Experimental Evaluation of Biochar and TiO₂ Synergy Optimization in Concrete
Researchers tested M30 grade concrete mixes replacing partial cement with biochar and anatase-phase TiO₂ nanoparticles, finding that a 1% BC + 0.5% TiO₂ mix achieved 41.19 MPa compressive strength at 7 days but exhibited strength regression by 28 days due to thermal eigenstress and micro-cracking at biochar–paste interfaces. The findings highlight a durability limitation for biochar-based concrete composites, indicating that nano-TiO₂ accelerates early hydration at the cost of long-term mechanical performance.
This study evaluates the performance of M30 grade concrete incorporating biochar and anatase-phase titanium dioxide (TiO₂ nanoparticles) as partial replacements for cement. The research investigates three mix variants: Specimen S1 (1% biochar + 0.5% TiO₂), Specimen S2 (1% biochar + 1.75% TiO₂), and Specimen S3 (2% biochar + 3% TiO₂) by weight of OPC Grade 43 cement. Fresh workability was measured using slump tests, while hardened mechanical performance was assessed through compressive and split tensile strength tests at 7-day and 28-day curing periods.
The optimal mix, Specimen S1, achieved a 7-day compressive strength of 41.19 MPa, surpassing the M30 target, and a split tensile strength of 23.86 MPa. The slump test result of 110 mm indicates medium-to-high workability, demonstrating the effectiveness of biochar pre-saturation and optimized mix proportions. An unusual strength regression between 7 and 28 days was noted, attributed to early hydration acceleration by nano-TiO₂, thermal eigenstress accumulation, and micro-crack development at biochar–paste interfaces.
Source: Biochar Feed