Structural performance of R.C. Beam with septage ash and hybrid fibre

The scarcity of aggregate resources hence the rise in the incorporation of waste materials in the partial replacement of concrete. Septage ash derived from thermal faecal sludge treatment plants has been identified as having the possibility for partial substitution in the construction industry’s demand for cement, a non-renewable material. This study aimed to develop an innovative product utilising septage ash as a cement substitute, thereby reducing natural resource consumption and minimising waste disposal in an environmentally sustainable manner. Incorporating septage ash not only decreases concrete production costs but also helps mitigate industrial pollution. However, it affects the strength and fresh properties of concrete. One approach to address this issue involves the use of hybrid fibres (HyF) and superplasticisers in concrete mixtures. Concrete mixes were prepared with septage ash replacing 10%, 20%, and 30% of the cement. Additionally, 0.06% glass fibre (GF) and 0.3% polypropylene fibre (PF) by volume of concrete were incorporated. The cube and cylinder specimens were cast and tested for compression and splitting tension, respectively. The impact of hybrid fibre (GF + PF) inclusion on workability was examined. Four categories of concrete mixes were used to cast two reinforced beams measuring 1800 × 200 × 100 mm each. These reinforced concrete beams were analysed for their structural behaviours, including energy absorption, toughness, stiffness, load deflection, and ductility. The study results indicate that incorporating septage ash at a 20% cement replacement level, along with hybrid fibres in reinforced concrete beams, proves to be both economically and technically advantageous.