The construction industry consumes a large quantity of cement, which therefore leads to a high CO2 emission due to the cement manufacture. The partial replacement of cement by supplementary cementations materials (SCMs) is considered as the most promising alternative to reduce the environmental impact of this industry. This investigation aims to evaluate the performance of calcinated clay (calcined bentonite at 850 °C) used as partial replacement of cement in cement-based mortar. The evaluated performances include the physico-chemical and mechanical properties, as well as microstructural characteristics.. Various characterization tests, including laser granulometry, X-ray diffraction (XRD), and X-ray fluorescence spectrometry (XRF) have been investigated. In addition, the hardened properties of different mortar mixtures were also investigated. Mortar mixtures incorporating different calcinated clay percentages corresponding to 8, 10, 12, and 14%, by mass of total binder content, were proportioned. Termogravimetric analysis (TGA) and its derivative (DTG), Differential scanning calorimetry (DSC), and microstructural (Scanning electron microscopy (SEM)) analysis were carried out on samples of mortar mixtures. Furthermore, the 28-d hardened properties were assessed to assess the pozzolanic activity of the investigated mixtures. Strength activity index (SAI), DSC, and TGA analyzes are presented. The obtained results showed that all the mixtures exhibited adequate pozzolanic activity conforming to the ASTM C618 specifications.

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In order to decrease the fitting deviation between rheometrical measurements and empirical parameters using slump test, this paper proposes a new analytical method to evaluate the high yield stress of materials (cement pastes).In doing so, an experimental study was performed for measuring the empirical characteristics by cylindrical mold with different water to binder ratios (w/b) by aiming to increase the yield stress. Parallelly, experimental observations showed clearly the unyielded zone at flow stoppage of high yield stress samples. Based on these results, an idea was formed to applied metallic element at inlet of mold in order to push the spreading of paste. The obtained results of the model proposed in this paper were compared with the yield stress evaluated from shear flow curves using AR2000-rheometer with plate-plate geometry at rate-controlled. In fact, this study demonstrates the applicability and novelty of the present model in the process of relating the empirical parameters to yield stress.

In the construction sector, the non-renewable world resource of sand is largely used to produce mortar and concrete. It has been estimated that over 10 billion tons of sand have been produced, with 1.2 billion tons used in concrete over the last decade, which leads to a progressive reduction of available construction materials and environmental impacts. Since desert sand resources are abundant in arid region of Adrar (Southern Algeria), it would be viable to use desert-sand as an alternative material for the production of self-compacting concrete. Therefore, self-compacting concrete is experiencing significant demand in that arid region since it offers socio-technical and economic solutions to stakeholders in the construction and public works industry. Furthermore, the present study aims to address the concerns of these stakeholders. The results obtained showed that the self-compacting concrete that was made with local materials, behave correctly, both in the fresh and hardened states. This concrete included a 1% super plasticizer dosage, a gravel-to-sand (G/S) ratio varying between 0.8 and 1.1, and additions of limestone fillers up to 50% relative to the mass of cement for self-compacting concrete made with dune sand, while this percentage could go up to 38% for self-compacting concrete made with corrected sand (63% crushed sand with 37% dune sand).