碾压混凝土凝结时间的影响因素研究

Experimental Study of Effects of Factors on RCC Setting Times

碾压混凝土(RCC)坝存在大量水平层面,对RCC的层间力学性能和渗透性能产生了不利影响。初凝时间是控制RCC层间间隔时间的基本标准。研究RCC初凝时间的影响因素具有重要意义。本试验采用贯入阻力法研究了不同减水剂掺量和施工扰动因素对碾压混凝土凝结时间的影响。试验表明:掺有缓凝成分的减水剂含量越高,凝结时间越长;施工扰动对湿筛砂浆的凝结过程产生了一定程度的破坏,从而减缓了其凝结过程,延长了初、终凝时间。本试验为碾压混凝土现场铺筑的层间间隔时间控制提供了参考依据。

There exist large amounts of horizontal layers in roller compacted concrete(RCC) dams. These horizontal layers have negative effects on permeative and mechanical properties of RCC. Initial setting time is a fundamental criteria for controlling intermittent time between RCC layers. Studying factors influencing RCC setting times is essential. Effects of different portions of water reducers and construction vibrations on RCC setting times are studied, using the concrete penetration resistance method.Experimental results show that, the higher the number of contents of water reducers mixed with retarding components is, the longer its setting time becomes; construction vibrations exert negative influence on the setting process of wet screened mortar, therefore elongating its setting process and its setting time.Results of this test provides some reference for the time control when paving RCC layers on-site.