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水泥与石粉对聚羧酸系减水剂的竞争吸附及机理
作者：高瑞军1，郭君华1，张瑞康2，王宏霞1，高春勇1，张恒志2
（1.中国建筑材料科学研究总院有限公司 绿色建筑材料国家重点实验室，北京 100024；
2.项城市中腾建材科技有限公司，河南 周口 466200）
摘要：针对机制砂高石粉含量及应用环境变化导致混凝土流动性显著下降的问题，在石粉等质量替代水泥的条件下，通过研究水泥浆体流动性变化规律及与环境温度的相关性、石粉与水泥对聚羧酸减水剂（PCE）的竞争吸附性能，揭示其竞争吸附机理。结果表明：在20、40 ℃条件下，石粉替代率为20%时水泥净浆流动度较纯水泥浆体分别减小了5.3%、24.3%，对流动度影响显著；当PCE折固掺量为0.3%时，水泥对PCE的吸附量为0.41 mg/g并达到饱和，石粉对PCE的吸附量为0.58 mg/g，且随PCE掺量的增加吸附量持续增大。石粉对PCE的吸附能力强于水泥颗粒，环境温度的升高会加快水泥颗粒和石粉对减水剂的吸附。
关键词：石粉；聚羧酸系减水剂；吸附；温度；分散性能；机理
中图分类号：TU528.042+.2 文献标识码：A 文章编号：1001-702X（2022）06-0116-04
Competitive adsorption and mechanism of cement particles and stone powder on polycarboxylate superplasticizer
GAO Ruijun1，GUO Junhua1，ZHANG Ruikang2，WANG Hongxia1，GAO Chunyong1，ZHANG Hengzhi2
（1.China Building Materials Academy，State Key Laboratory of Green Building Materials，Beijing 100024，China；
2.Xiangcheng Zhongteng Building Materials Technology Co. Ltd.，Zhoukou 466200，China）
Abstract：In view of the problem that the high content of stone powder in manufactured sand and the change of applied environment will lead to the significant decline of the workability of concrete，in this paper，the change law of the fluidity of cement paste，its correlation with the ambient temperature，and the competitive adsorption performance of stone powder and cement on polycarboxylate superplasticizer（PCE） were studied under the condition of equal substitution of stone powder. Meanwhile，the mechanism of competitive adsorption was revealed. The results show that the fluidity of cement paste replaced by 20% stone powder decreases by 5.3% and 24.3% respectively at 20 ℃ and 40 ℃ compared with pure cement paste，the influence of temperature on the fluidity is significant. The results of adsorption amount show that when the solid content of PCE is 0.3%，the adsorption amount of PCE on cement particles reaches saturation，and the saturated adsorption amount is 0.41 mg/g，the adsorption amount of PCE on stone powder is 0.58 mg/g，and continues to increase with the increase of PCE content. The results show that the adsorption capacity of PCE on stone powder is stronger than that of cement particles and the increase of ambient temperature will accelerate the adsorption of PCE on the surface of cement particles and stone powder.
Key words：stone powder，polycarboxylate superplasticizer，adsorption，temperature，dispersion properties，mechanism