Experimental study on compressive strength and frost resistance of steam cured concrete with mineral admixtures: Fid-Bau Portal

Experimental study on compressive strength and frost resistance of steam cured concrete with mineral admixtures

Chen, Bo / Chen, Jialin / Chen, Xudong / Qiang, Sheng / Zheng, Yongjie

Highlights • The compressive strength of concrete without and with mineral admixtures under different curing regimes were tested. • The frost resistance of steam cured concrete was tested. • The compressive strength and AE signal of steam cured concrete after F-T cycle were analyzed. • The pore structure characteristics of steam cured concrete under different F-T times were analyzed.

Abstract The study of frost resistance and mechanical properties of steam cured concrete is helpful to understand the state of precast concrete elements in a complex environment. In this paper, the compressive strength of concrete under 10 working conditions, such as standard cured system, steam cured system, no mineral admixtures, single ground granulated blast furnace slag (GGBS) and fly ash (FA) mixed with GGBS, was tested at the age of 180d. It is found that the compressive strength of concrete under standard cured system is 4.71% to 18.46% higher than that under steam cured system, although steam cured improves the strength at the initial stage. The addition of FA and GGBS can make up 14% to 16% strength defects caused by steam cured system. The compressive strength of steam cured concrete (ZF40℃) is the highest when the steam cured temperature is 40℃ and the mixture ratio of FA and GGBS is 2:3. On this basis, the frost resistance of ZF40℃ specimens was studied. The results showed that the surface degradation degree of steam cured concrete gradually deepened with the increase of freeze–thaw (F-T) cycles, and the extracted surface roughness ranged from 0.066 ∼ 0.505 mm. The relative dynamic elastic modulus and mass loss rate decreased with the increase of F-T cycles, and the maximum loss rate were 69.4% and 1.41%, respectively. In addition, the compressive strength test, acoustic emission (AE) signal monitoring and acquisition of pore structure characteristics were carried out to understand the mechanical properties of steam cured concrete under F-T cycles conditions. The results show that the compressive strength decreases with the increase of F-T cycles, and the strength loss rate is within 10% per 50 cycles. The overall activity of AE signal decreases with the increase of F-T cycles, and the damage form gradually changes from the initial tensile damage to the later shear damage. Porosity and pore size range basically increase with the increase of F-T cycles. Pore deterioration is the main reason for the decrease of compressive strength of steam cured concrete under F-T environment.