An investigation on the suitability of hydrated building lime from travertine limestone outcrop of Bogongo, South West of Cameroon

peer reviewedIn the present study, physico-chemical investigations were carried out on hydrated lime produced from the limestone of the travertine outcrop of Bogongo in the South West Region of Cameroon. The aim was to evaluate the suitability of that hydrated lime as building lime. The raw material was characterized and then fired at 900 °C. The fired product was hydrated, dried and also characterized. Chemical and mineralogical analyses, density, BET specific surface measurements and thermal analyses were performed. Results were compared to those for an EN 459-1 CL 90-S industrial commercial hydrated lime. It has been shown that, hydrated lime production using the raw material from the Bogongo travertine could yield products with almost similar physico-chemical properties compared to imported CL 90 S hydrated lime, thus could have positive consequence in the commercial exploitation of the Bogongo travertine limestone outcrop.11. Sustainable cities and communitie

Comparative Study of Reinforced Concrete Design Norms (BAEL 91, BS8110 and Eurocode 2) on the Design of a two Span Beam in Cameroon

This research compares the beam longitudinal reinforcement areas required by different international design norms or design provisions that deals with the design of reinforced concrete structures namely the French norms: Bétons Armée aux Etats Limites’ (BAEL) 91 revised in 99, the British standards BS8110 and the Eurocode 2(EC2) as used with the Frech national annex ( NF EN 1992-1) and the British national annex (BS EN 1992-1).  The aim of this research was to determine which code or norms provides the most safe and economical design in Cameroon. From the literature, the study first gathered information on the design criteria and beam analysis from the different international norms as well as on the properties of steel reinforcement bars and concrete. The study adopted a continuous beam of 2 spans for the design. Concrete grade 20/25 and 12mm diameter bars were chosen. The yield strength of reinforcing steel, the density of reinforced concrete and the effective depth (d) depended on the requirements of each code. The area of tensile reinforcement obtained by EC2 (both France and Britain National annex) is smaller than that of BAEL 91 and BS8110 at support and at spans as well. This shows that Eurocode 2 results in more economical areas of reinforcement steel bars than when designing with BAEL 91 or BS8110.  Since Eurocode 2 results in smaller required steel reinforcement areas, this decreases the steel reinforcing bars congestion in a structural member. The BEAL91 has the highest required steel reinforcement area due to its lower yield strength amongst all the other codes under study. The study recommends that Cameroon should as a matter of urgency draw up her national annex and starts the full implementation of Eurocode 2 in order to enjoy its manifold benefits

An investigation on the suitability of hydrated building lime from travertine limestone outcrop of Bogongo, South West of Cameroon

peer reviewedIn the present study, physico-chemical investigations were carried out on hydrated lime produced from the limestone of the travertine outcrop of Bogongo in the South West Region of Cameroon. The aim was to evaluate the suitability of that hydrated lime as building lime. The raw material was characterized and then fired at 900 °C. The fired product was hydrated, dried and also characterized. Chemical and mineralogical analyses, density, BET specific surface measurements and thermal analyses were performed. Results were compared to those for an EN 459-1 CL 90-S industrial commercial hydrated lime. It has been shown that, hydrated lime production using the raw material from the Bogongo travertine could yield products with almost similar physico-chemical properties compared to imported CL 90 S hydrated lime, thus could have positive consequence in the commercial exploitation of the Bogongo travertine limestone outcrop.11. Sustainable cities and communitie

Substitution of sodium silicate with rice husk ash-NaOH solution in metakaolin based geopolymer cement concerning reduction in global warming

Rice husk ash (RHA), a by-product from the rice industry, was used as principal source of amorphous silica for the production of sodium silicate solution (MR ∼ 3) used for the replacement of standard commercial sodium silicate in the mix-design of metakaolin based geopolymer composites. Three initial concentrations of NaOH were considered (8, 10 and 12 M) with the aim to investigate on the optimum dissolution and formation of silica oligomers capable to act as binder during the geopolymerization. Results (FT-IR and XRD) showed that RHA-NaOH sodium silicate solutions have characteristics similar to that of standard commercial sodium silicate and the residual carbonates present in the viscous pastes can be monitored during the preparation of geopolymers using the mix-design. Combined 25 vol% standard sodium silicate solution with ∼75 vol% of RHA-NaOH based sodium silicate solution conducted to good polycondensation, densification, high flexural strength (∼8 MPa) and low porosity similar to that of the standard matrix of metakaolin based composites. The new approach is found promising for the significant reduction of the Global Warming Potential of Geopolymers

Potential of Some Granites from Foumban (West Region of Cameroon) as Fluxing Materials for Ceramics

peer reviewedThis study focuses on the mineralogical, geochemical and petrographic characterization of three granite rock samples (LTP, LTS and LTMB) from Foumban, West Region of Cameroon. Fusibility tests were carried out on the samples containing the highest amount of alkali to assess the potential of these materials as fluxing admixture for ceramics. The results show that the granite consists of alkaline feldspars, notably orthoclase and microcline of perthitic micro-texture, plagioclases (in particular albite) and also mafic minerals such as amphibole and pyroxene. The quantity of alkali in the samples is quite high (16.83% for LTS, 17.08% for LTMB and 18.87% for LTP) compared to standard data. Fusibility tests carried out on the samples having the highest alkali content (LTMB and LTP) showed that the vitreous phase appears between 1050˚C and 1100˚C in these samples when they were heated. The Fe2O3 and TiO2 content of LTMB (3.01% and 1.49% respectively) led to a brown colour of its fired product. Therefore, based on their composition, these materials can be used as feldspathic fluxes for the formulation of ceramic products.11. Sustainable cities and communitie

The viability of calcined clays and volcanic scoria from western Cameroon as Supplementary Cementitious Material (SCM)

peer reviewedIn order to promote the use of calcined clays and volcanic scoria from the western Cameroon as Supplementary Cementitious Material (SCM), the physical, chemical and mechanical properties of fresh and hardened cements were investigated. The cement was formulated by substituting 10, 20, 30, and 40% of clinker by calcined clays from Mayouom (Mkm) and Balengou (MKb), and volcanic scoria from Foumbot (PNf). For each of the three raw materials, the loss on ignition is less 1%, the sum %SiO2 + %Al2O3 + %Fe2O3 is greater than 70%, amorphous phase is present and pozzolanic reactivity with the Chappelle test is greater than 80% of Ca(OH)2 consumed. This makes it possible to classify MKm, MKb and PNf among the pozzolanic materials. The addition of calcined clay to the clinker, result to an increase in the water to cement ratio, unlike the Foumbot pozzolan, which does not really affect this ratio. The three raw material act as setting retarders, with PNf having a greater retarding effect than MKm and MKb. The compressive strengths of the cements formulated in this study shows that with 10% clinker substitution, cements of class 42.5 can be obtained, and that from 20% onwards, the cements obtained are of class 32.5. However, an addition of more than 20% PNf in the clinker produces cements with strength less than 30 MPa at 28 days. Calcined clay from Balengou and Mayouom could be used as a viable alternate source of SCM for cement production with better performances compared to volcanic scoria from Foumbot