Refereed Journals

Geotechnical and mineralogical properties of black cotton soils obtained from the Accra plains of Ghana were evaluated with the aim of using it as potential component of drilling mud. Samples were collected from Dowhenya, Tsopoli and Prampram, air dried, crushed and subjected to geotechnical, chemical, mineralogical, physico-chemical properties and free swell index laboratory tests. The index properties show that, the black cotton soils have over 70% clay content with very high plasticity. However, the commercial bentonite had over 90% clay with an extremely high plasticity. Chemically and mineralogically, the black cotton soils are similar to the commercial bentonite except that, it contains a lot more of the oxides that have no influence on the desirable properties of the soil as compared to the commercial bentonite. It was also determined from the chemical, mineralogical and physico-chemical properties that, the black cotton soils contain Ca-montmorillonite while the commercial bentonite contained Na-montmorillonite as the dominant clay minerals. However, an addition of 10% Na2CO3 improved the free swell index of the black cotton soils and hence its properties are expected to compare much closely with those of commercial bentonite.

Concrete is the most widely used construction material in the world compared to other known construction materials including steel, glass, aluminum and timber. The reason for its wide usage is because of its low embodied energy, an indicator of carbon emissions into the environment. However, since the volume of concrete used globally is very huge, the environmental impact is great and hence any little improvement on concrete ingredients will have real impact. A possible improvement of concrete is a good focus on Portland cement since embodied carbon dioxide in concrete is a function of cement content in the mix. In this work two sets of mortars were formulated; one with clay pozzolans and water reducers and the other was the pozzolans containing no water reducers. The performance of the two sets of mortars were evaluated based on their strength properties which were performed in accordance with the ASTM C109 standards. In the work, Portland cement was replaced by the clay pozzolan between 10% and 40% by weight. The clay pozzolan used was from waste crushed bricks obtained. The results of the blended cement mortars were compared with the unblended cement mortars. The results of the study indicated that for the mortars containing pozzolan and the water reducers, the optimum cement replacement was 30 wt.% of the pozzolan. For the mortars containing only the pozzolans, the strength values recorded a progressive reduction with the increasing content of the pozzolan in the cement matrix. The study recommended that 30 wt.% replacement of cement and the addition of water reducers could be used to formulate 42.5 grade cement whereas between 20-30 wt.% of only pozzolan content could be fit for a 32.5 grade of cement

Calcined or partially calcined clay can be used to replace a significant portion of portland cement, which reduces the associated CO2 footprint, and in Western Africa, to use a locally available material. However, clay source properties influence thermal activation and ultimate pozzolan city. In this study, clay from the Ashanti region of Ghana was thermally activated at calcination temperatures of 600, 800, and 1000°C (1112, 1472, and 1832°F). The raw clay and the calcined products were characterized in terms of mineralogy and silica intensity using X-ray diffraction (XRD) and solid-state silicon magic angle spinning nuclear magnetic resonance (29Si MAS NMR). The impact of the calcined clay material on Portland cement was analysed based on the pozzolanic strength activity index (PSAI). The influence of the calcined material on Portland cement in terms of formation of polymerized phases including calcium aluminosilicate hydrates and lime consumption was determined using 29Si MAS NMR and thermal gravimetric analysis (TGA). The results of the study indicated that optimum calcination temperature of the clay was 800°C (1472°F), where more reactive pozzolanic phases were formed. The study concluded that the use of calcined clay at optimum calcination temperature together with Portland cement improves the strength of mortar. The improvement in strength is consistent with the observed increased polarization between the reactive phases of the calcined clay and cement phases as well as the higher degree of pozzolanic reaction of Portland and calcined clay mixtures at the hardened state compared to only Portland cement.

The focus of this study was to identify the economic opportunities and dangers of the tollbooth to traders in order to explore enabling and realistic approaches to addressing street trading in tollbooth areas. The study set out to examine the locational advantages and disadvantages and the spatial characteristics of the street traders and their operations. The aim of this research was also to understand the locational problems and to explore means of integrating street traders’ activities into spatial planning process to ensure a sustainable socio-economic growth. This research was carried out by using Ashanti region because it is a nodal commercial town where trading activities from the north and south of the country converge which has led to a proliferation of street trading activities in the town. This has been achieved in this report through a review of the literature and focuses on the theory regarding the informal sector, street trading in tollbooth areas and its linkage to urban planning. A number of research methods were used in gathering of data. These include observation, and a field survey and a sample of 85 street hawkers were interviewed. The major research findings show that the spatial distribution of tollbooth and street traders around them occur in knots of four areas; Ejisu Besease, Tabre, Mamponteng and offinso-Ahenkro. There stand no planned places for street traders around tollbooth and they are located in spaces which are meant for other uses. Field Research was done from the 16^th September 2019 to the 19^th September 2019. The main objective of this study is to draw attention to the various hazards involved in the street hawking business and benefits these street hawkers gain from selling around tollbooths. These hazards may or may not be known to many especially the street hawkers themselves, which is why they may choose to engage in this line of business. The following findings emerged: firstly, it is evident that many of the hawkers enter into this line of business due to its low capital requirement. Others do not choose to be part of these activities but are forced into it to augment family income.  Secondly, it was observed that hawkers face many dangers as a result of their line of work. These come in the form of motor accidents, health dangers as a result of emissions from vehicles, excessive standing and running as well as continuous exposure to vagaries of the weather.

Majority of hawkers in the area were found to be females between the ages of 15 and 40 years. It was revealed that poverty, low educational attainment and family responsibilities are some of the issues that push hawkers into the business. Hawkers further expressed low start- up capital and manageable profits as some factors that attract them to the hawking business. Another issue is that since tollbooth areas have become an asset for sustainable livelihoods, location is key to the sustainability of microenterprises.  This results in contestations and conflicts with urban authorities and some indigenes of the town where the tollbooth is sited. Based on the study and evidence from the survey findings, recommendations have been made to address and manage street trading to ensure that resultant spatial problem are avoided. This approach does not seek to perpetuate activity, but rather attempts to limit its negative and undesirable effects on the urban environment. This report proposes that street trading should not be treated as an ‘after-thought’, but rather the spatial dynamics should be understood and the space needs of street traders must be considered in town planning.