二灰稳定碎石再生水泥混凝土基层材料的性能研究

Study on Properties of Lime-Fly Ash Stabilized Macadam Recycled Cement Concrete Base Material

摘要: 室内试验研究了二灰稳定碎石再生用作水泥混凝土基层材料的性能，分析了二灰碎石再生料的材料特性，设计了再生混凝土的配合比，分析了其力学特性、耐久性、收缩特性和疲劳特性。结果表明，二灰碎石再生集料具有较好的形状特征和表面特性，与新集料相比，其表观密度、堆积密度低，吸水率高且吸水速率快，压碎值低；利用再生细集料的再生混凝土强度明显低于仅利用再生粗集料，增加再生粗集料用量，材料抗压强度降低而抗折强度提高，推荐设计配合比为水泥:再生粗集料:碎石:砂 = 1:2.24:1.49:1.92；二灰碎石再生水泥混凝土具有较高的温缩系数与干缩系数，尤其养生前14天的干缩系数增加迅速；二灰碎石再生集料混凝土的抗渗等级为S10，最大抗冻循环次数为90次，满足一般工程混凝土耐久性要求；二灰碎石再生混凝土疲劳性能与普通水泥混凝土相近。

Abstract: The performance of lime-fly ash stabilized gravel regenerated as cement concrete base material was studied in laboratory. The properties of lime-fly ash gravel recycled material were analyzed, and the mix proportion of recycled concrete was designed to study the mechanical characteristics, durability, shrinkage and fatigue. The results showed that the recycled aggregate of lime-fly ash gravel had better shape and surface characteristics. Compared with the new aggregate, the recycled aggregate had lower apparent density and bulk density, higher water absorption, faster water absorption rate and lower crushing value. The strength of recycled concrete using recycled fine aggregate was obviously lower than that using recycled coarse aggregate. The increase of recycled coarse aggregate resulted in the decrease of the compressive strength and the growth of the flexural strength. The design mix proportion of cement:recycled coarse aggregate:crushed stone:sand is recommended as 1:2.24:1.49:1.92. The lime-fly ash gravel recycled cement concrete had higher temperature shrinkage and dry shrinkage coefficients, especially for the dry shrinkage coefficient, which increased rapidly during the curing age in the first 14 days. The lime-fly ash gravel recycled aggregate concrete permeability grade was S10 with the antifreeze number up to 90 cycles, which met the concrete durability requirements in general engineering. The fatigue performance of lime-fly ash gravel recycled concrete was similar to that of ordinary cement concrete.