Application of High Performance Concrete with Compound Admixtures of Fly Ash and Perlite Powder in Pavement of Highway

Based on former experimental achievement in laboratory, application and construction of high performance concrete (HPC) in pavement of highway were introduced to the paper. The HPC was proportioned with compound admixtures of 12% fly ash and 12% perlite powder replacing cement in equal mass. Perlite powder of both is a new mineral admixture, originated natural volcanic rock perlite composed of mainly aluminosilicate glass, was ground to mostly under 45 μm so as to possess pozzolanic activity, and then added to concrete as a supplementary cementitious material to substitute for partial cement. Multiplex of the two admixtures is profitable to increase workability, mechanical properties and durability during post-stage for concrete in varying degrees. The testing slump and construction fit of the fresh concrete in situ were shown that both of admixtures improved workability of the concrete. HPC samples remained in field and drilled from pavement were determined and investigated on mechanical properties and durability by means of test. It has been observed by inspected result of that flexural strength of these concrete are above 5 MPa at 28 cured days and compression strength about 40 MPa. The indexes of their abrasion resistance distribute throughout 1.94—2.63 kilo-rotation/mm at 90 days. These measured mechanical characteristics are so large enough to the technical specification of heavy traffic grade highway on mechanical property. To investigate durability of the HPC, the charge passed and the chloride diffusion coefficient in concrete at 90 cured days obtained from the accelerated chloride migration test were determined with RCM experimental equipment. The values of charge passed in the concrete were lower and ranged in 449—928 Coulomb, which revealed that the HPC are also better permeability resistance of chloride ion and be able to sustain in environment of chloride salt for 100 years. The chloride diffusion coefficients of the HPC were scattered in 1.4—4.7×10-12m2s-1. These parameters exhibited completely the HPC better or excellent for electrical indication of concrete’s ability to resist chloride ion penetration referent to relevant standards and information.