再生细骨料自密实混凝土性能研究

Study on properties of self-compacting concrete with recycled fine aggregate

再生细骨料在混凝土中应用,可有效解决建筑垃圾的再生利用问题。研究了再生细骨料掺量(0、25%、50%、75%)和预饱水时间(0、2h、24h)对再生细骨料自密实混凝土工作性、力学性能和耐久性的影响规律。结果表明,再生细骨料降低新拌自密实混凝土的工作性。抗压强度随着再生细骨料取代率的增加及预饱水时间的减少而降低,但再生细骨料自密实混凝土后期强度增长率较高。混凝土28d抗压强度高于50MPa,56d抗压强度超过65MPa。28d抗折强度为7.6~8.2MPa,劈裂抗拉强度为4.2~5.1MPa。饱水再生细骨料会降低混凝土抗冻融性。混凝土抗冻性随着预饱水时间的降低而提高。

Use of recycled fine aggregate(RFA)in concrete could effectively resolve the construction waste issue.The effect of replacement ratio(0,25%,50%,75%)of RFA and pre-wetting time(0,2 h,24 h)on the properties of self-compacting concrete(SCC)was studied,including workability,mechanical properties and durability.Testing results show that the RFA reduces concrete workability.The compressive strength decreases as the replacement ratio increases and pre-wetting time reduces.However,the SCC with RFA has higher strength development ratio at late age.The 28-day compressive strength is above 50 MPa and 56-day strength over 65 MPa.The 28-day flexural strength ranges from 7.6 to 8.2 MPa.The 28-day splitting tensile strength is between 4.2 and 5.1 MPa.The saturated RFA could reduce the freezing-thawing resistance of concrete,which is increased as the pre-wetting time decreases.