1st International Conference on Transportation Infrastructure and Materials (ICTIM 2016) ISBN: 978-1-60595-367-0
Graphene Oxide Modified Pervious Concrete with Fly Ash as Sole Binder Gang Xu1 and Xianming Shi2 1
Laboratory for Advanced & Sustainable Cementitious Materials, Department of Civil & Environmental Engineering, Washington State University, Pullman, WA 99164-2910;
[email protected] 2 Associate Professor, Department of Civil & Environmental Engineering, Washington State University, Pullman, WA 99164-2910;
[email protected]; Corresponding author
ABSTRACT: In this study, a graphene oxide modified pervious concrete was developed by using a low-reactivity, high-calcium fly ash as sole binder, chemical activators and other admixtures. The density, void ratio, mechanical strength, infiltration rate, Young’s modulus, and degradation resistance of pervious concrete were measured against other three controlled groups. The test results indicated that the graphene oxide modified fly ash pervious concrete is comparable to the Portland cement pervious concrete. While the addition of 0.03% graphene oxide (by weight of fly ash) increased the compressive strength, split tensile strength, Young’s modulus and degradation resistance of fly ash pervious concrete noticeably, the void ratio and infiltration rate were reduced. INTRODUCTION Pervious concrete is a special type of concrete with a high porosity that allows water from precipitation and other sources to pass through directly. The infiltration effect provided by pervious concrete pavements can recharge the groundwater and reduce the amounts of total suspended solids, total phosphors, total nitrogen and metals in the ground water (Schaefer et al. 2006). A typical pervious concrete mix design contains Portland cement. It is well known that Portland cement has some environmental concerns: the high-energy consumption and the release of air pollutants and greenhouse gases related to mining and manufacture. In order to make the pervious concrete environmentally friendly and sustainable, fly ash, a by-product of coal fired power plant, has been chosen in this study to fully replace Portland cement in the pervious concrete since it has been used as a partial cement replacement in the concrete for years (Palomo, Grutzeck, and Blanco 1999). In this work, we used a low-reactivity, high-calcium fly ash (defined in Table 1) as sole binder for pervious concrete with alkali activation at room temperature. Graphene oxide (GO) was also used to facilitate the polymerization of reaction products from alkali activation. Previous studies (Lv et al. 2014; Gong et al. 2015 and Ranjbar et al. 2015) indicated that GO can improve the overall performance of cement mix significantly by regulating cement hydration, providing crack branching and bridging mechanism and acting as nanofillers. Therefore, GO shows significant potential for the application in fly ash-based pervious concrete of high strength and durability. The following sections detail the process of developing pervious concrete with a low-reactivity, high-calcium fly ash as the sole binder. A fly ash based pervious concrete could not only reduce the demand for
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Portland cement, but also divert the fly ash from industrial wastes, which could otherwise cause serious environmental problems. Table 1. Fly Ash Spheres Reactivity (Enders 1995). CaO (% wt.) >25
