Research On Application Of Diabase-fine-sand Concrete In Expressway Engineering

With the rapid development of construction undertakings, the resource of concrete aggregates is restricted. In some areas, excellent aggregates have been exploited and utilized, only low-quality aggregates left. Considering from construction economy, utilizing low-quality has been an inexorable trend .In order to decrease the unit cost of concrete and increase the utilization of local building material, this paper, dealing with practical projection, studies on preparation of concrete with low-quality diabase and green sand (fine sand) as aggregates through experiment.The investigation and evaluation on the two material diabase and fine sand have been summarized first in this paper, the quality of the two materials is poor. For diabase, the content of elongated and flaky particles in crushed stone is on the high side, about 12%~15% and its gradation is harmful. And for fine sand, its fineness modulus fluctuates between 1.6 and 2.4 and the gradation is harmful. Furthermore, the two materials are unstable in quality.Secondly, preparation of concrete with low-quality diabase and fine sand as aggregates and its basic performance are mainly studied through experiment. The results show that:(l) No matter the fine aggregate using medium sand or fine sand, the strength of diabase concrete will be always a little higher than that of limestone concrete. But the elongated and flaky particles in crushed stone and its harmful gradation lead to poor workability, that segregation and weeping of concrete is serious; (2) In high-strength concrete with w/c less than 0.4,the fine sand will which will decrease by 5%~10%. The surface character of fine sand equally leads to segregation and weeping; (3) According to rheological research of fresh cement pastes, poor workability can be resolved through the way of utilizing diabase stone chips replacing sand as aggregate and mixing active material such as fly ash; (4) By selecting diabase aggregate, optimizing mixture ratio and rigorously enforcing construction course,low-quality diabase and fine sand can be fully ultilized into preparation of qualified concrete posesing highjnedium and low strength.Finally, the author briefly discusses the application of diabase-fine sand concrete hi engineering, and summarizes a set of technology on the construction of this concrete.