Effect of Curing Environment on Properties and Microstructure of Metakaolin Based Geopolymers
In order to explore the influence of curing environment on the drying shrinkage-cracking characteristics and mechanical properties of metakaolin based geopolymers,the effects of different curing environments on properties(compressive strength,shrinkage)and microstructure of metakaolin based geopolymers were studied systematically.The results indicate that alternating temperature changes(freeze-thaw cycles)have a significant impact on the structure of metakaolin based geopolymers,which is not conducive to the development of metakaolin based geopolymer material properties.Low humidity is conducive to the elimination of water molecules in the system,thus forming a more compact gel phase,which is conducive to the development of compressive strength,but increases the drying shrinkage rate and porosity.In various curing environments,the compressive strength of specimens under dry curing(temperature(20±0.5)℃,humidity(50±5)％)reaches 73.94 MPa at 28 d,an increase of 68.77％compared to the specimens under standard curing(temperature(20±0.5)℃,humidity not lower than 95％),and the drying shrinkage rate at 28 d is 237.5 x 10-4,with a maximum porosity of 45.73％.
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