Investigation of ion chelator and mineral admixtures improving salt-frost resistance of cement-based materials

摘要

Ion chelator can improve the self-healing ability of cement-based materials. In this paper, the effects of the mixture of ion chelator and mineral admixture (slag or fly ash) on salt-frost resistance of cement-based materials were investigated. The internal structure and mechanical properties of the mortars with ion chelator and mineral admixture before and after salt-frost cycles as well as curing were studied. The results show that the pore structure, mechanical strength and salt-frost resistance of the mortar mixed with ion chelator and slag are better than those of mortar mixed with ion chelator and fly ash. Compared with the control mortar, the harmful pores (larger than 0.1 mm) ratio of the mortar with ion chealtor and slag declined by 44.5%, while the compressive strength increased by 40.7%. After 100 times salt-frost cycles, the mass loss ratio, harmful pores proportion and compressive strength loss ratio of the mortar with ion chelator and slag had declined by 42.5%, 24.7% and 35% respectively than the control mortar. Curing 28 days after salt-frost, the mortar mixed with ion chelator has good self-healing ability, the compressive strength recovery ratio and harmful pores reduction ratio are 21.18% and 27.04%, respectively. A large amount of needle-like repair products appear in the pores of the mortar mixed with ion chelator. The results of the energy-dispersive spectroscopy and X-ray diffraction tests proved that the main products in the pores and cracks of the mortar are CaCO3 and CaSiO3. (C) 2019 Elsevier Ltd. All rights reserved.