The chemical debonding energy, initial interfacial frictional bond strength and slip-hardening coefficient between polyvinyl alcohol (PVA) fibres and an engineered cementitious composite (ECC) matrix were obtained by means of single PVA fibre pull-out tests. The effect of three moisture states (fully saturated, semi-saturated and fully dry) on the bonding properties between the PVA fibre and ECC matrix at three target temperatures (25°C, 0°C and −20°C) was investigated. It was found that, at 25°C, the bonding properties decreased with an increase in moisture content. At 0°C and −20°C, the bonding properties increased with an increase in moisture content. At −20°C in the fully saturated state, the bonding load was too large to cause fibre rupture. The bonding properties were found to increase with decreasing temperature in the fully saturated and semi-saturated states and decrease with decreasing temperature in the fully dry state. This study of the effect of low temperature and moisture state on the bonding properties between PVA fibres and ECCs provides theoretical support for how to ensure good ductility when ECCs are in service at low temperature.
{"title":"Effect of low temperature and moisture on bond properties of PVA fibres and engineered cementitious composite matrix","authors":"Shuling Gao, Qing Wang","doi":"10.1680/jadcr.22.00003","DOIUrl":"https://doi.org/10.1680/jadcr.22.00003","url":null,"abstract":"The chemical debonding energy, initial interfacial frictional bond strength and slip-hardening coefficient between polyvinyl alcohol (PVA) fibres and an engineered cementitious composite (ECC) matrix were obtained by means of single PVA fibre pull-out tests. The effect of three moisture states (fully saturated, semi-saturated and fully dry) on the bonding properties between the PVA fibre and ECC matrix at three target temperatures (25°C, 0°C and −20°C) was investigated. It was found that, at 25°C, the bonding properties decreased with an increase in moisture content. At 0°C and −20°C, the bonding properties increased with an increase in moisture content. At −20°C in the fully saturated state, the bonding load was too large to cause fibre rupture. The bonding properties were found to increase with decreasing temperature in the fully saturated and semi-saturated states and decrease with decreasing temperature in the fully dry state. This study of the effect of low temperature and moisture state on the bonding properties between PVA fibres and ECCs provides theoretical support for how to ensure good ductility when ECCs are in service at low temperature.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136297047","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}
C. Colman, D. Bulteel, Bouarroudj Mohamed Elkarim, S. Rémond, L. Courard
Recycled aggregates, and especially the fine (0/4 mm) fraction, are often contaminated with sulfates coming from gypsum residues on the demolition site. When these aggregates are used in concrete, the sulfates can induce internal sulfate attack which causes the expansion of concrete. Standard EN206 sets the water soluble sulfate limit at 0.2 % by weight of the aggregate but other studies suggest this limit could be safely increased. In addition to the sulfate content, other parameters like the porosity and alkalinity of a mix have been seen to influence the swelling results. In this study, the different proposed sulfate limits are evaluated on concrete made with 100 % fine recycled aggregates. It is also researched whether mixing parameters could change the swelling amount regardless of sulfate content. The results showed that the incorporation of fine recycled aggregates with sulfate contents up to 0.8 mass% is safe when combined with coarse natural aggregates. If coarse recycled aggregates are used, the sulfate content of fine recycled aggregates could reach up to 0.3 %. The swelling caused by these sulfate levels was not high enough to be influenced by porosity or alkalinity.
{"title":"Expansion of concrete by secondary ettringite formation, caused by fine recycled aggregates contaminated with gypsum","authors":"C. Colman, D. Bulteel, Bouarroudj Mohamed Elkarim, S. Rémond, L. Courard","doi":"10.1680/jadcr.22.00043","DOIUrl":"https://doi.org/10.1680/jadcr.22.00043","url":null,"abstract":"Recycled aggregates, and especially the fine (0/4 mm) fraction, are often contaminated with sulfates coming from gypsum residues on the demolition site. When these aggregates are used in concrete, the sulfates can induce internal sulfate attack which causes the expansion of concrete. Standard EN206 sets the water soluble sulfate limit at 0.2 % by weight of the aggregate but other studies suggest this limit could be safely increased. In addition to the sulfate content, other parameters like the porosity and alkalinity of a mix have been seen to influence the swelling results. In this study, the different proposed sulfate limits are evaluated on concrete made with 100 % fine recycled aggregates. It is also researched whether mixing parameters could change the swelling amount regardless of sulfate content. The results showed that the incorporation of fine recycled aggregates with sulfate contents up to 0.8 mass% is safe when combined with coarse natural aggregates. If coarse recycled aggregates are used, the sulfate content of fine recycled aggregates could reach up to 0.3 %. The swelling caused by these sulfate levels was not high enough to be influenced by porosity or alkalinity.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43040791","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}
Corrosion of cementitious materials of concrete in acid environment is crucial for the safety and durability of infrastructures. This work prepares two groups of specimens of ordinary Portland cement (OPC) and metakaolin-based geopolymer (MKG) to investigate their corrosion in 1 mol/L nitric acid solution. Changes of morphology, mass, compressive strength, pH, chemical elements, crystal phases, pores are compared and analysed. Results show the surfaces of ordinary Portland cement are corroded into petaloid grooves due to the relatively severe reaction between the calcium hydrated products and nitric acid solution. The porosity of OPC specimens increases greater than that of MKG specimens whose main compositions react relatively mildly with the nitric acid solution. However, large quantities of fragments are peeled away from the MKG specimens, and their losses of mass and compressive strength are also greater than those of OPC specimens. But the porosities of MKG specimens change little. And the strength loss of MKG specimens is mainly due to the broken matrix structure and the newly formed porous silicious framework.
{"title":"Corrosion of ordinary Portland cement and metakaolin-based geopolymer immersed in nitric acid solution","authors":"Qifeng Lyu, Anguo Chen, Pengfei Dai","doi":"10.1680/jadcr.22.00108","DOIUrl":"https://doi.org/10.1680/jadcr.22.00108","url":null,"abstract":"Corrosion of cementitious materials of concrete in acid environment is crucial for the safety and durability of infrastructures. This work prepares two groups of specimens of ordinary Portland cement (OPC) and metakaolin-based geopolymer (MKG) to investigate their corrosion in 1 mol/L nitric acid solution. Changes of morphology, mass, compressive strength, pH, chemical elements, crystal phases, pores are compared and analysed. Results show the surfaces of ordinary Portland cement are corroded into petaloid grooves due to the relatively severe reaction between the calcium hydrated products and nitric acid solution. The porosity of OPC specimens increases greater than that of MKG specimens whose main compositions react relatively mildly with the nitric acid solution. However, large quantities of fragments are peeled away from the MKG specimens, and their losses of mass and compressive strength are also greater than those of OPC specimens. But the porosities of MKG specimens change little. And the strength loss of MKG specimens is mainly due to the broken matrix structure and the newly formed porous silicious framework.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48058710","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}
To solve the hidden safety brought by iron tailings powder (ITP). The preparation of green binding materials through ITP have shown bright prospects. However, low activity limits the use of ITP as a supplementary cementitious material in large amounts. Therefore, the activity of ITP at different milling times and sintering temperatures, and its effect on the properties and microstructure of blended cement were studied. The results revealed that ITP has a filling effect and provides additional nucleation sites. In addition, ITP exhibits pozzolanic activity in the later stage, and consumes more hydration products CH, which promotes the formation and deposition of C-S-H, which are all related to its specific surface area. These also provide the conditions for cement paste densification, and lay a foundation for blended cement strength. Moreover, the environmental impact and cost of plain cement were higher than those of mixed cement. Highlights The activity of activated ITP is related to its specific surface area. ITP has a filling effect and provides additional nucleation sites. It takes a long time for iron tailings powder to exert pozzolanic activity. The activated ITP undergoes a secondary reaction to form a hydration product. The environmental impact and cost of pure cement were higher than mixed cement.
{"title":"Properties and microstructure of blended cement containing activated iron tailings powder","authors":"B. Liu, H. Meng, G. Pan, Dongxu Li","doi":"10.1680/jadcr.22.00113","DOIUrl":"https://doi.org/10.1680/jadcr.22.00113","url":null,"abstract":"To solve the hidden safety brought by iron tailings powder (ITP). The preparation of green binding materials through ITP have shown bright prospects. However, low activity limits the use of ITP as a supplementary cementitious material in large amounts. Therefore, the activity of ITP at different milling times and sintering temperatures, and its effect on the properties and microstructure of blended cement were studied. The results revealed that ITP has a filling effect and provides additional nucleation sites. In addition, ITP exhibits pozzolanic activity in the later stage, and consumes more hydration products CH, which promotes the formation and deposition of C-S-H, which are all related to its specific surface area. These also provide the conditions for cement paste densification, and lay a foundation for blended cement strength. Moreover, the environmental impact and cost of plain cement were higher than those of mixed cement. Highlights The activity of activated ITP is related to its specific surface area. ITP has a filling effect and provides additional nucleation sites. It takes a long time for iron tailings powder to exert pozzolanic activity. The activated ITP undergoes a secondary reaction to form a hydration product. The environmental impact and cost of pure cement were higher than mixed cement.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42191073","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}
H. Öz, M. Güneş, H. E. Yücel, O. Ersoy, Yunus Sever, Sevgi Demirel
In this study, the usage of an alternative material as supplementary cementitious materials were researched for the design of high performance mortars (HPMs). For this purpose, SWMs (aspect ratio of 22:1) were produced from calcite and quartz sand. Then, SWMs were replaced with the ratios of 0, 3, 6, 9 and 12% by the cement weight to investigate the fresh, mechanical, and shrinkage properties of HPMs. Test results showed that the mechanical and shrinkage properties of HPMs had an improvement up to 9% of SWMs due to its special particle characteristics. The compressive strength, flexural strength, modulus of elasticity, fracture toughness and fracture energy of HPM incorporating 9% of SWM was higher than that of the control mixture by 8.8-9.1%, 7.5-9.9%, 4.7-6.7%, 8.9-4.6% and 13.2-2.5% at 28-90 days, respectively. Similarly, these ratios for maximum drying shrinkage and average crack width were determined as 10.5% and 58.3%, respectively, at the end of 60 days. These findings were also supported by SEM/EDX and TGA/DTA. Moreover, the potential environmental impacts resulting from the production of 1 kg SWM and HPM incorporating 9% SWM were evaluated using the life cycle analysis software (LCA) SimaPro 8.5.0.0. Based on the LCA results, SWMs with acicular particle structure can be used as an alternative material to develop sustainable concrete structures.
{"title":"Life Cycle Assessment and Shrinkage Properties of Sustainable Green HPMs with Eco-Friendly SWMs","authors":"H. Öz, M. Güneş, H. E. Yücel, O. Ersoy, Yunus Sever, Sevgi Demirel","doi":"10.1680/jadcr.22.00010","DOIUrl":"https://doi.org/10.1680/jadcr.22.00010","url":null,"abstract":"In this study, the usage of an alternative material as supplementary cementitious materials were researched for the design of high performance mortars (HPMs). For this purpose, SWMs (aspect ratio of 22:1) were produced from calcite and quartz sand. Then, SWMs were replaced with the ratios of 0, 3, 6, 9 and 12% by the cement weight to investigate the fresh, mechanical, and shrinkage properties of HPMs. Test results showed that the mechanical and shrinkage properties of HPMs had an improvement up to 9% of SWMs due to its special particle characteristics. The compressive strength, flexural strength, modulus of elasticity, fracture toughness and fracture energy of HPM incorporating 9% of SWM was higher than that of the control mixture by 8.8-9.1%, 7.5-9.9%, 4.7-6.7%, 8.9-4.6% and 13.2-2.5% at 28-90 days, respectively. Similarly, these ratios for maximum drying shrinkage and average crack width were determined as 10.5% and 58.3%, respectively, at the end of 60 days. These findings were also supported by SEM/EDX and TGA/DTA. Moreover, the potential environmental impacts resulting from the production of 1 kg SWM and HPM incorporating 9% SWM were evaluated using the life cycle analysis software (LCA) SimaPro 8.5.0.0. Based on the LCA results, SWMs with acicular particle structure can be used as an alternative material to develop sustainable concrete structures.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42509051","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}
Md. Nabi Newaz Khan, Manjur A Elahi, Jhutan Chandra Kuri, P. Sarker, Faiz Shaikh
This study examined the efficacy of waste glass cullet as a substitute materials to natural fine aggregate in alkali activated composites when exposed to H2SO4 and HCl acid solutions for one year. The changes in physical appearance, surface alkalinity, mass, mechanical strength and microstructure of the hardened samples before and after immersion in acid solutions were investigated. The findings of the experimental work indicated that the physical, mechanical and microstructural damages of the specimens due to acid attacks increased with the rise of glass aggregate percentages. This is attributed to the smooth surface texture and angularity of the glass cullet which affected the bond with the damaged paste matrix at the interfacial transition zone (ITZ) and increased the porosity. However, the acid resistance performance of the mortars containing up to 50% glass aggregate was found satisfactory when compared with the mortar without glass fine aggregate. Therefore, the use of waste glass cullet as a partial replacement of natural sand by up to 50% is considered feasible in alkali activated systems against acid exposures.
{"title":"Acid Resistance of Alkali Activated Composites Containing Waste Glass Fine Aggregate","authors":"Md. Nabi Newaz Khan, Manjur A Elahi, Jhutan Chandra Kuri, P. Sarker, Faiz Shaikh","doi":"10.1680/jadcr.21.00022","DOIUrl":"https://doi.org/10.1680/jadcr.21.00022","url":null,"abstract":"This study examined the efficacy of waste glass cullet as a substitute materials to natural fine aggregate in alkali activated composites when exposed to H2SO4 and HCl acid solutions for one year. The changes in physical appearance, surface alkalinity, mass, mechanical strength and microstructure of the hardened samples before and after immersion in acid solutions were investigated. The findings of the experimental work indicated that the physical, mechanical and microstructural damages of the specimens due to acid attacks increased with the rise of glass aggregate percentages. This is attributed to the smooth surface texture and angularity of the glass cullet which affected the bond with the damaged paste matrix at the interfacial transition zone (ITZ) and increased the porosity. However, the acid resistance performance of the mortars containing up to 50% glass aggregate was found satisfactory when compared with the mortar without glass fine aggregate. Therefore, the use of waste glass cullet as a partial replacement of natural sand by up to 50% is considered feasible in alkali activated systems against acid exposures.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45554590","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}
Shu-hui Lei, Dongdong Zhou, Li Fang, Qiaozhen Yang, F. Cheng
The effect of early hydration behavior on the long-term performance of cement is profound, but its study is lacking. The early hydration behavior and mechanical properties of basic magnesium sulfate (BMS) cement were investigated by using electrodeless resistivity test combined with compressive strength measurement, XRD, SEM and Mercury intrusion porosimetry (MIP). As a result, the early hydration process of BMS cement can be clearly divided into three stages including induction period, acceleration period and deceleration period according to the resistivity variation curve. A linear correlation between the resistivity and setting time of BMS cement is established. Thus the initial setting time and final setting time of BMS cement can be estimated using feature point A (the time that the growth rate of resistivity starts rising) and feature point B (the time for the maximum growth rate of resistivity) on the differential curve of electrical resistivity, respectively. Moreover, a linear fitting equation between the resistivity (24 h) and compressive strength of BMS cement curing for 28 d is determined. The correlation coefficient is as high as 0.9979. Using the fitted linear equation, the long-term strength (28 d) of BMS cement can be precisely predicted by the measured resistivity (24 h). This study provides us a feasible, accurate and in situ method for understanding the early hydration behavior and quality monitoring of BMS cement.
{"title":"Study on Early Hydration Behavior and Mechanical Properties of Basic Magnesium Sulfate Cement Using Electrodeless Resistivity Measurements","authors":"Shu-hui Lei, Dongdong Zhou, Li Fang, Qiaozhen Yang, F. Cheng","doi":"10.1680/jadcr.22.00031","DOIUrl":"https://doi.org/10.1680/jadcr.22.00031","url":null,"abstract":"The effect of early hydration behavior on the long-term performance of cement is profound, but its study is lacking. The early hydration behavior and mechanical properties of basic magnesium sulfate (BMS) cement were investigated by using electrodeless resistivity test combined with compressive strength measurement, XRD, SEM and Mercury intrusion porosimetry (MIP). As a result, the early hydration process of BMS cement can be clearly divided into three stages including induction period, acceleration period and deceleration period according to the resistivity variation curve. A linear correlation between the resistivity and setting time of BMS cement is established. Thus the initial setting time and final setting time of BMS cement can be estimated using feature point A (the time that the growth rate of resistivity starts rising) and feature point B (the time for the maximum growth rate of resistivity) on the differential curve of electrical resistivity, respectively. Moreover, a linear fitting equation between the resistivity (24 h) and compressive strength of BMS cement curing for 28 d is determined. The correlation coefficient is as high as 0.9979. Using the fitted linear equation, the long-term strength (28 d) of BMS cement can be precisely predicted by the measured resistivity (24 h). This study provides us a feasible, accurate and in situ method for understanding the early hydration behavior and quality monitoring of BMS cement.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49506798","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}
In this work, polyether, acrylic acid and oleic acid were used as raw materials to synthesize oleic acid modified polycarboxylate superplasticizer (OA-PCE) by emulsion polymerization, and the synthesis process was optimized by orthogonal experiment. The colloidal interfacial chemistry results concluded that OA-PCE was more capable of reducing the surface tension of aqueous solutions than unmodified traditional polycarboxylate superplasticizer (JS-PCE), and the adsorption capacity on cement particles was more significant. The isothermal adsorption behavior of two kinds of polycarboxylate superplasticizers on cement conformed to the Freundlich isothermal adsorption equation, and it was a physical adsorption process by electrostatic action. The effect of the OA-PCE dosage on the flowability of cement slurry was preliminarily investigated by rheological behavior testing, according to the yield stress, plastic viscosity and thixotropic ring area of slurry, which showed that 0.35 wt% addition of OA-PCE in cement had the optimum effect. The mechanical properties results showed that the compressive strength values of concrete with OA-PCE (0.35 wt%) at 4 h and 7 d were 117.1% and 88.3% higher than those of control group, respectively, which all met the standards for the use of concrete in metro pipe sheets. Therefore, OA-PCE synthesized by emulsion polymerization had certain significance for the development of polycarboxylate superplasticizer both in terms of polymerization methods and practical applications.
{"title":"Synthesis of Modified Polycarboxylate Superplasticizer and Effect on Properties of Cement","authors":"Xiaoyu Zhang, W. Zhen, S. Guan, Junliang Chen","doi":"10.1680/jadcr.21.00212","DOIUrl":"https://doi.org/10.1680/jadcr.21.00212","url":null,"abstract":"In this work, polyether, acrylic acid and oleic acid were used as raw materials to synthesize oleic acid modified polycarboxylate superplasticizer (OA-PCE) by emulsion polymerization, and the synthesis process was optimized by orthogonal experiment. The colloidal interfacial chemistry results concluded that OA-PCE was more capable of reducing the surface tension of aqueous solutions than unmodified traditional polycarboxylate superplasticizer (JS-PCE), and the adsorption capacity on cement particles was more significant. The isothermal adsorption behavior of two kinds of polycarboxylate superplasticizers on cement conformed to the Freundlich isothermal adsorption equation, and it was a physical adsorption process by electrostatic action. The effect of the OA-PCE dosage on the flowability of cement slurry was preliminarily investigated by rheological behavior testing, according to the yield stress, plastic viscosity and thixotropic ring area of slurry, which showed that 0.35 wt% addition of OA-PCE in cement had the optimum effect. The mechanical properties results showed that the compressive strength values of concrete with OA-PCE (0.35 wt%) at 4 h and 7 d were 117.1% and 88.3% higher than those of control group, respectively, which all met the standards for the use of concrete in metro pipe sheets. Therefore, OA-PCE synthesized by emulsion polymerization had certain significance for the development of polycarboxylate superplasticizer both in terms of polymerization methods and practical applications.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43067402","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. Kothari, Ilda Tole, H. Hedlund, Tommy Ellison, A. Ćwirzeń
The effects of a partial replacement of Ordinary Portland cement (OPC) with three types of calcium sulfoaluminate (CSA) cements (40 wt% and 20 wt%) were investigated. The obtained results were generally in agreement with previously published data but with few interesting exceptions. Setting times were shortened due to the formation of ettringite. The maximum hydration temperature increased for concretes containing 40 wt% of CSA but decreased when 20 wt% replacement was used. The decrease was related to the deficiency of the available sulfates, which limited the formation of ettringite. The presence of extra anhydrite and calcium oxide was associated to the delayed establishment of the second temperature peak in contrast to OPC-based concretes. Their surplus delayed calcium aluminate and belite reactions, and triggered renewed formation of ettringite, C-S-H and portlandite. Effects of aluminum hydroxide were also indicated as possibly important, although not proved experimentally in this research. The slightly lower compressive strength measured for mixes containing 40 wt% of CSA were linked with more formed ettringite. The same factor was indicated as the key to the reduction of the total shrinkage in mixes containing 40 wt% of CSA and increased for the lower CSA replacement level. In that case, the insufficient amount of formed ettringite caused too small expansion, which could not efficiently mitigate or compensate the developed shrinkage.
{"title":"Partial replacement of OPC with CSA cements – effects on hydration, fresh-, hardened-properties","authors":"A. Kothari, Ilda Tole, H. Hedlund, Tommy Ellison, A. Ćwirzeń","doi":"10.1680/jadcr.22.00054","DOIUrl":"https://doi.org/10.1680/jadcr.22.00054","url":null,"abstract":"The effects of a partial replacement of Ordinary Portland cement (OPC) with three types of calcium sulfoaluminate (CSA) cements (40 wt% and 20 wt%) were investigated. The obtained results were generally in agreement with previously published data but with few interesting exceptions. Setting times were shortened due to the formation of ettringite. The maximum hydration temperature increased for concretes containing 40 wt% of CSA but decreased when 20 wt% replacement was used. The decrease was related to the deficiency of the available sulfates, which limited the formation of ettringite. The presence of extra anhydrite and calcium oxide was associated to the delayed establishment of the second temperature peak in contrast to OPC-based concretes. Their surplus delayed calcium aluminate and belite reactions, and triggered renewed formation of ettringite, C-S-H and portlandite. Effects of aluminum hydroxide were also indicated as possibly important, although not proved experimentally in this research. The slightly lower compressive strength measured for mixes containing 40 wt% of CSA were linked with more formed ettringite. The same factor was indicated as the key to the reduction of the total shrinkage in mixes containing 40 wt% of CSA and increased for the lower CSA replacement level. In that case, the insufficient amount of formed ettringite caused too small expansion, which could not efficiently mitigate or compensate the developed shrinkage.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45592811","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 dielectric properties of cement concrete are not only related to the dielectric properties and volume ratio of each component, but also related to frequency and temperature. In order to analyze these influencing factors, a dielectric constant test was done in the laboratory. Experimental results show that the dielectric constants decrease linearly with temperature increasing and decreases exponentially with the increase of frequency. Based on the experimental rules, a new dielectric model including frequency and temperature is established and verified by experiments. The verification results show that the calculation accuracy of the comprehensive dielectric model after considering the influence of frequency and temperature is improved by 25.5%, which meets the requirements of engineering detection accuracy. The model is applied to engineering practice, and the calculation methods of pavement structural layer thickness and moisture content are developed. The results show that the comprehensive dielectric model established in this paper has smaller error and higher accuracy. Using this dielectric model, the data conversion between different frequency and temperature can be achieved. The research results of this paper can provide reference and basis for the quality evaluation of concrete structures.
{"title":"Comprehensive dielectric model of cement concrete including frequency and temperature","authors":"Meili Meng, Zhanglan Chen, F. Wang","doi":"10.1680/jadcr.21.00196","DOIUrl":"https://doi.org/10.1680/jadcr.21.00196","url":null,"abstract":"The dielectric properties of cement concrete are not only related to the dielectric properties and volume ratio of each component, but also related to frequency and temperature. In order to analyze these influencing factors, a dielectric constant test was done in the laboratory. Experimental results show that the dielectric constants decrease linearly with temperature increasing and decreases exponentially with the increase of frequency. Based on the experimental rules, a new dielectric model including frequency and temperature is established and verified by experiments. The verification results show that the calculation accuracy of the comprehensive dielectric model after considering the influence of frequency and temperature is improved by 25.5%, which meets the requirements of engineering detection accuracy. The model is applied to engineering practice, and the calculation methods of pavement structural layer thickness and moisture content are developed. The results show that the comprehensive dielectric model established in this paper has smaller error and higher accuracy. Using this dielectric model, the data conversion between different frequency and temperature can be achieved. The research results of this paper can provide reference and basis for the quality evaluation of concrete structures.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":"1 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2022-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41431294","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：