兰新铁路第二双线混凝土矿物掺合料掺量优化试验研究

Optimization research on the contents of mineral admixture of concrete in the 2nd double line of Lanzhou-Xinjiang Railway

通过对不同混凝土的坍落度、坍落扩展度、不同龄期强度和电通量等指标的测定,研究了粉煤灰和磨细矿渣粉的掺量对兰新铁路第二双线新疆段混凝土的工作性、强度和耐久性的影响.研究结果表明:粉煤灰的掺入可提高混凝土的流动性,抑制水泥早期水化反应速度,而磨细矿渣粉的掺入可提高混凝土的粘聚性和保水性,对流动性不利;两者均能有效降低混凝土电通量.粉煤灰和磨细矿渣粉按适当比例复合掺入对混凝土性能的改善具有更好的效果,对于C30混凝土,粉煤灰掺量为15%,磨细矿渣粉掺量为15%,对于C40混凝土,粉煤灰掺量为15%,磨细矿渣粉掺量为20%,对于C50混凝土,粉煤灰掺量为10%,磨细矿渣粉掺量为30%时,混凝土的工作性、强度和耐久性最好.

The effects of contents of mineral admixture such as fly ash, blast-furnace slag powder on the workability, strength and durability of concrete in the Znd double line of Lanzhou-Xinjiang railway were researched in this paper by measuring slump, slump flow, compressive srtengh with different age and electric flux of several concretes with different mineral admixtures. The test results show that, the fluidity of concrete can be improved and early hydration reaction of cement is inhibited by adding fly ash. When the concrete is mixed with blast-furnace slag powder, both its cohesiveness and water retention could be improved. And yet its fluidity is depressed. Both the fly ash and blast furnace slag can re- duce the electric flux through concrete. Moreover, the composite addition of fly ash and blast-furnace slag powder have better improvement effects on the performance of concrete than either one alone. The workability, strength and durability of concrete are best when the contents of blast-furnace slag and fly ash are both 15 %for C30, and as far as C40 concrete is concerned, the contents of blast-furnace slag and fly ash are respectively 90% and 15%, and their contents are changed into 30% and 10% with reference to C50 concrete.