Assessment of the dependency of the relationship between speedy moisture tester and traditional oven method values in granular road construction materials

Abstract

Moisture regulation in natural granular road construction materials significantly influences the strength and stiffness properties of embankments and pavement layers. However, quick and accurate moisture determination prior to compaction remains a challenge as the most reliable Traditional Oven Method (TOM) is time-consuming and delays decision-making during construction. The Speedy Moisture Tester (SMT) is commonly used in the field for rapid moisture determination due to its convenience, low operating costs, no power source requirements and ease of use. This study investigated the relationship between SMT and TOM results in natural granular road construction materials, focusing on materials commonly used in Uganda's road construction industry. The study involved controlled laboratory tests using both SMT and TOM methods for a wide range of material properties. Eleven regression models were developed for different material classes, establishing relationships between SMT values, specific material properties, and the true moisture values determined by TOM. Results indicate that the relationship between SMT and TOM values vary substantially with material properties. The SMT values and percentage of materials not tested in the equipment due to particle size limitation were strong predictors in the developed models. The generalized model (A-2-6 and A-2-7), A-3 model and A-1-b model demonstrated reliable prediction, suggesting their field applicability. The findings offer a practical framework for integrating SMT into road construction quality control, enhancing efficiency and decision-making. It is recommended that further research be conducted to establish SMT models for engineered road construction materials and other materials not tested in the study like silt and clays. As well as investigating SMT performance under varying humidity and temperature conditions.