Effect of pozzolanic reaction of zeolite on its internal curing performance in cement-based materials

In the present study, effect of pozzolanic reaction of zeolite on its internal curing performance in cement-based materials was experimentally investigated. Firstly, the pozzolanic activity of zeolite particles was tested. Then, influences of zeolite pozzolanic reaction on the pore structure, morphology, water absorption and water release performance of zeolite particles were studied. Finally, cement paste specimens with zeolite internal curing were prepared, the hydration degree of cement, pozzolanic reaction degree of zeolite and internal relative humidity were tested, and the internal curing mechanism of zeolite coupling with pozzolanic reaction was discussed. The test results show that, 1) pozzolanic reaction can increase the pore volume and water absorption of zeolite particles, when the reaction degree reaches 10.85%, the pore content increases from 0.030 mL/g to 0.054 mL/g, and the water absorption increases from 3.82% to 5.52%; 2) in zeolite internally cured cement paste with curing age of 28d, when zeolite-cement replacement increases from 10% to 30%, zeolite reaction degree in OPC paste decreases from 22.8% to 20.7%, and that in SAC paste decreases from 20.9% to 19.9%; 3) the humidity saturation period of cement paste is shortened by zeolite internal curing, but the relative humidity is improved after it drops below 95%–96%; 4) when zeolite-cement replacement increases from 0 to 30%, the humidity of OPC paste increases from 87.8% to 92.0%, and that of SAC paste increases from 88.8% to 91.4% at curing age of 28d. •pozzolanic reaction can increase the pore volume content of zeolite.•pozzolanic reaction can improve the water absorption of zeolite particles.•zeolite internal curing shortens the humidity saturation period of cement paste.•IRH of cement paste can be improved by zeolite after dropping to 95%.