Torsional strength of reinforced concrete beams with incorporating agricultural waste ash

The current research examines and assesses the outcomes of different agricultural waste concrete (AWC) beams under torsional forces. Five beams were cast and tested, with four of them including different types of agricultural waste ash, such as black gram pod ash (BGA), green gram pod ash (GGA), horse gram pod ash (HGA), and pigeon pea stalk ash (PPA), partially replacing cement in the concrete mix. The fifth beam was made using a regular concrete mix. Based upon the compressive and split tensile strength results, 8% content of all agricultural waste ash were selected as the optimum mix of each agricultural waste ash concrete mixes. Beam specimens prepared from these four types of concrete were subjected to pure torsional moment up to failure. The investigation was carried out to find the various performance metrics including failure pattern, first crack load, ultimate torque at failure along with twisting angle were observed. From the torque vs. twisting angle curves, torsional stiffness and ductility index were also evaluated for these four types of concrete and compared with conventional concrete beam. It was observed that the ultimate torque (T_u) of the BGA8, GGA8, HGA8 and PPA8 beam was 38.46%, 15.38%, 7.69% and 23.07% higher than the conventional concrete (CC) beam. In addition, experimental torques were compared with predictions of torsional strength as per ACI 318 M-14 model. Minimum torsional reinforcement in beams is essential to prevent beam failure due to cracking. AWC concrete specimens exhibit more excellent flexibility than conventional concrete beams.