建筑用不同取代率粉煤灰再生混凝土的力学性能及耐久性能研究  

Study on the mechanical properties and durability ofrecycled fly ash concrete with different substitution rates for construction

作　　者：翟思敏 黄金霞 ZHAI Simin;HUANG Jinxia(School of Civil Engineering Management,Hebei University of Science and Technology,Baoding 071000,China)

机构地区：[1]河北科技学院建筑工程管理学院,河北保定071000

出　　处：《功能材料》2024年第4期4121-4126,共6页Journal of Functional Materials

基　　金：国家自然科学基金项目(11562013)。

摘　　要：以废弃混凝土为再生骨料,采用湿法粉磨处理I级粉煤灰,制备出不同取代率粉煤灰再生混凝土,通过XRD、SEM、力学性能测试、干缩率测试等手段,研究了不同取代率的I级粉煤灰对再生混凝土的力学性能和耐久性能的影响。结果表明,湿法粉磨处理后的粉煤灰表面玻璃体被破坏,火山灰效应增强,从而提高了再生混凝土的水化速率,使水化产物C—S—H和AFt数量增加,混凝土密实度增大。粉煤灰再生混凝土的抗压强度随粉煤灰取代率的增大先增大后降低,粉煤灰取代率45%的混凝土的抗压强度最大为42.05 MPa,其水化产物Ca(OH)_(2)的含量最多为11.742%。挠度测试表明,粉煤灰取代率45%的混凝土屈服阶段对应的载荷为217 N,挠度最大为1.7 mm,在28 d时粉煤灰取代率45%的混凝土的干缩率最低为1.021×10^(-4)。综合可知,粉煤灰取代率45%的混凝土性能最优。Using waste concrete as recycled aggregate,Grade I fly ash was treated with wet grinding to prepare recycled concrete with different replacement rates of fly ash.The effects of different substitution rates of Grade I fly ash on the mechanical and durability properties of recycled concrete were studied through XRD,SEM,mechanical performance testing,and dry shrinkage testing.The results show that the glass body on the surface of fly ash after wet grinding treatment is destroyed,and the volcanic ash effect is enhanced,thus improving the hydration rate of recycled concrete,increasing the number of hydration products C—S—H and AFt,and increasing the compactness of concrete.The compressive strength of fly ash recycled concrete first increases and then decreases with the increase of fly ash replacement rate.The maximum compressive strength of concrete with a 45%fly ash replacement rate is 42.05 MPa,and the content of its hydration product Ca(OH)_(2) is up to 11.742%.The deflection test shows that the yield stage of concrete with a 45%replacement rate of fly ash corresponds to a load of 217 N,with a maximum deflection of 1.7 mm.The minimum dry shrinkage of concrete with a 45%replacement rate of fly ash at 28 d is 1.021×10^(-4).Overall,it can be concluded that concrete with a 45%replacement rate of fly ash has the best performance.

关 键 词：粉煤灰 再生混凝土 取代率 力学性能 挠度 干缩率 

分 类 号：TU560.25[建筑科学—建筑技术科学]