Settlement of fresh concrete—an effective stress model

Abstract

Synopsis The settlement of fresh concrete under load is examined both theoretically and experimentally. It is shown that settlement depends on the effective stress to which the intergranular structure is subjected, and that the settlement has two major components. One of these is immediate settlement due to compression of the pore fluid and the intergranular structure in response to applied load. The other is consolidation settlement created by the dissipation of pore water with time which gradually transfers load from the pore water onto the intergranular structure. A reduction in consolidation settlement will reduce the risk of settlement cracking and void formation around reinforcing bars. For discrete cycles of loading, such as placing of concrete in layers, a direct measure of consolidation settlement as a proportion of total settlement is given by a pore water pressure coefficient.