Fundamental characterisation of surface and internally protected concrete pavement and highways

Abstract

Despite excellent service history, concrete pavement faces accelerated deterioration due to water and chemical ingress through micro cracks and surface voids. Surface applied protective materials, especially silane, have been widely used to hinder the deterioration process of concrete structures. However, concrete pavements, in particular, are not protected at the moment due to the concerns over their frictional properties. The improper performance of silane when applied to wet surfaces and its inconvenient application method, especially if applied to concrete roadways and bridges, drove researchers to look for some new alternative materials. Accordingly, the internal incorporation of protective materials into fresh concrete mixtures and the application of some new alternative surface applied materials on concrete started to emerge. For the materials to be effectively benefited as protective treatments, some significant issues and impediments must be addressed by research: (I) The unsatisfactory mechanical properties emphasised in the literature as the main drawback of the internal integration method; (II) the affinity of the surface applied materials to moisture at the time of application, which is reflected on the rejection rate of concrete to the applied materials and, consequently, their efficacy in protecting concrete. In this research, the internal integration of crystalline material into fresh concrete and the application of new materials on the surface of matured concrete, namely; liquid crystalline material, fluoropolymer, silicate resin were used and compared with traditional silane. Standard and non-standard methodologies were utilised in this research to investigate the performance of the protective materials and to build an indepth understanding of their mechanism of interaction with concrete pavement. Results demonstrated the enhancement of concrete’s strength by more than 42% after optimising the added dosage of the integrated crystalline material and the water-to-cement ratio (w/c) of the concrete mix. Also, water absorption and chloride diffusion have been reduced by more than 65% and 90% respectively after the internal integration process. Applying the newly-developed surface applied materials to matured concrete with high moisture contents resulted in enhanced performance compared to silane when tested for water absorption and chloride penetration. Two standard and non-standard prolonged freeze-thaw investigations of all the materials, either internally integrated or surface applied, signified the adequate long-term performance of the treatments. Overall, this research lays the foundations for using the proposed treatments in the construction industry.