Utilization of millet husk ash as a supplementary cementitious material in eco-friendly concrete: RSM modelling and optimization

The environment has been greatly impacted by the increase in cement consumption. However, a huge quantity of energy is consumed and large amount of poisonous gases releases into the atmosphere during the cement production, which harms the environment. In order to decrease not only cement manufacturing but also energy usage and to aid in environmental protection, scientists are attempting to introduce agricultural and industrial waste materials with cementitious characteristics. Therefore, millet husk ash is used as supplementary cementitious material (SCM) in the concrete for producing sustainable environmental. The main purpose of this investigation is to check the workability, compressive strength, splitting tensile strength, flexural strength and drying shrinkage of concrete incorporating 0 %, 5 %, 10 %, 15 % and 20 % of MHA as SCM in concrete. A total of 165 concrete samples was made with mix proportion of 1:1.5:3 and cured at ages of 7, 28, and 90 days. The investigational outcomes displayed that there was an improvement in compressive strength, tensile strength, and flexural strength by 11.39 %, 9.80 %, and 9.39 %, correspondingly, at 10 % of MHA replacement of cement. Also, the water absorption reduced as MHA content increased after 28 days. There was also a reduction in drying shrinkage of concrete as the MHA increased after 28 days. Though, the workability is declined as the proportion of MHA increased in concrete. Moreover, the embodied carbon is declined while the content of PC substituted with MHA rises in concrete. In addition, response prediction models were built and validated using ANOVA at a 95 % significance level. R² values for the models varied from 87.47 to 99.59 percent. The study concludes that the accumulation of 10 % MHA in concrete has a favourable effect on the characteristics of the concrete.