免振捣泵送混凝土的工作性评价

Evaluation on Workability of Self-Compacting Pumpcrete

免振捣混凝土的首要特征是其优良的工作性能特别是流动性能和抗离析性能.探讨了坍落度、压力泌水、扩展值、中边差、倒坍落筒流下时间、Orimet仪的流出速度、L型流动实验等多种评价免振捣泵送混凝土工作性能的指标及其优缺点;经对比分析并结合实验研究和工程实际,提出了实用的新拌免振捣混凝土工作性评价指标及其合理取值区间:坍落度一般应控制在230～260 mm,倒坍流下时间8～15 s,扩展值600～700 mm,中边差值≤25 mm,压力泌水实验中的S10不超过40%,V140在40～110 mL.

The primary characteristic of self-compacting concrete is its workability, especially fluidity and segaregation-resistance ability. Proposing simple evaluation methods and evaluation values are the key factors affecting the popularizing of self-compacting concrete technology. The advantage and disadvantage of several methods for evaluating the workability of self-compacting pumpcrete, such as slump, bleeding under pressure, slump flow, the outpour time of inverse slump cone, the flow speed of Orimet meter, and L-shaped mould flow test, are discussed in this paper. The practical index and its suitable range for evaluating the workability of self-compacting pumpcrete are also proposed.Generally, for self-compacting pumpcrete, slump should be 230～260mm, the outpour time of inverse slump cone should be 8~15s, slump flow should be 600~700mm, S_(10) in bleeding test under pressure is less than 40%, the difference between the center and the brim in slump test is less than 25mm, and V_(140 )in bleeding test under pressure should be 40~110 mL.