Journal of Building Engineering 31 (2020) 101370 Available online 26 March 2020 2352-7102/© 2020 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Journal of Building Engineering Water absorption and sorptivity of alkali-activated ternary blended composite binder Md Maruf Hossain a, * , Md Rezaul Karim b, ** , Md Manjur A Elahi c , Muhammad Fauzi Mohd Zain d a Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, Australia b Department of Civil Engineering, Dhaka University of Engineering & Technology, Gazipur, Bangladesh c Project Engineer, Construction Services Department, Intertek - PSI, Houston, TX, United States d Faculty of Engineering and Built Environment, University Kebangsaan Malaysia, Selangor, 43600, Malaysia ARTICLE INFO Keywords: Pozzolans Alkali-activated binder Water transport properties Water absorption Sorptivity ABSTRACT This study examined the crucial durability properties of cementitious materials named water absorption and sorpitivity of two alkali-activated binders (AAB) namely AAB-1 and AAB-2, which incorporated a different composition of pozzolans including rice husk ash, fy ash, palm oil fuel ash, and slag. NaOH with a concentra- tion of 2.5 M was used to activate these binders. While the water absorption was measured at 28, 90, 180, and 270 days the sorptivity test was performed at 90, 180, and 270 days on mortar specimens. The test result indi- cates the AABs absorbed more water than OPC, especially at the initial period, which reduced over the curing period. Porous microstructure and consequential lower compressive strength of AABs has been considered re- sponsible for this. Similarly, the sorptivity value was higher for both AAB than OPC. The higher water absorp- tion and lower strength of AABs lead to a higher sorptivity. The water transport properties can be improved through increasing the strength and making a dense microstructure by optimizing the properties of pozzolans and the mixture composition of AAB. 1. Introduction To curtail the ever-increasing CO 2 emission, the experts from the academia and industry have been moving toward to develop a ce- ment-free and sustainable binder by using pozzolanic materials in- cluding slag, fy ash (FA), palm oil fuel ash (POFA) and rice husk ash (RHA). A wide range of studies were conducted in the feld of alkali- activated binders (AAB) by using slag and FA that were activated with NaOH, KOH and Ca(OH) 2 separately or in combination with sodium/ potassium silicate [1 –5]. It is explicitly reported that the AAB has the potential to impart mechanical properties including compressive strength, splitting tensile strength and elastic modulus at early age as well as it is less energy-intensive and releases less CO 2 into the atmos- phere than conventional OPC [6 –10]. Many researchers reported that AAB containing slag show an effec- tive strength and mechanical properties along with improved durabil- ity properties. El-Sayed el al [11]. studied durability and mechanical properties of water-cooled slag using a combination of sodium hy- droxide and sodium silicate activator where an equivalent dosage (3:3) of these two activators outperformed different dosage of sodium hydroxide. On the other hand, in another study on activated slag, sodium silicate was reported to perform better followed by sodium carbonate and sodium hydroxide with exactly same molar concentra- tion [12]. Vance et al. [13] also examined mechanical properties of activated slag concrete where 2.0 M was observed as optimum among 1.0 M; 1.5 M and 2.0 M. In a review on the performance of fy ash based activated binder, Al Bakri et al. [14] highlighted the molar con- centration, types, curing conditions as the infuential factors. Thok- chom et al. [15] examined the acid resistance of fy ash based geopolymer and observed no impact while Wallah reported a negligi- ble drying shrinkage of heat-cured fy ash concrete [16]. The effect of curing method and molar concentration of NaOH on compressive strength and durability (acid and sulfate) of activated RHA based mortar was studied by Kim et al. [17] where increased curing period * Corresponding author. ** Corresponding author. E-mail addresses: md.maruf.hossain@uon.edu.au (M.M. Hossain), rezaul@duet.ac.bd (M.R. Karim). https://doi.org/10.1016/j.jobe.2020.101370 Received 1 August 2019; Received in revised form 2 December 2019; Accepted 21 March 2020