摘要
研究了水胶比、聚羧酸减水剂(PCE)分子结构、高吸水性树脂(SAP)及阴离子型黏度调节剂(VMA)对砂浆流变性能的影响。结果表明:提升水胶比能降低砂浆的屈服应力和塑性黏度并提高其流动度保持能力。PCE的掺入可显著降低砂浆的屈服应力且PCE侧链的空间位阻作用是一个主要原因。侧链抑制PCE在水泥颗粒表面的吸附。增加PCE侧链长度对水泥浆初始流变性影响较小。SAP通过降低砂浆中自由水含量来提高其屈服应力和塑性黏度,其作用机理与降低水胶比的作用相似。VMA在低掺量下通过桥接作用提高砂浆的屈服应力,但对塑性黏度影响不大;高掺量下,VMA的桥接作用减弱却能大幅提高液相的黏度,因而对砂浆屈服应力的提升作用减弱而大幅提高其塑性黏度。
Effects of water-binder ratio,polycarboxylate superplasticizers(PCEs)with different molecular structures,super-absorbent polymer(SAP)and an anionic viscosity modifying agent(VMA)on the rheological properties of mortar were investigated.The results show that increasing the water-binder ratio simultaneously reduces the yield stress and plastic viscosity of mortar and increases the fluidity retention capacity.The addition of PCE reduces the yield stress of mortar and the steric hindrance induced by the side carbon chains is one of the main reasons for the dispersion effect of PCE.The side carbon chains inhibit the adsorption of PCE on the surface of cement particles.Increasing the length of the side chains of PCE has little effect on the initial rheology.SAP increases the yield stress and plastic viscosity of mortar by reducing its free water content,and its action mechanism is the same as reducing the water-binder ratio.VMA improves the yield stress of mortar due to the bridging effect at low dosages,but has little effect on the plastic viscosity.At high dosages,the bridging effect of VMA weakens but the viscosity of liquid phase greatly increases,thus decreasing the enhanced effect on the yield stress of mortar and greatly increasing the plastic viscosity of mortar.
作者
张朝阳
喻建伟
孔祥明
蔡熠
ZHANG Chaoyang;YU Jianwei;KONG Xiangming;CAI Yi(Institute of Building Materials,Department of Civil Engineering,Tsinghua University,Beijing 100084,China)
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2020年第5期622-631,共10页
Journal of The Chinese Ceramic Society
基金
科技部重点研发计划(2017YFB0310002):长寿命混凝土制品关键材料及制备技术
国家自然科学基金面试项目(51778333)。
关键词
砂浆
流变性能
水胶比
聚羧酸减水剂
黏度调节剂
mortar
rheological property
water-to-binder ratio
polycarboxylate superplasticizers
viscosity modifying agent
