Proposed simplified method of geopolymer concrete mix design

Abstract

The research aims to determine the best combination of the controlling factors that govern geopolymer concrete’s mechanical and physical properties by utilizing industrial waste. Therefore, a review on the controlling factors was conducted. Firstly, it is to identify the controlling factors, namely chemical composition, alkali activation solution, water content, and curing condition. Secondly, understanding the relationship between these controlling factors and the properties of geopolymer concrete. These factors are analysed to the mix proportion components. Finally, a new proportion method is proposed based on combining ACI 211 standard and recommended molar ratios of oxides involved in geopolymer synthesis. The effect of aggregate has been taken into account by applying the absolute volume method in mix design. Based on the results of the study, it is expected to determine the optimal mix proportions based on multi-responses.

Prediction of the Compressive Strength of Fly Ash Geopolymer Concrete by an Optimised Neural Network Model

“…The input variables for geopolymer concrete were, however, not unified, and the authors did not follow a unified method. Through simple calculations, the datasets were converted into equivalent variables, which enabled a design method for FA geopolymer concrete that was similar to that of Portland cement concrete [ 44 ].…”

“…Ingredient proportions: FA ash content: The weight of the FA was taken in kg/m 3 in the design-mix as the most solid component of the geopolymer solids (GS) [ 21 , 44 ]. The effect and interaction of the aggregate are similar to those of Portland cement concrete [ 21 , 44 ]. Therefore, two parameters have been used.…”

“…The second parameter was the geopolymer solids–total aggregate ratio (GS/T agg (kg/m 3 )), which reflects the effect of the interaction between the total aggregate (filler material) and the geopolymer solids (matrix) in the composite. The superplasticiser was taken as a weight percentage of the raw material (FA) [ 21 , 44 ]. Alkali activator and water: In the case of a two-part geopolymer, different terms have been used to define the variability of the alkali activator, such as the molarity of sodium hydroxide (M), the content of sodium hydroxide (SH), the sodium silicate module (Ms) and the sodium silicate–sodium hydroxide ratio (SS/SH).…”

“… Alkali activator and water: In the case of a two-part geopolymer, different terms have been used to define the variability of the alkali activator, such as the molarity of sodium hydroxide (M), the content of sodium hydroxide (SH), the sodium silicate module (Ms) and the sodium silicate–sodium hydroxide ratio (SS/SH). Both the sodium hydroxide solution and the sodium silicate solution were usually mixed 1 day prior to mixing the geopolymer concrete, producing the final sodium silicate (Na 2 SiO 3 ) composition [ 21 , 44 ]. Interestingly, for one-part geopolymers, the alkali activator was solid sodium silicate (Na 2 SiO 3 ) [ 46 ].…”

“…Therefore, Na 2 O% and SiO 2 /Na 2 O were directly calculated from the Ms. From a practical point of view, it is more feasible to convert the alkali activator solution’s variables (M, SH, Ms and SS/SH) to the equivalent of Na 2 O%, SiO 2 /Na 2 O ratio and water in the alkali solution rather than converting the solid alkali activator’s variables (Na 2 O%, SiO 2 /Na 2 O ratio). Calculations of the solid parts of the alkali activation solution were based on the chemical composition, molecular weight and weight of each component in kg/m 3 , as described by [ 21 , 44 ]: where NaOH is the weight of the hydroxide sodium solids in the sodium hydroxide solution, SH is the weight of the sodium hydroxide solution, % GS SH is the weight percentage of the sodium hydroxide solids in the sodium hydroxide solution, Na 2 O is the sodium oxide, is the weight of the sodium oxide weight in the sodium hydroxide solution, is the molecular weight of the sodium oxide, is the molecular weight of the sodium hydroxide, is the weight of the silicate solid in the sodium silicate...…”