D.A. Morales, S. Mandal
Texas State University,
United States
Keywords: sustainable construction, energy efficiency, recyclable materials
Summary:
Concrete is the most widely used construction material globally due to its versatility, strength, and affordability. However, conventional concrete production carries a significant environmental burden. Cement manufacturing alone accounts for nearly 8% of global CO₂ emissions, and traditional curing consumes large volumes of water and energy, particularly in cold climates. These factors not only increase environmental impact but also raise construction costs. Developing innovative, sustainable solutions that maintain structural performance while reducing resource use and cost is therefore essential. This study presents a novel, customer-oriented approach by incorporating biochar derived from hemp hurd—the woody core of the hemp plant—together with guar gum and recycled construction materials into concrete. Hemp hurd biochar is a carbon-rich, renewable material produced via pyrolysis of hemp residues under limited oxygen conditions. Its highly porous microstructure enhances moisture retention and thermal insulation, reducing the need for continuous external water curing and stabilizing internal temperatures, which lowers energy consumption. Guar gum, a natural, low-cost polymer derived from guar beans, further improves workability, cohesion, and internal water retention, supporting more efficient hydration and reducing shrinkage cracks. The use of guar gum is particularly novel in combination with hemp hurd biochar, as it synergistically enhances moisture retention within the porous biochar matrix. Integrating recycled aggregates also reduces material costs and promotes circular economy principles. Concrete mixes with 1% and 2% hemp hurd biochar by weight of cement, along with guar gum, were evaluated for mechanical and durability performance. At 7 days, compressive strength increased from 11.71 MPa (control) to 15.38 MPa (2% biochar). At 14 days, it rose from 14.01 MPa to 20.09 MPa, and at 28 days, from 19.58 MPa to 20.10 MPa. Water absorption decreased from 8.2% (control) to 7.2% (1% biochar) and 5.7% (2% biochar), reflecting improved durability and reduced maintenance requirements. The combined use of hemp hurd biochar, guar gum, and recycled materials provides multiple benefits: lower water and energy consumption during curing, reduced material costs, enhanced compressive strength, and increased resistance to water ingress. This approach produces cost-effective, energy-efficient, and environmentally friendly concrete suitable for modern construction projects. In conclusion, the integration of hemp hurd biochar and guar gum offers a novel, eco-friendly, and customer-focused solution, transforming agricultural waste and natural polymers into high-performance, low-cost concrete that reduces environmental and economic impacts while supporting sustainable construction goals.