基于流变参数多样本统计的自密实混凝土稳定性及均匀性分析方法

Analyzing Methods for Stability and Homogeneity of Self-Compacting Concrete Based on Rheological Parameters of Multiple Samples Statistics

自密实混凝土具有流动性大、密实度高的特点,常被用于钢管混凝土等特殊工程结构,但其制备及施工过程极易受工程现场复杂因素影响,产生不可控的工作性能波动,目前缺乏基于流变学本质的分析控制指导方法。本文统计并分析了实际工程现场的混凝土流变参数,结果表明混凝土的流变参数在多样本条件下符合良好的对数正态分布。根据样本95%置信区间进行了整体混凝土稳定性分析,将s0∈[194.75,225.76]∩∈[88.76,95.00]作为混凝土稳定性良好的判据;并结合混凝土在泵管内的流动形式对现场调整的混凝土的流变参数进行分析,讨论流变性能的调控方向,提出基于混凝土流变参数的可泵性区间(τ_(s0)=[54.17,391.76]∪μ=[52.77,126.66])和流变性能优化方法。基于现场统计的流变参数曲线特征,从本质上揭露了混凝土的内部均匀性特征,提出了现场施工的自密实混凝土均匀性判据,为自密实混凝土均匀性评价体系、流变性能调控、配合比设计提供理论依据。

Self-compacting concrete with high fluidity and compactness is often used in the special engineering structures such as concrete-filled steel tubes.However,its preparation and construction process are highly susceptible to complex factors at the engineering site,resulting in uncontrollable fluctuations in its workability.There is still a lack of analytical control methods based on essence of rheology.This paper makes an analysis of the rheological parameters of concrete according to the data collected from actual engineering sites.The results show that the rheological parameters of concrete well conform to a log-normal distribution under multiple sample conditions.Besides,an analysis of the overall concrete stability was carried out according to the 95%confidence interval of the samples,using s0∈[194.75,225.76]∩∈[88.76,95.00]as a criterion for good concrete stability,and the rheological parameters of concrete adjusted on site were analyzed along with the flow behavior of concrete in the pump pipe.The direction of rheological property regulation was discussed,and methods for optimizing pumpability ranges(τ_(s0)=[54.17,391.76]∪μ=[52.77,126.66])and rheological parameters were proposed based on concrete rheological parameters.By revealing the inherent homogeneity of the concrete through the analysis of the characteristics of the rheological parameter curves,the paper proposed a criterion for the homogeneity evaluation of self-compacting concrete on site,providing a theoretical basis for the homogeneity evaluation,rheological property regulation and mix proportion design of self-compacting concrete.