偏高岭土和稻壳灰对自密实混凝土力学性能影响

Effect of Metakaolin and Rice Husk Ash on Mechanical Properties of Self-compacting Concrete

为研究偏高岭土和稻壳灰对自密实混凝土力学性能的影响,分别以5%、10%、15%的偏高岭土和10%、15%、20%的稻壳灰替代部分水泥,制备了16种不同配合比的自密实混凝土试件,研究了新拌自密实混凝土的工作性和硬化后自密实混凝土的抗压强度、劈裂抗拉强度,并对其微观结构进行了对比分析.结果表明:新拌混凝土和易性随着偏高岭土和稻壳灰的掺入逐渐降低;自密实混凝土的28 d抗压强度和劈裂抗拉强度随着偏高岭土替代水泥比例的增加逐渐增加,随着稻壳灰替代水泥比例的增加逐渐减小;当偏高岭土和稻壳灰协同使用时,可以显著改善混凝土的微观结构,两者掺量分别为10%时,形成的C-S-H凝胶致密且分散,自密实混凝土的抗压强度和劈裂抗拉强度最大.

In order to study the effect of metakaolin and rice husk ash on the mechanical properties of self-compacting concrete,16 kinds of self-compacting concrete specimens were prepared where cement was replaced by weight in three proportions of 5,10 and 15%by metakaolin and 10%,15%and 20%by rice husk ash,respectively.The workability of freshly mixed self-compacting concrete and the compressive strength and splitting tensile strength of hardened self-compacting concrete were studied.The microstructure of the self-compacting concrete was compared and analyzed.The results show that the workability of fresh concrete gradually decreases with the incorporation of metakaolin and rice husk ash.The 28d compressive strength and splitting tensile strength of self-compacting concrete gradually increase with the increase of the proportion of metakaolin instead of cement,and gradually decrease with the increase of the proportion of rice husk ash instead of cement.When metakaolin and rice husk ash are used synergistically,the microstructure of concrete can be significantly improved.When the content of the two is 10%,the C-S-H gel formed is dense and dispersed.Self-compacting concrete has the highest compressive strength and splitting tensile strength.