Development of alternative cementitious binders for 3D printing applications: A critical review of progress, advantages and challenges

3D printing is a promising technology of great significance in several industries including construction. In line with the urgent need to reduce the environmental impacts of the built environment, traditional binders such as Portland cement are being substituted by suitable alternative binders. This paper systematically reviews the recent advances in the use of key alternative binders such as geopolymers/alkali-activated systems, aluminate cements, MgO-based cements, gypsum-based materials, and limestone-calcined clay-based cementitious materials in the context of 3D printing. A detailed discussion on the progress of research in the use of such alternative binders in the development of 3D-printed components is presented, highlighting the main advances made in recent years, challenges faced and potential solutions to enable the large-scale application of these products. A comprehensive evaluation of the key properties controlling the performance of 3D-printed components prepared with different mixture proportions and curing conditions is also included. The information and recommendations provided in this review aim to pave the way for the direction of future research in this area, with the goal of providing guidance on designing 3D-printed composites with the desired sustainability, cost and flexibility.