A probable mathematical relationship between (Si/Al) ratio and (Ca/Si) ratio on the compressive strength of an iron ore tailings sample arising out of geopolymeric reactions

Abstract

In geopolymer reactions, with lime rich compound addition, the strength parameter is dependent on the molar ratios of (Si/Al) and (Ca/Si), such that (Si/Al) ratio contributes to short period and (Ca/Si) ratio contributes to long period strength development. In the present study a mathematical model has been proposed to identify the role of each on compressive strength development through exponential mathematical relationship, such that, N1 is an exponent of (Si/Al) ratio and N2 is an exponent of (Ca/Si) ratio indicating short period and long period strength development parameter respectively, while C is the compressive strength developed on keeping the samples for different extended time periods. The values of N1 and N2 can be found out by solving linear equations relating (Si/Al) ratio, (Ca/Si) ratio, and compressive strength values of different experimental batch compositions. Calculated and selected additions of sodium silicate, sodium hydroxide, lime and GGBS in iron ore mine tailing samples indicated that the values of N1 and N2 merged with each other after 7 days reaction period, but after 28 days reaction line due to N1 is found above that of N2. It is concluded that for long period strength development (Si/Al) ratio is more important in comparison to (Ca/Si) ratio.