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Abstract: The aim of the present paper was to investigate the efficiency of polyether polyol as shrinkage-reducing admixture on pastes and mortars prepared with calcium sulfoaluminate cement (CSA). CSA was prepared by mixing CSA clinker and re-crystallized gypsum in different proportions. Three types of polyether polyol were added at a dosage of 1.5wt% of CSA when hydrating pure pastes and standard mortars. The engineering properties of mortars (compressive strength, drying shrinkage) and the microstructure of pastes were investigated. The results show that polyol reduces drying shrinkage of CSA-based mortars without affecting the nature of hydrates formed. The effect of polyol mainly depends on its molecular weight. [Copyright &y& Elsevier]

Abstract: The development of cement-based screed unbound to its support is still limited because of the curling that occurs at the corners and perimeter of the screed. This phenomenon is mainly due to the moisture gradient that appears within the thickness of the screed: the upper surface dries and shrinks, whereas lower regions dry less and stay wetter. This paper demonstrates this phenomenon can be mitigated through the use of calcium sulfoaluminate cement instead of ordinary Portland cement. Experiments utilizing an original, specially designed device, show that curling is 3.5 times lower when calcium sulfoaluminate cement is used compared to ordinary Portland cement. The moisture gradient within the thickness of the screed is also lower. A model based on simplified poroelasticity theory describes both fluid transfer and hydro-mechanical coupling. The comparison between experimental and calculated results shows that the model gives a good estimation of the kinetics of the mass loss, and that the numerical simulation is an effective tool to predict curling due to drying. [Copyright &y& Elsevier]

This paper presents four innovative utilizations of calcium sulfoaluminate (CSA) cement:–development of concrete with high early strength: 40 MPa, 6 h after its preparation, and higher than 55 MPa after 24 h,–design of self-leveling screed with limited curling, when unbonded to its support,–design of self-leveling topping mortar presenting the following properties: time of workability higher than 30 min, set within 75 min, and low drying shrinkage (<250μm/m).–glass-fiber-reinforced cement (GFRC) composites that can be demolded 4 h after casting and present high ductility and durability after aging in different weathering conditions. [Copyright &y& Elsevier]

Every year in EU nations, it is estimated that 3 million tonnes of automotive shredder residue (ASR) are generated. Half of the ASR is composed of rubber, textiles and plastics, which can be either transformed into alternative fuel or recycled. The second half, which is landfilled, is incombustible and has not yet been valorized.This waste contains 30% organic matter, as well as inorganic compounds such as quartz, calcite, magnetite, hematite, and anhydrite. It is also very rich in zinc (1–3.5%) and lead (0.7–3.3%). These elements are powerful retarders of ordinary Portland cement. For this reason, two ways of processing of this waste have been investigated: (1) transformation into aggregates after a thermal treatment followed by a chemical treatment or (2) directly into concrete with the use of calcium sulfoaluminate cement.This second way is especially very interesting for engineers and scientists. As established by leaching tests, zinc and lead are integrated and fixed in the structure of ettringite, the main hydration product of calcium sulfoaluminate cement. Therefore, it is possible to produce concrete for some applications including road construction from this currently landfilled “waste” (i.e., the ASR is shown to be useful recyclable material that can be converted into an environmentally friendly “green” concrete). [Copyright &y& Elsevier]

Abstract: Materials with a cement matrix classically present early-age volume variations (shrinkage and/or swelling). This intrinsic early-age behavior strongly influences the length of time the buildings and structures will last because of the micro-cracking and cracking that results from it. One explanation for the macroscopic shrinkage is the presence of pore pressure in the porous medium. In this study, fine modeling of the coupling mechanism behind these internal strains is proposed. The chemical reaction associated with hydration is considered as the main force behind the hydric and mechanical evolutions in an endogenous configuration. Thus, the influence of chemical contraction, porosity, pore-size distribution and pore pressure are central to the study in the light of the numerical and experimental results obtained. A self-leveling layer of mortar of sulfo-aluminous concrete base was used. [Copyright &y& Elsevier]