Causes of Delays in Highway Construction Projects in Ghana

Delays in construction projects are a global phenomenon, causing a multitude of negative effects on the key project participants – clients, consultants, and contractors. The main purpose of this study is to identify the causes of delay of highway construction projects in Ghana to determine the most important to the key project participants. Literature review and semi-structured interviews of 12 key players in the implementation process were conducted. Thirty five possible causes of delay were identified and further grouped into ten categories. A questionnaire survey was conducted on the resulting list of delay causes for the identification of the most important causes of delay. The relative importance of the individual causes were determined and ranked by their Relative Importance Index. The findings revealed that the five most important causes of delay in road construction projects in Ghana are 1) Delay in honouring payment certificates 2) Equipment failure 3) Shortage of materials 4) Poor site management 5) Late delivery of materials on site. It is hoped that the findings of this paper will help project participants to act on critical causes to minimize delay of their projects. Key Words: Highway construction projects, Ghana, Relative Importance Index

Assessment of Suitability of Plastic Waste in Bituminous Pavement Construction

The use of plastic products is on the increase daily. The disposal of plastic wastes is a problem in many developing countries like Ghana. These are non-biodegradable products that pose environmental pollution problems to mankind. If these materials can be suitably utilized in road construction, the pollution and disposal problems may be partly reduced.  In recent years, applications of plastic wastes have been considered in road construction with great interest in many developing countries. These plastic wastes are compatible with bitumen at specified conditions. This research aims at determining the suitability of using waste plastic materials as modifiers in bituminous road pavement construction. The waste polymer-bitumen blend was prepared in various proportions and the rheological properties determined in the laboratory. The results indicate that the properties of polymer-modified AC-10 viscosity graded bitumen were enhanced with better binding properties, and can be used in asphalt concrete pavement construction with improved quality and savings. Keywords: Non-Biodegradable, Plastic Waste, Polymer-modified, viscosity graded

The Effect of Maximum Coarse Aggregate Size on the Compressive Strength of Concrete Produced in Ghana

An experiment was conducted to determine the effect of different sizes of machine crushed gneisses used in Ghana for concrete production on the compressive strength of concrete. Coarse aggregate samples of maximum sizes of 10mm, 14mm and 20mm were used to produce concrete at constant water/cement ratio of 0.63. In all the experiments, the concreting procedures and materials were kept constant whiles the maximum coarse aggregate sizes were varied. A total of 36 concrete cubes were crushed at 7, 14, 21 and 28 days to determine their compressive strengths.The results show that the smallest coarse aggregate size gave the highest compressive strength and lowest slump at constant water/cement ratio.  A regression analysis also shows that the relationship between the maximum coarse aggregate size and the compressive strength follows a polynomial with R2= 1; indicating that the model is reliable. The optimum maximum coarse aggregate size for the best compressive strength of 28 day concrete was therefore found to be 8mm for the water/cement ratio of 0.63. The analysis further shows that as heterogeneity increases the compressive strength of concrete reduces. Keywords: Gneiss, compressive strength, aggregate sizes, slump, heterogeneity.

Engineering Geological Characteristics of Quartzite Types for Concrete Production in Ghana

The production of concrete in Ghana involves the use of several mineral aggregates such as gneisses, granites, granodiorites and quartzites. The use of quartzites for concrete, however, is well patronized especially by private low cost housing builders due to its low cost compared to other alternatives. Quartzites are known to have strength characteristics which are not uniform and as such vary from low to high depending on their metamorphic state.This research provides some Engineering Geological characteristics of quartzite types used for concrete works in parts of Southern Ghana and offers a classification of quartzites for easy field identification by Construction Engineers. The results of strength tests and petrologic examination confirm that there are different types of quartzites with strengths that correlate positively with their level of geologic state. In addition, the most metamorphosed quartzite was found to be resistant to weathering and useful for producing concrete for structural work. Keywords: Quartzite types, aggregate strength, quartz, concret

An Experiment to Determine the Effect of Partial Replacement of Natural Sand with Manufactured Sand on the Strength of Concrete

Natural sand is getting depleted from the environment, because of over exploitation for construction purposes, resulting in loss of vegetation and fertile land for farming. An investigation was, therefore, conducted to determine the suitability of using manufactured sand from crushed gneisses as partial replacement for natural sand for concrete production. In the experiment natural sand was replaced with manufactured sand of the same grading as the natural sand, while keeping all other variables constant. Apart from the control concrete sample which had 100% natural sand all the other samples were treated to 10%, 20%, 30%, 40% and 50% replacement of the natural sand with manufactured sand. Concrete cubes of 150mmx150mmx150mm were made with the various proportions of cement, sand and stones in a mix ratio of 1:2:4, water -cement ratio of 0.45 and cured over 28 days.The results of compressive strength tests show that the strength of the concrete cubes with varying amounts of natural sand and manufactured sand changed marginally. This was interpreted to mean that the partial replacement of natural sand with manufactured sand up to 50% in concrete results in about 6% increase in the strength of the concrete. Manufactured sand, therefore, is regarded as suitable for concrete production on the basis of strength. However, it may affect the concrete in the long run because it contains higher amounts of deleterious substances as compared to the natural sand. Keywords: Manufactured sand, Natural sand, Concrete, Compressive strength, Gneis

An Experiment to Determine the Prospect of using Cocoa Pod Husk Ash as Stabilizer for Weak Lateritic Soils

A study was conducted to determine the extent to which the engineering and geotechnical properties of a lateritic soil for road construction works can be improved by using cocoa pod husk ash (CPHA) additive.Natural lateritic soil samples were collected from test pits near El wak Sports Stadium, Accra, Ghana and were subjected to Atterberg’s limit and particle size distribution tests as well as compaction and California Bearing Ratio (CBR) tests. The soil was then treated with 0.5%, 1.0%, 2.0%, 4.0%, 6.0%, 8.0%, and 10.0% of CPHA and then tested for variations in the engineering properties.From the various tests carried out on the natural soil sample, and when CPHA was added, it was observed that CPHA has a significant negative effect on the maximum dry density and a positive significant effect (p<0.05) on the liquid limit. The addition of CPHA to the soil however, did not significantly (p>0.05) affect the California Bearing Ratio, optimum moisture content, plastic limit and plasticity index, and therefore the CPHA is regarded as a poor soil stabilizer. Other findings show that CPHA has no pozzolanic properties. Keywords: Cocoa pod husk ash, stabilizer, lateritic soil, pozzolanic properties

Effect of Sawdust on the Compressive Strength of Concrete

This study was undertaken to investigate the properties of concrete produced by partial replacement by weight of sand with sawdust generated from different species of wood. The sawdust used in this investigation consist of the wood species, Piptadeniastrum africanum (leguminosae family), Triplochiton scleroxylon (sterculiaceae family) and Celtis mildbraedii, locally known as Dahoma, Wawa and Essa respectively. The addition of sawdust to the concrete was done by 5% increment up to 25% by weight of the fine aggregate. Concrete cubes of size 150mm x150mm x 150mm were prepared after batching and mechanical mixing for the compressive strength tests.  The compressive strength tests were carried out after 28 day curing of the concrete cubes in accordance with BS EN12390-3:2009 series. Sawdust blend concrete from wawa - a lightwood species gave the best result of 5.3 N/mm2 at 28 days. The optimum replacement of sand with sawdust has been found to be 5% for lightwood species. Keywords: Batching, Mechanical mixing, Sawdust, Compressive strength

Medieval Occitan grammatical writings: the adaptation of Latin linguistic analysis to vernacular languages.

Digitisation of this thesis was sponsored by Arcadia Fund, a charitable fund of Lisbet Rausing and Peter Baldwin

Comovement between agricultural commodities and stock returns of commodity-dependant sub-saharan Africa countries amidst the COVID-19 pandemic

The study analyses the comovement between agricultural commodities (cocoa, coffee, corn, cotton, and soybeans) and sub-Saharan African equities (BRVM, Ghana, Kenya, Mauritius, and Uganda) heavily exposed to shocks from the COVID-19 pandemic spanning from January 2017 to December 2022. Through bivariate and multivariate wavelet analysis, the study identifies the adaptive and asymmetrical nature of the sampled markets both in the pre-pandemic and pandemic periods. The results highlight commodities as the main driving force behind equities, with few exceptions, and reveal these markets' safe-haven and hedge potential during the pandemic and the normal periods, except for the multivariate case. The bivariate findings suggest that global investors can consider investing in agricultural commodities and the sampled equities for enhanced portfolio diversification. By examining the interconnectedness of the sampled market across different timeframes and investment horizons, the study has uncovered significant implications for policy-making, portfolio diversification strategies, and risk management approaches