改性再生混凝土力学性能的试验研究

Experimental study on mechanical properties of modified recycled concrete

为提高再生粗骨料混凝土的力学性能,分别选用硅酸钠溶液和硅烷溶液对再生粗骨料进行单一改性,同时使用硅烷溶液对硅酸钠溶液处理后的再生粗骨料进行二次改性,并测定改性粗骨料再生混凝土的抗压强度和劈裂抗拉强度,结合核磁共振技术表征改性前后再生混凝土内部的孔隙结构变化。结果表明:改性再生粗骨料的表观密度、吸水率及压碎指标均优于未改性组,且二次改性效果优于一次改性;改性粗骨料使再生混凝土的强度得到不同程度的提升,经过浓度8%的硅酸钠溶液先处理、浓度12%的硅烷溶液二次改性的再生混凝土的力学性能最佳,其抗压强度、劈裂抗拉强度较未改性组分别提高了22.30%、28.48%;粗骨料改性后再生混凝土的T_(2)图谱的3个峰值均减小,峰值点均向左偏移,说明改性粗骨料使再生混凝土的孔隙体积减小,内部结构更加致密,从而明显提高了再生混凝土的强度。

To improve the mechanical properties of recycled coarse aggregate concrete, sodium silicate solution and silane solution are used to modify the recycled coarse aggregate separately, and the silane solution is used to modify the recycled coarse aggregate after sodium silicate solution treatment. The compressive strength and splitting tensile strength of modified coarse aggregate recycled concrete are measured. The changes of pore structure in recycled concrete before and after modification are characterized by NMR. The results show that the physical properties of the modified recycled coarse aggregate are better than those of the unmodified group, and the secondary modification effect is better than that of the singlie modification. Modified coarse aggregates increase the strength of recycled concrete to varying degrees. The mechanical properties of recycled concrete prepared from coarse aggregate which was first treated with sodium silicate solution(8%) and modified with silane solution(12%) are the best. Compared with the unmodified group, its compressive strength and split tensile strength are increased by 22.30% and 28.48% respectively. The three peaks of the Tspectrum of recycled concrete after coarse aggregate modification are all reduced, and the peak points are all shifted to the left, indicating that the modified coarse aggregate reduces the pore volume of recycled concrete and makes the internal structure denser, thereby significantly improving the strength of recycled concrete.