# Feasibility of Non-Remanufactured Waste Bottle Glass as Supplementary Cementitious Material
## 2 Methodology
### Durability Indicators  
According to published studies, the durability of mortars/concretes with glass powder is usually improved. The durability-related results obtained in this work are described below. Electrical resistivity measurement may be a simple indicator of the durability of cement-based materials [9; 16]. The electrical resistivity depends on the pore structure, such as porosity and pore connectivity, and pore solution conductivity. As such, electrical resistivity provides valuable information regarding cementitious materials' microstructure and hydration process [29; 47; 48]. Figure 12 shows the electrical resistivity results of mortars between 7 and 86 days. At an early age, 7 days, the resistivity was similar among mortars under study. Afterwards, a substantial increase for glass powder mortars occurs, reaching, at 86 days, 65.2 and 62.9 ohm-metre for WG10 and AGWG10, respectively, while for the REF mortar, the result was 46.3-ohm metre. This translates as an increase of about 40% for glass powder mortars. The enhancement in the electrical resistivity of cement pastes modified with waste glass can be attributed to pore refinement in the microstructure resulting from the eventual pozzolanic behaviour of WG and AGWG. This corroborates past research [29; 47; 48]. Figure 12 also suggests that the resistivity of glass mortar mixtures will continue to increase beyond 84 days. Figure 11: Mechanical strength at 7 and 28 days: (**a**) flexure; (**b**) compressive. Figure 12: Electrical resistivity between 7 and 86 days. The average sorptivity was 0.0490, 0.0370, and 0.0440 mg/(mm\({}^{2}\)\(\times\) min\({}^{0.5}\)) for the REF, WG10, and AGWG10 mortars, as presented in Table 7. Using waste glass powder slightly improved the capillary water absorption of mortars, namely WG. The pozzolanic reaction provided by the reaction of GP with calcium hydroxide seemed to decrease the porosity of mortars. Previous studies also observed decreased sorptivity with increased GP content [28,45]. The results from the rapid chloride migration test are presented in Table 8, including the chloride penetration depths (X\({}_{\text{d}}\)) and the corresponding average values of non-steady-state chloride migration coefficients, D\({}_{\text{nssm}}\). As can be perceived, the D\({}_{\text{nssm}}\) was similar among the mortars, being slightly higher for the WG10 mortar, followed by REF and ASGW10. As such, WG slightly decreases resistance to chloride ion penetration, which might be related to higher PSD than cement and AGWG (see Table 2), as discussed in Section 2.1.4. Moreover, these results were not expected. Improved performance on cement-based mortars against aqueous chloride solution is reported in the literature, as discussed in Section 1. A decrease in carbonation resistance was noticed for mortars with the incorporation of glass powder, as presented in Table 9, which follows previous findings [21,24,25] and is typically observed on some SCMs when used as a cement replacement [44], which is probably due to CH reduction. Figure 13 depicts the ASR linear length change of the REF, WG10, and AGWG mortars. According to ASTM C 1567, a mortar with an expansion lower than 0.10% after 16 days (and 14 days after immersion in 1 N sodium hydroxide solution at 80 \({}^{\circ}\)C) is expected to have a low risk of deleterious expansion. The mortar mixture is considered potentially expansive if the expansion exceeds 0.10 % at 16 days after casting. The expansion limit of 0.1% is highlighted in Figure 13 (horizontal dotted red line). When Portland cement is the binder (REF mortar), the mixture is classified as potentially expansive according to ASTM C 1567. Mortar prisms presented an expansion of 0.10% after 14 days of immersion in NaOH at 80 \({}^{\circ}\)C. Concerning WG10 and AGWG10, glass powder mitigates deleterious ASR expansion compared with the REF mixture, with expansion values of 0.05 and 0.03%, respectively, after 14 days of immersion in NaOH at 80 \({}^{\circ}\)C. Figure 13 also suggests that the expansion of