Slag valorization from electric arc furnaces in concrete paver formulation

Slag is produced in enormous amounts by steelworks, which are scrap metal recycling industries that produce steel wire rods and steel reinforcing bars. In the absence of a sustainable recovery route, the latter pose a possible environmental risk. This work is concerned with the valorization of this by-product in the production of concrete pavers. To accomplish so, the slag was previously evaluated using X-ray fluorescence, particle size analysis, density, absorption coefficient, and other criteria that are recommended for usage in this field. The pavers were then manufactured using the Dreux Gorisse recipe, with slag substituting the gravel. The results demonstrate that the slag is rich in iron, which is characterized by lime, silica, and magnesia rates of 31.73%, 16.33%, and 16.33%, respectively, low percentages of manganese and alumina. The water absorption rate is between 2.6% and 2.8%, and their density is similar to 3.6 kg/l. Los Angeles has a 20-coefficient. As a result of their inclusion in the design of the pavers, they were able to split in line with the NF EN 1338 standard and retained a reasonable degree of tensile strength

Coupled effect of elevated thermal exposure and nanochannel confined water on the phase transformations and mechanical changes in calcium silicate hydrates paste

International audienc

Influence of the physical and chemical characteristics of sediment fillers on the properties of mastic asphalt

International audienceThis study aims to optimize the integration of dredged sediments as fillers in formulations of hydrocarbon materials such as “mastic asphalt” for sealing applications. River sediments were collected from the Hauts de France region are the following ones: Aire sur la Lys (ASL), Urban Community of Arras (ARS), European Metropolis of Lille (MEL), and Noyelles sous Lens (NSL) to identify the impact of integrating them in asphalt formulations. Pure asphalt mortars were formulated (AP1) according to the specifications. Asphalt based on limestone fillers have achieved mechanical performance set by the standards. It can be seen that MEL and NSL sediments have a limited use because of their high organic matter content and their high rate of Intergranular voids (RV), which leads to overconsumption of Bitumen. However the calcination of these sediments at 550 °C can remove the organic matter and give a better improvement in physical and mechanical performance than the quicklime treatment. Asphalt-based calcined sediment at 550 °C (NSLC) has been shown to deliver up to 80% improvements in the mechanical performance in comparison to the raw sediment mix. In addition, the use of a soft grade of Bitumen gave impressive benefits with the sediment fillers which can reach up to 23% substitution and reducing the quantity of Bitumen up to 19%. © 2023 Elsevier B.V

Formulation of Compressed Earth Blocks Stabilized by Glass Waste Activated with NaOH Solution

Due to the increase in demand for building materials and their high prices in most developing countries, many researchers are trying to recycle waste for use as secondary raw materials. The aim of this study is the optimization of a mixture of compressed earth blocks based on two sediments. These sediments were tested through the Vicat test to determine the proportion of each one and the optimal water content. The mixtures were treated by adding 10% of blast furnace slag and different proportions of dissolved glass in a NaOH solution. The results indicated that the mixture of 70% Oran sediments with 30% Sidi Lakhdar sediments treated with 4% glass waste produced a CEB (compressed earth block) with high compressive strength with low porosity. In addition, formulated CEBs have a very good resistance to water immersion

A comparative study of natural Tunisian clay types in the formulation of compacted earth blocks

This study investigates the physico-chemical, mineralogical and thermal characteristics of three natural Tunisian clays collected from Gafsa (A1), Zeramdine (A2) and Nabeul (A3). The aim was to promote an appropriate formulation of materials and to obtain optimal compacted earth blocks (CEB). Results of mineralogical analysis of clays revealed the dominance of kaolinite (>13.58%), illite (>25.7%), quartz (>18%) and a minor fraction of smectite phases. Chemical analysis of the clays major elements showed a SiO2 content exceeding 50% and a percentage of Al2O3 higher than 18%. Particle size distribution showed that clay fractions varied from 10 to 20%. Plasticity index defined a plastic character while the values of specific surface area were around 60 m2/g. This discrepancy has an effect on the behavior of these clays in CEB, notably their mechanical properties. From this characterization, it appears that all the sampled clays are suitable as raw material for CEB application. The prepared CEB formulations varied according to compaction energy and binder dosages. In this work, lime served as a binder at different rates (4, 6, 8 and 10%) to ameliorate the quality of CEB. Unconfined Compressive Strength values were determined by Static method test. Then bulk density, shrinkage and porosity values of samples were determined. Compressive strength could reach 7 MPa with lime supplementation in sample A1. The static compaction onto the sand-clay mixture achieved a value of density superior to 2 g cm−3 with lime supplementation in sample A1. Overall, the Gafsa clay was the most suitable for CEB preparation. Also, lime improved the compressive strength of the matrix, in addition to its ecological merits. © 2019 Elsevier Lt

Formulation of mortars based on thermally treated sediments

International audienc

Study of the polymer mortar based on dredged sediments and epoxy resin: Effect of the sediments on the behavior of the polymer mortar

International audienceSeveral studies have shown the potential of upgrading sediments in the civil engineering field. However, the complexity of sediments represents a scientific challenge in terms of their management. This study presents the river sediments recovery in a thermosetting matrix. The characterization results epoxy mortars show the feasibility of incorporating dredged sediments up to 50% substitution rate of natural sand. Moreover, according to the physic, mechanical, thermal and chemical evaluations of the thermosetting matrices, it appears that the performances depend on the factors of the rate of resin and the rate of sediments used. Indeed, the difference between the performances of resin mortars containing sediments and mortars without sediments is reduced by a resin content equal to 18%. In comparison with cementitious matrix mortars, the performances of polymeric mortars are well above. Finally, the SEM observations of different formulations made it possible to explain the results observed at the macroscopic scale. © 2019 Elsevier B.V

Effect of basalt fiber inclusion on the mechanical properties and microstructure of cement-solidified kaolinite

The polypropylene fibers, which are currently attracting enormous attention in various geotechnical applications, carry a risk of aging under an integrated effect of heat, oxygen, light and other environmental factors, causing potentially infrastructure failure. An eco-friendly and biologically inactive material – basalt fiber, which has excellent natural resistance to aging and can eliminate aging-associated disasters, deserves more attention in geotechnical field. However, quite few studies are available on the beneficial reuse of basalt fibers to improve the engineering performance of soils. Therefore, this study aims to incorporate the sustainable basalt fiber and clarify how its inclusion impacts the mechanical properties and microstructure of cemented kaolinite. The experimental programs are comprised of three types of tests, i.e. two to examine the compressive strength and triaxial shear behavior and one to evaluate the microstructure properties. The results indicate that the basalt fiber reinforcement plays an essential role in enhancing the compressive strength and peak deviatoric stress of cemented and uncemented kaolinite. The inclusion of basalt fibers improves the ductility and weakens the brittleness of cemented kaolinite. The compressive strength increases with basalt fiber content and curing time, and reaches the peak at the fiber content of 0.2%, followed by a reduction due to the formation of weak zone at higher fiber content. The peak deviatoric stress is elevated until reaching the maximum at the basalt fiber content of 0.4%, after which further addition of basalt fiber tends to reduce its reinforcing effect. The peak deviatoric stress increases as the basalt fiber length is shortened and the confining pressure is raised. The strength gain of cement-basalt fiber inclusion is much more than the sum of strength increase induced by them individually. The combination of basalt fiber and cement has the virtues of both cement-stabilized and basalt fiber-reinforced kaolinite. The SEM analysis reveals that the mechanical interaction in the form of interface bonding and friction between kaolinite particle, cement hydration product and basalt fiber is the dominant mechanism controlling the reinforcement-cementation benefits. The bridging effect (reinforcement) of basalt fibers and binding effect (cementation) of hydration products make a major contribution to the formation of stable and interconnected microstructure, which results in an evident improvement in the mechanical behaviour of cemented kaolinite. The combination of basalt fiber and cement stabilization would be an innovative and effective method for geotechnical engineering works such as soft ground improvement. © 2020 Elsevier Lt