Rola A. Hasbini

With escalating adverse effects, climate change is, presently, a critical global issue. The primary agent is the atmospheric high level of carbon dioxide and other pollutants. Concrete significantly contributes to greenhouse gas emissions. Green building is, therefore, a professional responsibility. This analysis briefly proposes various possibilities for reverting to green concrete in construction, advising strategies and solutions implementable at the several life cycle phases of the construction material. Multi-faceted sustainable aspects would pertain to eco-friendly extraction and manufacturing processes, thermal energy-efficient layout, scrubbing of pollutants, and recyclability. In particular, the study sheds light on an important experimental possibility of symbiosing the inert building material with the biological realm: the Living Concrete. At Politecnico Di Milano – Department of Architecture, Built Environment & Construction Engineering, we, first, realized a symbiotic concrete tile with macro-algae Ulva lactuca; then, we developed the experiment to conceive a novel “living concrete” construction finish material designed to absorb/scrub carbon dioxide from the atmosphere. This material consists of concrete blocks with Chlorella vulgaris cultivated on their surface. C. vulgaris is common microalgae with photosynthetic activity. This new photosynthetic concrete finish material was further developed and realized at the University of Verona – Department of Biotechnology with the help of expert professors. Researching effective negative greenhouse gas emissions techniques (NGHGET) from the chemical, physical and/or biological realm presents a valid approach to address and solve climate change problem.

Climate change is a global critical issue. High carbon dioxide emissions and concentrations are important factors. In the construction field, concrete contributes significantly to greenhouse gas emissions. Therefore, a pioneering team of researchers has developed a new “living concrete” construction finish material capable of scrubbing carbon dioxide from the atmosphere. The material consists of ASTM (ASTM is the acronym for American Society for Testing Materials)-certified concrete block(s) with Chlorella vulgaris cultivated on the surface. Chlorella vulgaris is a common micro-algae with photosynthetic activity; these species require water, nutrients, light, and carbon dioxide to live while releasing oxygen in return. The “living concrete” block was developed in dedicated laboratories; its photosynthetic activity was quantified. Proposed as an external application assembly to a new or an existing building envelope—up to 3 m high, i.e., anthropogenic street-level emissions, or installed on roof(s) in horizontal mode—this concrete/biological composite material reverses carbon dioxide emissions and may present itself as a valid solution for climate change issues in urban moderate climates.

This paper is a short review of green concrete as claimed per latest related available literature. Green concrete refers to concrete mixture with lower carbon footprint, during its total life cycle, as compared to ordinary concrete mixture. This may be due to its composition of one or more green component (s) such as silica fume or fly ash, or to its capacity, as a building material, to reduce one or more pollutant (s) and/or to any other sustainable concrete procedure such as reduced raw materials depletion. A leading Italian concrete production group claims the provision of a new air scrubbing green concrete combining all of the above techniques. The claimed air scrubbing is based on a photocatalytic principle whereby natural or artificial light activates an oxidation process converting noxious pollutants into harmless compounds. Green concrete promotes sustainability in a creative way; thus, improving global human health.