Eggshell and Walnut Shell in Unburnt Clay Blocks

Agricultural residues/by-products have become a popular choice for the manufacturing of building materials due to their cost-effectiveness and environmental friendliness, making them a viable option for achieving sustainability in the construction sector. This study addresses the utilisation of two agro-wastes, i.e., eggshell and walnut shell, in the manufacture of unburnt clay blocks. The experiments were carried out on three series of samples in which first eggshell (10–50%) and walnut shell (5–20%) were incorporated individually and then combined (5% walnut, 10–30% eggshell) in the mixture to assess their influences on the physical and mechanical properties of the unburnt clay blocks. This study performed the following tests: Density, capillary water absorption, linear shrinkage, flexural and compressive strength. The results indicated that eggshell enhanced the strength relative to the control sample when the materials were employed individually, but walnut shell lowered it. Moreover, combining the two materials in the mixer reduced the strength of the samples even further. Nevertheless, the inclusion of the waste materials decreased the density, capillary water absorption coefficient and linear shrinkage of the samples. The findings indicate that eggshell has great potential for unburnt clay block manufacture. However, walnut shell integration needs further research

Thermophysical Properties of Sawdust and Coconut Coir Dust Incorporated Unfired Clay Blocks

Sawdust and coconut coir dust are agro-wastes/by-products which are suitable for use as raw materials to manufacture unfired clay blocks due to their excellent physical and mechanical properties. A limited number of studies have been conducted on the utilisation of these agro-wastes in clay block production, and they have mostly been devoted to investigating the physicomechanical properties, with less attention given to the thermal properties. Moreover, the majority of the studies have used chemical binders (cement and lime) in combination with agro-waste, thus increasing the carbon footprint and embodied energy of the samples. Furthermore, no research has been performed on the thermal performance of these agro-wastes when incorporated into clay blocks at the wall scale. Therefore, to address these limitations, the present study developed unfired clay blocks incorporating sawdust and coconut coir dust (0, 2.5, 5, and 7.5% by weight), without the use of chemical binders, and evaluated their thermal performance, both at the individual and wall scales. The experiments were divided into two phases. In the first phase, individual sample blocks was tested for basic thermal properties. Based on the results of the first phase, small walls with dimensions of 310 mm × 215 mm × 100 mm were built in the second phase, using the best performing mixture from each waste type, and these were assessed for thermal performance using an adapted hot box method. The thermal performance of the walls was evaluated by measuring the heat transfer rate from hot to cold environments and comparing the results to the reference wall. The results showed that thermal conductivity decreased from 0.36 W/mK for the reference sample, to 0.19 W/mK for the 7.5% coconut coir dust sample, and 0.21 W/mK for the 7.5% sawdust sample, indicating an improvement in thermal insulation. Furthermore, the coconut coir dust and sawdust sample walls showed a thermal resistance improvement of around 48% and 35%, respectively, over the reference sample wall. Consequently, the findings of this study will provide additional essential information that will help in assessing the prospective applications of sawdust and coconut coir dust as the insulating material for manufacturing unfired clay blocks

Influence of Sawdust Particle Sizes on the Physico-Mechanical Properties of Unfired Clay Blocks

Sawdust, which is a waste/by-product of the wood/timber industry, can be utilised as a valuable raw material in building material production due to its abundance and low cost. However, the application of sawdust in the manufacture of unfired clay blocks has received little investigation. Furthermore, the impact of different sawdust particle sizes on the properties of unfired clay blocks has not been studied. Therefore, this study screened sawdust at three different particle sizes: SP-a (212 μm < x < 300 μm), SP-b (425 μm < x < 600 μm) and SP-c (1.18 mm < x < 2.00 mm), to examine their effects on the physical and mechanical properties of unfired clay blocks. The density, linear shrinkage, capillary water absorption and flexural and compressive strengths were among the tests performed. Different sawdust percentages, i.e., 2.5%, 5%, 7.5% and 10% of the total weight of the clay, were considered. The tests results show that when sawdust was added to the mixture, the density of the samples reduced for all particle sizes. However, the linear shrinkage increased in SP-a samples but decreased in the other two particle size samples as the sawdust percentage increased from 2.5% to 10%. On the other hand, the capillary water absorption coefficient increased while the strength decreased with increasing sawdust content for all three groups. The highest compressive strength (CS) and flexural strength (FS) were achieved at 2.5% of sawdust content. Furthermore, it was observed that SP-b (CS—4.74 MPa, FS—2.00 MPa) samples showed the highest strength followed by SP-a (CS—4.09 MPa, FS—1.69 MPa) and SP-c (CS—3.90 MPa, FS—1.63 MPa) samples. Consequently, good-quality unfired clay blocks can be manufactured using sawdust up to 2.5% with particle sizes ranging between 600 and 425 μm

Influences of Agro-wastes on the Physico-mechanical and Durability Properties of Unfired Clay Blocks

The increasing demand for construction materials along with the challenge of waste management has necessitated the development of sustainable materials utilising wastes properly. Therefore, this research examines the utilisation of various agricultural wastes, such as Eggshell Powder (ESP), Sawdust Powder (SDP) and Coconut Husk Powder (CHP), in the production of unfired clay blocks. Samples were made with various percentages of wastes: 10–50% of dry wt. of clay for ESP and 2.5–10% for SDP and CHP. In this study, the physico-mechanical and durability properties of unfired clay blocks were investigated by conducting density, linear shrinkage, capillary water absorption, flexural strength, compressive strength, ultrasonic pulse velocity test, drip test and water spray test. The tests were carried out in two phases, with the first phase including the individual integration of waste in the mixture and the second phase combining ESP (10–30%) with the optimum SDP (2.5%) and CHP (2.5%). The test results show that when the additives were used individually, the 40% ESP samples performed the best whereas for SDP and CHP 2.5% content showed better performance. Contrarily, the samples' overall characteristics deteriorated when ESP, SDP, and CHP were used together. Nevertheless, all the samples met the strength requirement of the standards and passed the durability tests. The results of this study might be useful in assessing the potential of ESP, SDP and CHP for the production of unfired clay blocks as well as finding a feasible solution to the waste management problem

Diversity of anopheline species and their <it>Plasmodium</it> infection status in rural Bandarban, Bangladesh

<p>Abstract</p> <p>Background</p> <p>Historically, the Chittagong Hill Tracts (CHT) of Bangladesh was considered hyperendemic for malaria. To better understand the contemporary malaria epidemiology and to develop new and innovative control strategies, comprehensive epidemiologic studies are ongoing in two endemic unions of Bandarban district of CHT. Within these studies entomological surveillance has been undertaken to study the role of the existing anopheline species involved in the malaria transmission cycle throughout the year.</p> <p>Methods</p> <p>CDC miniature light traps were deployed to collect anopheline mosquitoes from the sleeping room of the selected houses each month in a single union (Kuhalong). Molecular identification was carried out for available <it>Anopheles</it> species complexes. Circumsporozoite proteins (CSP) for <it>Plasmodium falciparum</it>, <it>Plasmodium vivax</it>-210 (Pv-210) and <it>Plasmodium vivax</it>-247(Pv-247) were detected by Enzyme-linked immunosorbent assay (ELISA) from the female anopheline mosquitoes. To confirm CSP-ELISA results, polymerase chain reaction (PCR) was also performed.</p> <p>Results</p> <p>A total of 2,837 anopheline mosquitoes, of which 2,576 were female, belonging to 20 species were collected from July 2009 -June 2010. <it>Anopheles jeyporiensis</it> was the most abundant species (18.9%), followed by <it>An. vagus</it> (16.8%) and <it>An. kochi</it> (14.4%). ELISA was performed on 2,467 female mosquitoes of 19 species. 15 (0.6%) female anophelines belonging to eight species were found to be positive for <it>Plasmodium</it> infection by CSP-ELISA. Of those, 11 (0.4%) mosquitoes were positive for <it>P. falciparum</it> and four (0.2%) for Pv-210. No mosquito was found positive for Pv-247. <it>An. maculatus</it> (2.1%, 2/97) had the highest infection rate followed by <it>An. umbrosus</it> (1.7%, 2/115) and <it>An. barbirostris</it> (1.1%, 2/186). Other infected species were <it>An. nigerrimus</it>, <it>An. nivipes, An. jeyporiensis</it>, <it>An. kochi</it>, and <it>An. vagus</it>. Out of 11 <it>P. falciparum</it> CSP positive samples, seven turned out to be positive by PCR. None of the samples positive for Pv-210 was positive by PCR. In terms of abundance and incrimination, the results suggest that <it>An. maculatus</it>, <it>An. jeyporiensis</it> and <it>An. nivipes</it> play important roles in malaria transmission in Kuhalong.</p> <p>Conclusion</p> <p>The findings of this study suggest that even in the presence of an insecticide impregnated bed-net intervention, a number of <it>Anopheles</it> species still play a role in the transmission of malaria. Further investigations are required to reveal the detailed biology and insecticide resistance patterns of the vector mosquito species in endemic areas in Bangladesh in order to assist with the planning and implementation of improved malaria control strategies.</p