塑性混凝土相对弹性变形特性试验研究

Experimental Study on the Relative Elastic Deformation of Plastic Concrete with Low Strength

为了探讨塑性混凝土应力-应变曲线直线段P_1和P_2的取值范围,从而得出弹性模量的取值,通过对4组不同混凝土配合比的48个试件,进行了单轴抗压强度试验。通过试验绘制了典型应力-应变曲线,选取了曲线的近似直线段,进而分析割线模量和计算区间内切线模量均值的相近程度,并对直线段弹性模量计算公式中如何对P_1和P_2取值进行了研究。试验结果表明:塑性混凝土应力-应变曲线上升段存在近似直线段;塑性混凝土的强度<5MPa时,选取60%和80%峰值应力作为弹性模量计算公式中P_1和P_2的值比较符合塑性混凝土的实际情况;反之,则需要更进一步的研究。试验研究成果为解决低强度塑性混凝土材料性能取值难问题提供了一种较好的方法。

In order to determine two endpoints（ P_1 and P_2） in the straight-line segment of stress-strain curve of plastic concrete,and to obtain the elastic modulus,we carried out uniaxial compression test on 48 concrete specimens of four different mix proportions. Through analyzing typical stress-strain curve,we selected approximated straight-line in the curve,and compared the secant modulus with mean value of tangent modulus. On this basis,we studied how to determine P_1 and P_2. The results show that 1） the approximated straight-line segment appears at the ascent stage in the stress-strain curve of plastic concrete; 2） with given strength of plastic concrete less than 5MPa,it is suitable to choose 60% and 80% of peak stress as the elastic modulus of P_1 and P_2,respectively,otherwise,further study is required. Finally,the research offers a method for determining the values of material performance of plastic concrete with low strength.