Oil palm boiler clinker (OPB) is a waste byproduct obtained at elevated temperature in an oil palm processing mill. Moreover, in recent years, Concrete filled steel tube (CFST) has been used widely in structures throughout the world. This paper presents an experimental and numerical study on novel sustainable composite beam by using OPB as replacement of natural coarse aggregate in CFSTs. Steel hollow beams (3.2m length) infilled with natural aggregate concrete and OPB concrete were subjected to flexural load and elevated temperature. The parameters selected for the experimental tests were the cross-section type (square, rectangular) and the infilling type (natural aggregate concrete and OPB concrete). The thermal response, failure modes, critical temperature, temperature distribution in steel tube and infilled concrete, deflection along the span and fire concrete contribution ratio were evaluated. The critical temperature and fire concrete contribution ratio of OPB CFST was found to be higher than natural aggregate CFST, showing superior performance of OPB CFST. Thereafter, simulations were performed and more than 50 models were analyzed to evaluate the effect of yield strength of steel (235-400 MPa), compressive strength of infilled concrete (30-75 MPa), load ratio (0.3-0.6), width-to-depth ratio (2-0.5) and steel ratio (4.4%-2.1%) on the fire resistance time of CFST beam. It was found that the increase in load ratio, steel ratio and yield strength of steel has adverse effected on the fire resistance (FR) time of CFST member. However, the FR time increased significantly with an increase in compressive strength of infilled concrete and cross-sectional dimension of CFST member. Finally, the experimental results were compared with existing equations for CFST columns filled with natural aggregate concrete. It was found that current equations may underestimate the fire resistance of CFST filled with OPB.

Introduction

Malaysia palm oil industry is the world’s 2nd largest palm oil industry, with an annual production of 19.67 million metric tons of crude palm oil (Ibrahim et al., 2017). Despite producing valuable products, the palm oil industry also generates agricultural wastes (biomass). From the consumption of large amount of natural resources (forest land and water) (Javed et al., 2018; Musikavong and Gheewala, 2017a, b; Suttayakul et al., 2016) during cultivation, to the production of huge amount of environmental pollutants during processing, palm oil industry is severe threat to the environment. The pollutant produced from oil palm industry contributes to global warming, eutrophication, acidification and air pollution (Bessou et al., 2014; Saswattecha et al., 2015). That’s why, oil palm industry is well known in many countries for its harmful environmental 35 impacts. In Malaysia, 80 million dry solid biomass waste was yielded in 2010 only and is expected to reach up to 110 million by 2020 from palm oil industry only (Malaysia, 2011; Ng et al., 2012). Various types of solid wastes like palm fiber, oil palm shell, oil palm boiler clinker and empty fruit branches are produced at the end of palm oil processing stages. Oil-palm-boiler clinker (OPB) is a waste material obtained by burning off solid wastes at elevated temperature of 850°C during the process of palm oil extraction (Aslam et al., 2016b; Jumaat et al., 2015). OPB usually has no economic value and are abundantly available (Hartono et al., 2016; Shafigh et al., 2014). Most of the OPB is used for covering the potholes on the roads within the vicinity of the plantation areas, which affect the environment directly (Kanadasan and Abdul Razak, 2015).