Date of this Version
Gholami, S., Hu, J., and K, Y-R. (2019). Development of High-Performance Rapid Patching Materials for Pavement Repair. NDOT Research Report SPR-P1(18) M071.
Concrete pavements exhibiting severe distresses which require patching are commonly observed in the concrete pavement in Nebraska. Due to the requirements of opening pavement to traffic after placing the rapid patching materials, it is essential for that concrete to achieve high early strength. To ensure this, a high cement content and chloride-based accelerators are currently used in the Nebraska Department of Transportation (NDOT) Portland cement-based rapid-patching materials. Besides its associated high cost, high cement content tends to result in a less stable mix with high shrinkage, high heat of hydration, and high cracking potential. In addition, using chloride-based accelerators has adverse effects on concrete durability. Also, the effect of the low ambient temperature has a considerable impact on the strength gain and needs to be assessed to estimate the traffic opening. Therefore, this project studied the performance of rapid patching materials for three different aspects: reducing cement content through optimizing aggregate gradation, replacing conventional calcium chloride with a non-chloride accelerator, and partial replacement of type I/II or type III cement with type IP cement. Fresh, early-age, mechanical, durability performance and constructability were evaluated on each of the developed mixture design. The performance of developed mixes at low ambient temperature (50 and 60°F) was also evaluated. Overall, it appears that, with the optimized aggregate gradation, mixes with reducing cement content by up to 100lb/yd3 together have good constructability and can meet the general requirements, which were confirmed from the evaluation of key parameters, including early-age compressive strength, modulus of rupture, bond strength, surface resistivity, drying shrinkage, and alkali-silica reaction (ASR) resistivity. The non- chloride-based accelerator showed promising behavior as an alternative accelerator. The developed mixes exhibit satisfy early-age and 28-day compressive strength, modulus of rupture, and bond strength. The free shrinkage can be reduced by up to 30% with the lower cement content. The tendency of ASR deterioration can be reduced significantly by replacing 50% Type III cement with Type IP cement. Finally, as expected, when experiencing a low ambient temperature, strength growth can be delayed and employing PR3 mixes will be a more viable option to reduce the traffic closure durations.