砂石岩性对混凝土抗渗和干缩性能的影响分析

Analysis of the Influence of Sand Properties on Impermeability and Dry Shrinkage of Concrete

依托广西壮族自治区桂中治旱乐滩水库引水灌区工程,研究了该工程所在地涉及的3种岩性砂石的物理、化学特性,并通过正交试验分析了不同水胶比下,3种岩性砂石对混凝土抗渗和干缩性能的影响规律。研究结果表明:砂石的坚固性和碱集料反应可分别通过吸水率、快速砂浆棒法来表征,以加快施工进度;砂石的岩性对混凝土抗渗性能与干缩性能的影响均较为显著,这主要与砂石的吸水率有关;3种岩性砂石中,石灰岩的吸水率和膨胀率均最大,其配制的混凝土抗渗和干缩性能最差,而辉长岩存在一定的碱集料反应危害。因而,在不考虑集料处治的情况下,推荐采用闪长岩作为工程建设中混凝土的主要砂石集料。

Relying on the drought control project of Guizhong Letan reservoir diversion irrigation area in Guangxi Zhuang Autonomous Region,the physical and chemical properties of three types of lithic sands used in the site were studied.Under different water-binder ratio,the influence laws of the lithic sands on the impermeability and dry shrinkage performance of concrete were analyzed by orthogonal tests.The results show that the solidity and alkali aggregate reaction of sand and gravel can be characterized by water absorption rate and fast mortar bar method respectively to speed up the construction progress;The influence of lithology of sand-gravel on the impermeability and dry shrinkage performance of concrete is significant,which is mainly related to the water absorption rate of sand and gravel;Among the three lithologies of sand-gravel,limestone has the largest water absorption rate and swelling rate,which the concrete formulated has the worst impermeability and dry shrinkage performance.The diorite has a certain hazard of alkali aggregate reaction.Therefore,gabbro is recommended to be the main sand-gravel aggregate for concrete in engineering construction without considering the aggregate treatment.