Development and characterization of ceramic waste powder-slag blended geopolymer concrete designed using Taguchi method

The ability to utilize industrial by-products in the production of cement-free geopolymer concrete is a promising technology. However, the development, characterization, and optimization of geopolymer concrete made with ceramic waste powder (CWP) and ground granulated blast furnace slag (or simply slag) have not been examined yet. This paper investigates the mechanical and durability properties of geopolymer concrete incorporating CWP and slag. Taguchi method was employed to design sixteen CWP-slag blended geopolymer concrete mixes. Five factors with four levels were considered in the design, including binder content, CWP replacement percentage by slag, alkali-activator solution to binder ratio (AAS/Binder), sodium silicate (SS) to sodium hydroxide (SH) ratio (SS/SH), and SH solution molarity. Results showed that geopolymer concrete properties remarkably degraded when CWP served as the sole binding material. However, combining 40 % CWP and 60 % slag yielded superior performance than the control mix made with 100 % slag. Correlations between mechanical and durability properties were developed in the form of regression models. The optimal compressive strength response (58.9 MPa) of CWP geopolymer concrete was attained using 450 kg/m³ of binder content, 60 % of CWP replacement by slag, 0.5 of AAS/Binder, 1.5 of SS/SH, and 10 M of SH solution molarity. Scanning electron microscope and energy-dispersive X-ray spectroscopy highlighted the formation of calcium aluminum silicate hydrate and calcium silicate hydrate gels. Experimental findings provide evidence of the ability to utilize CWP in the production of structural grade geopolymer concrete.