Foundry slag has different characteristics from blast furnace slag, such as its high SiO₂ content and low basicity (CaO/SiO₂ < 1), which prevent it from being used as a cementitious component. Lime slurry is a waste product with a high CaO content and can be used to increase the basicity of the mixture. The aim of this study is to obtain new supplementary, eco-cementitious material composed of foundry slag and lime sludge. The compositions were designed with binary basicity (molar ratio of CaO/SiO₂) ranging from 1.0 to 1.4. Clinker was replaced with the proposed material in the range of 6–34 wt% and the performance of the different cement compositions was tested. The results showed that replacing 20 wt% of clinker with the new eco-cementitious material with binary basicity of 1.2 resulted in cement with the same mechanical strength as the reference cement. The new material reacted with free CaO to generate additional calcium silicate hydrate. The initial setting time of the cement containing the new eco-cementitious material was 240 min, acting as hydration reaction retardant. The technical feature of the new eco-cementitious material allows the use of both wastes in cement composition, contributing to the requirements of circular economy.

New materials and technologies used in construction constantly need improvements, whereby the leveraging of new raw materials for the manufacture of products already in use, such as paving, is required. Thus, this study aimed to determine the mechanical and thermal behavior of pavers containing waste glass and São Tomé stone waste to verify their potential application as cold diffraction. Thereafter, they were comminuted and added to the mixtures for making the pavers having glass waste and São Tomé stone in the range of 0-30% by weight. Mechanical compressive strength and thermal heat absorption tests were performed. Results showed that the replacement of fine aggregates with waste glass and São Tomé stone waste in pavers reached a mechanical resistance of approximately 85% and 73% of that of the reference paver, respectively. The results show that reducing the waste content of pavers can increase the mechanical strength to reach the NBR 9781/87 values. However, pavers with lower mechanical strength can be used in paving pedestrian sidewalks, where the loads are low. Pavers with 30% glass waste achieved a 5.5% reduction in the maximum temperature, which could contribute to the reduction of urban heat islands.