The use of waste materials from various processes as pavement layers has long been an option for disposing of such materials. Huge volumes of material are typically required to construct pavement layers and this option provides the opportunity for disposing of large volumes of materials without requiring landfill areas. Electrolytic Manganese Dioxide (EMD) is produced in South Africa from manganese ore through the process of electrolysis. Belt filter residue from the EMD production residue is thixotropic, and is dried by adding lime. The dried product is known as Inerted Manganese Product (IMP). IMP has been used successfully in pavement layers in South Africa. Uncertainty regarding the optimal Construction Moisture Content (CMC) led to research where five sections with IMP base layers were constructed at different CMCs, followed by monitoring of both short-term and long-term stiffness development in the layer. Data analysis consisted of evaluation of changes in base layer stiffness, focusing on the effect of the differing CMC contents. The paper covers the experimental design, data collected and analyses, leading to conclusions regarding the optimal CMC required to obtain optimal short-term stiffness in the IMP-constructed base layer.