Substitution of Aggregates in Concrete and Mortar with Coltan Mining Waste: Mechanical, Environmental, and Economic Impact Case Study

The mining process involves drilling and excavation, resulting in the production of waste rock and tailings. The waste materials are then removed and stored in designated areas. This study aims to evaluate the mechanical strength and the environmental and economic impact of using Coltan Mining Waste (CMW) as a substitute for aggregates in concrete and mortar production. To achieve this, the CMW needs to be characterised. The Dreux Gorisse method was primarily used to produce concrete with a strength of 20 MPa at 28 days. The mortars, on the other hand, were formulated according to the NF P 18-452 standard. The environmental impact of using CMW as substitutes for natural aggregates in the production of concrete and mortar was analysed using SimaPro software. The results showed that mortars and concrete made with CMW have comparable compressive strengths to the reference mortar and concrete;reduce the negative impact on ecosystem quality, human health, resources, and climate change. It has also been shown that the substitution of aggregates by CMW reduces the cost of concrete and mortar as a function of the distance from the aggregate footprint.

Impact of Earthquake Action on the Design and Sizing of Jointed Masonry Structures in South Kivu, DRC

This article deals with the investigation of the effects of seismic impacts on the design and dimensioning of structures in South Kivu. The starting point is the observation of an ambivalence that can be observed in the province, namely the non-consideration of seismic action in the study of structures by both professionals and researchers. The main objective of the study is to show the importance of dynamic analysis of structures in South Kivu. It adopts a meta-analytical approach referring to previous researches on South Kivu and proposes an efficient and optimal method. To arrive at the results, we use Eurocode 7 and 8. In addition, we conducted static analysis using the Coulomb method and dynamic analysis using the Mononobe-Okabe method and compared the results. At Nyabibwe, the results showed that we have a deviation of 24.47% for slip stability, 12.038% for overturning stability and 9.677% for stability against punching through a weight wall.

Characterization of Clay Materials and Performance Evaluation of Fired Clay Composites Made for Low-Cost Housing

This study deals with the physico-chemical, mineralogical and geotechnical characterization of alluvial clays from Batchenga in Cameroon with a view to their use as building materials for housing. The alluvial clay (Arg.All) was collected in the locality of Batchenga at the village Natchigal (4˚20'40''N and 11˚37'40''E at 378 m altitude) and was fired between 900˚C and 1100˚C. Characterization was performed by XRD, XRF, DTA/DTG, and firing tests. XRD, XRF, DTA/DTG infrared analysis methods were performed on these clays. The linear shrinkage, mechanical strengths, water absorption, porosity and density were measured on the fired products. The results obtained show that the major oxides are for the Arg.Lat SiO2 (72.13%), Al2O3 (14.1%), Fe2O3 (4.45%) and for the Arg.All: SiO2 (48.91%), Al2O3 (23.79%), Fe2O3 (9.54%). The fired products based on alluvial clay, present the flexural strength of 4.45 MPa at 900˚C and 6.80 MPa at 1100˚C. As for those based on lateritic clay, the flexural strength is 0.53 and 0.76 MPa respectively at 900 and 1100˚C. The porosity is 33.69% at 900˚C and 22.93% at 1100˚C for the alluvial clay and 39.55% at 900˚C and 36.01% for the lateritic clay at 1100˚C. Water absorption is 18% to 11.16% for alluvial clay and 22.43% to 21.16% for lateritic clay at 900˚C and 1100˚C respectively. These results suggest that alluvial clay and its firing products have better physico-chemical, geotechnical and mechanical characteristics regardless of the firing temperature of the manufactured products. The addition of degreaser is recommended to improve the mechanical performance of lateritic clay.

Recovery of Mining Wastes in Building Materials: A Review

The use of materials from waste in buildings compensates for the lack of natural resources, solves the problem of waste management and provides an alternative technique for protection of the environment. There are a large number of industrial wastes that are used for full or partial replacement of raw materials in some construction materials. This review assesses mining waste in concrete as a substitute for aggregates and cement;in fired bricks as a substitute for soil;and in road backfill as a substitute for soil. This paper reviews some mining tailings, mine waste rocks and some slags obtained in the exploitation and/or processing of some ores including iron, gold, lead, phosphate, copper, coal, etc. Different physical properties, mechanical properties, chemical properties, heavy metal content, mineralogic composition, geotechnical properties and environmental properties (leaching test) of the mine wastes were examined. The physical, mechanical and environmental properties of the materials obtained by substitution of raw materials by mine waste were examined and compared to reference materials. Mining waste in cementitious materials offers good compressive strengths, while the porosity of the concrete and/or mortar is a factor influencing its toxicity. As for the waste in fired bricks, fired at a temperature of 900°C or more, it offers convincing compressive and flexural strengths. The few research studies obtained on the use of mining waste in road embankments have shown that mining waste can be used as a sub-base layer and backfill as long as it is not toxic. In addition, several other mining wastes require special attention as substitutes for raw materials in construction materials, such as coltan, cobalt.

Contribution to the Characterization of Lateritic Soils for the Manufacture of Compressed Stabilized Earth Bricks

The aim of this study is to contribute to the mastery of the physical characteristics of lateritic soils in order to improve their use for the manufacture of Compressed Stabilized Earth Bricks (CSEB) in the province of North Kivu in the Democratic Republic of Congo (DRC). The study of the physical characteristics of lateritic soils was carried out. Samples were subjected to experimental identification tests on the physical characteristics (water content, density characteristics, particle size distribution and consistency). The results of the laboratory analysis of soil samples show that the water content varies between 5.4% and 36.99%. The density of the solid grains has an arithmetic mean of 2.5 g/cm3. The apparent density varies from 0.83 to 1.35 g/cm3. As for the dry density, it is in the range of 0.61 to 1.25 g/cm3. These relatively low densities indicate that the material studied has a significant degree of deformability. From the particle size analysis, it appears that the material studied contains an important fraction of fine particles. According to the consistency study, the soils studied are plastic clay as Ap class according to the Central Laboratory for Roads and Bridges (CLRB) geotechnical classification system. The particle size curves of the studied samples are within the preferential range of good soils for the manufacture of CSEB. The points representing the studied samples are within the preferential plasticity range of good soils for the manufacture of CSEB. From the above parameters, it appears that the studied material is well adapted for the manufacture of the Compressed Stabilized Earth Bricks.