3D-printing of cementitious materials is an innovative construction approach with which building elements can be constructed without the use of formwork. Despite potential benefits in the construction industry, it introduces various engineering challenges from the material point of view. This paper reviews the properties of extrusion-based 3D-printed cementitious materials in both fresh and hardened states. Four main properties of fresh-state printing materials are addressed: flowability, extrudability, buildability, and open time, along with hardened properties, including density, compressive strength, flexural strength, tensile bond strength, shrinkage, and cracking. Experimental testing and effective factors of each property are covered, and a mix design procedure is proposed. The main objective of this paper is to provide an overview of the recent development in 3D-printing of cementitious materials and to identify the research gaps that need further investigation.

The goal of the described research is an interactive computer system for the design of customized mass housing. Shape grammars are the formalism proposed to systematize the design rules required for such a system. A shape grammar for Alvaro Siza's patio houses at Malagueira, a 1200-unit development still being designed and constructed today, is presented. The grammar is based on the corpus of thirty-five houses designed between 1977 and 1996. The generation of houses in the grammar proceeds by the recursive dissection of rectangles locating four different functional zones (patio, living, services, and sleeping) and the key placement of the staircase. The schematic generations of two existing houses and the detailed generation of a novel one illustrate the grammar.