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The use of calcined clays as supplementary cementitious materials provides the opportunity to significantly reduce the cement industry’s carbon burden; however, use at a global scale requires a deep understanding of the extraction and processing of the clays to be used, which will uncover routes to optimise their reactivity. This will enable increased usage of calcined clays as cement replacements, further improving the sustainability of concretes produced with them. Existing technologies can be adopted to produce calcined clays at an industrial scale in many regions around the world. This paper, produced by RILEM TC 282-CCL on calcined clays as supplementary cementitious materials (working group 2), focuses on the production of calcined clays, presents an overview of clay mining, and assesses the current state of the art in clay calcination technology, covering the most relevant aspects from the clay deposit to the factory gate. The energetics and associated carbon footprint of the calcination process are also discussed, and an outlook on clay calcination is presented, discussing the technological advancements required to fulfil future global demand for this material in sustainable infrastructure development.

Climate changes and global warming are an international issue around the world and caused by the accumulation of greenhouse gases, and one of these reasons Portland cement industry which releases high amounts of CO2, which causes 65% of the global warming effect. So the essential component for sustainable development in the construction industry is the improvement of alternatives for cement. One of the promising materials in the field of concrete industry is the geopolymer concrete, which attracted spotlight over the past decade with its comparable performance with Portland cement. This paper presents a systematic review of different research works done in the region of geopolymer concrete based metakoalin reinforced with polypropylene fiber and under ambient temperature. The mechanical behavior was enhanced significantly through experimental results. The compressive strength was improved 14.75% with 1% of polypropylene fiber while the increment of splitting tensile strength was 12.3 %, 15.76 % respectively. The flexural strength of specimens was also improved when compared with the non-fiber geopolymer concrete. The highest increment obtained with 1.5% of fiber volume content was 27.3%. Modulus of elasticity was also improved with increment to 13.1%, when compared with the non-fiber geopolymer concrete, also from experiment adding of fibers lead to a decrease in the density of GPC. The compressive performance and flexural performance of fiber-reinforced geopolymer concrete were also better than specimens without fiber

This work is a Scanning Electron Microscope (SEM) study to investigate the behaviour of Metakaolin based GPC mixes with and without cement and containing recycled concrete aggregate. Three (3) GPC mixes and Normal Concrete mix (NC) designed mingled and tested to achieve the goals of this research. Control specimens were cast from each mix to determine the mechanical properties for each mix. (12) SEM micrographs from carefully selected samples. SEM study confirmed that the presence of recycled concrete aggregate can be a source of generating cracks and fissures. The un-hydrated cement particles in recycled aggregate can contribute to further hydration when contact with water. Also, the metakaolin based GPC matrix with natural aggregate showed enormous with unrealized morphology, which indicates amorphous. Finally, the replacement of 20% of Metakaolin with cement led to enhance mechanical properties.

This paper presents experimental study of structural behavior of thin Reactive Powder Concrete (RPC) wall panels subjected to axial eccentric uniformly distributed loading with varying steel reinforcement ratio (ρ) and aspect ratio (AR= H/L). The experimental program included testing of six two-way thin RPC wall panels, fixed at all sides and applying the load axially with eccentricity equal to (t/6). The results indicates that the ultimate strength of the RPC wall panel decreases with increase in AR from (1.25 to 2.00) for panels with H/t = 18.75. The decreasing in ultimate load for RPC wall panels is about 16% and 38.7%, for an increase in AR from 1.25 to 2.0 for panels with ρ = 0.012566, and about 6.38% and 36.2%, for an increase in AR from 1.25 to 2.0 for panels with ρ = 0.007854.The ultimate strength of RPC wall panel increases with an increase of percentage of steel reinforcement ratio (ρ). For an increase in reinforcement ratio from ρ = 0.007854 to ρ = 0.012566 the increase is about (6.4, 4.76 and 2.22) % for walls with AR (1.25, 1.50 and 2.00) respectively. The lateral deflection decrease with the increase of percentage of steel reinforcement ratio from (0.007854 to 0.012566) under two-way in plane loading, When AR= 1.25 the reduction about (1.22 times) and When AR= 2.00 the reduction about (1.11 times). The lateral deflection of RPC wall panels decrease with the increase in aspect ratio.