Hanizam Awang and Mohammed Zuhear Al-Mulali, Utilising Unground Oil Palm Ash in Producing Foamed Concrete and Its Implementation as an Interlocking Mortar-Less Block. journal = {International Journal of Civil and Environmental Engineering}, [online]. World Academy of Science, Engineering and Technology. February 2016, vol. 111(3). 347 - 352 [viewed 19 September 2024]. Available from: https://publications.waset.org/pdf/10003993.