Investigation of the Fermentation Mode of Rice Husk for the Stabilization of Earth Plaster

Despite its low resistance to humidity, adobe remains the most widely used material for housing construction, particularly in developing countries. The present study aims to assess different modes of use of fermented RH and to evaluate their influence on the behavior of raw earth for application in plaster. The influences of two types of RH are evaluated: granular rice husk (RHg) and powdered RH (RHp). The clay mainly consists of clay (40%), silt (22%), and sand (38.4%), with a small proportion of gravel (0.24%). Its liquidity limit is 40% and the plasticity index is 26.5%. The mixtures were designed using earth and each of the two rice husks at the volumetric content of 10%, 15% and 20% of the total volume mixed with water 36.5%, 38.5% and 40.3% and fermented for three weeks. Each fermented mixture was added to the soil to form the paste, and 40 × 40 × 160 mm3 test speciments were made for characterization. The results generally show an improvement in the physico-mechanical properties and water resistance of the mortars containing fermented RH, with an optimal content between 10% and 15%. The powdered RH improved the performance of the mortar better than granular RH.

Influence of Heavy Fuel Oil on the Thermo-Physical and Erodibility Properties of Earthen Materials

This study focuses on the use of heavy fuel oil in construction material in Burkina Faso. Its mixture with silty or clayey soil is used as a coating to reinforce the walls of raw earth constructions which are very sensitive to water. The interest of this study is to determine erodibility, water content, while highlighting the influence of the porosity accessible by water on thermal diffusion in construction material containing heavy fuel oil. The heavy fuel oil was mixed with a silty-clayey soil, in different proportions, and water to make bricks samples on which tests were carried out. At the end of the experimental tests, it appears that the water content increases gradually, but not significantly with the addition of heavy fuel oil, which causes a slight increase in the speed of heat propagation through the material with reduced porosity, particularly those containing higher quantities of heavy fuel oil. Conversely, we note a good performance of heavy fuel oil in terms of water resistance properties such as porosity accessible by water and erodibility. This allows us to conclude that the mixture of heavy fuel oil and silty-clayey soil used as a coating material could greatly reduce water infiltration into the walls of housing constructions with raw earthen materials.

Thermomechanical and Hydrous Effect of Heavy Fuel Oil in a Building Material Based on Silty Clayey Soil

This study focuses on the use of heavy fuel oil in construction in Burkina Faso.Mixed with silty and/or clay soil,it is used as a coating to reinforce the walls of raw soil constructions which are very sensitive to water.The interest of this paper is to shed light on the thermomechanical and above all water effects of heavy fuel oil on a sample of silty clayey soil.To achieve this,we used heavy fuel oil added in different proportions to silty clayey soil,to make sample of bricks on which tests were carried out.At the end of the experimental tests carried out on materials made(bricks)with our soil sample,it appears that heavy fuel oil moderately reduces the mechanical resistance of bricks and slightly increases thermal diffusion through them.On the contrary,we note a very good water resistance of the bricks thanks to the heavy fuel oil,in particular their water absorption by capillarity.This confirms that the mixture of heavy fuel oil and a silty-clayey soil used as a coating makes it possible to prevent the infiltration of water into the walls of raw soil constructions.However,its use as a construction material does not guarantee very good mechanical resistance,and slightly increases thermal diffusion.

Analysis of Cropping Practices on Two Irrigated Perimeters of the Volta Blanche Basin with the Use of Shallow Groundwater

This study aims to analyze the development of small-scale irrigation using shallow groundwater in Nahouri province (south-central Burkina Faso). The methodological approach adopted was essentially based firstly on semi-structured surveys with producers who have adopted sump technology and the monitoring of groundwater level using the installed piezometers and secondly on geophysical prospection. Results obtained show that market gardening is mainly a family activity practiced on plots of 0.20 ha with a predominance of pepper cultivation occupying about 75% of cultivated areas. It was also highlighted that this agricultural activity faces several constraints that delay its development. These include: lack of water, land insecurity, small and fragmented farms and difficulty in selling products when they are put on local markets at the very same time as significant price drops. This problem is accentuated by the perishable nature of these market garden products. Despite these limiting factors, there is some satisfaction considering the income earned by farmers, most of whom are able to meet their primary needs. This work made it possible to conclude that even in zones which are not sedimentary formations, it is possible to mobilize groundwater, at a reasonable depth for agricultural purposes, without much effort to practice additional irrigation, knowing that evaporation carries harm to the use of dams.

Hydrogeophysical Characterization of a Fractured Aquifer by Using Cumulative Resistivity Method:Case Study of Obuasi Aquifer(Ghana)

Knowledge of the structure and geometry of aquifers is an important prerequisite when one wishes to sit a borehole.Such knowledge is currently obtained by VES(Vertical Electrical Soundings)whose interpretation is not always unequivocal in the sense that several resistivity models derived from VES can explain the same data set.The present study conducted in Obuasi region in Ghana aims at demonstrating the robustness of“cumulative resistivity”method in the characterization of the geometry of aquifers.The methodology developed consisted firstly in carrying out VES.These measurements were then interpreted using“cumulative resistivity method”.Secondly,drillings are conducted at the VES sites and lithologs established from cuttings were compared to the results from VES interpretation.The study reveals that the investigated aquifer consists of a resistant layer consisting of phyllite over 30-40 m topped by a conductive layer of reddish clay 20-30 m thick.These two layers rest on a lower electrical conductivity formation downward.This description can be considered as a typical alteration profile in a volcano sedimentary context.The results also show that the method is quite precise in half of the cases studied but sometimes it is impossible to get rid of the phenomenon of suppression since several layers are merged into a single layer.

Durability of Lightweight Concrete Using Oil Palm Shell as Aggregates

Oil Palm Shell (OPS) concrete can be used in different fields of construction. To determine more accurately the fields of application, it is important to know and understand the behaviour of OPS concrete over the long term and when it is in aggressive environments. This paper presents the results of studies conducted on the durability of OPS concrete. Water absorption capacity, electrical resistivity and apparent diffusion of chloride ions have been measured on different concrete samples. In addition, the behaviour of OPS concretes to carbonation was studied in an environment rich in carbon dioxide. Results show that OPS concrete has an absorptivity of 0.97 kg/m2·h1/2, an electrical resistivity of 64.37 Ω·m and an apparent diffusion coefficient of chloride ions of 3.84 × 10-12 m2/s after 90 days. All these results of OPS concrete are very close to those of concrete with normal aggregate and other lightweight concrete, which mean OPS concretes have globally good properties with regard to durability.

Hydrogeological Characterization of Continental Terminal and Oligo-Miocene Aquifers in the Tambacounda-Kaffrine Zone(Senegal)

This study aims to make a hydrogeological characterization of the aquifers of the Continental Terminal and the Oligo-Miocene.To do so,an analysis is conducted on the basis of hydrogeological parameters from 172 boreholes,10 of which are used for groundwater levels and flows analysis.The results of the statistical analysis of the hydrogeological parameters show that the average flow rate is 42.29 m^(3)/h,the average specific flow rate is 5.96 m^(3)/h/m,and the average transmissivity is 0.024 m^(2)/s.These values highlight the high productivity of aquifers from the Continental Terminal and the Oligo-Miocene.The results of piezometry showed that water flows from the south center to the northwest of Tambacounda where the largest depression is located and could even be the outlet of the system.The groundwater fluctuations between low water level and high water level seasons reveal a rise in the piezometric surface of the aquifers at the scale of the study area.

The Influence of Metakaolin from Saaba (Burkina Faso) over Physico-Mechanical and Durability Properties of Mortars

The paper evaluates the feasibility of reducing clinker in the Portland Cement production using local metakaolin in Burkina Faso. Standardized testing methods have been used for this purpose, and experiments were performed on mortar prisms containing different amounts of metakaolin. Important results about the physical, mechanical and durability characterization of blended mortars were carried out in this study. The obtained results are discussed based on available literature data. These results have shown increased physical and durability properties for blended mortars. Although the mechanical strengths remained relatively low for higher MK incorporations, the latter grow to surpass these of PC mortars (the reference) at 28, 56 and 90 days of curing. The results in the paper, have confirmed the possibility of using metakaolin to partially substitute cement, a possibility to reduce the CO2 production by the cement industry in Burkina Faso.

Hydrogeochemical and multi-tracer investigations of arsenic-affected aquifers in semi-arid West Africa

The semi-arid Sahel regions ofWest Africa rely heavily on groundwater from shallow to moderately deep (<100 m b.g.l.) crystalline bedrock aquifers for drinking water production.Groundwater quality may be affected by high geogenic arsenic (As) concentrations (>10 μg/L) stemming from the oxidation of sulphide minerals (pyrite,arsenopyrite) in mineralised zones.These aquifers are still little investigated,especially concerning groundwater residence times and the influence of the annual monsoon season on groundwater chemistry.To gain insights on the temporal aspects of As contamination,we have used isotope tracers (noble gases,3H,stable water isotopes (2H,18O)) and performed hydrochemical analyses on groundwater abstracted from tube wells and dug wells in a small study area in southwestern Burkina Faso.Results revealed a great variability in groundwater properties (e.g.redox conditions,As concentrations,water level,residence time) over spatial scales of only a few hundred metres,characteristic of the highly heterogeneous fractured underground.Elevated As levels are found in oxic groundwater of circum-neutral pH and show little relation with any of the measured parameters.Arsenic concentrations are relatively stable over the course of the year,with little effect seen by the monsoon.Groundwater residence time does not seem to have an influence on As concentrations,as elevated As can be found both in groundwater with short (<50 a) and long (>10^3 a) residence times as indicated by 3He/4He ratios spanning three orders of magnitude.These results support the hypothesis that the proximity to mineralised zones is the most crucial factor controlling As concentrations in the observed redox/pH conditions.The existence of very old water portions with residence times >10^3 years already at depths of <50 m b.g.l.is a new finding for the shallow fractured bedrock aquifers of Burkina Faso,suggesting that overexploitation of these relatively low-yielding aquifers may be an issue in the future.

Comparative Study on Geopolymer Binders Based on Two Alkaline Solutions (NaOH and KOH)

This study specifically investigated the influence of the composition of aluminosilicate material i.e. the substitution of metakaolin by rice husk ash and the nature of alkaline activators (Na+/K+) on mineralogical, structural, physical and mechanical properties of geopolymer binders. This influence was evaluated based on X-ray diffraction (XRD), Fourier Transform InfraRed spectroscopy (FTIR) and Scanning Electron Microscope (SEM analyses, apparent density, water accessible porosity, compressive strength and thermal properties. Two types of geopolymer binder were synthesized according to the type of alkali activator used, the NaOH-based geopolymer and the KOH-based geopolymer. The results of characterization performed after 14 days of curing of geopolymer samples showed that the activation of the aluminosilicate powder using alkaline solution led to change in their microstructure. The highest compressive strength was obtained with the NaOH-based geopolymer.

Impact of Smart Valley on Soil Moisture Content and Rice Yield in Some Lowlands in Burkina Faso

To reduce the impact of rainfall variability on lowland rice yields, Burkina Faso state develops lowlands for small rice farmers. However, the high cost of these infrastructures makes impossible to duplicate them to satisfy the needs which are enormous. The Smart-Valley technology which is actually popularized in certain coastal countries of West Africa would therefore be a boon to increase the productivity of the Sudanese lowlands if it well regulates runoff. The object of this study was therefore to know if smart valley technology could increase soil moisture in order to mitigate the impact of drought’s pockets on rice cultivation in the Sudanese lowlands. The experiment takes place in three lowlands during the rainy seasons 2018 and 2019. The climatic data comes from the meteorological stations in the study areas as well as those installed on the sites. The infiltration measurements were carried out using the double Muntz ring. The soil moisture measurement device consisted of a smart valley area of 5 ha and an undeveloped area of 5 ha per site. Sixteen tubes were installed per lowland allowing the humidity to be measured at a depth of 10, 20, 30, 40 cm using a probe. Four rice varieties, Orylux6, FKR62N, FKR19 and FKR64 were tested on plots of 0.25 ha per variety in the smart valley and undeveloped parts. The results showed that the humidity level was 12% higher in the smart-valley plots throughout the cycle compared to the unmanaged area. In addition, humidity decreases rapidly in unmanaged plots as rain becomes increasingly scarce. Finally, the smart-valley development allowed an average increase in rice yields of 21% compared to the average yield of undeveloped plots.

Assessment of the Effectiveness of Potassium Polyacrylate on Crop Production

Water control is a major problem in crop production, particularly in fragile ecosystems such as the Sahel. Water is the most important factor in plant productivity. Many initiatives have been developed in this direction, including all methods of irrigation and water and soil conservation. The objective of this work is to assess the effectiveness of this amendment in crop production in the context of climate variability. The methodology is based on experimentation to statistically compare the natural biomass on a soil of silty-clay-sandy texture, divided into two blocks, one of which is amended with potassium polyacrylate and the other is not. This study showed that the wet and dry biomasses produced on soils with potassium polyacrylate are significantly higher than those produced on unamended soils at the 5% threshold. Based on these results, potassium polyacrylate may be a solution to recurrent dryness pockets. However, uncontrolled environmental testing is necessary to confirm these results.

Comparative Study of the Reactivity of Clay Earth Materials for the Production of Compressed Earth Blocks in Ambient Conditions: Effect on Their Physico-Mechanical Performances

This study assesses the reactivity of four (04) different types of clayey earthen materials (Kamboinsé, Pabré, Saaba, and Kossodo) with Ca(OH)2, analytical lime (AL) versus lime residu (LR), in ambient conditions. The effect of the stabilization of the earth with the LR was also studied on the performances of compressed earth blocks (CEB). The lime content varied from 0% to 20% with respect to the mass of dry earth material. The analysis of the reactivity and physico-mechanical properties were respectively carried out on the solutions of the mixtures (earth + LR and earth + AL) and CEB (earth + LR). The mixtures were cured between 0 and 60 days at the ambient temperature of laboratory (30℃ ± 5℃). The results showed that the reactivity of the clayey earth materials with AL is comparable to that with the LR. At the same time, this reactivity improved the physical and mechanical properties of stabilized CEB depending on the type of earth material, lime content and curing time. The maximum values of the dry compressive strength, observed for each material stabilized with 20% LR, are 6 and 7 MPa (Kamboinsé), 8.8 and 9.3 MPa (Pabré), 6 and 6.5 MPa (Saaba), 8.8 and 9.7 MPa (Kossodo) respectively at curing time of 28 and 45 days. The structural efficiency of CEB was also improved which implies that, in the current conditions, the stabilization of earth materials using LR allows to produce the CEB for potential applications in wall masonry.