矿物掺合料对混凝土力学性能与开裂趋势的影响

Effect of Mineral Admixture on Mechanical Properties and Cracking Tendency of Concrete

通过拌合物和易性、混凝土基体抗压强度和平板开裂测试,研究粉煤灰和矿粉两种火山灰掺合料对混凝土力学与耐久性影响。结果表明:随着矿粉加量的升高,拌合物和易性逐渐变差,但是加入粉煤灰后和易性变化不大。加入火山灰掺合料混凝土7 d强度较纯水泥混凝土低,但28 d强度明显升高,这是由于早期火山灰反应不够,随着养护时间的延长,加入粉煤灰的试样水化度明显升高。体积收缩实验表明,加入矿粉后开裂程度增大,与平板实验矿粉开裂增大结果一致。

The concrete with fly ash and mineral powder was investigated. The effect of recycled admixtures on the mechanical properties and durability of concrete were analyzed based on the workability, the compressive strength and slab cracking test. The results show that the workability gradually becomes worse as the mineral powder amount increases. However, the workability basically unchanges after adding fly ash. The 7-d compressive strength of concrete with recycled admixtures is lower than that of pure cement concrete, and the 28-d compressive strength is significantly elevated. The volcanic reaction is insufficient in early stage. However, the hydration degree of the sample with fly ash can be improved due to the extension of curing time. The volumetric shrinkage experiment shows that the sample cracking degree is increased after adding mineral powder, which is consistent with the results of slab cracking tests.