Evaluating some geopolymer-based mortars for restoration purposes of damaged ancient Egyptian mural paintings

This study attempts to design some geopolymer formulas based on alkali activated kaolin, metakaolin and fly ash and other formulas mixed with hydraulic lime and powdered limestone for the utilization as restoration mortars for damaged ancient mural paintings at the Saqqara necropolis. For this, four geopolymer-based mixtures, in varying proportions, were prepared and tested. The mortars were prepared and evaluated at different NaOH molarities for physical and mechanical properties at three curing ages: 7, 14 and 28 days. The stability of the studied mortars against thermal-wet, acid attack and salt aging were assessed. Based on the physico-mechanical behavior and the compatibility of the components, the formula based on 15% fly ash (FA), 20% metakaolin (MK), 20% hydraulic lime (HL) and 50% sand was used to repair the multi-components plaster layers. While a formula contains 22.5% fly ash, 27.5% metakaolin and 50% sand was applied to treat the rock joints. The results proved the credibility of two formulas to be used as restoration mortars for different purposes including the injection of detached clayey layers, cracks repair and reinforcement of the rock joints.