# Durability Assessment of Eco-Friendly Bricks Containing
## 2 Materials Used in the Study  
**LKD and GGBFS:** LKD and GGBFS were combined in a 70:30 blend ratio for brick production.  
LKD has been identified as a possible replacement for OPC due to its high calcium content, alongside other compounds that highlight it as a favorable alternative binder material (ABM) [5; 14; 38]. Other compounds in LKD include SiO2, Al2O3, Fe2O3, and MgO, which are also in OPC in similar proportions [14].  
Ground granulated blast furnace slag (GGBFS) is a supplementary cementitious material (SCM) composed of CaO and SiO2 in good proportions. This composition, in combination with the CaO, SiO2, Al2O3, Fe2O3, and MgO from the LKD, was responsible for the strength obtained in the bricks produced [14]. Table 1 shows the chemical compositions of the LKD and GGBFS used in this study. Specific gravity (Gs) values of 2.75 and 2.65 were obtained for the LKD and GGBFS, respectively.  
**Tire rubber waste (TRW):** The properties and engineering applications of TRW have been previously reported in publications concerning its environmental, economic, and technical benefits [10; 13]. However, a prevalent challenge of strength reduction persists in concretes produced with TRW. This is due to the hydrophobic nature of the rubber material and the difference in stiffness between the cement paste and the rubber particles [39; 40]. This results in incomplete bonding between the cement paste and the rubber aggregates; hence, cracks easily occur when the samples are loaded externally. To address this shortcoming and enhance the mechanical properties of the rubberized samples, surface treatment of TRW with 10% (\(w/v\)) sodium hydroxide (NaOH) solution was carried out as recommended by previous research [14; 41; 42]. Furthermore, sieve analysis and Gs tests were carried out on the TRW crumbs, and values of 2.96 and 0.77 were obtained for the fineness modulus (FM) and Gs, respectively. The FM value obtained for the TRW was within the recommended limits from prior research [43; 44], and as specified by codes [45; 46] for fine aggregates. Hence, the fine TRW used in this study could partially replace fine natural aggregates (sand), since it possessed similar grading properties to the sand aggregates, as shown in Figure 1.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{8}{c}{**Chemical Composition (\%)**} \\ \cline{2-9}  & **CaO** & **SiO2** & **Al2O3** & **Fe2O3** & **MgO** & **K2O** & **Na2O** & **SO3** \\ \hline LKD & 63.42 & 20.04 & 4.90, & 3.49 & 1.11 & 0.35 & 0.43 & 2.35 \\ GGBFS & 42.1 & 33.1 & 13.2 & 0.3 & 6.5 & - & 0.5 & 2.0 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Oxides present in LKD and GGBFS.  
**Sand:** A gradation test was carried out to determine the particle size of the sand, and an FM of 2.47 was obtained. A \(G_{\text{s}}\) of 2.61 was also obtained for the sand sample. It is recommended that an FM within the range of 2.3-3 [45,46] or 2.2-2.8 [47] is suitable for brick production.  
**Water-reducing agent (WRA):** In this study, Sika Plastiment(r)-45 WRA was incorporated to improve the workability of the mix.