机制砂云母含量对混凝土性能的影响

Influence of mica content in manufactured sand on concrete performance

针对工程中机制砂云母含量高的问题,通过按不同比例混掺不含云母与含云母的机制砂的方法控制机制砂中云母含量,系统研究了机制砂云母含量对混凝土工作、力学和干缩性能的影响规律,提出掺入增强剂的方式对含云母机制砂混凝土进行改性,用SEM对28 d硬化砂浆微观形貌进行分析。结果表明:在固定用水量的情况下,混凝土减水剂掺量随着机制砂中云母含量的增加而增大,抗压强度随云母含量增大而降低;机制砂中云母含量对混凝土干缩率影响较小;掺入一定量的增强剂可以明显改善混凝土工作性能和抗压强度。砂浆微观形貌显示,含云母机制砂砂浆中云母呈现出薄片状,而掺增强剂砂浆生成的水化产物包裹在云母颗粒表面,使砂浆与云母间形成连续致密的过渡区,从而提升混凝土强度。

To reduce high mica content in manufactured sand in construction,it is usually controlled by mixing different proportions of manufactured sand without mica and with mica.The impacts of mica content on the workability,mechanical properties and dry shrinkage of concrete were systematically studied.The method of adding reinforcement agent to modify the concrete containing mica manufactured sand was put forward,and the micro morphology of harden mortar at 28 d was analyzed by SEM.The test results show that the dosages of concrete superplasticizer is increase with the increase of mica content in manufactured sand under the condition of fixed water consumption.The compressive strength decreases with the increase of mica content.The mica content in manufacture sand has little effect on the dry shrinkage of concrete.The workability and compressive strength of concrete were significantly improved by adding a certain amount of reinforcing agent.The micro morphology of the mortar shows that the mica in the mortar with mica presents thin sheet shape.The surface of hydration products by mortar mixed with reinforcement agent wrap on mica particles,forming a continuous and dense transition zone between the mortar and mica,so as to improve the concrete strength.