Engineers have created a new type of concrete that is stronger than conventional concrete while also capturing carbon dioxide from the atmosphere. The findings, reported in Carbon Research, suggest that adding carefully selected natural materials could give concrete a second role beyond construction by helping remove CO2 from the surrounding air. Researchers at Mepco Schlenk Engineering College in India developed the mixture as a possible way to make construction materials more sustainable.
Their approach targets a major environmental challenge: rising atmospheric CO2 levels driven in large part by fossil fuel use and cement production. The team, led by Srinivasan Revathi, focused on two natural additives. One was zeolite, a highly porous mineral, and the other was bamboo biochar, a carbon-rich material.
Both have large pore volumes and high specific surface areas, properties that make them well suited for trapping gas molecules. The researchers tested several versions of M35 grade concrete, which is commonly used in infrastructure designed for moderate traffic. They replaced fine aggregate with zeolite at levels of 25% and 50%.
They also substituted bamboo biochar for cement at concentrations of 0.5%, 1%, and 1.5%. Each formulation was tested for several important properties, including compressive strength, split tensile strength, water absorption, and impact resistance. The researchers were looking for a mix that could absorb more CO2 without weakening the concrete.
Ideally, they wanted the material to become stronger at the same time. One combination stood out from the rest. The mix containing 50% zeolite and 1% bamboo biochar (dubbed ZB5) delivered the best overall performance.
Its compressive strength reached 38.49 MPa, about 7.48% higher than conventional concrete. Its split tensile strength reached 4.39 MPa, representing a 15% improvement over the standard mixture. The researchers attribute the added strength to the interaction between zeolite's alumina-silicate structure and the hardness of bamboo biochar.
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