Optimal design and performance study of mix ratio of high-performance tunnel shotcrete
The 28 d compressive strength prediction equation of high-performance concrete is established by nonlinear regression of high-performance concrete with strength grade from C60 to C100 to nonlinear regression of high-performance tunnel shotcrete mix ratio test data,and the results show that there is a moderate negative linear relationship between the water-adhesive ratio and concrete strength,and a moderate positive linear correlation between the water-adhesive ratio and slump.The best value range of sand rate,water-to-adhesive ratio,polycarboxylic acid-based high-efficiency water reducing agent,silica ash dosage and fly ash can be obtained:the water-to-adhesive ratio is controlled between 0.21 and 0.32.The sand rate should be controlled between 29％and 41％.The content of polycarboxylic acid-based high-efficiency water reducing agent is controlled within from 1.49％to 2.48％.Silica ash:its content is controlled within from 5％to 10％.The fly ash content is controlled at from 21.5％to 31.5％.The permeability of concrete is worse when the water-cement ratio is lower;Silica ash and fly ash have an important impact on the improvement of the permeability of high-performance concrete.The mix ratio of No.13,in the process of freeze-thaw cycle,the quality of the specimen remains stable,at 75 cycles,there is an increase of 0.57％,and the completion of the entire freeze-thaw test is only 0.02％,the antifreeze performance of this ratio meets the requirements.With the increase of freeze-thaw times,the compressive strength of the concrete gradually decreases.When the number of freeze-thaw times was 300 times,the compressive strength of No.13,No.5 and No.9 decreased by 12.3％,24.0％and 21.7％,respectively,indicating that the frost resistance of the specimen was reduced after the fly ash was added.
万方数据
维普
