Engineered Biological Construction Material: Self-healing Concrete and Self-healing Carbon Negative Enzymatic Construction Materials (ECM)

Wang, Shuai

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Engineered Biological Construction Material: Self-healing Concrete and Self-healing Carbon Negative Enzymatic Construction Materials (ECM)

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Concrete, a mixture of calcium silicate hydrates (CSH) has become ubiquitous as a building material, used extensively in infrastructure such as bridges, airport runways, and buildings. However, these materials are also significant contributors to anthropogenic carbon dioxide (CO2) emissions. As a result, there is a growing need to develop sustainable alternatives that minimize the carbon footprint of cementitious materials. Although, strategies such as point-source CO2 capture, renewable fuels, alternative cement, and supplementary cementitious materials can yield substantial reductions in cement-related CO2 emissions, emerging enzymatic technologies based on enzymatic biomineralization mechanisms have the potential to revolutionize the production of concrete and significantly reduce its carbon footprint. In this presentation, inspired by the extremely efficient process of CO2 transport in mammal cells, a self-activated healing mechanism for a cementitious matrix and an ultra-strength self-healing enzymatic construction material (ECM) are proposed using Carbonic Anhydrase (CA) enzyme. The metalloenzymes allow the millimeter size of the crack self-healed autonomously on the enzyme modified cement matrix within 24 hours. Results also demonstrate that the self-healed concrete regains strength after incubation which indicated the enzymatic product behaves in excellent consistency with concrete material. The second part of this presentation outlines a method of developing carbon negative emission self-healing enzymatic construction material (ECM). A polymer backbone provides a scaffolding framework for carbonic anhydrase that initiates crystallization and establishes strong crystal bridges for the sand particles' connection. The critical findings from ECM can be highlighted that the compressive strength of ECM is more than two times of minimum acceptable cement mortar and significantly higher than any currently available biological construction materials. The specific strength of ECM is similar to lightweight concrete. In terms of self-healing, ECM can endure six healing cycles, with damage at the central flaw of the medium-scale beam, with a loss of about 50% of overall strength. Noted that the self-healing process only consumes carbon dioxide without an additional source of energy. A crystal growth model of ECM is governed by diffusion and developed for mineral bridge dimension prediction analysis. Inspired by the laser therapy on tumor tissue, we then proposed an advanced ECM that was integrated with nanoparticles to achieve rapid on-site curing and self-healing. The new ECM called ECM-n, first completed curing building material through the photothermal effect and overcame the complicated laboratory dehydration issue. The thermogenesis ability of the ECM-n was studied by finite element method and developed a heat transfer model for understanding the relation between temperature and power induction . We believe the ECM brings the sustainable building materials to the next level, which is the key to truly paving for carbon negative emission, self-healing, and multifunctional construction materials in frontier applications such as temporary shelter bases, building secondary structures, pipe transport in extreme weather and even space bases construction located at the high concentrations of carbon dioxide planet-Mars.

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