A synopsis of an experimental program on the development of a sustainable fly ash–slag blended geopolymer mortar (GPM) and lightweight geopolymer concrete (LGPC) is presented. Geopolymer mortar mixes were prepared incorporating industrial by-products and sustainable desert dune sand to study the effect of different mixing variables, including binding materials, curing temperature, and alkaline activator solution composition and content, on the rheological and mechanical performance. Optimum mix designs were then formulated into producing LGPC samples with different binding materials and curing temperature. Lightweight geopolymer concrete specimens exhibited a brittle behavior with a weakened structure due to low-strength lightweight aggregates. Lightweight geopolymer concrete made with dune sand and a fly ash to slag ratio of $3:1$ resulted in the highest compressive strength when cured for 24 h at 60°C. Microstructure characterization of LGPC specimens was also conducted. Scanning electron microscopy and differential scanning calorimetry showed the coexistence of an aluminosilicate hydrate geopolymer gel and aluminum-modified $\mathrm{C}─\mathrm{S}─\mathrm{H}$ gel as the main polymerization reaction products in an amorphous geopolymeric microstructure.

Alkali activation of fly ash and ground-granulated blast-furnace slag (GGBS) is a sustainable technology that promotes recycling of industrial by-products in the form of geopolymer composites. In this study, geopolymers are prepared with fly ash, GGBS, and desert dune sand (fines). The alkaline activator solution is formulated using sodium silicate and 14 M sodium hydroxide solutions. The effect of mixture proportioning and curing conditions on the workability, setting time, and compressive strength of geopolymers was examined. The investigated process parameters included percentage of fly ash replacement by GGBS, superplasticizer dosage, amount of fines, alkaline activator solution content, and sodium silicate to sodium hydroxide ratio. The final geopolymeric product could be enhanced by employing subsequent continuous and intermittent water curing techniques. Based on the experimental results, analytical models correlating mixture proportions with workability and 28-day compressive strength were developed for geopolymers made with 100% GGBS and equal proportions of fly ash and GGBS.

A brief history of Christchurch city is presented, including information on the introduction of unreinforced masonry as a popular building material and an estimate of the number of unreinforced masonry buildings in the Canterbury region currently. A general overview of the failure patterns that were observed in unreinforced clay brick and stone masonry buildings in the Christchurch area after the 2010 Darfield earthquake is provided. Case studies of the damage sustained to five unreinforced masonry (URM) buildings that were unretrofitted at the time of the earthquake, including photographic details, is documented. The performance of eight retrofitted URM buildings is then commented on, detailing the building characteristics and retrofit techniques. The case studies include the use of moment resisting frames, steel strong backs and strapping, diaphragm anchoring, surface bonded fibre reinforced polymer (FRP) sheets and cavity ties.