The project of “Accurate identification of concrete pavement diseases of highway and the rapid repair technology using a noval polymer” by Guangxi Transportation Science and Technology Group won the second prize of 2020 CCPA Concrete Science and Technology Award (Technology Advancement).

Cement concrete road pavement has the characteristics of high bearing capacity and low construction cost, yet it has the a variety of diseases which cannot be effectively eliminated. The surface diseases, such as aggregates exposure, voids and pits on the pavement surface would greatly impact the ride comfort. More serious  diseases including faulting of slab ends, pot holes and insufficient skid-resisting capability would affect the driving safety. Moreover, reduced bearing capacity of pavements and occurrence of voids beneath pavement base and even broken base would directly reduce the service life of the road.

Cooperated with Chang’An University, Guangxi Changchang Road and Bridge Construction Company, Nanning Normal University, and Guangxi Expressway Investment Company, Guangxi Transportation Science and Technology Group formed a project team in 2007 to carry out research on the following technologies to prolong the service life.

• Accurate identification and quantitative assessment of cement concrete road diseases.

• Rapid repair materials and the controllable high-performance application technology in complex environment.

• Base stabilization technology using new polymer grouting 

• The rapid surface repair technology using thin-overlay asphalt

• Overlay structure and material design technology for existing cement concrete pavement

• A low-cost and high-performance repair technique for multi-scale disease.

      The main research results of the project are as follows.

• By the methods of image enhancement, noise filtering, multi-scale selection of structural elements and morphological algorithm design, a multi-scale mathematical morphology edge detection combined with Ostu segmentation method and quantitative extraction digital recognition and characterization technology were developed. The pavement performance degradation was evaluated, considering the joint effect by the factors of load, temperature and humidity. The macro-micro integrated performance damage development model and life prediction model of cement concrete pavement under the condition of the three factors above were established. Considering the influence of base structure, material and temperature on the void beneath pavement slab, the control standard of dynamic deflection disease was established, and the quantitative prediction model of voids beneath concrete pavement slab in humid and hot environment was carried out. As a result, the accuracy of disease identification and performance degradation evaluation has been significantly improved. A systematic technology was developed inclusive of accurate identification, scientific evaluation and efficient positioning of cement concrete pavement surface and base diseases.

• The technology was developed to control the setting and hardening time of cementitious materials and to improve the bonding between old and new interface, and the mix proportion design method of phosphorus-silicon granular material based on reverse filling is proposed. A new polymer cement-based surface disease rapid repair material with controllable time, low cost and high performance and a new geopolymer for anti-corrosion base grouting with low temperature and concentration sensitivity were invented. The technology has shown significant advantages due to the low cost, long service life, rapid traffic resumption and notable performance improvement. The grouting material solved the existing problems of poor groutibility, segregation and low karst corrosion.

• The key control values of different repair methods of functional rapid recovery treatment to existing cement concrete pavement, and stabilization treatment before overlay are established. The thin overlay repair technology is developed. The structure and materials system for partial repair is established. These technologies promoted efficient utilization of original pavement structure, solved the problems of high cost of former thin overlay method, occurrence of reflection cracks and low adhesive property between inter layers of composite pavement.

The results of this project has been applied in the repair and restoration of Highways of G323, G359, S204, S210, Guangxi Bailong, Nanning city belt, in total 483 km in China. These technologies have significantly improved the durability, skid and wear resistance of cement concrete pavement, improved the maintenance technology, and have significant social and economic benefits.