不同石粉含量的片麻岩机制砂C50混凝土性能研究

Performance of C50 Concrete Made of Gneiss Manufactured Sand with Different Stone Powder Content

机制砂生产过程中会产生一定量的粒径小于75μm的石粉,而石粉含量对混凝土不同性能的影响规律和程度与石粉的岩性和品质有很大关系。为掌握片麻岩机制砂中石粉含量对C50混凝土性能的影响,获得配制C50混凝土用片麻岩机制砂的适宜石粉含量范围,文中研究了四种不同石粉含量(3%、5.3%、7.5%和10%)的机制砂配制的C50混凝土的工作性能、力学性能和耐久性能。结果显示,随着石粉含量的增大,机制砂混凝土达到等工作性能所需减水剂掺量增加,抗压强度、劈拉强度和弹性模量呈逐步增大趋势;机制砂混凝土的早期干缩随着石粉含量的增加而增大,后期干缩呈先增后减趋势,在石粉含量为7.5%时,最终干缩值最大。机制砂混凝土的抗氯离子渗透性随石粉含量增加而有所改善,抗冻性受石粉含量的影响不大,抗冻耐久性指数均超过90%。研究结果表明,片麻岩机制砂配制C50混凝土的适宜石粉含量为5%~7.5%。

A certain amount of stone powder with particle size less than 75μm is produced in the production process of manufactured sand,and the influence of stone powder content on different properties of concrete is closely related to its parent rock lithology and quality.In order to grasp the influence of stone powder content in the gneiss manufactured sand on the performance of C50 concrete and obtain the suitable content of stone powder for gneiss manufactured sand used for C50 concrete,the four C50 concretes were prepared with the gneiss manufactured sands containing stone powder of 3%,5.3%,7.5%and 10%,and the workability mechanical and durability properties of these concretes are stud-ied.The results show that with the increase of the stone powder content,the dosage of reducer required for the concrete to achieve the equal workability increases,and the compressive strength,splitting tensile strength and elastic modulus of concrete increased gradually;with the increase of the stone powder content,the early age dry shrinkage of manufactured sand concrete increases,and the later age dry shrinkage in-creases first and then decreases.The final dry shrinkage reaches the maximum when the content of stone powder is 7.5%.The chloride perme-ability of manufactured sand concrete is improved with the increase of the content of stone powder,while the frost resistance is hardly affected by the content,and the frost resistance durability index is all more than 90%.The results show that the suitable content of stone powder in the gneiss manufactured sand for preparing C50 concrete is 5%~7.5%.