Browsing by Author "Molez, Laurent"

Now showing 1 - 3 of 3

Characterisation and microstructure of high-performance concretes reinforced with metal fibres ripened in seawater
(Taylor & Francis, 2019) Boutiba, Aldjia; Chaid, Rabah; Molez, Laurent
High-performance concretes reinforced with metal fibres (SFRHPC) have multiple advantages when they are used in the marine environment. These materials provide high strengths at the young age that permit faster formwork stripping, resistance to hydrostatic thrusts due to the tides, structural elements sections’ reduction, as well as weight reduction of the structure, and the increase of the abrasion resistance to sand or gravel. The maritime works are exposed to specific seawater aggressions. Seawater contains aggressive salts, which damage the concrete and the steel that it may contain. These salts are mainly chlorides and sulphates. This study investigated the ripening of steel fibre-reinforced high-performance concrete, with 15% substitution of cement by blast furnace slag, in Rance (France’s seawater). This experimental study analysed the effect of 6 and 24 months of ripening of the sample, in aggressive water, on the characterisation of the concrete and the microstructure of the cement’s matrix and its fibres. Also, in this study, after two years of concrete conservation, we carried out the chemical and mineralogical composition of the seawater. The results showed that there is no significant alteration of concrete kept in seawater and the steel fibres were not altered. In other words, it stayed passivated even after two years of ripening
Effect of Slag on the Porosity and Microstructure of HPC Reinforced with Hybrid Steel Fiber
(ISRES Publishing, 2023) Boutiba, Aldjia; Chaid, Rabah; Molez, Laurent
Due to their structural and economic performance, high performance metal fiber concretes are increasingly used in construction, but with the addition of metal fibers, workability decreases as the amount of fibers added increases. In order to improve workability, a larger quantity of fines should be used than for ordinary concrete. The use of granulated slag reduces the amount of clinker needed to make cement. It is considered that granulated slag improves the workability of concrete. According to Manai, this is due to the very low rates of water adsorption by the granulated slag grains at the start of mixing. Also, the addition of granulated slag has a positive effect on the porosity, but also on the microstructure of the hydrates. These two characteristics are factors determining the compressive strength and durability of the cement paste. The aim of this study is to define the effect of blast furnace slag on the porosity and microstructure of high performance fibre-reinforced concrete. The results of SEM and DRX observation of the microstructure of the concrete samples show that the addition of ultra-fine granulated slag resulted in a relative improvement in porosity and microstructure.
Resistant to sulphate attack of high performance fibre concrete with the addition of slag
(Stowarzyszenie Producentow Cementu, 2015) Boutiba, Aldjia; Chaid, Rabah; Molez, Laurent; Jauberthie, Raoul