片麻岩石粉对机制砂泵送混凝土的拌合物性能影响研究

Study on the Effect of Gneiss Rock Powder on the Mixture Properties of Pumped Concrete with Manufactured Sand

利用工程中产生的低品质骨料制作掺合料来满足泵送混凝土性能对工程的降本增效具有重要意义。本文采用片麻岩骨料粉磨加工成不同细度的掺合料,研究50%和100%两种替代率情况下对泵送混凝土拌合物性能的研究。结果显示:与粉煤灰组分相比,片麻岩石粉混凝土初始流动性、保坍性均存在降低,随着片麻岩石粉比表面积从291m^(2)/kg提高至540m^(2)/kg,混凝土初始坍落度、扩展度均逐渐降低。片麻岩石粉相较粉煤灰颗粒圆球度明显不足,对水和外加剂有较高的吸附性。但片麻岩石粉混凝土在抗离析和抗泌水能力方面有所增加,且随石粉细度的增加,泌水率和离析率均有效降低,这对混凝土的施工性是有积极意义的。

The use of low-quality aggregates from production to make powder admixture which meet the requirements of pumped concrete for cost reduction and efficiency improvement has great significance.In this study,gneiss aggregate was ground into different fineness powder used by ball mill,and the effects of 50%and 100%replacement rates on the mixture properties of pumped concrete were studied.The results show that compared with the fly ash component,the initial fluidity and retention of gneiss powder concrete are lower.As the specific surface area of gneiss powder increased from 291 m^(2)/kg to 540 m^(2)/kg,the initial slump and spread of concrete gradually decreased.Compared with fly ash,the gneiss powder particles have obvious deficiencies in sphericity,and have a high affinity for water and additives.However,the gneiss powder concrete has increased resistance to segregation and bleeding,the bleeding rate and segregation rate decrease effectively as the fineness of the gneiss powder in‐creases,which is positive significance for the construction of concrete.