Refereed Journals

This work presents the effect of partially replacing metakaolin with Portland limestone cement to produce mortars for construction. Teleku Bokazo kaolin was explored as a SCM in the production of mortars. The hydration product between Portland limestone and metakaolin was studied. The kaolin was heat treated to form metakaolin and partially used to replace Portland limestone cement (PLC) in mortars to explore the optimum
replacement and its mechanical and durability effect. The samples were characterized using X-ray diffraction (XRD) for phases and crystallinity of the kaolin. Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) gave information on the functional groups formed during the hydration and structure and surface morphology respectively. The pastes and mortars produced were subjected to setting time, water
absorption, flexure and compression strength test. The mechanical properties were observed to increase with increasing metakaolin replacements. Therefore, from the results obtained, it is suggested that
20 % replacement of Portland limestone cement with Teleku Bokazzo metakaolin can be very suitable for construction applications.

This study investigated pozzolan from the co-firing of clay and rice husk. Rice husk was used to replace clay at 1.0%, 1.5% and 2.0% and calcined at 800°C. Pozzolanic strength activity index (PSAI) was performed on the calcined powder materials in accordance with the ASTM C311 standard. The calcined material that obtained the highest PSAI was selected and used to optimize the calcined pozzolan added to Portland cement. The optimum mixture proportions were used for ²⁹Si and ²⁷Al MAS NMR as well as water sorptivity and shrinkage studies which involved autogeneous and drying shrinkages. The results of the study showed that calcined clay that contained 2.0% rice husk had the optimum PSAI whereas 30 wt.% replacement content was the optimum cement replacement. The ²⁹Si and ²⁷Al MAS NMR showed that the superior strength of the optimum mortar mix to the control was due to a stable monosulphate phase formed at the octahedral environment and the formation of extra calcium aluminosilicate phases in the mortar mix. The initial and secondary sorptivity values of the pozzolan were 0.0055 and 0.0022 mm/sec^1/2 respectively, lower than the values of the control , which were 0.0299 and 0.0083 mm/sec^1/2 respectively. The shrinkage performances of the Portland cement-pozzolan mix were much enhanced than the unblended mortar mix. The inclusion of the co-fired materials reduced the embodied carbon by approximately 29%. The use of the co-fired material could be a sustainable means to dispose of waste rice husk and also reduce embodied carbon.

The Ghana Highway Code is the official state-recognised traffic teaching and learning ma­terial widely used in traffic schools and by motorists in Ghana. Ghana changed its traffic from left-hand to right-hand drive in 1974; the Code was subsequently published to, besides other reasons, guide road users to be reconditioned to a fresh standard of behaviour. However, 46 years after its publication, the content of the Code has been outgrown by new developments in the road environment and traffic systems, rendering the Code ineffective. Content analysis was used to ascertain the validity and reliability of the Code. Out of 95 mo­torists interviewed, 91.5% indicated they use or had ever used the Code, while 3.2% had not used it before and 5.3% did not know about it at all. Hundred percent of driving schools used the Code as teaching and learning material. It was concluded that the Code was an obsolete teaching and learning material. The implication was that, the wide user population of the Code had an adverse impact on learners. It was recommended that the Code be revised and republished as new edition.

School children form majority of injured children on Ghanaian roads. The objective was to observe the road use behaviour of public primary school pupils in Ablekuma Education Circuit, Accra. This unobtrusive observational study targeted Primary one to six pupils. Five behaviours were studied: Walking while crossing road; Stopping at the kerb; Looking left-right-left before crossing; Keep looking left-right-left while crossing and Facing traffic while walking. 882 pu­pils on their way to or from school were observed from eight schools. A little over two in three children stopped at the kerb before crossing the road while almost three in four children looked for cars before stepping off the kerb. A little over three in four children walked while crossing and less than one in four children kept looking while crossing. Not looking for cars before crossing, not facing on-coming traffic and not keeping looking for cars while crossing, were more associated with boys than girls (p < 0.001; 95%CI in all cases). Girls behaved significant­ly more safely than boys. In stopping at the kerb, there was no difference in gender behaviour (p < 0.135; 95%CI). Child Road Safety Education in Schools and Communities is recommended.

Traffic calming measures (TCMs) have been widely adopted as the major speed control devices in Ghana. While initial evaluations have underscored their effectiveness, little research has been conducted to assess their characteristics relative to design guidelines as well as the negative externalities associated with their misapplications. The objectives of this research were to; (i) establish the characteristics of TCMs, and their implications on mobility; (ii) to establish essential speed parameters in communities where TCMs are deployed (iii) to establish pavement conditions abutting traffic calming measures and; (iv) to analyse the accident typology on the Abuakwa to Bibiani road. Firstly, a radar gun and android speed measuring device were used to unobtrusively measure vehicles’ spot speeds and speed profiles, respectively, at different locations relative to the TCMs. Also, visual inspections were carried out to assess the pavement conditions surrounding the TCMs while a geodetic laser leveling instrument and a surveying staff were used to obtain the crown heights of the TCMs. Further, the accident typology on the candidate road were analyzed to establish how the TCMs are affecting road crashes. Vehicle speeds were generally lower than the posted speed limits in settlements which have TCMs. Nevertheless, the proportion of accident casualties being pedestrians despite lower speeds in settlements remains unacceptably high. Further, the collision typology on this highway were predominantly loss control and rear-end accidents suggesting that the TCMs are playing insidious roles in some of the crash types on this road. Pavement distresses such as depressions, cracks, rutting, raveling, potholes and deposit of debris were common in the vicinity of the TCMs. Our findings suggest that awareness creation among communities along the highway may be amenable to improving pedestrians’ safety than relying on only engineering countermeasures. The predominant collision types; loss control and rear-end implies that the TCMs are inadvertently contributing to some accident types. For a long term and sustainable speed control, bypassing settlements, use of active dynamic speed bumps (smart or intelligent speed bumps); and a deterrence-based electronic enforcement such as the Automatic Number Plate Recognition System which uses the demerit points offer better alternatives on the highways.