人工砂中碳颗粒对混凝土性能影响的试验研究

两河口水电站人工砂中含有悬浮碳颗粒,引起了混凝土用水量增加、含气量反复变化、施工性能不稳定等问题,从而增加了混凝土开裂的风险。利用混凝土试验,对比研究了不同的悬浮碳颗粒含量对混凝土用水量、胶砂用水量以及混凝土性能的影响,以期找出悬浮碳颗粒含量与混凝土性能之间的规律。结果表明:悬浮碳颗粒含量越大,混凝土用水量越高、引气剂掺量越大,但其对混凝土表面气泡、抗压强度、劈裂强度、弹性模量、极限拉伸值以及抗冲磨、抗冻、抗渗等耐久性能影响不大。在此基础上,采取了水洗降低碳颗粒含量、掺硅粉等控制措施,降低了胶凝材料用量,保证了混凝土质量。研究成果可为其他类似工程提供参考。

Experimental study on effect of carbon particles in artificial sand on concrete performance

The artificial sand of Lianghekou Hydropower Station contains suspended carbon particles, which causes the problems of increased water consumption of concrete, fluctuated gas content and unstable construction performance, increasing the risk of concrete cracking. In this paper, the effect of different suspended carbon particles content on concrete water consumption, cement mortar water consumption and concrete performance were studied by concrete test, and the law between suspended carbon particles content and concrete performance was found out. Results show that the higher the content of suspended carbon particles, the higher the water consumption of concrete and the greater the amount of air entraining agent. But it has little effect on the concrete surface bubbles, compressive strength, splitting strength, elastic modulus, ultra tensile value, and anti-wear, anti-freeze, anti-seepage and other durability properties. On the basis of this, some control measures such as reducing carbon particle content by water washing and adding silica powder are put forward to reduce the consumption of cementitious material and ensure the quality of concrete.