Application Of High-Proportion Fine Scoria Concrete Technology To The Tianjin Trunk Line Engineering Of South-to-North Water Diversion Middle Route Project

There are problems that alkaline-active reaction of concrete aggregate and groundwater erosion from local high water level, mainly sulphate erosion, in the Tianjin trunk line box culvert engineering of south-to-north water diversion middle route project. If the two problems are not solved properly, it will seriously affect the box culvert operation in the long term. To solve the problems, the paper studies the application of high-proportion fine scoria technology to the Tianjin trunk line engineering in order to present proper proportion of concrete aggregate that both can solve above problems and improve the durability of concrete. The main contents and achievements are as follows:(1) The simplex fly ash blend, simplex fine scoria blend and both fly ash and scoria blend methods are applied to study the restrain effect on alkali-active reaction of concrete aggregate. Five kinds of concrete aggregate are adopt in the experimentation, the 14d's expansion rates of which are 0.1%, 0.1%～0.2%,0.2%～0.3%,0.3%～0.4% and above 0.4% with mortar stick test. The causes of different coagulation combinations restrain effect on alkali-active reaction are analyzed by comparing ion concentrations of different combination slurries.(2) The optimization for proportion of concrete aggregate is studied due to the characteristics of Tianjin trunk line engineering. 12 groups of which have better general performances are selected through analyzing 154 concrete proportion tests and 159 alkali-active reaction restrain tests.(3) The abilities to resist deleterious ion erosion of the high-proportion concrete are deeply studied. The rules that concrete resists sulphate erosion are analyzed through anti-erosion coefficient and free-expansion rate tests under different components, and the results show that concrete which has high-proportion fine scoria can resist sulphate erosion outstandingly and anti-chlorin ion erosion study shows that relative diffusion rate of chlorin ion can be reduced remarkably by blending scoria.(4) The concrete performance such as physical mechanics capability, anti-crack capability, anti-carbon capability, anti-seepage capability and anti-freezing capability are analyzed through many tests, and the results show that the high-proportion fine scoria concrete can meet with the demands such as intensity, anti-seepage, anti-crack and anti-freezing durability etc.(5) The recommended fine scoria proportions of C25 and C30 concretes for Tianjin trunk line engineering are presented, which can meet with the demands such as construction, physical and mechanics capability, concrete durability etc.