机制砂在非洲某机场项目道面混凝土中的应用研究

Application of machine-made sand in pavement concrete of an airport project in Africa

非洲某机场项目所在地无天然河砂资源,仅有的机制砂又存在石粉含量远超相关规范要求的问题。为了利用现有材料配制出符合要求的道面混凝土,研究了机制砂母岩种类及石粉含量对道面混凝土抗折强度及工作性能的影响。结果表明,采用石灰岩石屑与水洗砂按4∶6的质量比复配作为细集料,使得细集料的石粉含量达到最佳15%左右,设计出了抗折强度与工作性能符合设计及规范要求、可用于项目实际施工的道面混凝土配合比,并针对机制砂混凝土的特性,为现场施工提出了能够有效减少泌水、拉毛困难、硬化后表面龟裂、剥离等问题的建议,可为类似的机场建设项目提供参考。

There is no natural river sand resource in the location of an airport project in Africa,and the only machine-made sand has the problem that the content of stone powder far exceeds the relevant specifications.In order to make use of the existing materials to prepare pavement concrete that meets the requirements,the influence of stone classification and stone powder content of machine-made sand to flexural strength and workability of pavement concrete was studied through experiments.The results show that the limestone chips and washed sand are used as fine aggregates in a mass ratio of 4 ∶6,so that the stone powder content of the fine aggregates can reach the optimum of 15%.Eventually,pavement concrete mixture proportion that can meet the requirements of codes and design documents and can be used in the actual construction was designed.Also,according to the characteristics of machine-made sand concrete,advices were given to solve problems such as bleeding,difficulty in surface finishing,cracking and scaling caused by the application of high-stone-powder-content machine-made sand in paving construction.The results of this study can provide experiences to the construction of similar airport projects.