Strength and Microstructural Performance of Nano-SiO2 Gel (NSG) Infused Alkaline Activated Ground Blast Furnace Slag-Ultrafine Palm Oil Fuel Ash (AAGU) Based Mortar YUSUF, Moruf Olalekan 1, 3, a , MEGAT JOHARI, Megat Azmi 1, b , AHMAD, Zainal Arifin 2, c and MASLEHUDDIN, Mohammed 3, d 1 School of Civil Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia 2 School of Material and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia 3 Research Institute, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia a moy12_civ023@student.usm.my, b cemamj@eng.usm.my, c zainal@eng.usm.my, d muddin@kfupm.edu.sa Keywords: Compressive-Strength; SEM+EDX; FTIR; POFA; GBFS; Nano-Silica. Abstract. The aim of this paper is to study the performance of infused nano-SiO 2 gel (NSG) on the developed alkaline activated binary blending of ground blast furnace slag (GBFS) and ultrafine palm oil fuel ash (UPOFA) based mortar (AAGU) using the constant mass of combined activators (10 M NaOH aq +Na 2 SiO 3aq (Ms = SiO 2 /Na 2 O=3.3)). The methods include using the 3-day compressive strength and microstructural characterization (SEM+EDX and FTIR) criteria. The finding revealed that the compressive strength of the mortar increased with NSG and the maximum strength achieved was 57.3 MPa signifying 21% strength gain compared to NSG-free sample. The NSG also played the role of microcracks and pore fillings, increased the product homogeneity and reduced its amorphousity due to silicate re-organization but has no effects on Si-Al substitution. Introduction In Malaysia and Thailand, palm oil production has left behind a huge amount of palm oil fuel ash (POFA) as solid wastes, so much that, there is need to find a means of disposing it safely to ensure a healthy environments. For instance, Malaysia produced about 3 million tons of POFA in 2007 while the annual production in Thailand was reported to be 0.1 million ton [1]. One of the ways to utilize these materials is in the mortar or concrete productions having identified it to be pozzolanic[2]. POFA can be processed or treated to enhance its aluminosilicate property [3, 4] by combining it in binary with another aluminosilicate materials such as the ground blast furnace slag (GBFS) in the development of alkaline activated binder (AAB). The strength and durability of such AAB can be enhanced by incorporating inorganic sources of Ca, Al and Si [5-7].This study observed the effect of nano-SiO 2 gel on the GBFS+UPOFA based AAB, and the results showed that the NSG improves the strength, homogeneity and amorphousity of the binder products. Materials and Methods Materials: Ultrafine palm fuel ash (UPOFA) and ground blast furnace slag (GBFS) Palm oil fuel ash (POFA) was obtained at Malaysian Southern Steel Company while Blast furnace slag (BFS) was collected from United Palm Oil Industry, Malaysia. The raw materials were first heated at 105 o C + 5 o C for 24 hrs to remove the inherent moistures. This was then followed by screening off debris materials using 600 and 300 µm sieve. The BFS was ground for 16 hrs to obtain the ground BFS (GBFS) while POFA was first ground for 8 hrs and then later milled for additional 8 hrs after 90 mins calcination at 500 o C + 50 o C, to obtain ultrafine POFA (UPOFA). The milling was done with mechanical rotating steel drum rotating at 180 rpm and contained 150 balls of different sizes ranging from 6 mm to 32 mm. Advanced Materials Research Vol. 856 (2014) pp 280-284 Online available since 2013/Dec/06 at www.scientific.net © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.856.280 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 2.91.115.49-07/12/13,16:10:49)