水工泵送及常态混凝土性能对比试验研究

泵送混凝土在拌合物状态及各材料用量上与常态混凝土相比存在较大差异,该差异会在硬化混凝土各项性能中得到体现。为了研究水工泵送混凝土和常态混凝土在力学及干缩性能方面的差异,设置了3组对比试验。在同水胶比下,随着水胶比的增大,泵送混凝土相对于常态混凝土在抗压强度、抗拉强度、拉压比及弹性模量等指标方面表现出明显的优势。在不同水胶比下,泵送混凝土的干缩率也均大于常态混凝土。28,60,90 d龄期的泵送混凝土和常态混凝土的干缩率受水胶比影响显著,而3 d和7 d龄期的干缩率则受水胶比影响不明显。2种混凝土早期干缩率发展较快,后期则相对缓慢,干缩率的平均增长速率随龄期增加呈幂函数变化。该研究可以为泵送混凝土在水利工程中的应用提供一定的借鉴。

Comparative Study on Properties of Hydraulic PumpingConcrete and Normal Concrete

Hydraulic pumping concrete differs greatly from normal concrete in terms of mixture state and material dosage.These differences will be reflected in the performance of hardened concrete.In order to study the differences in mechanics and shrinkage properties of hydraulic pumping concrete and normal concrete, we designed three groups of comparative test.Results revealed that in the presence of given water-binder ratio, pumping concrete was superior to normal concrete in compressive strength, tensile strength, tension-compression ratio and elastic modulus with the increase of water-binder ratio;while under different water-binder ratios, the shrinkage rate of pumping concrete was still higher than that of normal concrete.Moreover, the shrinkage rate of pumping concrete and normal concrete at the age of 28d, 60d and 90d were affected significantly by water-binder ratio;whereas the shrinkage rate at the age of 3d and 7d were not affected obviously.The shrinkage of the two concretes developed rapidly in the early stage, but was slowly in later stage.The average growth rate of drying shrinkage is in a power function relationship with age.