Title: Formwork Pressure of Self-Consolidating Concrete Containing Recycled Coarse Aggregates
Author(s): Joseph J. Assaad and Jacques Harb
Publication: Materials Journal
Appears on pages(s): 491-500
Keywords: formwork pressure; recycled aggregates; self-consolidating concrete (SCC); thixotropy
The successful use of highly flowable self-consolidating concrete (SCC) containing recycled concrete aggregate (RCA) in structural applications entails proper assessment of lateral pressure developed on vertical formworks. Three series of relatively low to high stable SCC mixtures were considered in this paper; the virgin aggregates were substituted by 25, 50, 75, and 100% RCA. Regardless of SCC composition, test results have shown that mixtures prepared with increased RCA replacement levels led to reduced initial pressure measured after placement, as well as accelerated rates of pressure drop over time. The former phenomenon was related to higher RCA surface roughness that increases internal friction, while the latter was attributed to higher water absorption that improves concrete stability. A series of regression models based on thixotropy and relative water absorption of aggregates were developed to predict the effect of RCA on SCC formwork pressure.