Experimental Study on the Coupling of Freeze-Thaw Cycle and Chloride Corrosion of Alkali Slag Cementitious Materials

Alkali-activated-slag cementitious material (AASCM) is distinguished by minimal energy consumption, reduced pollution, and superior mechanical properties; however, it is prone to issues such as susceptibility to cracking and inadequate frost resistance. To facilitate its application in cold region construction, research on AASCM modifications was conducted following freeze-thaw cycle and chloride ion corrosion coupling tests. The test results show that the AASCM made of recycled rubber and coal ash does not change much in shape or appearance after 100 freeze-thaw cycles, with a mass loss rate of less than 5% and a compressive strength loss rate of less than 25%. Furthermore, the AASCM containing recycled rubber, coal ash, and straw fiber demonstrates an effective resistance to freeze-thaw and chloride ion coupling, maintaining its appearance and shape without notable changes and exhibiting a mass loss rate of less than 25% following 100 such tests. Following 100 tests for freeze-thaw and chloride ion coupling, the appearance and morphology of AASCM exhibited no significant alterations, with a mass loss rate below 5% and a compressive strength loss rate under 25%; microscopic analysis revealed that the C-A-S-H gel maintained a relatively dense and stable structure. Adding recycled rubber to the AASCM matrix can slow the spread of cracks, make the material more flexible, and make it more resistant to frost. Straw fibers can stop cracks from getting bigger, and adding coal ash helps make more C-A-S-H gel, which improves the AASCM's mechanical properties.