相同和易性和强度条件下天然砂和机制砂混凝土配合比研究

Study on Mix Proportions of Manufactured Sand Concrete and Natural Sand Concrete with the Same Strength and Workability

研究了相同和易性和强度等级条件下,天然砂混凝土和机制砂混凝土配合比的差异。结果表明:在坍落度40~200 mm、强度等级C20~C45范围内时,通过同时提高2%~4%的砂率和0.037~0.082的浆骨比,可以使机制砂混凝土具有与天然砂混凝土相同的和易性;当水灰比相同时,砂率和浆骨比的调整并不影响机制砂混凝土的28 d抗压强度,水灰比定则对机制砂混凝土仍然适用;当坍落度相同时,随着强度等级的提高,机制砂混凝土较天然砂混凝土的浆骨比增量增加;在低坍落度(40 mm)条件下,对于不同强度等级的混凝土,掺加减水剂均可减少机制砂对混凝土砂率和浆骨比的影响。

The difference of the proportion of mixture between natural sand concrete and manufactured sand concrete under the condition of the same workability and strength grade was studied.The results show that by increasing the sand ratio(2%~4%)and the paste-aggregate ratio(0.037~0.082),the workability of manufactured sand concrete with the slump of 40~200 mm and the strength grade of C20~C45 can be the same as that of natural sand concrete.When the water cement ratio is the same,the adjustment of sand ratio and paste-aggregate ratio does not affect the 28 d compressive strength of manufactured sand concrete,and the water cement ratio rule is still applicable to manufactured sand concrete.Under the same slump,the increment of the paste-aggregate ratio of manufactured sand concrete compared with natural sand concrete increases with the increase of the strength grade.Under the condition of low slump(40 mm),the influence of manufactured sand on sand ratio and paste-aggregate ratio of concrete can be weakened by adding water reducing agent.