施工误差对铁路桥梁高性能混凝土性能影响试验研究

Test Study on the Influence of Construction Error on the Properties of High Performance Concrete for Railroad Bridge

通过试验研究减水剂和水泥计量误差、振捣时间及静停时间差异对高性能混凝土性能的影响。研究表明:减水剂掺量由1.15%降至0.8%时,随着减水剂掺量的减少,混凝土拌合物的坍落度和坍落度扩展度降低,抗压强度增大,而电通量呈"先升高后下降"的趋势;在水泥用量上下波动20 kg.m-3范围内,随着水泥用量的增加,坍落度降低,抗压强度增大,电通量产生一定波动,但总体呈下降趋势;振捣时间在5～20 s时,随着振动时间的增加,拌合物的含气量无明显变化,抗压强度先增大后减小,电通量先下降后升高,振动时间超过20 s后产生严重的离析现象,抗压强度显著下降,电通量大幅度升高;拌合物静停时间在0～30 min时,随着静停时间的增加,振捣前拌合物的含气量降低,但是振捣成型后的含气量无明显变化,抗压强度略有增长,电通量呈下降趋势。

The influence of superplasticizer and cement measurement errors, the variations of vibrated time and static time on the properties of high performance concrete was studied through tests. Studies show that when the superplasticizer dosage descends from 1.15% to 0. 8%, the slump and dispersion degree decreases while the compressive strength increases, but the electric flux presents ＂first increase and then decrease＂ trend with the reduction of superplasticizer dosage. When cement consumption fluctuates around 20 kg · m^-3 on the basis of the benchmark mix, the slump decreases while the compressive strength increases, and the electric flux presents a downward trend with the increase of the cement consumption. When the vibrated time is changed from 5 to 20 s, the gas content of the mixture has no obvious change, the compressive strength increases first and then decreases, while the electric flux first decreases then increases with the increase of the vibrated time. When the vibrated time is larger than 20 s, the mixture segregates seriously, with the compressive strength decreases and the electric flux increases significantly. When the static time of the mixture is between 0 min and 30 min, the gas content of the mixture reduces before being vibrated; while it has no obvious change after being vibrated, the compressive strength increased slightly, and the electric flux presents a downward trend.