Study On Application Of Manufactured Sand In Ba-Nan Highway

This paper based on the project of BaNan highway manufactured-sand application technology research, it systematically researches the problems of manufactured-sand concrete which has a poor workability of be prone to segregating and bleeding, and analyses the manufactured-sand influence law to concrete. It also discusses the rational sand rate selection principle of manufactured-sand concrete when preparing and the workability optimization technique measures of manufactured-sand concrete. In addition it explores the mix proportion design of manufactured-sand concrete. The main research contents and results are as follows:(1).It tests two strength grade C30and C50’s workability of manufactured-sand concrete, and researches the workability’s influence law of manufactured-sand concrete which have different strength grade under themselves graduation character and different content of micro-fines, less than0.15mm sub-tailing. The results showed that the content of micro-fines and less than0.15mm sub-tailing in manufactured-sand concrete can effectively improve the concrete workability, and they have different workability influence law with different strength grade of concrete. It advices preparing manufactured-sand concrete with good workability, the manufactured-sand micro-fines content must be controlled at8%-12%in C30and low intensity level; and at4%-8%in C50and high intensity level; C30requires the content of less than0.15mm sub-tailing, and must be controlled at13%-20%, C50must be controlled at7%-15%; Manufactured-sand’s high quality grading curve shape is stretched S form, the second is down jog form, and stretched converse S form and up jog form are the worst.(2).It explores the principle to ensure rational sand rate and workability optimization technique measures of manufactured-sand concrete through workability tests of different manufactured-sand concrete and workability optimization tests research of manufactured-sand concrete. Make sure the different strength grade manufactured-sand concrete’s rational sand rate through the manufactured-sand concrete’s content of micro-fines and less than0.15mm sub-tailing. The way to single-doped II grade fly ash is the best and the economy way to improve workability of manufactured-sand concrete.(3).This paper improves the existing concrete mix proportion overall calculation method in order to fit manufactured-sand mix proportion design. It uses the least square method to regression analysis the manufactured-sand concrete’s Bolomy coefficients A and B, and gets the regression coefficients which apply for manufactured-sand concrete mix proportion design: A=0.533, B=0.476. Through the experiments, comprehensive consideration of the mechanical properties and durability of concrete index for the low W/S at0.28-0.30, then the recommended paste to aggregate ratio is0.48; The paste to aggregate ratio is0.53when the low W/S at0.30-0.34. Last it uses improved overall calculation of mix design to design manufactured-sand high-performance concrete, and tests its early stage and late stage strength, carbonation resistance and anti-chloride ion penetration ability. Determine the manufactured-sand C60high-performance concrete optimal mineral admixture’s adding way is10%FA+40%SG.