寒冷地区城市小型道桥高品质混凝土研究

Study on high performance concrete used in miniature bridge of city in cold area

为提高寒冷地区城市小型道桥普通混凝土工程的内在质量和表面质量,结合某桥梁工程的不同部位、不同强度等级混凝土的设计及施工验收技术要求,探索了普通混凝土高品质建造的配合比优化、表面质量的保证、桥墩高耐冻融循环和桥面混凝土耐盐冻的相关技术特征。研究表明,掺聚羧酸高性能减水剂的混凝土试件的混凝土表面状况最好,气泡总数、单位面积上的气泡数和气泡平均半径3个指标均最小,掺萘系高效减水剂的指标次之,掺氨基磺酸盐高效减水剂的试件3个指标均最高。基准混凝土氯离子渗透系数较高,普通强度等级的混凝土掺入聚羧酸减水剂和优质掺合料,具有很好的耐氯离子渗透能力,C40复掺的效果最佳,氯离子渗透性很低。C30桥墩混凝土300次冻融循环其强度损失为7.6%,表面无剥落现象;C40混凝土桥面板混凝土的耐盐冻试验其质量损失率小于3.8%;表现出很好的抗冻性。

In order to improve the internal and surface quality of ordinary concrete used in miniature bridge of city in cold area,explores the related technological characteristics of the optimum mix proportion for high quality building of ordinary concrete,surface quality guarantee,and high resistance to natural freeze-thaw cycle of piers,and salt-frost resistance of concrete for bridge deck,Combine the study on the different parts of the certain bridge engineering,the different strength grade of the concrete design and the construction technical requirements.The results show that the concrete samples which mixes with poly carboxylic acid has the best surface appearance.And its total bubbles,the number of bubbles in unite area and average value of bubbles are all the least.These indexes of concrete samples which mixes with effective naphthalene water-reducing agent takes second place.And these indexes of concrete samples which mixes with aminosulfonic-based superplasticizer is the highest.The chloride ion permeability coefficient of standard concrete is superior.If ordinary concrete mixes with poly carboxylic acid and superior admixture,its ability of enduring chloride permeability are very good.C40 concrete has the best effect by combined admixture of these two kinds of material.Its chloride ion penetration is very low.The strength loss of C30 concrete used in piers is 7.6%,after 300 times of freeze-thaw cycles.And there is no flake phenomenon on the surface of it.In the experiment of salt-frost resistance of concrete for bridge deck,the mass loss rate is less than 3.8%.And it shows good freezing resistance.