Alternative Binders for Increased Sustainable Construction in Ghana—A Guide for Building Professionals

Sustainable concepts and practices have taken a centre-stage in different fields of studies and professions. This is because human activities continue to threaten the carrying capacity of earth resources as well as life basic needs such as shelter. Ghana, a developing nation, has been characterized with a boom in construction activities. In almost every constructional work, Portland cement remains the main binding agent that is used to bind aggregates together in a monolithic unit. The overdependence of the Ghanaian construction industry on Portland cement has contributed to huge sums of foreign exchange used to import cement ingredients, high cost of buildings and annual artificial shortages of cement which leads to high cost of the product. In this work, alternative binding agent—pozzolana cement, is reported with regards to the theory behind its utilization, laboratory results and practical applications. Results obtained from both the laboratory and the field works have shown that the future binder for the Ghanaian construction industry is pozzolana cement. CSIR-Building and Road Research Institute recommends it for the construction industry for use in various forms of construction such as block making, concrete and mortar works.

Preliminary Evaluation of Some Engineering Properties of Laterite as Foundation and Construction Materials in Muglad Basin in Sudan

This paper reports and evaluates the subsurface investigations of lateritic soil in Muglad Basin. Lateritic soil is described as highly weathered and altered residual/transported soil formed by the in-situ weathering and/or decomposition of rocks in the tropical and sub-tropical regions with hot, humid climatic conditions. The field works include excavation of test pits, drilling of boreholes and performing of SRT （standard penetration test）. The engineering properties of soil such as sieve analysis, consistency, compaction test, CBR （California bearing ratio） test are deduced in the laboratory. Lateritic soil is also evaluated to be used as foundation and construction materials. Concretionary lateritic soil is valuable road pavement materials, widely used in the tropics as sub-base, base material and for gravel roads. The term laterite, however, has tended to be indiscriminately applied in tropical highway engineering to any red soil. Lateritic soils in this study area were classified as reddish brown, medium dense to very dense, clayey silty sand with noodles of quartz and gravels. According to laboratory test, the lateritic soil was found to be good as construction materials, and can be used for embankment purposes; on the other hand, blending such materials with gravels can improve the low CBR values.

Failure Investigation for Recently Constructed Road in Khartoum State

This paper will visually and experimentally assess the level of deterioration of one of the new constructed ring road pavements in Khartoum State as well as to examine and identify the causes of the failed pavement. A series of field and laboratory exercises were carried out on the materials that were used in the construction of the designated pavement. Huttab, a natural gravelly material, was used in both subbase and base blend of this deteriorated pavement. The experimental tests consisted of two tasks： the first covered the study of the actual causes of pavement distress, whereas the second explored typical base material alternatives that satisfy base course needs. The tests involved basic tests and dynamic tests such as sieve, Atterberg limits, linear shrinkage, compaction, CBR （Calitbrnia bearing capacity）, abrasion whereas the dynamic tests included MR （resilient modulus）, and PD （permanent deformation）. The routine tests showed that an improper base blend was used in the failed road that resulted in excessive rutting whereas in the second tests scenario the results showed that the proper base blend from the named materials gave high strength and stiffness values and low PD compared to the natural one. On the other hand, the pure crushed sample reported high MR values and the lowest PD compared to the base blend alternative.

Impact of Moisture Variation on Some Foundry Properties of Fori Silica Sand

Moulding Sand for metal casting is usually sourced from either natural deposit or synthetic mix of refractory sand grain binder and moisture. Each of the mix constituent is important in determining the characteristics of sand. The binding agent is responsible for bendability thereby determining the size of voids within the sand grain, while moisture level determines the plasticity of the foundry sand. Tests using American Foundry Society (AFS) Standard were followed in carrying out the experiment on Fori sand deposit to determine its suitability for foundry use. The sand was collected from the river bank of Fori, in Fori Community, Maiduguri, Borno State. The experimental test equipment includes: laboratory sand mixer, sand rammer, universal strength testing machine, permeability-meter, oven, mouldability machine, and as well as quick moisture teller. The chemical composition of the materials was carried out using atomic absorption spectrophotometer (AAS) model PG990AFG. The silica content in the material sample is about 78.65%, and with the traces of other elements, such as CaO (1.07%), Fe2O3 (0.76%), Al2O3 (15.81%), MgO (1.01%), TiO2 (2.21%), K2O (3.87%), and Na2O (1.16%), respectively. These percentages are within acceptable limits. The results of the physical properties revealed that the sand sample has clay content of 15.32% which is above the standard range of 10% - 12% recommended for natural moulding sands required for producing good quality castings. Other foundry properties of Forinatural moulding sand conducted include “moisture content” in the following ranges of percentages, 7.6%, 6.5%, 5.8%, 4.2% and 2.9% with the corresponding value of green compressive strength of (43.95, 53.47, 69.56, 68.21 and 61.16 KN/m2), dry compressive strength (93.50, 96.52, 105.50, 146.50 and 152.49 KN/m2), and permeability No. of 340, 390, 410, 430 and 440 respectively. It is clear from the test that, the lower the moisture content, the higher the dry compressive strength of the materials. The refractoriness value of the materials is 1400 ℃. The results of the physical and other foundry properties carried out show that Forisilica sand is suitable for casting non-ferrous alloys like bronze, brass and aluminium, and cast iron.

Effect of Curing Environment on the Strength Properties of Cement and Cement Extenders

Curing of cement based products such as concrete and mortar, is very important to achieve good strength and durable products. However the curing environment plays a pivotal role in the overall quality of cement based products in terms of strength development. ASTM C192 allows moist curing either in a fog room or under water. However, these must meet ASTM C511 which controls temperature, and specifically for water curing, the concentration of calcium ions in the curing solution. Unfortunately in many parts of the world, water curing literally means curing in tap water. This is done primarily because there is a lack of knowledge or ignorance regarding the mobility and roll of calcium hydroxide in the curing process. To illustrate the differences, in this study, straight ASTM Type I/II Portland cement and that mixed with powdered waste clay bricks as a cement extender were used to prepare two different batches of mortars. The chemical properties of the powdered waste clay brick met the ASTM C618 standard specifications for Class N pozzolans. Both mortar specimens were cured under two different environment comprising of either water and lime saturated water. Mortar specimens were tested for compressive strength at 3, 7, 14 and 28 days of either curing conditions. Test results indicated that mortar specimens cured in lime saturated water obtained higher strength than those cured in fresh water at all ages of curing. Statistical inference drawn from ANOVA testing showed that curing conditions had significant impact on strength development of the blended and unblended cement systems. The study recommends that testing of concrete and mortar samples and other research related works be performed in lime saturated water other than fresh water.

Signalization options to improve capacity and delay at roundabouts through microsimulation approach:A case study on arterial roadways in Ghana

Roundabouts are very useful when flows are balanced but can have operational challenges when flows increase.Most roundabouts on arterial roadways in Ghana experience recurring congestion during peak traffic.The four roundabouts between Ejisu Municipality and Asokwa Municipality on the N6 highway are typical of the situation found on arterials countrywide.They experience recurring long queues and delays during the peak hours and over-representation of truck rollover accidents.In Ghana,historically,most roundabouts with capacity problems have been developed into interchanges at very high cost without consideration of other effective at-grade configurations.When roundabouts are signalized,various configurations can be explored to enhance capacity while preserving the safety benefits.Using simulation techniques,various configurations and design options were tested for their effectiveness at two of the roundabouts,located at KNUST police station and Ejisu,with similar demand and high left turning volumes.The objectives of this study were to a)evaluate the performance of the selected roundabouts on the corridor;b)explore alternative intersection configurations to improve capacity and delay.Using video data collection techniques,2-h time stamped footages of AM and PM peak traffic flows were captured for two days.Geometric design parameters of the existing roundabouts,queue lengths,travel times,and approach flows were also captured.VISSIM models of the selected roundabouts were developed and calibrated for the baseline conditions.Signalized unconventional roundabout configuration,with a phase for major road through traffic were simulated and assessed for capacity,delay and queue length.The results showed that signalized roundabout intersections effectively increased capacity by as much as 50%in some cases,reduced delay and queue length significantly,and maintained the benefits of roundabouts including safety.The performance could be further enhanced by introducing separate left turn phases to reduce conflicts or through a right turn U-turn(RTUT)concept.

Evaluation of Subsoil Corrosivity Condition around Baracaia Area Using the Electrical Resistivity Method--A Case Study from the Muglad Basin, Southwestern Sudan

This paper evaluate subsoil corrosivity using the electrical resistivity method which was carried out to determine the subsoil resistivity and estimate the degree of corrosion, the resistivity measurements were conducted by using SAS300c resistivity meter. This involves applying a voltage into the soil through metal electrode and measuring the resistance to the flow of electric current. An AC-power supplies current flow （I） between two outer electrodes and the resultant voltage different （V） between two inner electrodes is measured using the Wenner Arrangement. The soil resistance given by R = V/I. This needs to be standardized over a unit length, the resistivity p which measured in ohm-m the equation is, ρ= 2ДdR. There are many factors control the ground resistivity such as soil composition, moisture content, pore water chemistry and pH. The results of the survey show inverse proportion between corrosivity and electrical resistivity, therefore resistivity method is very useful to incipient the corrosion as well as effective, quick, reliable and economic method. Structures such as natural gas, crude oil pipelines and steel constructions were reported to have been affected by soil corrosion all around the world, it can be concluded that sub soil corrosivity around the study area increases southwestern ward with depth.

Evaluation of Cost Effectiveness of Onibode Fire-Clay for Production of High Quality Refractory Bricks

In establishing a plant or factory, the cost-benefit analysis is needed to determine the viability for such financial investment on the project. In this paper, the cost establishing a factory of 200,000 bricks per annum capacity, for the production of high quality refractory bricks from locally available raw materials in Nigeria was evaluated. The evaluation was conducted on the virgin refractory material (100%) as well as with varied percentages (10% - 40%) of alumina additions. The result of cost benefit analysis indicated that, the project was viable, with the highest cost at N1,203.66 per brick as against N1,800 (at 3 years projections) of the imported brick. The payback period for the capital investment was very short (within two years). The findings will aid investors in decision makings.

Influence of Mineral Admixtures on Essential Properties of Ternary Cement Blends

Two CaCO3-based materials （limestone and clamshells） and steel slag were used as mineral admixtures in cement to produce ternary blends and their influences on hydration and portlandite formation were analyzed. Additionally, mechanical properties were determined. These properties were determined using X-ray diffraction and scanning electron microscopic/energy dispersive X-ray analytical techniques as well as applying methods specified by EN （European Standards） and ASTM （American Standards for Testing and Materials）. The portlandite （Ca（OH）E） content was considerably reduced from 36.9% of reference cement to between 13.79% and 15.5%. With the water demand and setting times of the cements containing up to 10%, admixtures did not change significantly. The mechanical tests results showed that ternary blends produced 2-day strengths higher than that specified by EN 197-1 and that blends containing up to 20% admixtures can be used to produce both Class 32.5N and 42.5N cements.

Construction of Micropiles Using Pressure Techniques

This paper discusses the technique of casting concrete ofmicropiles with pressures and the consequence of comparisons with normal way of casting concrete （casting with gravity）. Preliminary geotechnical studies have been made in specific area in Sudan to predict the soil parameters and then an experimental work has been done for an estimated number ofmicropiles with different diameters and different techniques of placing concrete with various amount of pressure. This study was carried out to learn the usefulness of this technique in the field of structural foundations in Sudan. Capacities of micropiles were compared in cases of non-pressure casting （normal way of casting concrete） and pressure casting. Through the results, it was found that the entry of pressure factor in the operation of casting concrete increases the capacities of micropiles. The increased value of ultimate load depends on the amount of pressure applied.

Technical Profile on the Production of Pozzolana (An Emerging Construction Material) in Nigeria

Pozzolana which is an eco-friendly and cheap supplementary cementious material has not been established on a commercial scale in the construction industry in Nigeria. Hence, this paper is aimed at presenting a feasibility study to show the viability and highlight the business opportunities available for local and foreign investors in the area of pozzolana production in Nigeria. The paper discussed the technical requirements and estimated start-up capital for setting up a Pozzolana production plant from calcinated of Fifteen Thousand Tonnes Annual Production Capacity. An outline for start-up capital identified building and civil work, furniture and fixtures, machinery and equipment requirement, intangible assets, and seed fund. Raw materials/utilities and organizational requirement for annual production were also presented. The investment is viable with a total investment cost of $507,321.23, annual net profit of $107,961.70 and a payback period of 4.7 years. The net profit ratio and rate of return are 16.28% and 21.28% respectively. The findings and understanding of the technical and financial requirements from this work will aid investors in making decisions. The project if carried out will reduce cement contents in concrete and mortar structures, with eco-friendly cement admixtures and subsequently reduce the cost of construction in general.

Spatial Analysis for Determining Accessibility to Bus Stops in Kaduna Metropolis

Bus stop accessibility is a vital component of a successful transportation system. This study aimed at spatially analyzing bus stops to determine their physical accessibility considering the connecting roads surrounding the bus stops. This research used satellite imagery, Global Navigation Satellite System and Kaduna State Traffic and Environment Law Enforcement Authority documents. The spatial analysis covered bus stop accessibility and obtained data of transport routes, bus stop coordinates, bus stop spacing and physical characteristics of bus stops. GIS buffer, network and area analysis was used in measuring bus stop accessibility considering the road network surrounding it. The ratio of ideal access coverage to the actual access coverage of a stop was calculated. Paired sample statistics were used to compare ideal and actual access coverage;the finding revealed a significant difference between the ideal and actual access coverage. A range of 0 - 1.0 was used in the analysis where, a bus stop is less accessible the closer the value is to 0, and more accessible the closer the value is to 1.0. Linear regression statistics was used to determine if the level of accessibility of a bus stop is dependent on the length of roads within the buffer. This revealed that at R = 0.694, a strong degree of correlation exists between the level of accessibility and road length within the buffer. The study concluded that before siting bus stops, surrounding road networks need to be considered in order to make them accessible.

Analysis of geo-spatiotemporal data using machine learning algorithms and reliability enhancement for urbanization decision support

We present systematic analyses of the temporal dynamics of the growth of Kumasi,the fastest growing city in Ghana using 20-year Landsat timeseries data from 2000 to 2020(with 1986 Landsat image as a baseline).Two classification algorithms–random forest(RF)and support vector machines(SVM)–were used to produce binary(built-up/non-built up)maps for all years within the temporal span.We further implemented an anomaly detection and temporal consistency algorithm followed by a changing logic to correct the classification anomalies due to image contamination from the cloud and other sources.The mean overall accuracies obtained for RF and SVM were 94.9%(kappa=0.90)and 95.5%(kappa=0.91),respectively.Our results reveal that the mean builtup area percentages of the metropolis are approximately 74,65,47,and 23 for the years 2020,2010,2000,and 1986,respectively,representing a mean annual change of 3.5%over the 34 years.With the present lack of labeled data in Ghana for in-depth analyses of the evolution of land use,we believe that this study serves as an initial attempt to a better understanding of the effects of increasing anthropogenic activities due to urbanization,on human and environment health.