In this study, the cement was regenerated using completely recyclable mortar (CRM) as raw cement meals. The effects of silica modulus (SM) and aluminum modulus (AM) on the CRM properties, burnability of raw meal, and clinker properties were studied. The results showed that with a higher SM and lower AM, less melt would be available to facilitate the diffusion of CaO towards belite to form alite. The compressive strength of recycled cement increased with the increase of AM when SM=2.7 and 2.2 and decreased with the increase of AM at a low SM (SM=1.7). The suggested rate value of raw meals using CRM is a medium SM (SM= 2.2 or SM=2.7) and AM=1.5-1.8 with a calcination temperature of 1400 ℃. The strength of both CRM and the obtained recycled cement clinker is relatively high. Moreover, the calcination temperature could be further reduced to 1300℃ or 1350℃with a low SM (SM=1.7) and AM (AM=0.9-1.5). Though the CRM had a lower early strength, it had a relatively high strength in the later stage. However, its water absorption is significantly increased compared to the control group.
{"title":"The regeneration of cement from completely recyclable mortar: effect of raw materials compositions","authors":"Yunpeng Liu, Yingying Cui, Xianxin Tong","doi":"10.1680/jadcr.23.00129","DOIUrl":"https://doi.org/10.1680/jadcr.23.00129","url":null,"abstract":"In this study, the cement was regenerated using completely recyclable mortar (CRM) as raw cement meals. The effects of silica modulus (SM) and aluminum modulus (AM) on the CRM properties, burnability of raw meal, and clinker properties were studied. The results showed that with a higher SM and lower AM, less melt would be available to facilitate the diffusion of CaO towards belite to form alite. The compressive strength of recycled cement increased with the increase of AM when SM=2.7 and 2.2 and decreased with the increase of AM at a low SM (SM=1.7). The suggested rate value of raw meals using CRM is a medium SM (SM= 2.2 or SM=2.7) and AM=1.5-1.8 with a calcination temperature of 1400 ℃. The strength of both CRM and the obtained recycled cement clinker is relatively high. Moreover, the calcination temperature could be further reduced to 1300℃ or 1350℃with a low SM (SM=1.7) and AM (AM=0.9-1.5). Though the CRM had a lower early strength, it had a relatively high strength in the later stage. However, its water absorption is significantly increased compared to the control group.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141803862","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}
Extracting more information about reactions and parameters governing the build-up formation process, in the preheater system of the clinker burning line, could be an efficient tool to better attenuate their formation. In order to control their appearance, diagnosis steps of mineralogical analysis application for process optimization (MAA-PO) are suggested. Mineralogical characterization is carried out on three samples taken from different layers of the same build-up. The qualitative and quantitative X-ray diffraction, combined with chemical analysis and IR study, shows that Ternesite is the key mineralogical phase responsible for their growth and consolidation. Its appearance is governed by solid-solid reactions promoted by the available sulfate liquid phases, mainly Ca –langbeinite, as well as C12A7 and C4AF presence. The hot powder calcination degree, SO3 amount, LSF, SR and MA are operational data that have been correlated to the build-up mineralogical analysis. Based on this correlation, it is possible to predict the reactions kinetics involving in each layer formation and to estimate the development time of each. Results showed that MAA-OP is a promised novel approach to optimize clinker production process parameters.
在熟料烧成线的预热器系统中提取更多有关堆积形成过程的反应和参数信息，可以有效地减少堆积的形成。为了控制堆积物的出现，建议采用矿物学分析应用于工艺优化（MAA-PO）的诊断步骤。矿物学特征描述是对取自同一堆积层不同层的三个样本进行的。通过定性和定量 X 射线衍射，结合化学分析和红外研究，发现特立尼达岩是导致其生长和固结的关键矿物相。它的出现受制于硫酸盐液相（主要是 Ca -langbeinite）以及 C12A7 和 C4AF 的存在所促进的固固反应。热粉煅烧度、SO3 量、LSF、SR 和 MA 是与堆积矿物学分析相关联的操作数据。根据这种相关性，可以预测每一层形成的反应动力学，并估计每一层的形成时间。结果表明，MAA-OP 是优化熟料生产工艺参数的一种新型方法。
{"title":"Build-up formation in cement kiln preheater: qualitative and quantitative mineral characterization","authors":"Sahar Belgacem, Haykel Galai","doi":"10.1680/jadcr.22.00077","DOIUrl":"https://doi.org/10.1680/jadcr.22.00077","url":null,"abstract":"Extracting more information about reactions and parameters governing the build-up formation process, in the preheater system of the clinker burning line, could be an efficient tool to better attenuate their formation. In order to control their appearance, diagnosis steps of mineralogical analysis application for process optimization (MAA-PO) are suggested. Mineralogical characterization is carried out on three samples taken from different layers of the same build-up. The qualitative and quantitative X-ray diffraction, combined with chemical analysis and IR study, shows that Ternesite is the key mineralogical phase responsible for their growth and consolidation. Its appearance is governed by solid-solid reactions promoted by the available sulfate liquid phases, mainly Ca –langbeinite, as well as C12A7 and C4AF presence. The hot powder calcination degree, SO3 amount, LSF, SR and MA are operational data that have been correlated to the build-up mineralogical analysis. Based on this correlation, it is possible to predict the reactions kinetics involving in each layer formation and to estimate the development time of each. Results showed that MAA-OP is a promised novel approach to optimize clinker production process parameters.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141806070","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 present study is comprehensive research on application of biocementation for enhancing the properties of concrete having rice husk ash (RHA) as a supplementary cementitious material (SCM). RHA has a large potential to be used as SCM because it has high silica content which eventually forms C-S-H gel by reacting with calcium and water, which increases strength of the cementitious material. However, using high doses of RHA causes a decrease in concrete strength because excessive silica is available to react with Ca(OH)2, forming silica clumps within the concrete matrix, which reduce the bonds within the concrete constituents causing micro cracks. Hence to mitigate this problem, enzyme induced calcium carbonate precipitation (EICCP) process was used to treat the micro cracks, and enhance the mechanical and durability properties of RHA blended concrete. Results showed that EICCP process enhanced the strength of the mix at each replacement level and 10% replacement level exhibited optimum results. With nearly 29% increment in compressive strength. This mix also exhibited enhanced durability as compared to the control specimens. Since concrete constitutes a significant portion of embodied carbon footprint, using greener concrete mixes like “Experimental Mix” has the potential to considerably decrease the carbon footprint of construction.
{"title":"Application of biomineralization for enhancement of interfacial properties of rice husk ash blended concrete","authors":"Rishabh D. Junwale, M. Latkar","doi":"10.1680/jadcr.23.00190","DOIUrl":"https://doi.org/10.1680/jadcr.23.00190","url":null,"abstract":"The present study is comprehensive research on application of biocementation for enhancing the properties of concrete having rice husk ash (RHA) as a supplementary cementitious material (SCM). RHA has a large potential to be used as SCM because it has high silica content which eventually forms C-S-H gel by reacting with calcium and water, which increases strength of the cementitious material. However, using high doses of RHA causes a decrease in concrete strength because excessive silica is available to react with Ca(OH)2, forming silica clumps within the concrete matrix, which reduce the bonds within the concrete constituents causing micro cracks. Hence to mitigate this problem, enzyme induced calcium carbonate precipitation (EICCP) process was used to treat the micro cracks, and enhance the mechanical and durability properties of RHA blended concrete. Results showed that EICCP process enhanced the strength of the mix at each replacement level and 10% replacement level exhibited optimum results. With nearly 29% increment in compressive strength. This mix also exhibited enhanced durability as compared to the control specimens. Since concrete constitutes a significant portion of embodied carbon footprint, using greener concrete mixes like “Experimental Mix” has the potential to considerably decrease the carbon footprint of construction.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141809499","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}
Nano-silica is used in various composite materials as a kind of filler with good performance. In this study, hydrogen peroxide was used to repair and activate the hydroxyl group on the surface of nano-silica, and chitosan phosphate ester was loaded onto the surface of nano-silica through intermolecular dehydration to prepare nano-silica@ chitosan phosphate ester, and nano-silica@ chitosan phosphate ester was added to the magnesium oxychloride cement for water resistance modification. The results showed that the addition of nano-silica@ chitosan phosphate ester increased the compressive strength of magnesium oxychloride cement at different ages, and the compressive strength of the modified magnesium oxychloride cement at 7 days and 28 days were 116 MPa and 127 MPa, respectively, which increased by 11.5% and 5.8% compared with the unmodified samples. The compressive strength of the modified magnesium oxychloride cement reached 102 MPa after 28 days of water immersion, which was 8.3% higher than that of the phosphoric acid modified sample under the same water immersion duration. At the same time, it was found that nano-silica@ chitosan phosphate ester can increase the fluidity of magnesium oxychloride cement slurry, accelerate the hydration reaction rate and refine the pores.
{"title":"Effect of nano-silica@ chitosan phosphate ester on the mechanical properties and water resistance of magnesium oxychloride cement","authors":"Qihao Liu, Qian Jia, Ru-Dong Chen","doi":"10.1680/jadcr.23.00240","DOIUrl":"https://doi.org/10.1680/jadcr.23.00240","url":null,"abstract":"Nano-silica is used in various composite materials as a kind of filler with good performance. In this study, hydrogen peroxide was used to repair and activate the hydroxyl group on the surface of nano-silica, and chitosan phosphate ester was loaded onto the surface of nano-silica through intermolecular dehydration to prepare nano-silica@ chitosan phosphate ester, and nano-silica@ chitosan phosphate ester was added to the magnesium oxychloride cement for water resistance modification. The results showed that the addition of nano-silica@ chitosan phosphate ester increased the compressive strength of magnesium oxychloride cement at different ages, and the compressive strength of the modified magnesium oxychloride cement at 7 days and 28 days were 116 MPa and 127 MPa, respectively, which increased by 11.5% and 5.8% compared with the unmodified samples. The compressive strength of the modified magnesium oxychloride cement reached 102 MPa after 28 days of water immersion, which was 8.3% higher than that of the phosphoric acid modified sample under the same water immersion duration. At the same time, it was found that nano-silica@ chitosan phosphate ester can increase the fluidity of magnesium oxychloride cement slurry, accelerate the hydration reaction rate and refine the pores.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141806408","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 early-age strength of grouting material is crucial for tunnel support under high geothermal temperatures. Grouting materials (such as the most commonly used cement slurry) hydrate and solidify under the condition of variable temperature curing after entering the real stratum. However, the development process of early strength of cement paste under the condition of variable temperature curing is still unclear. This study aims to elucidate the environmental effects of high ground heat tunnels on the early strength development of cement stone. The cement slurry undergoes variable temperature curing under three different temperatures (T=40℃, 60℃, 80℃) and two different relative humidity conditions (H=5%, 95%) through design experiments. Through the compressive strength test, combined with X-ray diffraction (XRD), scanning electron microscope (SEM) and nuclear magnetic resonance (NMR), the microscopic characteristics were studied. The results indicate that the strength of cement stone under variable temperature curing is lower than that under constant temperature curing at the same temperature. The influence of variable temperature curing conditions on the strength variation of samples with high W/C and age was greater at 80℃. The research results are helpful to understand the influence of environmental effects of high ground temperature tunnels on the properties of grouting materials.
灌浆材料的早期强度对于隧道在高地温条件下的支护至关重要。灌浆材料（如最常用的水泥浆）进入实际地层后，在变温固化条件下水化凝固。然而，水泥浆在变温固化条件下早期强度的发展过程尚不清楚。本研究旨在阐明高地热隧道对水泥石早期强度发展的环境影响。通过设计实验，水泥浆体在三种不同温度（T=40℃、60℃、80℃）和两种不同相对湿度条件（H=5%、95%）下进行变温养护。通过抗压强度试验，结合 X 射线衍射（XRD）、扫描电子显微镜（SEM）和核磁共振（NMR），研究了水泥的微观特性。结果表明，水泥石在变温养护条件下的强度低于相同温度下的恒温养护条件。变温养护条件对高 W/C 和龄期样品强度变化的影响在 80℃ 时更大。研究结果有助于了解高地温隧道环境效应对灌浆材料性能的影响。
{"title":"Strength characteristics of cement slurry in high geothermal tunnel environment","authors":"Meng Wang, Weihao Li, Zhiheng Wang, Chunyu Zhang, Changzhi Shao, Xianjie Xu, Ping Jiang, Yan-kai Liu, Rentai Liu","doi":"10.1680/jadcr.23.00105","DOIUrl":"https://doi.org/10.1680/jadcr.23.00105","url":null,"abstract":"The early-age strength of grouting material is crucial for tunnel support under high geothermal temperatures. Grouting materials (such as the most commonly used cement slurry) hydrate and solidify under the condition of variable temperature curing after entering the real stratum. However, the development process of early strength of cement paste under the condition of variable temperature curing is still unclear. This study aims to elucidate the environmental effects of high ground heat tunnels on the early strength development of cement stone. The cement slurry undergoes variable temperature curing under three different temperatures (T=40℃, 60℃, 80℃) and two different relative humidity conditions (H=5%, 95%) through design experiments. Through the compressive strength test, combined with X-ray diffraction (XRD), scanning electron microscope (SEM) and nuclear magnetic resonance (NMR), the microscopic characteristics were studied. The results indicate that the strength of cement stone under variable temperature curing is lower than that under constant temperature curing at the same temperature. The influence of variable temperature curing conditions on the strength variation of samples with high W/C and age was greater at 80℃. The research results are helpful to understand the influence of environmental effects of high ground temperature tunnels on the properties of grouting materials.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141660505","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}
Calcium Sulfoaluminate (CSA) cements are known for their special properties, such as shrinkage compensation and high early-age strength. These properties are dependent on the hydrated phase assemblage, which in turn is governed by the phases present in the initial anhydrous cement. However, the anhydrous CSA phase quantification via XRD Rietveld can be challenging due to the presence of overlapping peaks, polymorphs, and preferred orientation. To overcome this problem, an approach involving high-resolution large-area Raman imaging (5mm x 5mm, 250,000 pixels, with 10 μm/pixel resolution) complemented by XRD analysis is introduced. This integrated approach of combined XRD and Raman Imaging is found to be crucial in the initial identification of phases that are present in a CSA system. Most importantly, quantitative analysis shows a strong correlation (R2 > 0.99) and agreement (variation < 5 wt.%) between the two independent methods, adding confidence and reliability to the phase assemblage obtained by this dual technique approach.
{"title":"Phase quantification of anhydrous CSA cements: a combined X-ray diffraction and Raman imaging approach","authors":"Chirayu Kothari, Nishant Garg","doi":"10.1680/jadcr.23.00238","DOIUrl":"https://doi.org/10.1680/jadcr.23.00238","url":null,"abstract":"Calcium Sulfoaluminate (CSA) cements are known for their special properties, such as shrinkage compensation and high early-age strength. These properties are dependent on the hydrated phase assemblage, which in turn is governed by the phases present in the initial anhydrous cement. However, the anhydrous CSA phase quantification via XRD Rietveld can be challenging due to the presence of overlapping peaks, polymorphs, and preferred orientation. To overcome this problem, an approach involving high-resolution large-area Raman imaging (5mm x 5mm, 250,000 pixels, with 10 μm/pixel resolution) complemented by XRD analysis is introduced. This integrated approach of combined XRD and Raman Imaging is found to be crucial in the initial identification of phases that are present in a CSA system. Most importantly, quantitative analysis shows a strong correlation (R2 > 0.99) and agreement (variation < 5 wt.%) between the two independent methods, adding confidence and reliability to the phase assemblage obtained by this dual technique approach.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141350073","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. Jakob, Jennifer Viola Rudolph, J. Wolf, Jürgen Neubauer
With the ongoing development of new technologies like 3D printing, the requirements for the performance of cementitious materials become more complex. Setting on demand, while the workability of the material is retained until placement, is an important aspect of this usage. A ternary CSA-OPC-C$ system was developed to achieve setting on demand in a 2-component setup, where two retarded cementitious components were mixed after specific times of storage. The kinetics of the individual systems and the blend were examined by heat flow calorimetry, quantitative X-ray diffraction and pore water analysis. The rheological development was monitored by a penetration test method. The results show that the performance of the blend is independent of the storage time of the individual components and can be tailored by changes in the retarder dosage in the individual components. The initial reaction in the blend is characterized by the simultaneous dissolution of ye'elimite and C3S, resulting in the formation of ettringite as the sole detectable hydrate phase. The fate of silicon remains unclear as with the methodology at hand no silicon incorporating hydrate phase can be identified.
随着 3D 打印等新技术的不断发展，对水泥基材料性能的要求也变得更加复杂。按需凝结，同时在浇注前保持材料的可加工性，是这种用途的一个重要方面。我们开发了一种三元 CSA-OPC-C$ 系统，用于在双组分设置中实现按需凝结，其中两种缓凝胶凝组分在特定储存时间后混合。通过热流量热仪、定量 X 射线衍射和孔隙水分析对单个体系和混合体系的动力学进行了研究。流变发展情况则通过渗透试验法进行监测。结果表明，混合物的性能与单个成分的储存时间无关，并且可以通过改变单个成分中缓凝剂的用量来调整。混合物的初始反应特点是叶焰硝和 C3S 同时溶解，形成乙丁睛石作为唯一可检测到的水合物相。硅的去向仍不清楚，因为根据现有的方法，无法确定含有硅的水合物相。
{"title":"Hydration of a 2-component CSA-OPC-mix – timing of component blending & setting on demand","authors":"C. Jakob, Jennifer Viola Rudolph, J. Wolf, Jürgen Neubauer","doi":"10.1680/jadcr.23.00231","DOIUrl":"https://doi.org/10.1680/jadcr.23.00231","url":null,"abstract":"With the ongoing development of new technologies like 3D printing, the requirements for the performance of cementitious materials become more complex. Setting on demand, while the workability of the material is retained until placement, is an important aspect of this usage. A ternary CSA-OPC-C$ system was developed to achieve setting on demand in a 2-component setup, where two retarded cementitious components were mixed after specific times of storage. The kinetics of the individual systems and the blend were examined by heat flow calorimetry, quantitative X-ray diffraction and pore water analysis. The rheological development was monitored by a penetration test method. The results show that the performance of the blend is independent of the storage time of the individual components and can be tailored by changes in the retarder dosage in the individual components. The initial reaction in the blend is characterized by the simultaneous dissolution of ye'elimite and C3S, resulting in the formation of ettringite as the sole detectable hydrate phase. The fate of silicon remains unclear as with the methodology at hand no silicon incorporating hydrate phase can be identified.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141360929","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}
M. Marroccoli, A. Telesca, B. Lothenbach, F. Winnefeld
Belite-calcium sulfoaluminate (BCSA) clinkers are usually obtained at temperatures lower than 1350°C by burning a raw meal composed of limestone, clay, natural gypsum and bauxite. The use of limestone quarry waste, dredged sediments, water potabilization sludge and flue gas desulfurization gypsum as complete substitutes for natural raw materials was investigated. Two BCSA clinkers based on natural raw materials and on waste materials, respectively, were synthesized in a laboratory electric furnace. Two BCSA cements were prepared by blending the clinkers with natural anhydrite at the same calcium sulfate / ye'elimite ratio, and their hydration behaviour was investigated. The BCSA cement made from the waste materials showed a faster early reaction than the one prepared from natural raw materials. At later ages, both cements developed a similar hydrate assemblage, consisting mainly of ettringite, AFm-phases and strätlingite. Also the physical properties, i.e. compressive strength, porosity and volume stability, are rather similar, with the exception that late compressive strength (after 56 days) is significantly higher for the cement made from waste materials. The results show that it is possible to manufacture BCSA clinkers entirely from local waste materials.
{"title":"Synthesis and properties of a belite-CSA cement obtained using only waste materials","authors":"M. Marroccoli, A. Telesca, B. Lothenbach, F. Winnefeld","doi":"10.1680/jadcr.24.00005","DOIUrl":"https://doi.org/10.1680/jadcr.24.00005","url":null,"abstract":"Belite-calcium sulfoaluminate (BCSA) clinkers are usually obtained at temperatures lower than 1350°C by burning a raw meal composed of limestone, clay, natural gypsum and bauxite. The use of limestone quarry waste, dredged sediments, water potabilization sludge and flue gas desulfurization gypsum as complete substitutes for natural raw materials was investigated. Two BCSA clinkers based on natural raw materials and on waste materials, respectively, were synthesized in a laboratory electric furnace. Two BCSA cements were prepared by blending the clinkers with natural anhydrite at the same calcium sulfate / ye'elimite ratio, and their hydration behaviour was investigated. The BCSA cement made from the waste materials showed a faster early reaction than the one prepared from natural raw materials. At later ages, both cements developed a similar hydrate assemblage, consisting mainly of ettringite, AFm-phases and strätlingite. Also the physical properties, i.e. compressive strength, porosity and volume stability, are rather similar, with the exception that late compressive strength (after 56 days) is significantly higher for the cement made from waste materials. The results show that it is possible to manufacture BCSA clinkers entirely from local waste materials.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141385620","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 problem of low early-phase reactivity of ferrous extraction tailing of nickel slag (FETNS), the effects of Ca(OH)2 as an alkali activator on the working performance, mechanical properties, and hydration products of FETNS-ordinary Portland cement (OPC) composite cementitious system were studied. The results show that the addition of Ca(OH)2 shortens the initial setting time of the composite cementitious system by about 40% and the final setting time by about 20%. The compressive strength at 3d, 7d, 28d and 60d is increased by 51.95%, 45.27%, 8.53% and 8.9%, respectively. The microstructure inside the pastes is characterized by scanning electron microscopy (SEM). X-ray diffraction (XRD), simultaneous thermal analysis (TG-DTG), nitrogen adsorption test (N2-Sorption isotherm), and low-field nuclear magnetic resonance (LF-NMR) analysis show that the incorporation of Ca(OH)2 increases the reaction degree of the composite cementitious system, and more C-S-H gel and ettringite (AFt) are generated to fill the internal pores, which improve the compactness of the structure. The incorporation of Ca(OH)2 can stimulate the early-phase reactivity of the composite cementitious system, promote the formation of reaction products, and optimize the internal pore structure.
{"title":"Feasibility study of adding alkali activator Ca(OH)2 into ferrous extraction tailing of nickel slag-ordinary Portland cement composite cementitious system: working performance, mechanical properties, and reaction mechanism","authors":"Yanning Song, Hong-zhuo Qiao, Qiong Feng, Chao Wei, Jianghua Zheng, Hong-zhuo Qiao","doi":"10.1680/jadcr.23.00168","DOIUrl":"https://doi.org/10.1680/jadcr.23.00168","url":null,"abstract":"To solve the problem of low early-phase reactivity of ferrous extraction tailing of nickel slag (FETNS), the effects of Ca(OH)2 as an alkali activator on the working performance, mechanical properties, and hydration products of FETNS-ordinary Portland cement (OPC) composite cementitious system were studied. The results show that the addition of Ca(OH)2 shortens the initial setting time of the composite cementitious system by about 40% and the final setting time by about 20%. The compressive strength at 3d, 7d, 28d and 60d is increased by 51.95%, 45.27%, 8.53% and 8.9%, respectively. The microstructure inside the pastes is characterized by scanning electron microscopy (SEM). X-ray diffraction (XRD), simultaneous thermal analysis (TG-DTG), nitrogen adsorption test (N2-Sorption isotherm), and low-field nuclear magnetic resonance (LF-NMR) analysis show that the incorporation of Ca(OH)2 increases the reaction degree of the composite cementitious system, and more C-S-H gel and ettringite (AFt) are generated to fill the internal pores, which improve the compactness of the structure. The incorporation of Ca(OH)2 can stimulate the early-phase reactivity of the composite cementitious system, promote the formation of reaction products, and optimize the internal pore structure.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141384554","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}
Nanoparticles are widely used in construction. Here, nano-SiO2 is employed, in a way that prevents agglomeration of the nanoparticles, as pozzolanic material to improve Portland cement hydration and to improve the properties of the concrete. To explore the effect of nano-SiO2 and core-shell PS@SiO2 on cement properties, spherical polystyrene particles were prepared by dispersion polymerization of styrene in polar solvents and characterized by FTIR and E-SEM. The core shells PS@SiO2 were synthesized by Stöber method. The results showed an amorphous nano-SiO2 layer can be deposited uniformly on polystyrene particles. This core/shell structure was reducing the aggregation of nano-SiO2 effectively. It was shown that PS@SiO2 particles improved the concrete performances compared to blended cement with nano-SiO2 due to the agglomeration affect. Highlights • Core/shell PS@SiO2 nanoparticles with a uniform coating layer were prepared. • As-prepared nanoparticles were characterized by a variety of advanced methods. • Nanoparticles accelerate hydration and lower the spatial weight of cement paste. • Core/shell nanoparticles improve cement hydration much better than nano-SiO2.
{"title":"Enhancing cement hydration by core/shell PS@SiO2 nanoparticles","authors":"Meytal Shalit, Maya Radune, Yaniv Knop, Y. Mastai","doi":"10.1680/jadcr.23.00203","DOIUrl":"https://doi.org/10.1680/jadcr.23.00203","url":null,"abstract":"Nanoparticles are widely used in construction. Here, nano-SiO2 is employed, in a way that prevents agglomeration of the nanoparticles, as pozzolanic material to improve Portland cement hydration and to improve the properties of the concrete. To explore the effect of nano-SiO2 and core-shell PS@SiO2 on cement properties, spherical polystyrene particles were prepared by dispersion polymerization of styrene in polar solvents and characterized by FTIR and E-SEM. The core shells PS@SiO2 were synthesized by Stöber method. The results showed an amorphous nano-SiO2 layer can be deposited uniformly on polystyrene particles. This core/shell structure was reducing the aggregation of nano-SiO2 effectively. It was shown that PS@SiO2 particles improved the concrete performances compared to blended cement with nano-SiO2 due to the agglomeration affect. Highlights • Core/shell PS@SiO2 nanoparticles with a uniform coating layer were prepared. • As-prepared nanoparticles were characterized by a variety of advanced methods. • Nanoparticles accelerate hydration and lower the spatial weight of cement paste. • Core/shell nanoparticles improve cement hydration much better than nano-SiO2.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140991435","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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