In this study, 1 H low-field NMR was used to compare the liquid absorption-release behaviour of superabsorbent polymers (SAPs) in Portland cement (PC) paste, NaOH-activated slag (SH-AAS) paste, and water glass-activated slag (WG-AAS) paste. The liquid absorption of SAPs in the PC paste was lower than that in the SH-AAS paste and the WG-AAS paste. The liquid release was also faster, which was mainly due to the higher Ca 2+ concentration in the pore fluid of the PC system. In the AAS system, although the Ca 2+ concentration in the pore fluid was low, the Na + concentration was much higher than that in the PC system due to the activator. The Ca 2+ in the PC system is an important factor affecting the swelling of SAPs, while in the AAS system, the swelling limitation of SAPs is the result of the combined effects of Ca 2+ and Na + , with Na + being dominant.
An electrodeposition method and its experimental device for rehabilitation of cracks in reinforced concrete were proposed. Porous concrete is proposed to simulate cracked concrete, and mass increment, permeation coefficient and sound velocity of ultrasonic wave were used to be evaluating indicators of healing effectiveness of crack rehabilitation in this method. Effect of currency density, concentration of electrolyte solution on healing effectiveness of porous reinforced concretes with different total void ratio was studied. The experimental results indicate that the simulation of porous concrete for cracks can reflect the healing effectiveness of electrodeposition method effectively. Total void ratio of porous concrete has little effect on healing effectiveness of electrodeposition at early ages. The higher the currency density or concentration of electrolyte solution is, the higher the electrodeposition rate and sound velocity in porous concrete are, and the lower the permeation coefficient of porous concrete will be. Mg(OH) 2 crystals produced in high current density are large, thin sheet-shaped and arranged loosely.
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