Test Study of Lateral Interaction Mechanism at Different Concrete Mixes Between Very EarlyAge Concrete and Structures

Abstract:

The lateral pressure of very earlyage concrete on the formwork directly affects the formwork design, whose numerical size is controlled by the casting rate, concrete mix，temperature, surface characteristics, size and shape of formwork and the depth of the casting concrete and so on. Therefore, the influencing mechanism is quite complicated. Based on theory analysis, a model test which can obtain the lateral pressure under the condition of different concrete mix was designed, and the measuring results were analyzed. The test results show that the vertical distribution of lateral pressure is similar to the hydrostatic pressure, but significantly less than the hydrostatic pressure. As the concrete watercement ratio increases, the initial template lateral pressure gets closer to the hydrostatic pressure, and the lateral pressure drops faster. The cancellation of lateral pressure occurs after the end of the dormant period of cement hydration. The accelerated rate of formation of hydrates enables the material to become selfbearing, which leads the rapid decrease of lateral interaction towards zero.

Key words:very earlyage concrete; formwork; lateral pressure; model test; concrete mix