高强自密实清水混凝土在桥梁预制构件生产中的应用研究

Research on the application of high strength self compacting fair faced concrete in the production of precast members of bridges

为提高预制自密实清水混凝土的工作性能和耐久性能,延长桥梁的服役年限,对C50墩柱和C60盖梁高强自密实清水混凝土展开室内试验研究。结果表明:C50墩柱自密实清水混凝土的最佳胶凝材料用量为570 kg/m^(3),其中粉煤灰、矿粉用量分别为120、60 kg/m^(3),砂的细度模数为2.7,砂率为44%;C60盖梁自密实清水混凝土的最佳胶凝材料用量为550 kg/m^(3),其中粉煤灰、矿粉用量分别为100、50 kg/m^(3),砂的细度模数为2.7,砂率为46%;C50和C60的抗冻性分别可达到F200和F250,平均开裂面积<1 mm^(2)/根,单位面积内的裂缝数量<1根/m^(2),单位面积的开裂面积<0.5 mm^(2)/m^(2),28、56 d电通量均可控制在800、500 C以内。设计的C50和C60高强自密实清水混凝土工作性能和耐久性能均较佳,可在一定程度上延长复杂环境下桥梁的服役性能。

In order to improve the working performance and durability of precast self compacting fair faced concrete and pro-long the service life of the bridge,an indoor experimental study was carried out on C50 pier column and C60 bent cap high-strength self compacting fair faced concrete.The results show that the best cementitious content of C50 pier column self compact-ing fair faced concrete is 570 kg/m^(3),among which fly ash is 120 kg/m^(3),mineral powder is 60 kg/m^(3),the best sand rate of C50 is44%,and the best cementitious content of C60 bent cap self compacting fair faced concrete is 550 kg/m^(3),among which fly ash is100 kg/m^(3)and mineral powder is 50 kg/m^(3),the optimum sand ratio of C60 is 46%,and the optimum sand fineness modulus of the two strength grades is 2.7.The frost resistance of C50 and C60 can reach F200 and F250 respectively,the average cracking area is less than 1 mm^(2)/piece,the number of cracks per unit area is less than 1 piece/m^(2),the cracking area per unit area is less than0.5 mm^(2)/m^(2),and the electric flux at the age of 28 d and 56 d can be controlled within 800 C and 500 C.The designed C50 and C60 high-strength self compacting fair faced concrete have better working performance and durability,which can prolong the service performance of the bridge in complex environment to a certain extent.