工程科学与技术2025，Vol.57Issue(6)：265-273,9.DOI:10.12454/j.jsuese.202400254
铝硅摩尔比对纳米水化硅铝酸钙及水泥早期水化影响研究
Effects of A/S Molar Ratio on Nano C‒A‒S‒H and Early Hydration Properties of Cement
摘要
Abstract
Objective Nano-hydrated calcium silicate(C‒S‒H)is a new type of nano early strength agent that effectively improves the early mechanical properties of cement-based materials.Currently,more Al-rich supplementary cementitious materials,such as finely ground blast furnace slag(GGBS)and fly ash(FA),are increasingly used as admixtures to reduce cement consumption.Al can enter C‒S‒H to form C‒A‒S‒H gel during the hydration process of cement.This study prepares nano C‒A‒S‒H with different A/S molar ratios and explores its effects on the hydration of Ordinary Portland cement(P·O),Slag cement(P·S),Fly ash cement(P·F),and Portland composite cement(P·C)at low temperature. Methods Nano C‒A‒S‒H solution with different A/S ratios was prepared by the in-situ co-precipitation method using analytical-grade Ca(NO3)2·4H2O,Na2SiO3·9H2O,Al(NO3)3·9H2O,NaOH,and polycarboxylic acid polymer(PCE,solid content 40%).C‒A‒S‒H with a theo-retical C/S molar ratio of 1.2 and A/S molar ratios of 0,0.02,0.04,0.06,0.08,0.15,and 0.20 were prepared and labeled as S0,S002,S004,S006,S008,S015,and S020,respectively.The stability and particle size of nano C‒A‒S‒H were characterized by visual inspection and a zeta potential analyzer.The initial and final setting times of pastes containing 4%nano C‒A‒S‒H were tested based on the Chinese standard at 10℃(Test methods for water requirement of normal consistency,setting time,and soundness of Portland cements,GB/T1346-2011).The compressive strength of mortars containing 0.04%nano C‒A‒S‒H was determined using a YAW-300 compressive and flexural inte-grated machine produced by Wuxi Jianyi Instrument.The pastes cured to specific ages were sampled for TG,SEM,and QXRD analyses to evaluate the effects of nano C‒A‒S‒H on the hydration progress of cement.In addition,the influence of optimized nano C‒A‒S‒H suspen-sion on the early hydration of Portland cement,fly ash cement,slag cement,and composite cement was investigated. Results and Discussions The results indicated that the average particle size of nano C‒A‒S‒H increased with the increasing Al/Si ratio.For in-stance,the average particle sizes of S0 and S002 were 97.4 nm and 181.2 nm,respectively.The C‒A‒S‒H suspension tended to become gelati-nous,and the stability of the suspension diminished with the increasing Al/Si ratio.The initial and final setting times were effectively shortened compared to the reference paste.The reduction in both initial and final setting times became more significant with the increase in the A/S ratio.The initial setting times of the cement pastes containing S0,S008,and S020 were reduced by 16.3%,53.6%,and 35.7%,respectively,compared to the reference paste,while the final setting times were reduced by 19.8%,44.5%,and 27.5%,respectively.The 8,16,and 24 h compressive strengths of mortars containing S008 increased by 120.0%,151.5%,and 170.6%,respectively,compared to the reference mortar.Similarly,the 8,16,and 24 h compressive strengths of mortars containing S015 increased by 130.0%,164.5%,and 201.8%,respectively,compared to the reference mortar.How-ever,no significant increase was observed for the 3 and 28 d compressive strengths of the mortars containing nano C‒A‒S‒H.The TG analysis indi-cated that the content of Ca(OH)2 in the cement paste was 4.19%after 16 h of hydration at 10℃,and the contents of Ca(OH)2 reached 5.29%and 5.80%after 16 h of hydration when S006 and S015 were used,increasing by 26.25%and 38.42%,respectively.In addition,the QXRD results indi-cated that the Ca(OH)2 content of the reference paste was 3.53%after 16 h of hydration,and the Ca(OH)2 content gradually increased to 6.79%with the increasing C‒A‒S‒H content,which was consistent with the TG results.The setting times of P·O,P·F,P·S,and P·C cement pastes mixed with C‒A‒S‒H seeds were effectively shortened.Nano C‒A‒S‒H exhibited the best adaptability to Ordinary Portland cement,and the initial and final set-ting times of the paste containing S006 were shortened by 26.01%and 25.05%,respectively. Conclusions The nano C‒S‒H suspension was a semi-translucent liquid that turned white when Al was incorporated.The particle size increases,and the stability of nano C‒A‒S‒H decreases with an increasing Al/Si ratio.Both nano C‒S‒H and nano C‒A‒S‒H enhanced the early strength of cement at 10℃,while the latter's compressive strength was not significantly affected.The compressive strength initially increased with the rising Al/Si ratio and then decreased,consistent with the observations from SEM images.The nano C‒A‒S‒H seeds exhibited varying promotion effects on Ordinary Portland cement(P·O),Slag cement(P·S),Fly ash cement(P·F),and Portland composite cement(P·C).The degree of promo-tion was related to the clinker content in the cement.关键词
纳米C‒A‒S‒H/铝硅比/早期水化,早强强度/Rietveld定量计算Key words
nano C‒A‒S‒H/aluminum silicon ratio/early hydration/compressive strength of early hydration/rietveld quantitative analysis分类
建筑与水利引用本文复制引用
鲁佳兴,房延凤,惠一心,王建琴,陈惠敏,廖峻锋..铝硅摩尔比对纳米水化硅铝酸钙及水泥早期水化影响研究[J].工程科学与技术,2025,57(6):265-273,9.基金项目
国家自然科学基金项目(52308252) （52308252）
2023年度辽宁省教育厅基本科研项目(JYTMS20231574) （JYTMS20231574）
2023年国家级大学生创新创业训练计划项目(202310153005) （202310153005）
