The setting time and early strength of shotcrete is greatly affected by the gypsum content of cement. In this paper, setting time and compressive strength, and microscopic methods such as XRD quantitative analysis, thermogravimetric analysis and scanning electron microscope observation were used to determine the effects of changes in gypsum content on the hydration and mechanical properties of cement mixed with accelerator at different temperatures. The results showed that an increase in the gypsum content of cement promoted the formation of ettringite (AFt) and decreased the setting times of cement pastes at 0°C, 20°C and 40°C. Mortar compressive strength test revealed that after curing at 0°C, 20 °C and 40°C, the highest compressive strength was exhibited with final molar C3A/SO3 ratio of 0.84, 0.84 and 1.18, respectively. The mechanical properties of hardened cement pastes were adversely affected by C3A/SO3 ratios that were too high or too low. When the C3A/SO3 ratio was too high, which facilitated conversion of AFt to monosulphate(AFm) and slowed C3S hydration. Conversely, when the C3A/SO3 ratio was too low, which enabled large numbers of AFt to occupy the space where C-S-H gels was formed, resulting in decalcification of C-S-H gels.
{"title":"Study on the effect of gypsum content in cement on the adaptability between cement and alkali-free accelerator at different temperatures","authors":"Qin Wang, Zhixiang Guo, Fanchao Zeng, Hongwei Wang, Huaixia Qin","doi":"10.1680/jadcr.23.00165","DOIUrl":"https://doi.org/10.1680/jadcr.23.00165","url":null,"abstract":"The setting time and early strength of shotcrete is greatly affected by the gypsum content of cement. In this paper, setting time and compressive strength, and microscopic methods such as XRD quantitative analysis, thermogravimetric analysis and scanning electron microscope observation were used to determine the effects of changes in gypsum content on the hydration and mechanical properties of cement mixed with accelerator at different temperatures. The results showed that an increase in the gypsum content of cement promoted the formation of ettringite (AFt) and decreased the setting times of cement pastes at 0°C, 20°C and 40°C. Mortar compressive strength test revealed that after curing at 0°C, 20 °C and 40°C, the highest compressive strength was exhibited with final molar C<sub>3</sub>A/SO<sub>3</sub> ratio of 0.84, 0.84 and 1.18, respectively. The mechanical properties of hardened cement pastes were adversely affected by C<sub>3</sub>A/SO<sub>3</sub> ratios that were too high or too low. When the C<sub>3</sub>A/SO<sub>3</sub> ratio was too high, which facilitated conversion of AFt to monosulphate(AFm) and slowed C<sub>3</sub>S hydration. Conversely, when the C<sub>3</sub>A/SO<sub>3</sub> ratio was too low, which enabled large numbers of AFt to occupy the space where C-S-H gels was formed, resulting in decalcification of C-S-H gels.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139055614","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}
Linnu Lu, Peng Wang, Yongjia He, Ma Jie, Fazhou Wang, Shuguang Hu
An approach for efficient re-utilization of waste cement paste powders is proposed, that is, the powders are heated to a certain temperature to prepare Regenerated Binding Materials (RBMs), and then rapid carbonated by high concentration CO2 to prepare high-strength products. The structural evolution during the heating process of waste cement paste powder and the carbonation process of RBMs were investigated by XRD, SEM, and 29Si NMR etc., and the compressive strength of the carbonated RBM samples was measured. The results show that the differences in carbonation reactivity, carbonation products of RBMs, and properties of carbonated RBMs are mainly attributed to the differences in structural order degree of newly formed β-C2S, the content of β-C2S, f-CaO and incomplete decomposed C-S-H in RBMs. The strength of the carbonated sample of RBM prepared at 1050 °C was the highest, followed by that prepared at 950 °C, which was significantly higher than those prepared at 650 °C, 750 °C and 850 °C. The content of highly ordered β-C2S in RBMs with high carbonation reactivity, and the dense stacking of the carbonation products are beneficial for the mechanical properties.
{"title":"Accelerated carbonation of regenerated binding material prepared with waste cement paste powder","authors":"Linnu Lu, Peng Wang, Yongjia He, Ma Jie, Fazhou Wang, Shuguang Hu","doi":"10.1680/jadcr.23.00098","DOIUrl":"https://doi.org/10.1680/jadcr.23.00098","url":null,"abstract":"An approach for efficient re-utilization of waste cement paste powders is proposed, that is, the powders are heated to a certain temperature to prepare Regenerated Binding Materials (RBMs), and then rapid carbonated by high concentration CO<sub>2</sub> to prepare high-strength products. The structural evolution during the heating process of waste cement paste powder and the carbonation process of RBMs were investigated by XRD, SEM, and <sup>29</sup>Si NMR etc., and the compressive strength of the carbonated RBM samples was measured. The results show that the differences in carbonation reactivity, carbonation products of RBMs, and properties of carbonated RBMs are mainly attributed to the differences in structural order degree of newly formed <i>β</i>-C<sub>2</sub>S, the content of <i>β</i>-C<sub>2</sub>S, <i>f</i>-CaO and incomplete decomposed C-S-H in RBMs. The strength of the carbonated sample of RBM prepared at 1050 °C was the highest, followed by that prepared at 950 °C, which was significantly higher than those prepared at 650 °C, 750 °C and 850 °C. The content of highly ordered <i>β</i>-C<sub>2</sub>S in RBMs with high carbonation reactivity, and the dense stacking of the carbonation products are beneficial for the mechanical properties.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139055687","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}
Meixun Peng, Yuanpeng Zhang, Wenjuan Liu, Fei Song
Supersulfated cements (SSC), being possible green alternatives to Portland cements, have demand to develop new kinds of precursors instead of blast furnace slag. The mixture of kaolin, quartz and NaOH was calcined to prepare SSC by grinding the clinkers with lime and gypsum. The preparation factors were investigated and multiple characterization methods were adopted to explore the calcination and hydration mechanisms. It is found that NaOH additive reduced the activation temperature of the kaolin and moderate addition of NaOH improved the compressive strength of SSC made from calcined kaolin. Quartz added into the kaolin calcined with moderate amount of NaOH promoted the compressive strength as well. Comprehensive characterizations indicated that the alkali-added calcination of the kaolin generated pozzolanic zeolite and sodium aluminosilicates along with inert nepheline at calcination temperature ≤ 950 °C. The hydration of SSC pastes tended to produce C(N)-A-S-H/N(C)-A-S-H gels and crystalline ettringite. Too much NaOH added into the kaolin calcined at temperature ≤ 950 °C led to generating calcium-absent geopolymer hydrates that restrained the compressive strength development. During NaOH-added calcination, quartz added into the kaolin hindered generating inert nepheline and produced cementitious N-S gels. The research facilitates the utilization of the massive discharged coal gangues rich in kaolinite and quartz by synthesizing SSCs uncostly.
{"title":"Synthesis and characterization of supersulfated cements from kaolin, quartz and NaOH","authors":"Meixun Peng, Yuanpeng Zhang, Wenjuan Liu, Fei Song","doi":"10.1680/jadcr.23.00160","DOIUrl":"https://doi.org/10.1680/jadcr.23.00160","url":null,"abstract":"Supersulfated cements (SSC), being possible green alternatives to Portland cements, have demand to develop new kinds of precursors instead of blast furnace slag. The mixture of kaolin, quartz and NaOH was calcined to prepare SSC by grinding the clinkers with lime and gypsum. The preparation factors were investigated and multiple characterization methods were adopted to explore the calcination and hydration mechanisms. It is found that NaOH additive reduced the activation temperature of the kaolin and moderate addition of NaOH improved the compressive strength of SSC made from calcined kaolin. Quartz added into the kaolin calcined with moderate amount of NaOH promoted the compressive strength as well. Comprehensive characterizations indicated that the alkali-added calcination of the kaolin generated pozzolanic zeolite and sodium aluminosilicates along with inert nepheline at calcination temperature ≤ 950 °C. The hydration of SSC pastes tended to produce C(N)-A-S-H/N(C)-A-S-H gels and crystalline ettringite. Too much NaOH added into the kaolin calcined at temperature ≤ 950 °C led to generating calcium-absent geopolymer hydrates that restrained the compressive strength development. During NaOH-added calcination, quartz added into the kaolin hindered generating inert nepheline and produced cementitious N-S gels. The research facilitates the utilization of the massive discharged coal gangues rich in kaolinite and quartz by synthesizing SSCs uncostly.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139055690","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}
This article discusses the mechanical and durability properties of aerated blocks. In present study, aerated blocks prepared by using different cementitious materials along with the alkaline solution (AS) in the absence of aluminium powder. The proportions of raw materials are chosen after performing two mix trials P1 and P2, keeping the density of blocks constant i.e., 800 kg/m3. Each mix is further tested under six curing mechanisms, viz, normal water curing, humidity chamber curing at (50°C and 70% relative humidity) for 6 hours and 10 hours, oven drying curing at 180°C for 6 hours and at 80℃ for 24 hours and using accelerated curing (ACT) at 65°C±5°C for 10±2 hours and named as trial “1”. In trial “2” the best curing mechanism is taken and construction and demolition waste are substituted at different proportions in place of flyash in both the mix proportions. Further, trial “3” is investigated on the best mix proportion by substituting glass powder at 50% and 100% with flyash and CDW, respectively. It is observed from experiments that aerated blocks manufactured with 50% CDW and heat curing done in the ACT showed high mechanical and durability properties after 7 days of hardening.
{"title":"Enhancing the performance of aerated concrete through accelerated curing and waste material integration","authors":"Pradyut Anand, Anand Kr Sinha, Puja Rajhans","doi":"10.1680/jadcr.23.00150","DOIUrl":"https://doi.org/10.1680/jadcr.23.00150","url":null,"abstract":"This article discusses the mechanical and durability properties of aerated blocks. In present study, aerated blocks prepared by using different cementitious materials along with the alkaline solution (AS) in the absence of aluminium powder. The proportions of raw materials are chosen after performing two mix trials P1 and P2, keeping the density of blocks constant i.e., 800 kg/m<sup>3</sup>. Each mix is further tested under six curing mechanisms, viz, normal water curing, humidity chamber curing at (50°C and 70% relative humidity) for 6 hours and 10 hours, oven drying curing at 180°C for 6 hours and at 80℃ for 24 hours and using accelerated curing (ACT) at 65°C±5°C for 10±2 hours and named as trial “1”. In trial “2” the best curing mechanism is taken and construction and demolition waste are substituted at different proportions in place of flyash in both the mix proportions. Further, trial “3” is investigated on the best mix proportion by substituting glass powder at 50% and 100% with flyash and CDW, respectively. It is observed from experiments that aerated blocks manufactured with 50% CDW and heat curing done in the ACT showed high mechanical and durability properties after 7 days of hardening.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138714790","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}
As the main hydration product of magnesium oxysulfate (MOS) cement, 517 phase (5Mg(OH)2·MgSO4·7H2O) is one of the main sources of MOS cement strength. At present, the experimental results show that calcium ions have a great influence on the stability of 517 phase, so this paper mainly explores the erosion process and mechanism of calcium ions on 517 phase. The 517 phase with 94.56 % purity was synthesized in this paper, and the erosion effect of different calcium salts on 517 phase was also characterized, where thermogravimetric-differential scanning calorimetry (TG-DSC), scanning electron microscope (SEM), transmission electron microscope (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD) were used to analyze the performance changes of 517 phase under different calcium salt erosion. The results show that in the solution, Ca2+ combined with SO42+ in 517 phase, resulting in an increase in the spacing between the MgO6 octahedron layers in 517 phase thus destroying the structure of 517 phase. Moreover, when ions diffused, MgO6 octahedron and Cl2+ recombined into 518 phase (5Mg(OH)2·MgCl2·8H2O). In addition, insoluble weddellite was also found to erode 517 phase to a certain extent, while the 517 phase blended with gypsum was stable. The simulation results of molecular dynamics also showed that Ca2+ had better adsorption ability for SO42+ and Cl2+ than Mg2+. When it was in contact with 517 phase, Ca2+ was absorbed near SO42+ and Cl2+ was brought into the system.
{"title":"Further study of the erosion mechanism of calcium salt on 517 phase","authors":"Yan Guan, Xiao Han, Zhiqi Hu","doi":"10.1680/jadcr.23.00078","DOIUrl":"https://doi.org/10.1680/jadcr.23.00078","url":null,"abstract":"As the main hydration product of magnesium oxysulfate (MOS) cement, 517 phase (5Mg(OH)<sub>2</sub>·MgSO<sub>4</sub>·7H<sub>2</sub>O) is one of the main sources of MOS cement strength. At present, the experimental results show that calcium ions have a great influence on the stability of 517 phase, so this paper mainly explores the erosion process and mechanism of calcium ions on 517 phase. The 517 phase with 94.56 % purity was synthesized in this paper, and the erosion effect of different calcium salts on 517 phase was also characterized, where thermogravimetric-differential scanning calorimetry (TG-DSC), scanning electron microscope (SEM), transmission electron microscope (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD) were used to analyze the performance changes of 517 phase under different calcium salt erosion. The results show that in the solution, Ca<sup>2+</sup> combined with SO<sub>4</sub><sup>2+</sup> in 517 phase, resulting in an increase in the spacing between the MgO<sub>6</sub> octahedron layers in 517 phase thus destroying the structure of 517 phase. Moreover, when ions diffused, MgO<sub>6</sub> octahedron and Cl<sup>2+</sup> recombined into 518 phase (5Mg(OH)<sub>2</sub>·MgCl<sub>2</sub>·8H<sub>2</sub>O). In addition, insoluble weddellite was also found to erode 517 phase to a certain extent, while the 517 phase blended with gypsum was stable. The simulation results of molecular dynamics also showed that Ca<sup>2+</sup> had better adsorption ability for SO<sub>4</sub><sup>2+</sup> and Cl<sup>2+</sup> than Mg<sup>2+</sup>. When it was in contact with 517 phase, Ca<sup>2+</sup> was absorbed near SO<sub>4</sub><sup>2+</sup> and Cl<sup>2+</sup> was brought into the system.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138680214","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}
China's salt lakes contain an abundance of magnesium resources, and salt-lake brine, a by-product of potash fertilizers, is often discharged back into the salt lakes, causing environmental damage. MgO from salt-lake brine can be used to produce magnesium oxychloride cement (MOC). However, the calcium impurities present in salt lakes affect the properties of MOC. To investigate the effects of these impurities, MgO was produced using a magnesium hydroxide precursor by calcination. By adding calcium hydroxide and calcium chloride, the incorporated calcium impurities were 0, 5, and 10% by mass of MgO. The compressive strength, heat of hydration, composition of the hydration product phases, and pore structure development of the MOC samples were evaluated. It was confirmed that Ca2+ ions increased the early strength of MOC as well as its rate of setting and hardening. However, the presence of calcium impurities did not change the composition of its hydration phase. This was primarily because the Ca2+ ions promoted the participation of MgO in the hydration reaction and enhanced the early strength of MOC. The findings of this study demonstrate the technical feasibility of utilizing magnesium resources from salt lakes to prepare MgO and apply it in the production of MOC.
中国的盐湖蕴藏着丰富的镁资源，而盐湖卤水是钾肥的副产品，经常被排放回盐湖，造成环境破坏。盐湖卤水中的氧化镁可用于生产氧氯化镁水泥（MOC）。然而，盐湖中的钙杂质会影响 MOC 的性能。为了研究这些杂质的影响，使用氢氧化镁前体通过煅烧生产氧化镁。通过添加氢氧化钙和氯化钙，掺入的钙杂质分别为氧化镁质量的 0、5 和 10%。对 MOC 样品的抗压强度、水化热、水化产物相的组成以及孔隙结构的发展进行了评估。结果证实，Ca2+ 离子提高了 MOC 的早期强度及其凝固和硬化速度。然而，钙杂质的存在并没有改变其水化相的组成。这主要是因为 Ca2+ 离子促进了氧化镁参与水化反应，提高了 MOC 的早期强度。本研究的结果证明了利用盐湖中的镁资源制备氧化镁并将其应用于 MOC 生产的技术可行性。
{"title":"Effects of calcium impurities on properties of magnesium oxychloride cement","authors":"Xinkuang Ning, Yong Zhang, Chengyou Wu","doi":"10.1680/jadcr.23.00182","DOIUrl":"https://doi.org/10.1680/jadcr.23.00182","url":null,"abstract":"China's salt lakes contain an abundance of magnesium resources, and salt-lake brine, a by-product of potash fertilizers, is often discharged back into the salt lakes, causing environmental damage. MgO from salt-lake brine can be used to produce magnesium oxychloride cement (MOC). However, the calcium impurities present in salt lakes affect the properties of MOC. To investigate the effects of these impurities, MgO was produced using a magnesium hydroxide precursor by calcination. By adding calcium hydroxide and calcium chloride, the incorporated calcium impurities were 0, 5, and 10% by mass of MgO. The compressive strength, heat of hydration, composition of the hydration product phases, and pore structure development of the MOC samples were evaluated. It was confirmed that Ca<sup>2+</sup> ions increased the early strength of MOC as well as its rate of setting and hardening. However, the presence of calcium impurities did not change the composition of its hydration phase. This was primarily because the Ca<sup>2+</sup> ions promoted the participation of MgO in the hydration reaction and enhanced the early strength of MOC. The findings of this study demonstrate the technical feasibility of utilizing magnesium resources from salt lakes to prepare MgO and apply it in the production of MOC.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138680033","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}
Juan Fu, Baorui Hu, Wei Guo, Yueyang Hu, Cuifeng Jiang
Belite sulfoaluminate cement is attracting increasingly attention and considered as a prospective alternative to Ordinary Portland cement (OPC) owing to the lower preparation temperature and CO2 emission. However, it still has disadvantages of poor workability and low early strength. Accordingly, this study investigated the effect of compound polycarboxylate superplasticizer (PCE) and early strength agent, calcium nitrite (Ca(NO2)2), on the flowability and early strength of BCSA cement. The variation patterns of setting time, fluidity, strength and PCE adsorption of the paste were measured. Furthermore, the hydration products and microscopic morphology were analyzed by the heat of hydration, X-ray diffraction analyzer and scanning electron microscope. The results showed that Ca(NO2)2 effectively enhanced the adsorption of PCE onto the surface of BCSA cement particles, leading to a notable improvement in the fluidity of the paste (reaching up to 275 mm). In the initial hydration stage, 0.7% PCE compounded with 1.2% Ca(NO2)2 inhibited the formation of ettringite (AFt), resulting in prolonged setting time. However, it deepened the hydration degree of BCSA for 3d and refined the hydration product, AFt crystals. Consequently, the compressive strength has been increased to 95.75 MPa and 107.13 MPa for BCSA cement at 3d and 28d, respectively.
{"title":"Effect of polycarboxylate superplasticizer and calcium nitrite on the fluidity and early strength of belite sulfoaluminate cement","authors":"Juan Fu, Baorui Hu, Wei Guo, Yueyang Hu, Cuifeng Jiang","doi":"10.1680/jadcr.23.00023","DOIUrl":"https://doi.org/10.1680/jadcr.23.00023","url":null,"abstract":"Belite sulfoaluminate cement is attracting increasingly attention and considered as a prospective alternative to Ordinary Portland cement (OPC) owing to the lower preparation temperature and CO<sub>2</sub> emission. However, it still has disadvantages of poor workability and low early strength. Accordingly, this study investigated the effect of compound polycarboxylate superplasticizer (PCE) and early strength agent, calcium nitrite (Ca(NO<sub>2</sub>)<sub>2</sub>), on the flowability and early strength of BCSA cement. The variation patterns of setting time, fluidity, strength and PCE adsorption of the paste were measured. Furthermore, the hydration products and microscopic morphology were analyzed by the heat of hydration, X-ray diffraction analyzer and scanning electron microscope. The results showed that Ca(NO<sub>2</sub>)<sub>2</sub> effectively enhanced the adsorption of PCE onto the surface of BCSA cement particles, leading to a notable improvement in the fluidity of the paste (reaching up to 275 mm). In the initial hydration stage, 0.7% PCE compounded with 1.2% Ca(NO<sub>2</sub>)<sub>2</sub> inhibited the formation of ettringite (AFt), resulting in prolonged setting time. However, it deepened the hydration degree of BCSA for 3d and refined the hydration product, AFt crystals. Consequently, the compressive strength has been increased to 95.75 MPa and 107.13 MPa for BCSA cement at 3d and 28d, respectively.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138579399","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, Mehmet Kemal Ardoğa, Mustafa Şahmaran
One of the contemporary approach to reduce the damage on cementitious composite resulted from freeze-thaw effect is the incorporation of the phase-change materials (PCM). In this study, the composites were produced adding n-tetradecane, which is a microencapsulated organic PCM, at rates of 0, 2, 4, 6 and 8 % of the cement weight. In two different simulations representing the climate conditions of the two distinct regions in Türkiye, its effect on restriction in temperature amplitudes which the composite experienced, was determined. It is determined that the PCM, the working range of which is similar to the temperature range applied to the composite in simulation was more successful to reduce the temperature amplitudes and the rate and type of the PCM should be chosen thoughtfully according to the climate conditions, which the composite is desired to use. Moreover, besides PCM's thermal properties, its effect on the mechanical properties and consistency results were investigated.
{"title":"Performance of the phase change material (PCM) to reduce freeze-thaw effect in cementitious composites","authors":"Fatih Acikök, Mehmet Kemal Ardoğa, Mustafa Şahmaran","doi":"10.1680/jadcr.23.00029","DOIUrl":"https://doi.org/10.1680/jadcr.23.00029","url":null,"abstract":"One of the contemporary approach to reduce the damage on cementitious composite resulted from freeze-thaw effect is the incorporation of the phase-change materials (PCM). In this study, the composites were produced adding n-tetradecane, which is a microencapsulated organic PCM, at rates of 0, 2, 4, 6 and 8 % of the cement weight. In two different simulations representing the climate conditions of the two distinct regions in Türkiye, its effect on restriction in temperature amplitudes which the composite experienced, was determined. It is determined that the PCM, the working range of which is similar to the temperature range applied to the composite in simulation was more successful to reduce the temperature amplitudes and the rate and type of the PCM should be chosen thoughtfully according to the climate conditions, which the composite is desired to use. Moreover, besides PCM's thermal properties, its effect on the mechanical properties and consistency results were investigated.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138576510","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 study, the effect of gold tailings on the frost resistance of engineered cementitious composites (ECC) was investigated. The ECC were made with three gold tailings dosages and four polyvinyl alcohol (PVA) fiber contents. A water-binder ratio (W/B) of 0.28 was used for all mixtures. Surface damage, mass loss, relative dynamic elastic modulus, compressive strength and damaged layer thickness were tested to investigate the frost resistance of ECC. The results indicate that the effect of gold tailings on the frost resistance of ECC is marginal. Moreover, the frost resistance of ECC increases with the increase of fiber content. The ECC with the addition of gold tailings have the same excellent frost resistance as those without gold tailings, indicating that it is feasible to replace silica sand with gold tailings up to 100% replacement in ECC. In addition, a predictive model of damaged layer thickness of ECC in function of gold tailings dosage and freezing-thawing (F-T) cycle was developed.
{"title":"Effects of gold tailings dosage and PVA fiber content on the frost resistance of ECC","authors":"Zhi Ge, Chuansong Chen, Yufeng Bi, Hongzhi Zhang, Yanhua Guan, Yongwei Yang, Yifeng Ling, Renjuan Sun","doi":"10.1680/jadcr.23.00115","DOIUrl":"https://doi.org/10.1680/jadcr.23.00115","url":null,"abstract":"In this study, the effect of gold tailings on the frost resistance of engineered cementitious composites (ECC) was investigated. The ECC were made with three gold tailings dosages and four polyvinyl alcohol (PVA) fiber contents. A water-binder ratio (W/B) of 0.28 was used for all mixtures. Surface damage, mass loss, relative dynamic elastic modulus, compressive strength and damaged layer thickness were tested to investigate the frost resistance of ECC. The results indicate that the effect of gold tailings on the frost resistance of ECC is marginal. Moreover, the frost resistance of ECC increases with the increase of fiber content. The ECC with the addition of gold tailings have the same excellent frost resistance as those without gold tailings, indicating that it is feasible to replace silica sand with gold tailings up to 100% replacement in ECC. In addition, a predictive model of damaged layer thickness of ECC in function of gold tailings dosage and freezing-thawing (F-T) cycle was developed.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138576376","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 cement mortar mixes were developed with the intent of testing the suitability of fine graded reclaimed asphalt pavement aggregates as a replacement for naturally fine materials. The natural fine aggregates were replaced in multiple percent levels of 25%, 50%, 75%, and 100% by weight. The results demonstrate that the mechanical qualities of the mortar mix are deteriorating. To address this, zinc industry waste - jarosite was used as a part replacement for cement in proportions of 5%, 10%, and 15%. Jarosite improved the microstructural, mechanical, and shrinkage properties. For instance, when comparing with the control mix, the mix containing 25% fine reclaimed asphalt pavement aggregates shows a reduction of 5.5% in hardened density and 14% in compressive strength. On the other hand, when 10% jarosite is included in the 25% fine reclaimed asphalt pavement mix, there is an observed increase of 4.85% in hardened density and 7% in compressive strength with respect to the mix containing 25% fine reclaimed asphalt pavement aggregates. As a result, the current study proposes using 10% jarosite when fine reclaimed asphalt pavement aggregates are used to make cement mortar mixes. Furthermore, a cost analysis is performed to determine the difference in construction costs. These findings are expected to inspire rational mix design recommendations for mortar mixes including fine reclaimed asphalt pavement aggregates, as well as bring environmental and economic benefits by lowering carbon footprints.
{"title":"Mechanical, durable, and microstructural properties of cement mortar mixes containing fine reclaimed asphalt pavement aggregates and zinc waste","authors":"Surendra Kumar Saini, Surya Kant Sahdeo, G.D.R.N. Ransinchung, Praveen Kumar","doi":"10.1680/jadcr.23.00046","DOIUrl":"https://doi.org/10.1680/jadcr.23.00046","url":null,"abstract":"The cement mortar mixes were developed with the intent of testing the suitability of fine graded reclaimed asphalt pavement aggregates as a replacement for naturally fine materials. The natural fine aggregates were replaced in multiple percent levels of 25%, 50%, 75%, and 100% by weight. The results demonstrate that the mechanical qualities of the mortar mix are deteriorating. To address this, zinc industry waste - jarosite was used as a part replacement for cement in proportions of 5%, 10%, and 15%. Jarosite improved the microstructural, mechanical, and shrinkage properties. For instance, when comparing with the control mix, the mix containing 25% fine reclaimed asphalt pavement aggregates shows a reduction of 5.5% in hardened density and 14% in compressive strength. On the other hand, when 10% jarosite is included in the 25% fine reclaimed asphalt pavement mix, there is an observed increase of 4.85% in hardened density and 7% in compressive strength with respect to the mix containing 25% fine reclaimed asphalt pavement aggregates. As a result, the current study proposes using 10% jarosite when fine reclaimed asphalt pavement aggregates are used to make cement mortar mixes. Furthermore, a cost analysis is performed to determine the difference in construction costs. These findings are expected to inspire rational mix design recommendations for mortar mixes including fine reclaimed asphalt pavement aggregates, as well as bring environmental and economic benefits by lowering carbon footprints.","PeriodicalId":7299,"journal":{"name":"Advances in Cement Research","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138576380","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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