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以桥梁高性能混凝土为研究对象,测试老混凝土约束下新混凝土板的收缩变形。通过试验分析界面粗糙度对其影响,并考察混凝土内部早期温、湿度变化与收缩应变的关系,分析养护时间对混凝土材料收缩应力的影响。结果表明:老混凝土约束下的新混凝土厚度随新老混凝土黏结界面粗糙度的提高而增大,新混凝土内部拉应力随界面粗糙度的提高而降低,但新、老混凝土界面粗糙度对黏结面处的收缩影响不显著;距黏结面越近的截面收缩应变越小,在黏结面处达到最小,表现出显著的不均匀性,并随龄期逐渐增大。延长养护时间可减小混凝土收缩变形和内部由于不均匀收缩导致的拉应力,降低混凝土板早期开裂的风险。
Taking the bridge high performance concrete as the research object, the shrinkage deformation of the new concrete slab under the constraint of the old concrete is tested. The influence of interface roughness was analyzed through experiments. The relationship between early temperature and humidity changes and shrinkage strain in concrete was also investigated. The influence of curing time on the shrinkage stress of concrete was analyzed. The results show that the thickness of new concrete confined by the old concrete increases with the increase of the roughness of the interface between the new and old concrete, and the internal tensile stress of the new concrete decreases with the increase of the interface roughness. However, the roughness of the new- The shrinkage effect is not significant; the closer the cross-sectional shrinkage strain to the bonding surface is, the smallest is the bonding surface, showing significant inhomogeneity and increasing with age. Prolonging the curing time can reduce the shrinkage of concrete and the internal tensile stress caused by uneven shrinkage, reduce the risk of early cracking of concrete slab.