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In recent years, many community-based conservancies (CBCs) led by non-governmental organizations (NGOs) have been established on land inhabited by pastoralists in Northern Kenya. Despite a growing body of research, little attention has been paid to the impacts on pastoralists’ climate change adaptation. We provide a deeper understanding by considering NGO-led community-based conservation (NGO-led CBC) as a new frontier of territorialization and adaptation to climate change and variability as a social-natural process. Based on an analysis of primary data collected in Samburu County, Kenya, we show that NGO-led CBC involves resource enclosures that aggravate conflicts over land rights and pastoralists’ vulnerability to climate change and variability by constraining their mobility. In relation, the legal and institutional environment promoted by NGO-led CBC leads to increased control over ecologically vibrant lands, which erodes pastoralists’ land tenure security and climate change adaptation. Although NGO-led CBC plays an important role in enhancing access to external finance and incentivizing diversification, governance mechanisms remain opaque and overshadow local institutions. Overall, we highlight the need for actors to carefully consider the implications of this conservation/development model for already hard-pressed land-dependent communities.

Grinding aids (GAs) are polar chemicals introduced in cement mills in either liquid or powder form to improve on mill grindability efficiency. Studies have shown that some GAs not only help in grinding efficiency but also play vital roles in improving the product particle size distribution, product ability to flow in the mill, grinding energy reduction, and improvement on the separator efficiency. This review investigated the impacts of the GAs on the performance of some properties of cement when used as either mortar and/or concrete. The influence of the GAs incorporation in cement grinding on properties such as workability and setting times of the placed concrete and/or mortar has been covered in this review. The performance of GAs on ordinary portland cement (OPC) and blended cements with other supplementary cementitious materials such as pozzolana, fly ash, and slag has also been discussed. This is in view to tapping the maximum benefits of using GAs in cement production and use. This review work established that GAs have a positive influence on mill performance when properly applied. It further established that blended cements work better when dosed with additives such as GAs and/or quality improvers when compared to OPC. The review work demonstrated that some superplasticizers help in lowering the water demand in highly blended pozzolanic-based cements. The review finally recommended that the future course of action in the production of blended cements should apply GAs. This is in order to help produce highly replaced blended cements that are sustainable.

The world’s growing population and industrialization have led to increased construction activities. This has increased the amount of waste aggregates which can be recycled in construction and cut the cost of infrastructure development. This study, therefore, reports the experimental findings for the effect of immobilizing Bacillus megaterium on the compressive strength and water absorption of laboratory prepared test mortar. Bacterial solution used in this work had a concentration of 1.0 × 107 cells/mL. The impact of recycled mortar impregnated with bacteria was studied after curing the specimens in water, saturated lime water, and 1.5% sulfuric acid. Compressive strength for test specimens cured in the three media was determined at the 2nd, 7th, 28th, and 56th day of curing. SEM analysis was done for mortars cured in acidic media and saturated lime water after curing for 28 days. The test results indicated that curing in water and saturated water improved the compressive strength, while the acidic medium lowered it. Recycled mortar is, therefore, an ideal material for immobilizing Bacillus megaterium before introduction into fresh concrete/mortar. The use of recycled mortar is a good strategy to reduce wastes from construction activities, save on the cost of construction materials, and enhance environmental conservation.

This paper reports study findings on the use of Lysinibacillus sphaericus (at 1.0 × 107 cells/ml concentration) to enhance and improve the physicomechanical and chemical properties of blended Ordinary Portland Cement (OPC). Blending was done separately with pulverized fly ash (PFA) and natural pozzolana (volcanic tuff) at substitution levels of 10%, 20%, 30%, 40%, 50%, 60%, and 70%. Mortar prisms of dimensions 40 mm by 40 mm by 160 mm were prepared and cured for the 2nd, 7th, 28th, 56th, and 90th days using Lysinibacillus sphaericus solution as mixing water and curing media. Commercial OPC and PPC mortar prisms cast and cured using distilled water were used as controls. Results showed that prisms treated with bacteria exhibited the highest performance on compressive strength development. Further microstructure analysis of blended cement incorporated with Lysinibacillus sphaericus bacteria showed significant amounts of reacted secondary cementitious materials compared to samples without bacteria. Bacteria presence was also found to reduce water demand during mixing and setting times and exhibited low porosity in relation to samples without bacteria. These results showed that the presence of alkaliphilic bacteria in the blended cement resulted in synergistic effect in enhancing the physicochemical and mechanical properties.

Efforts to reduce pressure on use of wood in particleboard formulation have included the use of non-wood materials such as crop residues. Physical and mechanical properties are determined by the number of the hydroxyl (-OH) groups. Hydroxyl (-OH) groups attracts water molecules through hydrogen bonding affecting water absorption (WA) and thickness swelling (TS). WA and TS affect curing process of adhesive. Curing process of adhesives affects the mechanical characteristics of formulated particleboards. These challenges have been acted upon continuously through research. This review paper presents crop residues used as alternative lignocellulose material source in particleboard formulation and the various advances that have been made to improve on the properties of the resultant particleboards. Improvement over time of the non-wood material in composite materials focusses on increasing water resistance and compatibility between lignocellulose and binder. Crop residues-based are used in making medium and low density particleboards. These boards have shown good mechanical characteristics which include modulus of rupture (MOR), modulus of elasticity (MOE) and internal bonding (IB). MOR, MOE and IB have over time been improved by enhancing chemical compatibility of lignocellulose material and the binders. Water absorption and thickness swelling remain challenge. This review paper further explored various methods of improving water absorption and thickness swelling of crop-residue based particleboards.

Conventional binders in the particleboards formulation involve use of formaldehyde resins. Epidemiologic studies show that formaldehyde is carcinogenic. Efforts to reduce formaldehyde emissions by use of scavengers has not been proven to reduce the emission. Molecular bonding of biobased adhesive molecules with lignocellulose materials provides an alternative way of producing composite material. In this study, maize stalk (MS), rice husks (RH) and sugarcane bagasse (SB) were used as sources of lignocellulose materials for particleboard formulation. SB, MS and RH were collected from their respective sites, sorted and dried. MS and RH were ground. Lignin content determination was done by drying lignocellulose material at 105 °C. Lignocellulose materials were prepared by hydrolysis of dried lignocellulose material with sodium hydroxide. Oxidized starch was prepared by oxidation of cassava peel starch using alkaline hydrogen peroxide. Particleboards were formulated through starch-lignocellulose polymerization at 60 °C compressed with 6.5 Nmm−2 pressure. Characterization of raw materials and formulated particleboards was done using XRD for mineralogical analysis, FTIR and NMR for elucidation of functional groups transformation. The results showed that esterification is the main process of chemical bonding in the particleboard formulation due to reaction between –COOH from starch and and OH- from lignocellulose. Etherification between hydroxyl groups from starch with hydroxyl groups from lignocellulose material. RH combined more through silication process with cassava peels starch than RH and SB showing materials containing high cellulose and hemicellulose content are more compatible. Composite materials formulated were used to produce medium density particleboards that can be used for making furniture and room partitioning.

Most of concrete structural failures are attributed to poor workmanship and poor engineering designs. Some microorganisms present in sewer systems can degrade the concrete and/or mortar. Concrete failures due to microbial attack has not attracted much attention especially in developing countries such as Kenya. This study investigated the effect of Thiobacillus intermedius bacteria on the performance of Ordinary Portland Cement (OPC). Preparation of test mortar prisms was done using the bacterial solution as either mix water, curing water or both. The control mortar prisms were prepared and cured in distilled water. Compressive strength test was done after 7th, 28th, 56th and 90th days of curing respectively. Results showed significant drop in compressive strength for the mortar prisms prepared and cured in bacterial solution as compared to the control mortar samples. Soundness and normal consistency increased significantly for the bacterial treated cement paste as compared to the control sample. Scanning Electron Microscopy (SEM) analysis showed severe damage on the bacterial treated cement mortar. This was characterized by formation of deleterious expansive products like ettringite and gypsum. Control mortar sample exhibited even formation of hydration products within the pore system.

In many countries large deposits of copper with no locally established copper based industries occur because known methods for extraction are prohibitively expensive and unaffordable. This study reports on an affordable and sustainable method for the extraction of copper. This was achieved through the use of a wet chemical method which makes use of hydrazones prepared in situ from chicken dung leached solution. The method involves the reduction of copper (II) ions leached from copper ore to zero valence using chlorine treated solution prepared from chicken droppings at a temperature range of 60–70 °C. The ore samples were pulverized to 250 micro millimetres and leached with hydrochloric acid to obtain leachate containing copper ions. The dissolved copper was reduced to copper metal and obtained by filtration. It was confirmed by XRFS analysis that, the metal purity was found to range between 60 and 80% depending on the ore used. In another experiment, chicken waste solution was used to extract copper from the ore. To the mixture, chlorine gas was then bubbledthrough a glass delivery tube to prepare the hydrazone in situ at a temperature range of 60–70 °C and a pure copper metal was obtained. The findings from this study have shown that there is great potential for the production of copper at low cost and this could be applied in both small-scale cottage industries and large industries using readily available resources such as chicken dung. Keywords: Hydrazones, In situ, Reduction, Zero valence, Chicken dung

Copper is found in several minerals in the earth's crust with varying the elemental and mineralogical composition. Several techniques of extraction have been investigated all in the effort of obtaining a cheaper and viable method. This paper reports on further works done on copper extraction using a wet chemical method. According to the method, reduction of copper (II) ions using hydrazones from chlorinated chicken waste leachate was stoichiometrically driven. The chicken dung leachate used was an impure bio-material in which the concentration could not be determined. It was, therefore, difficult to quantify the stoichiometric ratios of species in that reaction. This paper reports on a method of monitoring the extent of copper reduction by chlorinated chicken dung leachate using an aluminum electrode as an indicator. Mineral rocks were obtained from Maragwa Location in Tharaka Nithi County in Kenya. The samples were ground into a fine powder of 250 micro millimeters. The samples were then subjected to mineralogical analysis using X-ray diffraction (XRD). Chemical analysis was done using atomic absorption spectroscopy (AAS) and X-ray fluorescence spectroscopy (XRFS). Ground samples were leached using 1.0 M hydrochloric acid. The resulting leachate was treated with chicken dung leachate prepared from chicken dung in which chlorine gas was bubbled at a constant temperature of 28 °C. The pH of the resultant chicken dung leachate was adjusted from 4 to 12 using 1.0 M sodium hydroxide and then used as an electrolyte. An electrochemical cell was set up consisting of aluminum and graphite rods. The aluminum electrode was found not to corrode at pH above 11 while it was able to displace available copper ions. This property of the aluminum electrode was used to monitor when all copper ions were displaced. The recovered copper was analyzed using XRFS. The copper recovery rate from the samples ranged from 7.0 to 20.0 at level A and 7.4–26.8% at level B with a purity range of 84.9 level A to 88.6% level B. An overall positive potential in the reduction process confirmed the greater the tendency of copper reduction without an external source of electricity. The corrosion of the aluminium electrode in the process was not observed and therefore does not require frequent replacement. Therefore, a large scale extraction process needs to be investigated.

Formaldehyde-based resins are conventionally used as a binder in formulation of particleboard. Epidemiologic studies have shown that formaldehyde is carcinogenic. Efforts to reduce the health hazard effects of the fomaldehyde-based resin in the particleboard formulation have included use of scavengers for formaldehydes and use of an alternative binder. Use of scavengers for the formaldehyde increases the cost and maintenance of particleboard formulation. There is no proof that scavengers eliminate the emission of formaldehyde from particleboard. Use of biobased binders in particleboard formulation provides an alternative for eliminating use of the formaldehyde-based resin. However, the alternative is hindered by challenges, which include limitations of physical and mechanical properties. The challenge has continuously been acted upon through research. The paper presents an overview of the use of starch as an alternative binder. Improvement over time of the starch and limitations thereof requires to be addressed. Use of the modified starch has shown increased particleboard performance. Mechanical strength, such as modulus of rupture, modulus of elasticity, and internal bonding in particleboards, however, remains to be a challenge.

Conventional methods of making particleboards utilize wood chips. This has resulted in a decrease in the tree cover due to the increase in wood demand. The effect has been climatic change. Wood is bound using phenol formaldehyde resin. Because of the decrease in the forest cover, alternative lignocellulose materials are required. In this study, lignocellulose materials used include sugarcane bagasse, maize stock, and rice husks. The cassava-starch mix with borax was used as a binder in particleboard formulation. The lignin content was determined, and its effect on properties of boards was investigated. The resultant composite material was molded at a pressure of 6.5 N/mm2 and at 30°C. The resultant particleboards had mean densities ranging from 0.604 to 0.611 g/cm3. The modulus of elasticity ranged from 2364.2 N/mm2 to 3329.93 N/mm2, modulus of rupture ranged from 13.55 N/mm2 to 14.83 N/mm2, and internal bonding ranged from 1.613 N/mm2 to 2.370 N/mm2. The performance of the board was dependent on the lignocellulose material used. Fourier transform infrared spectroscopy analysis showed that main chemical bonding in the particleboard resulted from esterification of –COOH from lignocellulose and OH- from starch. The particleboards formulated were found to be of low-density-fibre standard used in a similar manner to the conventional low-density particleboards.