Reusing construction and demolition wastes for geotechnical and geo-environmental purposes has already become a research hotspot. This study was carried out to evaluate the feasibility of using recycled construction and demolition wastes in a partial substitution of cement to enhance the mechanical properties of soft soil. The strength and stiffness development of two types of recycled material (RM1 and RM2), incorporated with peat and clayey soil under 7, 14, and 28 days’ curing time, was investigated based on unconfined compressive strength and free–free resonance frequency test methods. The findings demonstrated that clayey soil showed an average of 2.5 times higher strength than peat with the addition of recycled materials, regardless of the type. However, after 14 days of curing, the strength remained constant for peat soil. Moreover, it is concluded that the studied granular recycled materials could be used to replace a part of the cement content to improve the strength and stiffness properties.

Cold in-situ recycling with foamed bitumen has become one of the most cost-effective and sustainable technologies due to working with low heating energy, less transport, and decreasing the use of new materials. This paper presents a benchmark laboratory study of the volumetric and mechanical properties of cold recycled foamed bitumen mixes blended with 100% reclaimed asphalt pavement (RAP) in the granular base layer. The air void content, indirect tensile strength, and resistance to moisture damage are tested to evaluate the impact of active filler, compaction technique, and geopolymer. It was found that the addition of active filler, regardless of the type, increased the moisture resistance between 30% and 35% compared to the mixture with no active filler. Moreover, the addition of slag-based geopolymer resulted in a substantial increase in tensile strength from 434 kPa to 823 kPa while leading to a sharp decrease from 70% to 38% in moisture resistance.