UC San Diego

Modern concrete has been the major construction material for nearly two centuries. Portland cement, the binder in modern concrete, is being produced worldwide in large quantity (more than 3 billion tons per year). However, cement production is pollutive and energy inefficient. It is a main source of greenhouse gas emission, and the energy consumption is significant. For the past a few decades, a number of “green concrete” concepts have been extensively studied.In this research, we systematically investigate the technology of compaction self-assembly (CSA). It is a general-purpose processing approach of low-binder-content composites, and can be applied to fabricate ultralow-binder-content polymer cement, algae-derived artificial lumber, and cement-based green concrete. Compared with their conventional counterparts, these materials use small amounts of binders to reach the desired properties. Consequently, the cost-performance balance, the carbon emission, and the energy efficiency can be superior. In the ultralow-binder-content polymer cement, ~4% polymer binder and ~96% sand form a strong solid. The polymer binder can be unsaturated polyester resin, epoxy, or waste plastics. The artificial lumber uses algae powders as the filler; 2-4% epoxy serves as the binder. The flexural strength is comparable with that of softwoods. It may open a door to upcycling the waste biomass from large-scale algae cultivation. The cement-based green concrete contains only ~14% ordinary portland cement. The key step is the section compaction self-assembly (S-CSA), in which a large part is processed section by section. It may pave the road to green buildings and green infrastructures of ultralow embodied carbon footprint.