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针对连霍高速公路郑洛段改扩建工程预制梁中出现的问题,通过改变粉煤灰的掺量,建立不同的试验工况,对粉煤灰混凝土的力学性能、干燥收缩、渗透性等性能指标进行研究。结果表明随混凝土强度等级的提高,粉煤灰的适宜最大掺量逐渐减小;随粉煤灰掺量增大,混凝土的干燥收缩值明显减小,混凝土的碳化深度逐渐增大,粉煤灰掺量对混凝土抗盐冻剥蚀性能的影响不明显,但含气量的影响较大。采用粉煤灰取代水泥,最大量达30%左右,预制梁体混凝土的粉煤灰取代量达20%左右。现场的工程实践表明,用粉煤灰取代水泥之后,混凝土工作性能大大改善,成本大幅度下降,适用性较好。
Aiming at the problems that occur in the prefabricated beam of Zhengluo Section of Lian-Huo Expressway, by changing the content of fly ash, different test conditions are established to study the mechanical properties, drying shrinkage and permeability of fly ash concrete Indicators for research. The results show that with the increase of concrete strength, the suitable maximum content of fly ash gradually decreases. With the increase of fly ash content, the drying shrinkage value of concrete decreases obviously and the depth of carbonation of concrete increases. The effect of dosage on the anti-freezing and denudation properties of concrete is not obvious, but the influence of gas content is larger. The use of fly ash instead of cement, the maximum amount of about 30%, prefabricated beam concrete fly ash replacement volume of about 20%. Field engineering practice shows that after replacing the cement with fly ash, the working performance of concrete is greatly improved, the cost is greatly reduced, and the applicability is better.