多功能型梳形共聚物超塑化剂的减缩机理

Shrinkage-Reducing Mechanism of Multi-functional Comb-like Superplasticizer(SRPCA) for Concrete

从表面张力、吸附性能、孔结构和毛细管附加压力的角度系统研究了多功能型梳形共聚物超塑化剂(SRPCA)对混凝土的减缩机理.结果表明:SRPCA在水泥颗粒表面产生强吸附,有效降低了混凝土孔隙溶液的表面张力,降低了毛细管附加压力,从而降低了硬化水泥净浆的收缩;掺加SRPCA后,硬化水泥净浆孔结构发生了较大变化,其孔隙率降低,孔隙分布变宽,内部相对湿度降低,进而减少了其干燥收缩;掺加SRPCA后,毛细管附加压力快速增长时段和终凝时间较接近,从而有效降低了混凝土的凝缩.

The shrinkage-reducing mechanism of a new type of multi-functional comb-like superplasticizer（SRPCA） has been investigated systematically in terms of surface force,adsorption behavior,pore structure and capillary under pressure.The results show that SRPCA can reduce the interface tension efficiently in pore solution in concrete due to its strong adsorption onto the cement particles,thus the capillary under pressure is lowered and the shrinkage of hardened cement paste is significanty decreased.It is also shown that the incorporation of SRPCA improves the pore structure of hardened cement paste markedly,leading to the decrease of porosity and broad size distribution,decrease of inner RH,and thus the drying shrinkage of concrete is reduced.In addition,the time point of the capillary under pressure increases rapidly is very close to the final setting time of cememt,which is the very reason that the setting shrinkage of concrete is reduced by adding SRPCA.