素混凝土与加筋混凝土力学性能的温度效应试验研究

Experimental study of the temperature effect on the mechanical properties of plain concrete and reinforced concrete

以素混凝土柱和加筋混凝土柱试件为研究对象,分别进行固定烘烤时间、变化温度和固定温度、变化烘烤时间的单轴压缩试验。在相同烘烤时间下,温度越高,素混凝土柱和加筋混凝土柱的弹性模量越小,峰值强度逐渐降低,峰值应变逐渐增大;素混凝土柱的残余强度逐渐减小,加筋混凝土柱的残余强度逐渐增大。温度升高,水泥浆体的脱水收缩和骨料的受热膨胀导致界面的微裂缝增加,削弱了混凝土强度。在相同的烘烤温度下,烘烤时间越长,素混凝土柱和加筋混凝土柱的峰值强度先升高再降低,残余强度越小。水泥凝胶体中的结合水开始脱出,增强了水泥颗粒的胶合作用,缓和了缝端的应力集中,有利于混凝土强度的提高。素混凝土柱的弹性模量逐渐减小;加筋混凝土柱的弹性模量逐渐增大;素混凝土柱的峰值应变逐渐增大,加筋混凝土柱的峰值应变逐渐减小。由于混凝土膨胀系数小,则混凝土环向挤压钢筋,从而使钢筋与混凝土之间的黏结力增大。

Taking plain concrete column and reinforced concrete column for research objects,the uniaxial compression experiments were carried out to fix baking time,change temperature and fix temperature,change baking time.In the same baking time,the higher the temperature,the smaller the elasticity modulus of the plain concrete column and reinforced concrete column,the peak strength decreased gradually and the peak strain increased gradually.The residual strength of plain concrete column decreased,and the residual strength of reinforced concrete column increased gradually.With the temperature increasing,the dehydration shrinkage of cement paste and the thermal expansion of aggregate lead to the increase of micro cracks in the interface,which weakens the strength of concrete.At the same baking temperature,with the increase of baking time,the peak strength of plain concrete column and reinforced concrete column increased first and then decreased,and the residual strength was smaller.With the bound water out of cement gel,the cementing effect of cement particles was enhanced,eased the stress concentration on the seam,which is conducive to improve the concrete strength.The elastic modulus of plain concrete column decreased gradually.The elastic modulus of reinforced concrete column increase gradually.The peak strain of the plain concrete column is gradually increasing,The peak strain of the reinforced concrete column decreases.Because the concrete expansion coefficient is small,the concrete squeeze steel bar,the bond strength between steel and concrete is improved.