Flexural Behaviour, Microstructure and Cost-Benefit Analysis of Ternary Binder Foamed Concrete

Foamed concrete is a controlled low-density concrete, and due to its excellent thermal insulating and acoustic absorption properties, its application has been on a steady rise. Palm Oil Fuel Ash (POFA), an agricultural waste generated by the Palm Oil industry and Eggshells, causes many environmental problems. The pozzolanic nature of POFA and the high calcium oxide content in Eggshell Powder (ESP) are the components that contribute to their suitability as a partial cement replacement in concrete. This experimental work studied the flexural behavior, as well as the compressive strength of lightweight ternary binder foamed concrete incorporating 20% - 25% POFA and 5% - 10% ESP by weight of the total binder, as partial cement replacement. The test results were analyzed and compared with conventional foamed concrete without POFA and ESP. It was observed that POFA is a class C pozzolanic material. The combined utilization of POFA and ESP increased the compressive and flexural compared with control concrete. Furthermore, most of the cracks of the prisms were nearer to the middle of the samples and between two locations of loads applied due to the same load value applied at both locations. It was also observed the air voids were blocked due to increased pozzolanic activity and development of C-S-H gels and thus increase in strength. The utilization of POFA and ESP in concrete can be beneficial in reducing the overall cost. The cost to produce 1 m3 of concrete incorporating POFA and ESP was reduced ranging from was reduced by 12.59% (with 20% POFA and 5% ESP) to 17.53% (with 25% POFA and 10% ESP). It can be concluded that the M4 concrete mix is the optimum and cost-effective, as the maximum cement content is replaced (35%), as well as the compressive and flexural strengths are significantly higher than the control concrete M0.