EXPERIMENTAL STUDY ON FROST RESISTANCE OF RECYCLED FINE POWDER CONCRETE

In the process of recycling construction waste to produce recycled aggregate, a large number of small particles with particle size less than 0.16 mm, namely recycled micro powder, are produced. These particles have certain activity and can be added into concrete as mineral admixture instead of cement. 10%, 20%, 30% and 40% replacement rates of recycled fine powder were used to replace cement to study the influence of such factors as replacement rate of recycled fine powder and water-binder ratio on the mechanical and frost resistance of recycled fine powder concrete, and to make a comparative study with fly ash concrete prepared by replacing cement with equivalent amount of fly ash. The results showed that the compressive strength of recycled fine powder concrete decreased with the increase of the content of recycled micro powder, but the law of frost resistance was just the opposite. When the water-binder ratio was 0.35, the compressive strength and frost resistance of the recycled fine powder concrete were slightly higher. Under the same conditions, the frost resistance of recycled fine-powder concrete was better than that of ordinary concrete and fly ash concrete. When the water-cement ratio was 0.35 and the recycled fine powder content was 30%, the recycled fine powder concrete had the best frost resistance, and the freeze-thaw cycle could reach 175 times.