粉煤灰代砂RCC配合比试验研究及应用

Test and Application of RCC Mix Proportion with Fly Ash instead of Sand

浆砂比是评价碾压混凝土拌和物性能的重要指标，根据近几年来RCC（碾压混凝土）筑坝实践经验，一般浆砂比值不低于0．42时，RCC泛浆效果好，可碾性强，能有效提高混凝土层间结合和骨料抗分离能力。向家坝水电站二期工程RCC近400×104m3，为满足混凝土层间结合，确保工程施工质量，满足工程质量标准提出RCC用人工砂石粉含量宜控制在16％～18％，混凝土浆砂体积比可满足要求。但是泄洪坝段抗冲耐磨混凝土在同期施工时，为提高混凝土抗裂性能，人工砂石粉含量要求控制在10％～14％，无法满足RCC用砂要求，因此对RCC配合比在原配合比的基础上提出以粉煤灰代砂方案，灰代砂配合比在实际施工过程中混凝土的泛浆效果和可碾性较好。

The slurry sand ratio is an important index to evaluate the performance of roller compacted concrete mixture.According to the practical experience in construction of roller compacted concrete(RCC) dam in the recent years,when the slurry sand ratio is not less than 0.42,RCC is of high bleeding quality and of high compactibility,and the concrete inter-layer bonding and the separation resistance ability of aggregates can both be greatly improved.The volume of RCC of the phase 2 project of Xiangjiaba Hydropower Plant is nearly 400×104 m3. In order to meet the concrete inter-layer bonding requirement,to ensure the construction quality of the project and to satisfy the project quality standards,the content of crushed aggregate dust was proposed to be 16%-18% as preferable,but when the erosion-and abrasion-resistant concrete of the spillway dam section was constructed simultaneously,in order to improve cracking-resistant performance of the concrete,the content of crushed aggregate dust was required to be 10% -14%.Then the sand requirement in RCC could not be satisfied.Therefore fly ash was used instead of sand in RCC based on the original mix proportion of RCC.The new mix proportion of RCC,in which sand was replaced by fly ash,produced the concrete that has higher bleeding quality and better compactibility.