Study on crack resistance and evaluation method of red mud based cementitious material stabilized stone

The semi-rigid base of pavement has the disadvantages of insufficient flexibility, drying shrinkage and temperature shrinkage, and the base is easy to crack due to shrinkage in the process of engineering service. As a new type of pavement base material, red mud based cementing material can replace cement 100% for road base construction. However, the evolution of crack resistance of red mud based cementing material is still unclear. Therefore, in this paper, the dry shrinkage and temperature shrinkage properties of the stabilized gravel layer of red slime based cementative material were taken as the research object, and the influence rules of factors such as the content of red slime based cementative material and health maintenance age on the shrinkage properties were explored. Experiment results exhibit that the cumulative dry shrinkage strain of stabilized crushed stone based on red slime cementing material is positively correlated with the curing age, and the growth rate decreases gradually. The cumulative dry shrinkage strain decreases first and then increases with the increase of the red slime cementing material content, and the cumulative dry shrinkage strain is the lowest when the content is 7%. The cumulative dry shrinkage coefficient of stabilized crushed stone of red slime based cementation material reaches the peak value at the age of 1d and then gradually decreases and tends to be stable. The cumulative dry shrinkage coefficient is much larger than that of the other three groups at the dosage of 8%. As a whole, the temperature shrinkage coefficient of stable crushed stone with red mud based cementing material increases first and then decreases with the increase of temperature, and the average temperature shrinkage coefficient decreases first and then increases with the content of red mud based cementing material, and the temperature shrinkage coefficient at 7 days is much higher than that at 28 days. At the age of 7 days, the stable gravel matrix is full of micro-cracks, and at the age of 28 days, the stable gravel matrix is more dense due to the increase of hydration products. Moreover, the mechanism of dry shrinkage and temperature shrinkage was revealed through SEM microscopic morphology analysis. Based on the grey relational analysis method, the dry shrinkage resistance index and temperature shrinkage coefficient were identified as the best rating indexes for the cracking resistance of the stable crushed stone of the red mud based cementing material, and the best cracking resistance was determined when the content of red mud cementing material was 7%.