Effect of Moisture Content of Wet Fly Ash on Basic Properties of Mortar and Concrete

Abstract

This study is aimed to investigate feasibility of using wet low CaO fly ash as a cement replacing material in concrete. Effect of moisture content of wet fly ash on basic properties of mortar and concrete is studied. The properties of mortar and concrete made with the wet fly ash are investigated and compared with those made with dry fly ash. Wet fly ashes prepared in the laboratory are used in the investigation. Moisture contents of the wet fly ashes are 25%, 45%, and 65%. The wet exposure period of fly ash is 3 months. The test results revealed that strength activity index and flow of mortar made with wet fly ash are slightly improved. Slump and compressive strength of concrete made with wet fly ash are also improved when compared to those made with dry fly ash. The effect of different moisture contents of the wet fly ash can be explained by the concept of double mixing method. The micro hardness test results showed that ITZ of the concrete made with wet fly ash is improved due to the effect of double mixing method.

Models for Predicting Free Water and Specific Heat of Pastes Containing Ground Granulated Blast Furnace Slag

“…2. θ hp,c and θ hp,slag are the ratios of minimum water to binder required to obtain maximum reactions of cement and slag, respectively. The values of θ hp,c and θ hp,slag are 0.21 and 0.30, obtained from previous studies [1,7]. W wgel (t) is defined as the weight of water entrapped in products of hydration and can be calculated from Eq.…”

“…A previous study reported that specific heat of concrete at a given time can be calculated based on weight fraction of each constituent and their specific heat values [6]. As the specific heat of water is the highest among all the constituents, specific heat of concrete is highly dependent on the free water content [7]. Transient technique provides accurate results for specific heat of hardening cement paste [3].…”