Chloride Penetration Resistance of Functionally Graded Concrete Based on NaOH Activated Slag and Portland Cement
ZHOU Wanliang, DENG Huan
Anhui Key Laboratory of Civil Engineering Structures and Materials, College of Civil and Hydraulic Engineering, Hefei University of Technology, Hefei 230009, China
Abstract: NaOH activated slag (NAS) has excellent resistance to chloride ion penetration, while Portland cement (PC)has poor resistance to chloride ion penetration. Covering NAS mortar layer on the surface of PC concrete can significantly improve the chloride ion penetration resistance of functionally graded concrete (FGC). The chloride penetration depth of FGC and NAS concrete soaked in 10%NaCl (mass fraction, the same below) solution for 84 days are only about 11.0 mm and 12.7 mm respectively, while that of PC concrete is 36.7 mm. BET test shows that the vo-lume of pores and the most probable pore diameter in NAS mortar are much larger than that in PC mortar. XRD test results show that Friedel’s salt is formed in NAS mortar and PC mortar after soaking in 10%NaCl solution. The main reason why NAS mortar has better chloride penetration resistance than PC mortar is that the paste has greater physical adsorption on chloride ions rather than finer pore diameter.
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