Application And Research Of High Performance Concrete In Subway Project

High-performance concrete was applied in Urumchi subway in 2014 for the first time.Most of aggregates in Urumchi are alkali-active aggregates.There are lots of aggressive substances in groundwater and soil,while the subway is located about 10-20 m under the ground.These substances erode reinforced concrete seriously,especially for sulphate attack.In order to ensure construction quality and durability,high-performance concrete technology has been applied in Urumchi subway construction.By aiming at the above-mentioned situations,high-performance concrete test research of coal ash and slag powder was conducted.Meanwhile,high-performance concrete test research of coal ash and YK-III(modified silica fume)was conducted.In addition,high-performance concrete mix design of the above-mentioned two schemes was conducted respectively.Inhibition of alkali-aggregate reaction and sulfate corrosion resistance ability were tested and studied.Results showed that 30% of mineral admixtures or above(slag powder with 15% of coal ash or above or 6% of YK-III modified silica fume with 24% of coal ash or above)was adulterated.Expansion rate of specimens didn't exceed 0.2%,which could restrain alkali-aggregate reaction effectively.With coal ash and slag powder,30% of adulterate amount could be used to resist erosion of 2500mg/L sulfate liquor or below.40% of adulterate amount or above could be used to resist erosion of sulfate ions with the concentration of being less than or equal to 8000mg/L.coal ash with 24% of adulterate amount or above+ 6% of YK-III(modified silica fume)could be used to resist erosion of sulfate liquor with the concentration of being less than or equal to 20250mg/L.At least 30% of mineral admixtures could make concrete have the higher sulfate corrosion resistance ability.6% of YK-III(modified silica fume)could improve anti-sulfuric acid corrosion resistance of concrete and also restrain alkali-aggregate reaction effectively.After adulterating modified silica fume,electric flux was smaller than 600 Coulomb and minimum was 288 Coulomb.Chloride permeability was lower.Anti-permeability performance was greater than or equal to P30.Adulteration of a little modified silica fume could improve durability of concrete obviously.According to qualified directory system in commercial concrete batching plant,supervision system in the station,and high-performance concrete mix expert verification system,quality control of various materials for concrete is used and construction unit should complete concrete pouring,vibration and maintenance to realize the high-performance target of concrete in the subway engineering.30% of mineral admixtures or above not only can restrain concrete alkali-aggregate reaction effectively,but also can make concrete have the stronger anti-sulfate corrosion resistance and the stronger durability.Meanwhile,concrete batching plant,design organization,concrete construction unit and raw material manufacturer should try their best to improve high-performance concrete quality and make high-performance concrete become durable in subway structure,so as to reduce costs for maintenance and reconstruction and form the great socioeconomic performance.