosero, E.O. Soriano Somarriba, B. Farivar, C.D. Murray","doi":"10.1680/jmacr.23.00067","DOIUrl":"https://doi.org/10.1680/jmacr.23.00067","url":null,"abstract":"Belitic calcium sulfoaluminate (BCSA) cement has well-established advantages such as a fast setting time, fast strength gain, long-term strength, shrinkage and sustainability. BCSA cement reaches an initial set in about 15 min at room temperature and can reach compressive strengths of over 27 MPa in about 2 h. While it can be mixed in a similar fashion to Portland cement (PC), a set retarder (such as citric acid) is usually required to achieve adequate working time and the design of mixtures differs slightly from PC designs. This paper provides guidance on establishing mix design criteria for BCSA cement. Slump and compressive strength studies measurements were taken for varying mixture proportions with strengths measured up to 1 year of hydration. For BCSA concrete mixtures, a relationship between water content and slump was established. Citric acid was found to increase the slump, especially at lower water contents. A relationship between setting time and citric acid dosage was proposed on the basis of mortar penetrometer and Vicat needle tests. X-ray diffraction analysis was also conducted on BCSA cement pastes with different water/cement (w/c) ratios. Crystalline structure growth was found to be directly related to the w/c ratio and inversely proportional to compressive strength.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135293276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Using geopolymer composites to reduce the use of Portland cement can decrease carbon dioxide emissions. The focus of this study was on improving the strength of a geopolymer composite by assessing the positive hybrid effect of nano-calcium carbonate (NCC) and polyethylene fibres (PFs) of different lengths (6 mm and 12 mm). Fresh and hardened properties, including flowability and strength, were investigated to evaluate the hybrid effect. Generally, the hybrid effects from the PFs of different lengths and NCC were negative for flowability, but the hybrid effects were positive on strength. The combination of 12 mm PF + 6 mm PF + 1% NCC was found to have the highest hybrid effect on bending strength, resulting from the good fibre–matrix bond. The bending strength of the PF-reinforced geopolymer composite was assessed based on a new regression coefficient (A), which takes into account the hybrid effect, the fibre–matrix bond strength and fibre dispersion. The new model for the bending strength of PF-reinforced geopolymer composites introduced in this paper is simpler and more effective than previous models provided in the literature.
使用地聚合物复合材料来减少波特兰水泥的使用可以减少二氧化碳的排放。本研究的重点是通过评估不同长度(6毫米和12毫米)的纳米碳酸钙(NCC)和聚乙烯纤维(PFs)的正杂化效应来提高地聚合物复合材料的强度。研究了混合效果的新鲜和硬化性能，包括流动性和强度。一般来说，不同长度的PFs和NCC的杂化效应对流动性是负的，而对强度是正的。12 mm PF + 6 mm PF + 1% NCC的组合对抗弯强度的混杂效应最高，这是由于良好的纤维基质结合。考虑混杂效应、纤维基质结合强度和纤维分散等因素，采用新的回归系数(a)对pf增强地聚合物复合材料的抗弯强度进行了评价。本文提出的pf增强地聚合物复合材料抗弯强度计算模型比已有的模型更简单、更有效。
{"title":"Assessment of hybrid effect between polyethylene fiber and nano-calcium carbonate for flowability and strength of geopolymer composite","authors":"Hui Li, Li Li, Ning Zhang, Qi Feng","doi":"10.1680/jmacr.23.00090","DOIUrl":"https://doi.org/10.1680/jmacr.23.00090","url":null,"abstract":"Using geopolymer composites to reduce the use of Portland cement can decrease carbon dioxide emissions. The focus of this study was on improving the strength of a geopolymer composite by assessing the positive hybrid effect of nano-calcium carbonate (NCC) and polyethylene fibres (PFs) of different lengths (6 mm and 12 mm). Fresh and hardened properties, including flowability and strength, were investigated to evaluate the hybrid effect. Generally, the hybrid effects from the PFs of different lengths and NCC were negative for flowability, but the hybrid effects were positive on strength. The combination of 12 mm PF + 6 mm PF + 1% NCC was found to have the highest hybrid effect on bending strength, resulting from the good fibre–matrix bond. The bending strength of the PF-reinforced geopolymer composite was assessed based on a new regression coefficient (A), which takes into account the hybrid effect, the fibre–matrix bond strength and fibre dispersion. The new model for the bending strength of PF-reinforced geopolymer composites introduced in this paper is simpler and more effective than previous models provided in the literature.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"63 18","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135874443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fatih Acikök, Ahmet Genç, Oğuzhan Şahin, İsmail Raci Bayer, Mehmet Kemal Ardoğa, Mustafa Şahmaran
In this study, it was aimed to produce the multifunctional cementitious composites with advanced thermal and electrical performance considering that these composites having high conductivity serve for the purpose of de-icing, electromagnetic shielding, anti-static, anti-corrosion, and so on. Carbon fiber (CF), and carbon powder (CP) were used singly or together to develop cementitious composites having high conductivity. The electrical resistance and thermal conductivity tests were performed to measure the conductivity of the cementitious composites. While mini-spreading test was applied to assess the consistency of the fresh-state cementitious composites containing conductive materials, in order to determine the distribution of the conductive material incorporated, SEM images were analyzed. In addition, compressive strength tests were carried out to determine the mechanical properties. According to the test results, the highest electrical conductivity result (197 Ω on the 1 st day) were obtained from the binary mixtures, while the highest thermal conductivity result (1250 mW/m.K on the 7 st day) were obtained from the mixtures containing only CP (by volume %0.6). 0.5% carbon fiber by volume mixture performed the worst in terms of mechanical and workability, with 20.5 MPa lower compressive strength and 16 cm lower mini-spread diameter values when compared to the control mixture.
{"title":"Comparison of thermal conductivity and electrical resistivity of carbon-based cementitious composites","authors":"Fatih Acikök, Ahmet Genç, Oğuzhan Şahin, İsmail Raci Bayer, Mehmet Kemal Ardoğa, Mustafa Şahmaran","doi":"10.1680/jmacr.22.00358","DOIUrl":"https://doi.org/10.1680/jmacr.22.00358","url":null,"abstract":"In this study, it was aimed to produce the multifunctional cementitious composites with advanced thermal and electrical performance considering that these composites having high conductivity serve for the purpose of de-icing, electromagnetic shielding, anti-static, anti-corrosion, and so on. Carbon fiber (CF), and carbon powder (CP) were used singly or together to develop cementitious composites having high conductivity. The electrical resistance and thermal conductivity tests were performed to measure the conductivity of the cementitious composites. While mini-spreading test was applied to assess the consistency of the fresh-state cementitious composites containing conductive materials, in order to determine the distribution of the conductive material incorporated, SEM images were analyzed. In addition, compressive strength tests were carried out to determine the mechanical properties. According to the test results, the highest electrical conductivity result (197 Ω on the 1 st day) were obtained from the binary mixtures, while the highest thermal conductivity result (1250 mW/m.K on the 7 st day) were obtained from the mixtures containing only CP (by volume %0.6). 0.5% carbon fiber by volume mixture performed the worst in terms of mechanical and workability, with 20.5 MPa lower compressive strength and 16 cm lower mini-spread diameter values when compared to the control mixture.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135918229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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