The effects of high volume nano palm oil fuel ash on microstructure properties and hydration temperature of mortar Nor Hasanah Abdul Shukor Lim a , Mohamed A. Ismail b,⇑ , Han Seung Lee b , Mohd Warid Hussin c , Abdul Rahman Mohd. Sam c , Mostafa Samadi a a Construction Material Research Group (CMRG), Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia b Dept. of Architectural Engineering, Hanyang University, Ansan, Republic of Korea c Construction Research Centre (UTM CRC), Institute for Smart Infrastructure and Innovative Construction, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia highlights  High volume of nano POFA as cement replacement improves strength.  Nano POFA reduces hydration temperature of massive concreting in early age.  Treatment of POFA increases pozzolanic properties and activity index. article info Article history: Received 3 February 2015 Received in revised form 12 May 2015 Accepted 15 May 2015 Keywords: Microstructure Palm oil fuel ash Mortar strength High volume Hydration temperature abstract The effect of high volume nano palm oil fuel ash in the mortar was investigated. This study covers basic properties like the morphology of the composite, the hydration temperature, strength activity index, thermal conductivity and microstructure properties with regards to the variations in the mix design process of mortar. The effects of fineness of the ash on the strength properties of mortar were also investigated. To get a better performance in terms of strength development, the ash used has gone through heat treatment and was ground up to less than 1 lm. The incorporation of more than 80% nano size palm oil fuel ash as cement replacement has produced a mortar having a compressive strength more than OPC mortar at a later age. The overall results have revealed that the inclusion of high volume nano palm oil fuel ash can produce a mortar mix with high strength, good quality and most importantly that is more sustainable. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction Affordable products with advanced properties are necessary towards the higher human development and sustainable economic growth. Therefore, reusing the abundant waste materials has become necessary especially waste coming from palm oil manufac- turing. It is estimated that ‘‘the total potential palm biomass from 4.69 million hectares of palm oil planted area in Malaysia in 2009 is 77.24 million tonnes per year comprising of 13.0 million tonnes of Oil Palm Trunks (OPT), 47.7 million tonnes of Oil Palm Fronds (OPF), 6.7 million tonnes of Empty Fruit Bunches (EFB), 4.0 million tonnes of Palm Kernal Shell (PKS) and 7.1 million tonnes of Mesocarp Fibre (MF) (all dry weight)’’ [1,2]. These wastes are usu- ally used as fuel in palm oil mill to generate electricity [3] and after the combustion in the boiler there are approximately 5% of ash generated [4] and another solid waste being produced. The need towards sustainability and sustainable environment has made the use of pozzolanic material in mortar popular. One of the latest additions of pozzolanic material is palm oil fuel ash (POFA) [5–7]. This POFA is the source of silicate that produced after the combustion of palm oil fibre, shell and mesocarp as fuel to generate electricity [8]. Few studies were done by other research- ers on the replacement of partial weight of cement by POFA [9,10], but there is still high amount of ash abundant in the landfill which lead to environmental problems. It is reported that the maximum strength gain occurred at the replacement level of 30% with the size of 45 lm but further increment in the ash content would reduce the strength of mortar gradually [5]. Besides, POFA was also used as nano filler [11]. The hydration temperature of mortar describes the hardening behaviour of it. The mix properties and component of materials http://dx.doi.org/10.1016/j.conbuildmat.2015.05.107 0950-0618/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +82 31 4005181; fax: +82 31 4368169. E-mail address: mismail@hanyang.ac.kr (M.A. Ismail). Construction and Building Materials 93 (2015) 29–34 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat