The durability properties of high volume oil palm biomass waste mortar

Abstract

Research works on the use of pozzolanic waste materials have continued to gain attention worldwide in an attempt to reduce the environmental problem due to carbon dioxide emission from cement manufacturing process. Nowadays, biomass wastes from oil palm industry are abundantly available in many parts of the world. In relation to that an increase in the production of oil palm will create a major disposal problem of the wastes. It is estimated that for every tonne of oil processed, nearly five tonnes of agricultural waste known as biomass are generated including Palm Oil Fuel Ash (POFA), Oil Palm Kernel Shell (OPKS) and Oil Palm Fibre (OPF). This research therefore, focuses on investigating the effects of nano POFA as cement replacement, OPKS as fine aggregates replacement and OPF as tensile strength enhancement on the properties and performance of biomass mortar. The size of the POFA used had been successfully reduced from micromolecular to the nano-size range by ball milling and the LOI was reduced during treatment process. Various tests were carried out to determine the characteristics of materials including X-ray fluorescence, transmission electron microscopy, sieve analysis and balling effect. The effects of biomass waste on fresh and hardened properties of mortar such as hydration temperature, compressive strength, splitting tensile strength, flexural strength, modulus of elasticity, water absorption, total porosity, chloride penetration, acid resistance, sulphate resistance, dry-wet cycle test and ultrasonic pulse velocity were also investigated. Furthermore, various techniques including X-ray diffraction, scanning electron microscopy, thermo gravimetric analysis and fourier transform infrared spectroscopy analysis were used to study the microstructure of the biomass mortar. The results show that the use of 80% nano size POFA has reduced the hydration temperature by 30% and produced higher compressive strength at the age of 28 days by 32% compared to normal mortar. In addition, the compressive strength of the 80% nano POFA mortar at 365 days was 25% higher than its 28 days strength, while the mortar density and porosity was reduced by 50% and 51%, respectively. Thus, grinding the raw POFA to a nano size particle has significantly improved the reactivity of the ash. The inclusion of high volume nano POFA and OPKS reduces the density of mortar due to the low density of the materials itself. The experimental results also showed that the durability and microstructural characteristics of the biomass mortar were significantly improved and better than control mortar. The inclusion of 0.7 % OPF was found to increase the splitting tensile strength and flexural strength up to 69 % and 65 %, respectively, as compared to normal mortar. The overall results revealed that biomass waste with some treatment can be used to produce mortar that is sustainable, higher strength and good durability.