Engineered soil and the need for lime-natural pozzolan mixture percentage approximation

The topic, engineered soil and the need for lime-natural pozzolan mixture percentage approximation is tried to be realized with the basic objective of initiating the identification of the percentage range for lime-natural pozzolan amender mixture approximation as in lime fixation for soil stabilization. The so far accomplished research sources were taken as bases of conceptual formulation. Amending of soil by using CaCO3 and the abundantly available local natural pozzolan showed a success to develop a wall making input for rural housing development. In due course, arriving at an approximate percentage fixation remained a challenge because of the lengthy time required for laboratory material characterization and the cost incurred. In here, though for a specific soil type, a possible method of range approximation is suggested based on: pre-initial lime consumption, initial lime consumption, optimum lime-natural pozzolan consumption and post-optimum lime-natural pozzolan consumption. The outcome indicated the rough range of 4.5% to 9.5% for lime-natural pozzolan mixture application as shown in the omc and mdd vs. amender percentage line graph; reflecting a possible answer to the stated objective

Enabling equitable collective action and policy change for poverty reduction and improved natural resource management in the Eastern African highlands:

"The role of local and external institutions in natural resource management (NRM) is gaining attention in the literature, fostering greater understanding of the relationship between collective action and poverty, collective action and equity, and the conditions under which collective action institutions take root. It has also led to increased understanding of how uncritical practices by external development institutions can propagate social inequities in NRM. Yet little research has been conducted to understand how to foster local collective action institutions where they are absent, or to improve institutional practice. This research integrates empirical and action research in an effort to generate ‘working solutions' to problems facing rural communities in their efforts to manage their natural resources in the highlands of Ethiopia and Uganda. Following a brief introduction to the literature and the research, findings are presented according to two distinct phases of research. Data are first presented on existing forms of collective action, the influence of local and external institutions on economic development, and NRM problems that persist despite their negative livelihood consequences. Action research themes selected from a list of identified problems are then presented in greater detail, with lessons learnt thus far in attempting to overcome institutional barriers to improved NRM. The paper concludes with a discussion of the implications of findings for research, institutional practice, and policy." authors' abstractNatural resource management, Collective action, Equity, Livelihoods, East African highlands, Gender, Environmental management,

Hydration and carbonation reaction competition and the effect on the strength of under shed air dried Amended Compressed Earth Blocks (ACEBs)

A research finding on amended soils for the production of blocks  and mortar with lime and natural pozzolan for earthen construction was reported in the EEA Journal of 2019. The use of the amenders was to take advantage of the binding property of lime and the low reactive behavior of natural pozzolans without any further energy demanding additional treatment. In the attempt, it was learned that the existence of hydration and carbonation reactions which are the driving engines of the whole formation are competing with each other at early age of curing. The effect of this phenomenon is that it might upset the maximum/optimum stabilizing effect that could be fully achieved. Furthermore, since the proposed method was defined for air dried curing but only under shed environment; it came to mind that such a challenge needs to be addressed before embarking on an industrial scale. Thus, the main objective of this research is to investigate the effect of hydration and carbonation reaction competitions on air dried blocks in lieu of those cured under the influence of moisture to make a decision on their ultimate use. In order to understand the existence of the reactions’ competition various curing mediums were experimented upon and a comparison is made to figure out the weakness of the air dried blocks and those matured at six more environments. From the finding, it is concluded that, among the contending curing conditions as for the purpose of this research, both under shed air drying and a plastic cover moist curing for 14 days and a subsequent 14 days air dry curing under the ambient lab environment (totaling 28 days) could equally be used as  convenient. It is also confirmed that, the proposed curing of ACEBs under shed within an air dry condition is a well suited proposition for the practice; since the competition doesn’t seem to affect its anticipated performance; per the finding

Embodied energy and CO2 emissions of widely used building materials : The Ethiopian context

Buildings use a wide range of construction materials, and the manufacturing of each material consumes energy and emits CO2. Several studies have already been conducted to evaluate the embodied energy and the related CO2 emissions of building materials, which are mainly based on case studies from developed countries. There is a considerable gap in cases of developing countries regarding assessment of embodied energy and CO2 emissions of these building materials. This study identified the top five most used construction materials (cement, sand, coarse aggregates, hollow concrete blocks, and reinforcement bars), which are also prime sources of waste generation during construction in the Ethiopian building construction sector. Then, what followed was the evaluation of the embodied energies and CO2 emissions of these materials by examining five commercial and public buildings within the cradle-to-site lifecycle boundary. The evaluation results demonstrated that cement, hollow concrete blocks (HCB), and reinforcement bars (rebars) are the major consumers of energy and major CO2 emitters. Cumulatively, they were responsible for 94% of the embodied energy and 98% of the CO2 emissions. The waste part of the construction materials has inflated the embodied energy and the subsequent CO2 emissions considerably. The study also recommended several strategies for the reduction of embodied energy and the related CO2 emissions. The research delivers critical insights into embodied energy and CO2 emissions of the five most used building materials in the Ethiopian construction industry, as there are no prior studies on this theme. This might be a cause to arouse awareness and interest among the policy makers and the wider public to clearly understand the importance of research on this crucial issue to develop national energy and CO2 descriptors for construction materials, in order to take care of our naturally endowed, but yet fragile, human habitat.Peer reviewe

Artificial intelligence for prediction of physical and mechanical properties of stabilized soil for affordable housing

Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Soil stabilization is the alteration of physicomechanical properties of soils to meet specific engineering requirements of problematic soils. Laboratory examination of soils is well recognized as appropriate for examining the engineering properties of stabilized soils; however, they are labor-intensive, time-consuming, and expensive. In this work, four artificial intelligence based models (OMC-EM, MDD-EM, UCS-EM+, and UCS-EM−) to predict the optimum moisture content (OMC), maximum dry density (MDD), and unconfined compressive strength (UCS) are developed. Experimental data covering a wide range of stabilized soils were collected from previously published works. The OMC-EM, MDD-EM, and UCS-EM− models employed seven features that describe the proportion and types of stabilized soils, Atterberg limits, and classification groups of soils. The UCS-EM+ model, besides the seven features, employs two more features describing the compaction properties (OMC and MDD). An optimizable ensemble method is used to fit the data. The model evaluation confirms that the developed three models (OMC-EM, MDD-EM, and UCS-EM+) perform reasonably well. The weak performance of UCS-EM− model validates that the features OMC and MDD have substantial significance in predicting the UCS. The performance comparison of all the developed ensemble models with the artificial neural network ones confirmed the prediction superiority of the ensemble models.Peer reviewe

Prediction of Compaction and Strength Properties of Amended Soil Using Machine Learning

In the current work, a systematic approach is exercised to monitor amended soil reliability for a housing development program to holistically understand the targeted material mixture and the building input derived, focusing on the three governing parameters: (i) optimum moisture content (OMC), (ii) maximum dry density (MDD), and (iii) unconfined compressive strength (UCS). It is in essence the selection of machine learning algorithms that could optimally show the true relation of these factors in the best possible way. Thus, among the machine learning approaches, the optimizable ensemble and artificial neural networks were focused on. The data sources were those compiled from wide-ranging literature sources distributed over the five continents and twelve countries of origin. After a rigorous manipulation, synthesis, and results analyses, it was found that the selected algorithms performed well to better approximate OMC and UCS, whereas that of the MDD result falls short of the established threshold of the setlimits referring to the MSE statistical performance evaluation metrics.Peer reviewe

Prevalence and Factors Associated with Meconium-Stained Amniotic Fluid in a Tertiary Hospital, Northwest Ethiopia: A Cross-Sectional Study

Background. Fetal bowel could pass meconium, a green viscous fluid, before or during labour and most intrauterine passage of meconium is associated with several fetomaternal factors that lead to increased risk of perinatal morbidity and mortality. Given that there is a paucity of data, this study was conducted to assess the proportion and associated factors of meconium-stained amniotic fluid (MSAF) in women who came for labour and delivery service in a tertiary hospital. Methods. A cross-sectional study was conducted from 1 June to 31 August 2018 among 606 labouring mothers at Felege Hiwot Referral Hospital, northwest Ethiopia. Study participants were selected using a systematic random sampling technique. Data were collected using an interviewer-administered pretested questionnaire and data checklist. Factors associated with MSAF were explored using multivariable logistic regression analysis. Results. MSAF occurred in 24.6% (149/606) of pregnancies. Nonreassuring fetal heart rate patterns (Adjusted Odds Ratio [AOR]: 21.9, 95% Confidence interval [95% CI]: 10.96–43.83), postterm pregnancy (AOR: 4.54, 95% CI: 2.24–9.20), duration of labour more than 15 hours (AOR: 2.83, 95% CI: 1.76–4.53), pregnancy-induced hypertension (AOR: 2.43, 95% CI: 1.45–4.05), oligohydramnios (AOR: 2.53, 95% CI: 1.25–5.12), interpregnancy interval less than 2 years (AOR: 2.24, 95% CI: 1.12–4.51), and monthly family income less than 5000 Ethiopian Birr (185 USD) (AOR: 2.03, 95% CI: 1.18–3.51) were significantly associated with MSAF. Conclusions. In this study, the proportion of MSAF was at 24.6% which was higher than a previous report in Ethiopia. Nonreassuring fetal heart rate pattern, postterm pregnancy, duration of labour more than 15 hours, pregnancy-induced hypertension, oligohydramnios, interpregnancy interval less than 2 years, and monthly family income less than 5000 Ethiopian Birr were factors associated with an increased risk for MSAF. Therefore, interventions aimed at detecting MSAF early should consider these factors

Hospital based surveillance of congenital rubella syndrome cases in the pre-vaccine era in Amhara Regional State, Ethiopia: A base line information for the country.

BACKGROUND:Rubella virus infection in early pregnancy lead to serious multi-organ birth defects known as congenital rubella syndrome (CRS). The incidence of CRS varies in different populations and the highest burden is found in developing countries in which rubella vaccination is not included in their national immunization programs. In Ethiopia, there is scarcity of data about congenital rubella syndrome. Therefore, the aim of this study was to determine the burden of CRS-related birth defects and its incidence in the pre-vaccine era in Amhara Regional State, Ethiopia. MATERIALS AND METHODS:A cross sectional study was conducted in Dessie, Felege-Hiwot and University of Gondar Referral Hospitals, from December 2015 to August 2017. After getting informed assent from each parent/guardian, blood was collected from infants < 1 year of age for laboratory determination of anti-rubella virus antibodies. Their socio-demographic data and clinical information compatible with congenital rubella syndrome were collected using WHO guideline. RESULTS:During the study period, a total of 50 infants suspected for congenital rubella syndrome were included in the study. All infants suspected for CRS were tested against rubella specific IgM and IgG [for infants ≥ 6 months of age] antibodies using ELISA method. Of these, 9/50 (18%) and 4/14 (28.6%) of them were laboratory confirmed and potential CRS cases, respectively. In the present study, the most common laboratory confirmed defect was ocular manifestations 6 (66.7%) followed by heart related problems 5 (55.6%). In the present study, most of the laboratory confirmed cases (66.7%) were reported among 1-5 months of age infants. In addition, 5 (55.6%) of the infants with laboratory confirmed CRS cases were male and 6 (66.7%) of them were from urban settings. In this study, the incidence of CRS was 0.4 per 1000 live births. CONCLUSION:In this study, nearly one fifth of the infants had laboratory confirmed congenital rubella syndrome and most of them had multiple rubella associated congenital defects at a time. Most of these congenital anomalies were reported among infants ≥ 1 month of age. Based on our result, the incidence of the CRS was line with the global incidence of the CRS in the pre-vaccine era. Therefore, establishing strong rubella/CRS surveillance system as well as introducing the rubella containing vaccine in the national immunization program might be important to reduce the burden of rubella and CRS in the country

Experimental Investigation on the Utilization of Marble and Scoria Powder as Partial Replacement of Cement in Concrete Production

This paper explores how marble and scoria powder can be used as partial substitutes for ordinary Portland cement in creating C-25 concrete. Both materials contain over 50% of the major oxides found in cement, with marble high in CaO and scoria high in SiO2. Experimental investigations were conducted to study the chemical, physical, mechanical, and fresh properties of concrete containing marble and scoria powder. For the investigation, 13 different mixes, including the control mix, were used with a constant water–cement ratio of 0.5 and a slump range of 25–50 mm for concrete with a compressive strength (CS) of 25 MPa. Marble-to-scoria ratio of 2 : 1, 1 : 1, and 1 : 2 was used, and then the combined fraction of both marble waste and scoria in concrete was increased from 0% to 20% in 5% range. Including the control test specimens, a total of 117 (150 × 150 × 150 mm) concrete cubes for CS test, 39 (100 × 100 × 500 mm) concrete beam specimens for flexural strength test, 39 (100 × 200 mm) cylinder specimens for splitting tensile strength (STS) test and, 39 (100 × 100 × 100 mm) cube specimens for water absorption test were cast and tested at 3, 7, 28, and 56 days. The test results indicate that marble and volcanic scoria powders with marble-to-scoria ratio of 1 : 1 could replace cement up to 15% without compromising the CS and up to 10% without compromising the flexural and STS; also, the water absorption decreases up to 10% replacement; however, the workability of the fresh mix decreases as the combined replacement level of marble and scoria increases. Generally, a 10% replacement with marble-to-scoria ratio of 1 : 1 produces concrete with higher compressive, flexural, tensile strength, and water absorption manifestations when compared to conventional concrete

Free Primary Education and Implementation in Kenya

Free primary education policy has substantially increased school enrollment rates in Sub-Saharan African countries. The success and sustainability depend on teachers’ perception, motivation, and proper implementation of the policy in the classroom. Few studies focus on teachers’ experiences and challenges in the process of implementing the policy. The current study presents theoretical reviews using the “bottom-up,” “top-down,” and incremental policy frameworks. The study used a desk review of the documents from the Ministry of Education and other published materials from an Education Research Program in Kenya. Findings suggest that there is no adequate empirical study to support the views and assertions concerning teachers’ experiences and motivation toward the implementation of free universal primary education policy in Kenya. There is a need for empirical research and programs to understand teachers’ experiences and challenges in translating education policy into practices