机制砂高抗冲磨超高性能混凝土(UHPC)的组成设计与工程应用

Composition design and engineering application of high abrasion-erosion resistance UHPC materials with manufactured sand

针对我国西部地区泥石流、洪水等严酷服役环境下桥梁墩柱存在的冲击磨损和空蚀问题,利用UHPC材料高强、高耐久的材料自身特点,通过机制砂替代石英砂,进行UHPC材料的抗冲磨组成设计。研究了矿物掺合料种类、粉煤灰微珠掺量、硅灰掺量、胶凝材料用量、水胶比对抗冲磨UHPC材料的工作性能、力学性能、抗冲磨性能的影响规律。结果表明,在胶凝材料用量、水胶比和纤维掺量相同的条件下,随着粉煤灰微珠掺量增加,混凝土的工作性能提高,抗冲磨强度下降,粉煤灰微珠适宜掺量为胶凝材料的17%;随硅灰掺量增加,超高性能混凝土的工作性能下降,抗冲磨强度提高,硅灰适宜掺量为胶凝材料的13%;随着胶凝材料用量增加,工作性能提高,抗冲磨强度先提高后降低,最佳胶凝材料用量为1150 kg/m^(3);降低水胶比,工作性能降低,抗冲磨强度先提高后降低,最佳水胶比为0.18。经过优化设计的抗冲磨UHPC抗冲磨强度为普通C50混凝土的3倍,已成功应用于四川省仁寿至屏山新市公路石盘特大桥。

In view of the impact wear and cavitation erosion problems of bridge piers in the harsh service environment such as debris flow and flood in Western China,the thesis uses machine-made sand instead of quartz sand and utilizes the advantages of UHPC material’s high strength and high durability to carry out the design of abrasion resistant UHPC material.The influences of mineral admixture type,fly ash microbeads content,silica fume content,cementing material content and water-binder ratio on the working performance,mechanical properties and abrasion resistance of abrasion resistant UHPC material were researched.The results show that,under the same conditions of cementitious material dosage,water-binder ratio and fiber content,with the increase of fly ash microspheres content,the working performance of concrete is improved and the abrasion resistance strength is decreased,and the suitable fly ash microspheres content is 17%of the cementitious material.With the increase of silica fume content,the working performance of UHPC decreases and the abrasion resistance strength increases.The suitable silica fume content is 13% of cementing material.With the increase of the dosage of cementitious material,the working performance is improved,and the abrasion resistance strength is firstly increased and then decreased.The optimal dosage of cementitious material is 1 150 kg/m^(3).When the water-binder ratio decreases,the working performance decreases,and the abrasion resistance strength increases first and then decreases,and the optimal water-binder ratio is 0.18.The abrasion resistant UHPC,which is optimized and designed,has an abrasion resistant strength three times that of ordinary C50 concrete,and has been successfully applied to the Shipan Bridge on the highway from Renshou to Pingshan in Sichuan Province.