后掺粗骨料工艺对高性能泵送混凝土性能影响研究

为解决建筑工程中高性能泵送混凝土的环境问题、成本问题,基于粗骨料嵌锁效应和界面水灰比强度理论,在保证高性能和泵送要求的条件下,提出了后掺骨料工艺,并对不同粗骨料后掺比例下的混凝土进行了力学性能和抗冻性能的研究。结果表明,随着粗骨料后掺比例的增大,7 d、28 d混凝土抗压强度持续增大,而28 d混凝土劈裂抗拉强度和抗折强度均呈先增大后减小的趋势;在冻融循环作用下,质量损失率的上升速率呈先减小后增大的趋势,而抗压、抗拉、抗折强度、动弹性模量以及超声波速的下降速率均呈先减小后增大的趋势。据此建议本C30高性能泵送混凝土的粗骨料最佳后掺比例为20%。

Experimental Study on Properties of High Performance Pumping Concrete with After-mixing Coarse Aggregate and Its Application Prospect

In order to solve the environmental problems and high cost issue of high-performance pumping concrete in con-struction engineering under the condition of ensuring high performance and pumping requirements ,the after-mixing coarse aggregate technology has been proposed based on the coarse aggregate interlocking effect and the strength theory of interfa-cial water-cement ratio .The mechanical properties and frost resistance of concrete with different after-mixing coarse ag-gregate proportion were analyzed in this research .The results show that the compressive strength of 7 d and 28 d increases continuously ,while the splitting tensile strength and flexural strength of 28 d increases first and then decreases with the increase of after-mixing coarse aggregate proportion .Under the action of freeze-thaw cycles ,the increasing rate of mass loss ratio decreases first and then increases ,while the descent rate of the compressive ,tensile ,flexural strength ,dynam-ic elastic modulus and ultrasonic wave velocity decrease first and then increase .Therefore it is recommended that the best after-mixing proportion of the C30 high-performance pumping concrete is 20% .