兰新铁路第二双线混凝土抗氯离子渗透性能试验研究

Experimental Study on Resistance to Chloride Ion Permeability of Concrete in 2nd Double Line of Lanzhou-Xinjiang Railway

基于对兰新铁路第二双线混凝土耐久性分析,研究了矿物掺合料掺量、砂的粗细程度、石子表面特征、环境条件与养护方法对兰新铁路第二双线混凝土抗氯离子渗透性能的影响。研究结果表明:矿物掺合料的掺入会提高混凝土的抗氯离子渗透性,且不同种类的矿物掺合料复掺时存在最优掺量,就文中混凝土,粉煤灰和矿渣粉掺量为15%时,混凝土的氯离子渗透性最低;此外,混凝土抗氯离子渗透性随砂的细度模数增大、石子破碎面所占比例降低而降低;保温材料能降低混凝土内外温差,因此昼夜大温差条件下,保温保湿养护的混凝土抗氯离子渗透性优于仅保湿养护的混凝土。

Based on the durability analyses of concrete in 2nd double line of Lanzhou-Xinjiang railway, the experimental study was to evaluate the effectiveness of mineral admixtures content, fineness modulus of sand, broken surface proportions of coarse aggregate, curing conditions and curing methods in high performance concrete. Test results indicated that the mineral admixtures used, fly ash and blast furnace slag can significantly increase the resistance to chloride ion permeability of concrete. Moreover, the best resistance to chloride ion permeability could be obtain from a combination of 15% fly ash and 15% blast furnace slag with 70% Portland cement in this paper. What ＂s more, resistance to chloride ion permeability increase with the increase broken surface proportions of coarse aggregate, but decrease with the increase fineness modulus of sands. The thermal material can effectively reduce concrete temperature variation in near surface and core region. Therefore, thermal and moisture insulation is a better curing method than moisture retention curing in an arid and diurnal temperature variation climates.