Bio-carbonated or pre-bio-carbonated reactive magnesium cement method for rapid pavement repair

When cement or similar binders are used for road repair, it takes a relatively long time to gain strength. A new method using bio-carbonated reactive magnesium cement (RMC) grout or pre-bio-carbonated RMC grout for rapid pavement repair or stabilization is proposed in this paper. To evaluate the effectiveness of the proposed method, five model tests were carried out by injecting bio-carbonated RMC grout at 5 different liquid-to-binder ratios into base or subbase materials. Two other model tests were also conducted using the pre-bio-carbonated RMC grout and ordinary Portland cement, respectively. After grouting, the change in the properties of the grouted base was assessed through temperature and ultrasonic pulse velocity changes. Plate load tests were also carried out 24 h after the treatment to assess the performances of the treatments. The model test results showed that the liquid-to-binder ratio had a great effect on the flowability of bio-carbonated RMC and the optimal liquid-to-binder ratio for bio-carbonated RMC grouting was between 6 and 8, within which the filling rate could be maintained uniform, and the pavement treated gain a relatively high strength in the failure load range of 1.6–3.1 kN. Compared with the treatment using bio-carbonated RMC, the treatment using the pre-bio-carbonation RMC method could accelerate the setting time and reduce the treatment time from 13 to 3 h and it also increased the failure load by 2.4 times and the reaction modulus of the pavement by 2.6 times.