温湿度异常引起混凝土收缩测试误差的修正

研究了混凝土收缩测试过程中环境温度和湿度异常波动引起的收缩测试误差。结果表明热胀冷缩是温度影响收缩测试的主要原因,引起的误差超过混凝土的收缩值,对收缩测试结果影响很大。热胀冷缩变形是可逆的,可通过在总变形中减去热膨胀变形对收缩测试结果进行修正,消除温度误差。环境相对湿度异常引起混凝土内部相对湿度变化,进而导致毛细孔压力改变,引起收缩测试误差。湿度异常对收缩的影响与相对湿度差值和持续时间成正比,与试件最小截面尺寸成反比,可据此对测试误差进行修正。

Correction of concrete shrinkage test errors caused by abnormal temperature and relative humidity

The deviation of concrete shrinkage test results due to the fluctuation of environmental temperature and relative humidity is investigated.The results show that thermal expansion is responsible for the influence of abnormal temperature on the shrinkage test of concrete.The error caused by the abnormal temperature is greater than the shrinkage strain hence has significant effect of the shrinkage tests.However,due to the thermal deformation is reversible,the errors can be eliminated by taking off the thermal expansion from the total strain.The unusual environmental relative humidity causes the change in the internal relative humidity of concrete,which leads to the change in the pressure of capillary pores in concrete,and therefore causes the error of shrinkage tests.The error of shrinkage due to unusual external humidity may be proportional to the difference in relative humidity between external and internal concrete and the duration of the abnormal humidity,and is inversely proportional to the minimum section size of specimen.Accordingly the shrinkage test errors can be corrected.