火山灰浆液改性再生粗骨料对混凝土性能的影响

Effects of recycled coarse aggregates modified by pozzolanic ash slurry on the performance of concrete

为了研究不同配合比的火山灰浆液改性再生粗骨料对混凝土性能的影响,通过正交试验对比分析了改性和未改性再生粗骨料的吸水率、表观密度和压碎指标,探讨了改性再生粗骨料对混凝土力学性能和抗氯盐侵蚀性能的影响。结果表明:与未改性再生粗骨料相比,改性再生粗骨料的吸水率和表观密度增大,压碎指标减小;在火山灰浆液中掺入30%复合掺合料后,随着复合掺合料中粉煤灰掺量的增加,再生混凝土的抗压强度降低,氯离子扩散系数增大;在火山灰浆液中掺入适量稻壳灰后,再生混凝土的抗压强度提高,氯离子扩散系数减小;在火山灰浆液中掺入适量分散剂后,再生混凝土的抗压强度降低,氯离子扩散系数增大;综合考虑再生混凝土的力学性能和抗氯盐侵蚀性能,火山灰浆液的最佳配合比为矿粉掺量30%、稻壳灰掺量3%、不掺粉煤灰和分散剂。

In order to study the effects of different proportions of pozzolanic ash slurry modified recycled coarse aggregates on the performance of concrete,the water absorption,apparent density and crushing index of modified and unmodified recycled coarse aggregates were compared through orthogonal tests,and the effects of modified recycled coarse aggregates on the mechanical properties and resistance to chloride corrosion of concrete were discussed.The results show that compared with unmodified recycled coarse aggregates,the water absorption and apparent density of modified recycled coarse aggregates increase,while the crushing index decreases.When 30%composite admixture is added into the pozzolanic ash slurry,the compressive strength of recycled concrete decreases,and the chloride ion diffusion coefficient increases with the increase of the content of fly ash in the composite admixture.The compressive strength of recycled concrete increases and the chloride ion diffusion coefficient decreases when the pozzolanic ash slurry is mixed with appropriate content of rice husk ash.The compressive strength of recycled concrete decreases and the chloride ion diffusion coefficient increases when appropriate content of dispersant is added into the pozzolanic ash slurry.Considering the mechanical properties and resistance to chloride corrosion of recycled concrete,the optimal proportion of pozzolanic ash slurry is 30%content of mineral powder,3%content of rice husk ash,and no fly ash or dispersant.