粉煤灰和硅粉对水下自密实混凝土性能的影响

Effect of fly ash and silica fume on the performance of underwater self-compacting concrete

针对传统混凝土自密实性能与水下抗分散性能无法良性共存的问题,以自密实混凝土为基础,通过掺入掺合料(粉煤灰、硅粉)及外加剂(减水剂、絮凝剂)调节改善混凝土工作性能,得到自密实且水下不分散的水下自密实混凝土,并研究粉煤灰和硅粉对水下自密实混凝土工作性能、力学性能及浆体孔结构的影响。结果表明,复掺粉煤灰和硅粉比单掺或无掺合料的混凝土具有更好的性能:拌合物流动度超过600 mm,且具备水下抗分散性能,28 d水下抗压强度能达到陆上强度的75%以上,浆体孔隙率较小,浆体孔径分布更为合理。粉煤灰适宜掺量20%~30%,硅粉适宜掺量10%~15%。

Aiming at the problem that traditional concrete′s self-compacting performance and underwater anti-dispersion cannot coexist,based on self-compacting concrete,by admixing admixtures(fly ash,silica fume)and additives(superplasticizer,flocculants)adjust and improve the working performance of concrete to obtain self-compacting and non-dispersing underwater self-compacting concrete.The effects of fly ash and silica fume on the working performance,mechanical properties and slurry microstructure of underwater self-compacting concrete were studied.The results show that the mixed fly ash and silica fume have better performance than the concrete with or without admixture the fluidity of the mixture exceeds 600 mm,and it has underwater anti-dispersion performance,and the 28 d underwater compressive strength can reach more than 75%of the strength on air,the porosity of the slurry is small,and the pore size distribution of the slurry is more reasonable.The suitable amount of fly ash is 20%~30%,and the suitable amount of silicon powder is 10%~15%.