渠道衬砌板水下不分散混凝土的配合比设计与性能研究

针对调水工程输水工况下输水渠道衬砌板破损修复难题,开展了适用于渠道衬砌板水下修复混凝土的制备与性能研究。采用水工自密实混凝土设计方法进行水下不分散混凝土的配合比设计,在满足水工自密实混凝土流动度和强度要求的基础上,通过掺入聚丙烯酰胺絮凝剂和硅粉提高混凝土的水下抗分散性能,并研究掺合料品种与掺量、水粉比、砂率、施工方式等因素对混凝土流动性、抗分散性和抗压强度的影响。研究结果表明,在采用倾倒法进行水下施工时,粉煤灰掺量25%、硅粉掺量15%,水粉比1.0,砂率42%的水下不分散混凝土可满足衬砌板水下施工要求。与单掺粉煤灰相比,复掺粉煤灰和硅粉可有效增强水下不分散混凝土的抗分散性和抗压强度并改善流动性。在保证流动性前提下,适当降低水粉比和砂率有利于提高水下不分散混凝土的抗分散性和抗压强度;采用导管法施工混凝土强度损失较小,90 d龄期水下混凝土强度与陆上混凝土强度相当。

Study on mixing ratio design and performance of non-dispersible underwater concrete for channel lining slab

Aiming at the problem of repairing the damage of the lining slab of water conveyance channel under the water delivery condition of water transfer project，the study on the preparation and the performance of the concrete suitable for underwater repair of channel lining slab is carried out． The mixing ratio of the non-dispersible underwater concrete is designed with the design method of hydraulic self-compacting concrete，and then the anti-dispersion performance under water is enhanced by means of mixing polyacrylamide flocculant and silica powder into the concrete on the basis of meeting the requirements of both the flowability and strength of the hydraulic self-compacting concrete，while the influences from the factors of the type and content，the water/powder ratio，the sand ratio and the construction method of the admixtures on the flowability，the anti-dispersion performance and the compressive strength of the concrete are studied as well． The study result shows that when the dumping method for underwater concrete construction is adopted，the non-dispersible underwater concrete with the mixing amounts of 25% fly ash and 15% silicon powder，the water/powder ratio of 1. 0 and the sand ratio of 42% can meet the underwater construction requirement of the non-dispersible underwater concrete． If compared with single mixing of ash fly，the multi-mixing of both ash fly and silicon powder can effectively enhance the anti-dispersion performance and the compressive strength of the non-dispersible underwater concrete， and then improve its flowability． Under the premise of ensuring the flowability，appropriately lowering the water/powder ration and sand ratio is favorable to enhance the anti-dispersion performance and the compressive strength of the non-dispersible underwater concrete，while the loss of the concrete strength is less，if the construction is carried out with conduit construction method，from which the strength of the underwater concrete is equivalent to that of the concrete on land