EVALUATION OF PAVEMENT PERFORMANCE RELATED PARAMETERS EMPLOYING SILICA BASED ADDITIVE COUPLING WITH ORDINARY PORTLAND CEMENT

Abstract

The stabilization of road pavement material is becoming a common process for improving the performance of road pavement structures. The consideration of cement stabilization for subgrade and base layer materials often provides a feasible solution to the road industry. Like all pavement material types, the design inputs should be determined using reliable test methods for cemented modified materials, which provide a good indication of the properties of materials. The road industry is dependent on strength testing of cement-stabilized materials as a means to ascertain material suitability for use. Only Strength properties do not provide reliable insight into the efficiency and durability of the stabilized layer. This is due to cement modified layer becoming very stiff and not strong enough to resist the heavy traffic load and adverse weathering conditions. Thus, the stabilized layer may be prone to cracking that leads to performance and durability related distresses. In the present research, conventional road material is stabilized by adding a silica based additive coupling with Portland cement and compacting it at optimum moisture conditions to improve the strength and durability of road pavement structures. Improvements in compaction characteristics, durability, strength and microscopic behaviour came out with the addition of this additive. Microstructure analysis revealed the formation of calcium silicate hydrate (CSH gels) and reduction in CH & SiO2. The presence of ettringites and thaumasites in later phases was negligible which confirmed the resistivity against freeze-thaw actions, and proved the design to be durable. The performance of this binder in pavement quality concrete (PQC) is also assessed in respect of the fresh, hardened, and microstructural characteristics of the PQC mixes. The beneficial impacts of the additive was observed when the additive begins to increase and started to form additional C-S-H gels on account of the introduction of SiO2 especially when the additive was utilized in a proportion of 4% by dry weight of cement. The application of this additive has significantly improved the strength and durability of road pavement structure. However, recent literature has shown that there are still uncertainties around mechanistic-empirical design procedures for road pavement with CTB layers. Accordingly, this research aims to achieve improved CTB characterization and mechanistic performance parameters, which could result in more economical and eco-sustainable application in the use of CTB material