Study of rheological properties of pumped concrete derived cement pastes

Resumo

The use of pumped concrete has become more common at reinforced concrete construction. There is an idea that fresh concrete, in order to be pumped, only needs to have high flow characteristics. However, the flow characteristics, which are usually measured by the Slump test, are not the only factors that influence the concrete pumping process. The use of rheology concepts has been employed by the scientific community for a better understanding of concrete behavior, relating the rheological parameters to the main properties of this composite material. Thus, the goal of this study is to investigate the effects of important variables in Portland concrete design in the rheological characteristics of pumped concrete derived cement pastes. To accomplish that, experimental tests such as flow, strain rate sweep, and Vane tests varying the water-cement relationship (w/c = 0.33; 0.35; and 0.43) and subjected to different hydration periods (15, 60, and 120 minutes) were performed. The analysis results showed the evolution of yield stress and apparent viscosity as a function of the hydration period and the reduction of water-cement relationship.