Technical Reports

Technical Reports

Book Introduction Order
Engineering Properties of Black Cotton Soils of Nigeria and Related Pavement Designs was the first publication arising from the Institute’s programme on the characterization of soils as subgrade materials for road construction in Nigeria. The objective of the study was to systematically investigate the properties of soils occurring in Nigeria. Methodology involved sampling a wide representation of soils from the field and conducting classification tests: Atterberg limits and particle size distribution. Strength parameters (California Bearing Ratio CBR) was also determined.

Click here to download pages 1-4

Report Summary Order
This Technical Report investigated the feasibility of Periwinkle Shell as substitute for coarse aggregate in the production of concrete in in parts of Nigeria. Large quantities of periwinkles occur in the lagoons and mudflats of the Niger Delta and Badagry and have been used extensively for construction in these parts without any technical information/specification for its use. In this study, the physical and mechanical properties of the periwinkle shells were determined. Also, properties of the concrete produced with these shells were evaluated. Previous studies had been conducted on the subject in the Materials and Research Division of the Federal Ministry of Works and Housing in 1968. The preliminary results indicates that periwinkle shell concrete may be regarded as light-weight concrete.

Click to open pages 1-4

Book Introduction Order
This is the first of a series of papers arising from the collaboration between the NBRRI and organizations which have the capacity to undertake research and development. This study was conducted in collaboration with Civil Engineering Department of Ahmadu Bello University Zaria with Henryk Waldemar Mroczek as focal person. A set of tables were presented in an attempt to simplify version of spiral transitions combined with selected circular curves to Nigerian Engineer’s practice. Each selection usually limits universality. However, it has been determined that tested set of rounded radii of curves combined with rounded lengths of spiral covers most cases in everyday designer’s and surveyor’s practice in the field of highway and railway engineering. It is sincerely hoped that these tables will be widely used in the design and the construction of roads.

Click here to download pages 1-4

Book Introduction Order
This report is the first in a series from a comprehensive research programme initiated by the Institute to study the influence of climate on building design in Nigeria. As a simple start, it was decided to collate existing climatic data collected by the Meteorological department over the past forty years or so. On the basis of the analysis of these data, four broad climatic zones were proposed for use in the architectural design of buildings. The main characteristics of these zones were given and general guidelines for their use in building design were provided. This report serves as the first of its kind as there is presently no report which documents such relevant information for the built industry.

Click here to download pages 1-4

Book Introduction Order
This report provides details of the design, fabrication and performance of two different types of solar water heaters suitable for application in urban and rural areas. The natural convection type solar water heater designed to heat 150 litres of water up to 600C by 4.00p.m daily essentially consists of two flat plate solar energy collectors and an insulated storage tank for storing the hot water for use in the following morning. The flat plate collectors are tube-in-plate type and can be constructed with locally available materials and local skilled labour. The second type of solar water heater known as built in storage type solar water heater consist mainly of eight large diameter pipes which perform dual function of absorbing solar  energy and storing the water in them. Since the collector itself acts as storage in this until water cannot be stored for use till the following morning but should be used same day by 10.00 p.m. The temperature attained in the built in storage solar water heater is higher than that of the convection type solar water heater. The special feature of this development is that the fabrication was made from materials available locally and can easily be replicated by individuals and agencies interested in the use of solar energy in urban and rural areas of Nigeria.

Click here to download pages 1-4

Book Introduction Order
The architect requires various solar data for the design of functional buildings which   protect their occupants from the adverse effects of solar radiation. Solar data for the tropics are not easily available locally because such data are contained mostly in publications by overseas research organisations. They are also available in a limited extent in one or two textbooks on tropical architecture. This situation puts a serious constraint on architectural practice in Nigeria. To remedy the situation for Nigerian architects, the Nigerian Building and Road Research Institute undertook an exercise to generate comprehensive solar data that are computed for general use. This report presents tables and charts of solar positions defined in azimuths and altitudes at different times of the day, and different days of the year for places situated at different latitudes in Nigeria. The concept of shadow angles and their application for the determination of shape and size of external louvres for shading windows is discussed. Tables of sunrise and sunset times change over times for vertical walls and duration of possible sunshine on horizontal (roof) and vertical (wall) surfaces are provided. The method of conversion from solar time to standard time is presented. The method of calculating solar radiation incident on building facades of different orientation is briefly described, with typical examples provided where necessary. This report will be found invaluable not only by architects but also by engineers, town planners and scientists involved in building design and research.

Click here to download pages 1-4

Book Introduction Order
Nigeria lies in the tropics and therefore receives a great amount of solar energy which could be judiciously harnessed for various applications. However, there appears to be no record of direct and intensive measurement of solar radiation in Nigeria to facilitate and encourage the rational use of the energy. To correct this, NBRRI established thirty solar energy measurement stations spread over the country. This report summarizes, in tabular form, the records of global solar radiation on a horizontal surface recorded at thirty stations in Nigeria. Integrated values of hourly and daily sums of global radiation recorded with LM-3000/10 solar recorder are given for each month in the units of watt-hours/m2 wherever the data is available. The records range from a few months at some stations to about twelve months on some others. Monthly means are also calculated and tabulated.

Click here to download pages 1-4

Book Introduction Order
This report describes the development of solar radiation models for Nigeria undertaken by NBRRI. The models are based on data from direct measurement undertaken by the institute (Chandra and Oguntase, 1986) and from meteorological data collected over the period 1951-1986 from forty stations in Nigeria maintained by the meteorological department, Federal Ministry of Aviation, Oshodi, Lagos. These models were used in evaluating future direct measurements of solar radiation and estimating solar radiation in remote areas where there are no direct measurements. Furthermore, these models provide mathematical expressions that can be used in the theoretical analysis of solar energy-related problems.

Click here to download pages 1-4

Book Introduction Order
Inadequate sound treatment in public and functional enclosures usually leads to excessive noise levels and reverberations thus creating difficulty in speech and communication. As a result, due attention is now given to acoustic performance of buildings especially conference, concert and cinema halls, theatres and auditoria. To achieve good acoustic performance, it is necessary to identify and properly apply materials with good acoustic performance. This report contains the acoustic properties of various local materials which were determined by the standing wave method. Special attention was given to fibre boards developed by NBRRI from local palm and coir fibres and rice husks. Other materials considered are some locally manufactured conventional boards from rigid and flexible polyurethane foams, expanded and extruded polystyrene, fibre cement and mineral fibres.

Click here to download pages 1-4

Book Introduction Order
The architect’s design is required to satisfy both the aesthetic and functional needs of the client. The design is functional if, among other requirements, the client can undertake his activities in the home comfortably. In this respect, the architect’s design is made easier if he has standards for the use of space for various activities in the home. This is particularly invaluable for areas where land is expensive and the economy is necessary, for example in the design of low-cost housing in urban areas. Up till date, the Nigerian architect has relied on standards of foreign countries whose cultural lifestyles are different from those in Nigeria. Naturally, these standards do not specifically cover activities peculiar to Nigerian culture.

Click here to download pages 1-4

Report Summary Order
Nigeria lies in the tropics and receives a tremendous amount of solar energy radiation which can be usefully tapped for various economic purposes. To effectively utilize the solar energy, it is necessary to have adequate knowledge of solar radiation levels in Nigeria in the form of tables and meaningful solar maps. The solar radiation maps presented in this report are based on direct solar radiation measurements and analysis of data from the Nigerian Meteorological Office records. In 1982, NBRRI established thirty experimental stations to measure the hourly and daily global solar radiation in various parts of Nigeria for a period of five years. Concurrently, climatic data from twenty stations of the Nigerian Meteorological office for thirty six years (1951-1986) were analyzed by means of empirical formula to convert into solar radiation data. The solar radiation maps are drawn from these two groups of data.

Click to open pages 1-4

Report Summary Order
Soon after its establishment, NBRRI undertook a review of urgent needs of the construction industry. One of the priority areas that emerged was the need to provide the various practitioners in the industry with vital information, data and parameters they need in the performance of their professional assignments. Perhaps the most glaring was the scarcity of climatological data for the design of buildings for thermal comfort. Such available were very limited and scattered in limited publications by overseas research organizations and one or two foreign books on tropical architecture. To remedy this situation, NBRRI decided to produce a single and compact publication containing all data available within the institute which are relevant to such design. This report presents such information in three sections; Section A deals with climatological data based on meteorological records for a period of over forty years. Section B contains solar positions, shadow throws and angles invaluable for design of louvres and shading devices. Section C deals with the application of solar times and sunshine duration to the design of roofs (horizontal surfaces) and walls (vertical surfaces). Typical design examples have also been provided.

Click to open pages 1-4

Report Summary Order
This report covers a phase of the institute’s research programme in which the main subgrade soils of Nigeria are investigated in an ordered manner to establish their engineering classification and properties. The information and data generated from the study includes results of detailed field and comprehensive laboratory investigations. In view of the high erosion potential in this area, this report is expected to serve as a useful tool for highway engineers in preliminary design and construction programmes.

Click to open pages 1-4

Report Summary Order
This report describes the use of the bump integrator as a simple and powerful tool for economically evaluating the performance of individual roads and for prioritizing roads for maintenance schedules. The bump integrator measures the road roughness which analyzed with other parameters can provide performance criteria for the road. In this report, three busy roads namely the Port-Harcourt – Enugu Expressway, the Ibadan – Lagos expressway and the Benin – Asaba Highway are investigated. This report is expected to serve as a useful tool for various road maintenance organizations in Nigeria.

Click to open pages 1-4

Report Summary Order
This project covers the second phase of the institute’s research programme in which the main subgrade soils of Nigeria are systematically investigated to establish their engineering classification and properties with regard to the planning, design and construction of roads. The first phase covered the problematic black cotton soils of North-Eastern Nigeria. The results of the investigation on the subgrade soils in the Federal Capital Territory are also described in this report. As a result of the high potential for accelerated infrastructural growth of the area, it is hoped that highway engineers will benefit tremendously from this publication.

Click to open pages 1-4

Report Summary Order
Road traffic accidents in Nigeria have reached such an alarming level that urgent remedial action must now be evolved to reduce them. Past efforts to reduce the high level of road traffic accidents were frustrated by lack of information on the factors that contribute to the accident process. This undesirable state of affairs was due mainly to current and uninformative method of recording road traffic accidents by the police in Nigeria. This method was developed by the police for purely criminal and was of very limited value in understanding the traffic processes. To rectify this situation, NBRRI, after a long period of perseverance, was able to undertake a pilot study of road traffic accident in Lagos state in1989. The outcome of this study is presented in this report and the unique feature of the report is the development of Road Traffic Accident (RTA) recording format which covers the main factors which influence the occurrence of road traffic accidents and which is also adequate for police use. The data obtained by this new RTA format, are analyzed by means of a computer programme developed for this purpose. The analysis has revealed some important and disturbing trends which can now be directly addressed to improve road safety in Lagos..

Click to open pages 1-4

Report Summary Order
The paper reviews the types and occurrence of limestone in Nigeria. Calcination of limestone and hydration of quick-lime are discussed. Method of manufacture of lime including the detailed procedures of loading and firing has also been given. Limestones from Nkalagu, Sokoto, and Ewekoro were chemically analyzed, and the strength and other properties of hydrated lime produced from Nkalagu limestone were investigated. A 2.5 tonne capacity vertical shaft kiln was designed for construction at the permanent site of the institute in Ota, Ogun State to further investigate the cottage production of lime on a pilot plant scale.

Click to open pages 1-4

Report Summary Order
This report provides in copious details the work done by NBRRI in determining the engineering properties of the subgrades in Bendel State for road design and construction. This is part of a comprehensive and long term programme in which the main subgrades covering the whole of Nigeria are systematically studied. Four previous reports covered the black cotton areas in North-east Nigeria, the soils of Rivers State, Imo state and the Federal Capital Territory. The data provided in this report are invaluable for the highway engineer and contarctor for planning, design and maintenance of highways in Bendel State (now Edo and Delta States). The report provides, within easy reach, data which otherwise will be most difficult to retrieve from many sources.

Click to open pages 1-4

Report Summary Order
As part of its programme to help professionals in the road construction industry, NBRRI initiated a long term programme to produce an engineering geological map of Nigeria for use in the planning, design and construction of highways. Such maps were hitherto not available in Nigeria. In view of the large area of the country to be covered, it became clear that the most effective method of executing this programme quickly and economically was the use of the new technology of remote sensing techniques. Accordingly, NBRRI decided to acquire the expertise in the use of remote sensing techniques.  This report illustrates the successful use of remote sensing techniques to evaluate a terrain for road design and construction. By this success, NBRRI has acquired a technology of great value and importance for the road industry and the institute is willing to share this technology with any professional who seeks its assistance in this field.

Click to open pages 1-4

Report Summary Order
In Nigeria, cases of building collapse abound and the rate of collapse has attained an alarming proportion. The cases leave gory tales of destruction of lives and properties and questions are usually asked and unconfirmed reasons for the collapse are levelled against unsuspected bodies or individuals involved in the construction processes. In some cases, probe panels are constituted to investigate collapse. Usually, experience and reports show that most of the questions asked in the event of a collapse are left largely unanswered. This study is aimed at addressing these and other issues related to building collapse in Nigeria by highlighting failure modes in buildings, identifying the causes of building collapse, determining the relevant preventive measures and creating a data bank for future use. The project will be executed in three phases; this is phase one and covers a study area of Lagos and Ibadan, which has been taken as a representative of the South-west zone. The other two phases will cover the North and eastern zones of Nigeria.

Click to open pages 1-4

Report Summary Order
This study focused on labour force utilization in construction which is one area often neglected in building construction processes but yet has a significant impact on the performance of any construction project. The neglect is due to the erroneous belief that not much can be done about labour force cost as it is dictated by market forces. Available literature has put the labour force cost at about 45% of building construction cost. Consequently, this study investigates the detailed effects of Labour force on work output/productivity and how these influence construction costs by identifying the remote causes for the increase in construction costs that are directly linked to labour, determining the minimum output of labour force per trade without mortgagaing quality, identify factors that can improve labour output and productivity, and proposing daily productivity rate per trade. The study revealed that many factors are responsible for low or high labour output. These include among other factors, the nature and type of contract, the type of supervisory personnel and the skill of the tradesmen. These factors when harnessed will lead to considerable labour cost reduction or savings in construction projects.

Click to open pages 1-4

Report Summary Order
This report presents the investigation results of a two-storey building which collapsed in Mararaba near Abuja. Mararaba is a sprawling urban development which, though located in Nassarawa State, has sprung up primarily as a result of the Nigerian Federal Capital city of Abuja. The competition for land for development and the cost of the commodity in the Federal Capital Territory drives investors to satellite towns within and outside the territory. Consequently, several building structures erected in such areas may be short of adequate regulation because of homeowners or contractors who want to cut corners. Following the investigation, it was concluded that the absence of geotechnical analysis meant for sizing the depth of foundations were arbitrary. The construction ignored structural design specifications in the sizing of the elements and reinforcements and provided slab thickness of only 90-100mm: clearly violating both limit states of design (ultimate and serviceability states) for a 6 meter spanning slab. The lapping of column reinforcement was below design provisions, thus pulling out at collapse while there is doubt as to whether columns and footings were ever provided at positions dictated in the structural drawing. These coupled with poor materials for concrete, too lean mix design and the apparent absence of technical supervision is identified as the causes of the catastrophe.

Click to open pages 1-4

Report Summary Order
In Nigeria, efforts at curbing this menace of building collapse appear to be uncoordinated, haphazard and sporadic. Initial interest and concern generated at the collapse of any building is hardly sustained, especially from professional bodies. It is in this light that NBRRI by her mandate has considered it necessary to look into the issue of building collapse in Nigeria and come up with possible remedies that could reduce the incessant cases to the barest minimum. This report contains the investigation of the collapse of 5-storey building (under construction) at (B Adenubi Close, Ikeja, Lagos. A team was setup to visit the site, ascertain through interviews, visual inspections and laboratory tests, the remote and immediate causes of the collapse. The team was also required to inspect documentations including drawings (if available) of the collapsed building and to interact with Municipal Regulatory Authorities with respect to the collapsed building. It was concluded that a combination of causes was responsible for the collapse; the concrete used for the construction work was of poor quality, regulations on construction process of allowing adequate curing period (21 days) before loading the next floor was not adhered to. Finally, the deliberate non-disclosure of information concerning the project and identities of its stakeholders by the State Physical Planning and Development Authority significantly negated the good intention of NBRRI to investigate the collapse with a view to unravelling the immediate and remote causes of the collapse in order to prevent future occurrences.

Click to open pages 1-4

Report Summary Order
The use of lime as a building material is well established in other countries. In Nigeria, however, the demand for quick construction with cement has led to the neglect of lime with its unique properties of workability, plasticity, reasonably good strength, and resistance to moisture penetration, freedom from cracking and long life. The production of lime in NBRRI and the establishment of lime production centres either at small or medium scale in the proximity of limestone deposits would impact on the national economy. This report primarily summarizes the origin, mineralogy, classifications and occurrence of limestone in Nigeria. It presents the preliminary data required for the exploration of the resource and conducts a few tests to qualify the types of lime limestones that can be harnessed for affordable housing in Nigeria. Though numerous simple tests like specific gravity, molecular weight, molecular volume and hardness, as well as visual specimen examination need to be done in future studies. However, this should be viewed as a first step in a work that should open windows of applications for affordable housing in Nigeria.

Click to open pages 1-4

Report Summary Order
Clays are complex materials that are of numerous applications as well as practical academic/research interest. Clays are used for a variety of products and purposes such as table ware, tiles, bricks, pipes and plumbing fixtures. Clays may also be used in insulation, medication, decolorants, concrete filler, paper sizing, furnace lining, filters, drilling lubricants, etc.  it is also worthy of note that in field applications in engineering construction, truly clayey materials could represent undesirable presence due to its compressibility characteristics and frequently, even expansion propensities, when in contact with moisture. The major commercial categories of clays are ball clays, refractory clays, heavy clay products also known as building or structural clays. A number of characteristics of clay are significant to the building industry because they determine their rational choice or applications for specific service conditions. This report presents results of a preliminary survey of some clay deposits in Nigeria in a study area of Lagos and Ondo States to identify locations where they are found and to determine their physical, chemical and engineering characteristics and compare characteristics with known standards. Based on their properties, suggestions were made on possible industrial uses of the clay samples collected. Finally, funding was a major issue that influenced the curtailment of sampling to fewer sites as well as the extent of tests conducted.

Click to open pages 1-4

Report Summary Order
This report examines the case of a collapsed building that occurred under construction, at a location along Coca-Cola road, Illorin, Kwara State, Nigeria. The building was under construction when it suddenly collapsed on 12th April, 2012 during the day at noon. The framed structure was proposed to be a two-storey building and its construction had reached the second suspended slab when it collapsed. The site was visited while the remains of the collapse were observed, materials used for the construction were examined and the soil condition was observed. The town planning authority in charge of approval of building was written in order to know the level of their involvement of the collapsed structure, while the architectural drawings were scrutinized.  The contractor and the client in the construction of the building could not be reached during the time period of these findings. The investigating team also observed and confirmed that the collapse occurred during the pouring of the first floor concrete, which suggests that the cause was as a result of poor scaffolding and inadequate support/props and arrangement. The issue of punitive measures that should be given to culprits was stressed. Proposed preventive measures were also suggested in the Nigerian context in order to reduce and possibly stop the incessant cases of building collapses.

Click to open pages 1-4

Report Summary Order
The total length of Nigeria’s road network is about 200,000km. Local Government Roads which are essentially rural and access roads, account for 70% of this road network. Of these only 2% are paved while 98% are unpaved. Paving these rural/access roads is usually expensive because the same type of heavy equipment deployed for paving highways are also used for rural/access roads. One of the key areas in which NBRRI made significant impact in recent years is the ‘‘Demonstration Projects’’ on the Construction of Rural/Access Earth Roads Using Community Based Construction Technology. This report describes the design and fabrication of Water-Bitumen Spraying Machine Fabricated from locally available Materials and made up of separate Water Tank and Bitumen heating/dispensing units. The sprayer is mounted on a Platform that is attached to a motorcycle that has been converted to a tri-motorcycle which is used to spray water for compaction and bitumen during road construction and maintenance. It is very ideal for cost-effective construction and maintenance of roads without using expensive conventional water sprayers and bitumen spreaders. Demonstration Access earth roads have been successfully constructed without sacrificing quality in many parts of Nigeria using this technology.

Click to open pages 1-4

Report Summary Order
The importance of cement and concrete products in the Nigerian construction industry cannot be overemphasized as it is one of the most versatile and widely used material in the construction industry. This implies that there is need to consistently verify the quality of cement and concrete products being used. Cube Moulds, Beam Moulds and Slump Cone Apparatus are simple robust equipment used every day in the construction industry. While the Cube Mould and Beam Mould are used for testing the strength of concrete and flexural strength of beams respectively, the Slump Cone apparatus is used for testing the workability of fresh concrete during construction. Unfortunately, all Cube Moulds, Beam Moulds and Slump Cone Apparatus in the country are imported. This prompted NBRRI to initiate in-house production of these simple devices, especially straight forward cube moulds. All these moulds and the slump cone were produced and successfully tested; the success of the test being in its rigid strength, ruggedness and smooth surfaces for de-moulding of the moulds or smooth flow of concrete through the slump cone. It has been analysed and the production of these items in Nigeria will save 30-40% from the cost of importation in addition to conserving foreign exchange. It is a simple innovation that government and entrepreneurs should patronize for Nigeria’s quest for industrialization, job creation and wealth generation.

Click to open pages 1-4

Report Summary Order
The collapse of buildings in Nigeria is a problem that has continued to constitute an unnecessary menace in the country. Numerous efforts by NBRRI in the past years have yielded several revelations in this regard. The efforts of the institute led to a full activity in May 2012 when the technical workshop on building collapse was hosted with very wide and comprehensive participation of stakeholders; and a complete proceeding of the conference has already been published by the institute. Even though this is no longer any major new insight to be gained in the visits to collapse sites, nonetheless it is important to continue to indulge in the analysis of all sites feasible for record purposes. This report has therefore even gone beyond the superficial routine of concrete and steel, into details of soil sampling and laboratory tests and analysis. It investigates a building collapse site located at No. 3 Ademola Awosika Road, close to the Living Faith Church Extension III. At the time of the visit, a team for the National Emergency Management Agency (NEMA) was met on site, rescue operations have been concluded at the site and most of the debris evacuated. Information for analysis was gathered through eye witness account, site evaluation, field tests (non-destructive), and laboratory tests investigation of the construction materials. As mentioned earlier, the rescue operation at the site had been concluded and most of the rubbles evacuated when the team arrived. Furthermore, the team could not lay hands on the Architectural and Structural drawings of the building. Based on the information gathered, the causes of the collapse could be a combination of one or more of poor quality materials, poor workmanship and lack of supervision, weak foundation, and failure of structural elements. Recommendations were also deduced and presented from results of the investigation.

Click to open pages 1-4

Report Summary Order
NBRRI has been conducting investigation of the subgrade soils of the Nation, from state to state, for the production of the digitized subgrade soils map. The objective of the program primarily give broad delineations that give overall guide as to the predominating soil classification in each of the areas. The technique used is not exactly random but some sort of representative sampling from each state based on equidistantly regulator spacing’s. The depth of samples are strictly limited to hand augering and borrow pit excavation depths of 0.5-1.5meters below ground surface. This report is focused on the study of the engineering characteristics of the subgrade soils of Kogi State, Nigeria. It was used to generate simple digitized subgrade maps which will be useful to road and highway designers.

Click to open pages 1-4

Report Summary Order
Speed is an important parameter in transportation engineering and in the analysis of traffic characteristics because it relates to time, comfort, safety, convenience and economics; hence in the determination of speed distribution of traffic stream in specific locations, spot speed studies are carried.  In this study, vehicle’s speed percentiles which are important in making speed related decisions are determined from the data collected in spot speed studies. The purpose of the study is to make comparative analysis of speed trends of divers during the day time and night time conditions along the inner ring road in the Abuja metropolis. This forms part of the analysis of traffic characteristics of the Abuja metropolis which is ongoing and also makes some comparison of the 85th percentile with the posted speed limit. The report presents the traffic condition on the Nnamdi Azikiwe to Murtala Muhammed expressway in Abuja. It was concluded that there was about 12.4 percent reduction in the daytime speed compared to night time speed; and that 80km/hr is suitable as posted speed limit for urban roads within the metropolis instead of 100km/hr during the day while 70km/hr is recommended during night. Also the speed distribution took a normal distribution based on the speed ration and the curves plotted.

Click to open pages 1-4

Report Summary Order
Polymers of different names and from different countries have in recent times been imported into Nigeria for use as stabilizing agents for tropical soils during construction. NBRRI conducted a contract research to evaluate the effect of the imported Nanotechnology-based polymer on the engineering properties of tropical soils. Four soil samples from Abuja were collected and subjected to testing at the NBRRI Materials Testing Laboratory, Abuja. In order to ascertain the effect of the polymer on the sampled soils, the investigation was carried out in two phases- determination of basic geotechnical properties of the untreated soils (index/classification and strength tests); and determination of strength improvements due to stabilization with the polymer. Based on results from the first phase, two soil samples (Sample 2 and Sample 4) were found to be non-plastic and did not meet the materials suitability criteria for application of the polymer, as prescribed by the product manufacturers. They would require further modification to bring them to meet the specified range. However, the other two samples (Samples 1 and Samples 3) fell within the range and were modified by adding 1% polymer by weight of soil. The results from the laboratory investigation show that the branded polymer is effective in improving the strength properties of the soil samples. It was observed that unsoaked CBR value for sample 1 increased to about four times whilst Sample 3 increased to about seven times. Similarly, the UCS of both samples improved by about five times. The results also show that the soil sample with the lower Plasticity Index PI (Sample 3) had a higher increase in strength properties compared to Sample 1. It was therefore deduced that the branded polymer tested can be used to effectively improve the strength properties of in-situ soils.

Click to open pages 1-4

Report Summary Order
Failures of flexible pavements (bituminous roads) have been prevalent in Nigeria which has raised great concern to both the government and road users. As part of its mandate, NBRRI deemed it necessary to carry out an investigation to determine the possible causes of such failures, and a case study was carried out on the Enugu-Port Harcourt dual carriageway in South-Eastern Nigeria.  This report covers an investigation of the extent to which the Enugu-Port Harcourt Expressway has deteriorated or failed; identify causes and proffer solutions. The investigation was conducted in several categories to determine the pavement characteristics such as properties of base, sub-base and sub-grade soils; traffic volumes by traffic counting; and characteristics of the type of bitumen used by cutting cores and extracting the bitumen for standard tests, such as Marshal Stability, flow, bitumen content, air voids, void mix aggregate and grading. Visual inspection of the pavement showed that due to the infiltration of both surface and ground water into the plastic shale sub-grade soil and overloading, cracks and potholes and structural base failure were very common for the whole stretch of the road. Traffic count data revealed a high volume of heavy vehicles with probably high axle load. As a result, there has been a tendency to exceed the maximum axle load limits. Flexible pavements deteriorate under traffic loads and climate effects. This fact, together with the revelation that the road is a very busy one as depicted in the traffic counts, poor sub-grade soil. Poor drainage system and high water table could be major causes of the road’s fast deterioration. The possible solutions could be to increase the thickness of pavement, use of concrete as base/sub-base, regular maintenance of the road, design of adequate drainage system, adequate supervision, etc. there will also be need for similar studies on other major roads in the country in order to recommend measures to elongate the life span of pavements.

Click to open pages 1-4

Report Summary Order
Providing adequate housing requires continuous research and investment especially inappropriate technologies that reduce the cost of construction and the cost to the environment. Compressed Stabilized Earth Blocks (CSEB) is one of such appropriate technologies. These CSEBs are basically lateritic soils which have been stabilized with cement and subsequently compressed in appropriate moulds. The formation of laterites is governed by the nature of the parent materials, topography, drainage conditions and climate; resulting in laterites of varying mineralogical compositions. The primary objective of this study was to ascertain the effect of mineralogical composition on the performance of CSEBs using laterite collected from the Federal Capital Territory (FCT) Abuja as a case study. Soil sample were collected from five identified borrow pits with the FCT. Preliminary geotechnical tests were conducted to determine the engineering properties of the soils before producing tests cylinders at varying cement contents (0-8%) and then determining the performance characteristics; compressive strengths (wet and dry), density and water absorption. X-Ray Diffraction (XRD) analysis was carried out on the specimens in order to determine their mineralogical compositions. The results from the study show that the soil samples consist of varying proportion of quartz and kaolinite alongside other materials. The statistical models developed show a significant correlation between quartz content and some performance characteristics of CSEBs (e.g. compressive strength and water absorption). However, the same models also show that changes in the kaolinite content may not be associated with changes in the compressive strength and water absorption. Hence, kaolinite content may not be a dependent variable of these parameters. The results of this study provide baseline data with regards to the characterization of laterites as further investigations needs to be conducted on laterites from other parts of the country.

Click to open pages 1-4

Report Summary Order
NBRRI has on many occasions, intervened to unravel reasons for the collapse of buildings and roads in order to provide case-history documentation for literary application to avert future failures. Usually, in-situ tests were conducted and specimens processed for laboratory tests and analysis. As time progressed, the institute considered the interventions as monotonous since no new insight and benefits of knowledge were being obtained anymore. Findings of most collapse cases were primarily pointing to poor materials application, especially concreting, undersized foundations, lapping deficiencies, etc. which led to conclusions of poor supervision and construction, lack of regulation, etc. Recently, a lot of the building collapse investigation activities have been to visit every collapse site and to critically observe whether there is a new patter of interest. However, the collapse of the Synagogue Church of all Nations (SCOAN) in the 2nd week of September 2014 was peculiar. The number of lives lost outstripped the total number of deaths due to similar mishaps in 2011, 2013 and 2014 put together. There had been a conflict between spirituality and factuality, considering the mystical nature of the operational application of the building. Ultimately, the decision had to be made to conduct a comprehensive scientific/technical investigation. This report presents the results of the inspections, tests analysis and deductions by a wide array of experts that cut across professional boundaries in the built environment. The report contains details of the first principled investigations and analysis that included digging/excavation and inspection of subsoils and sub-structural elements, back analysis, in-situ and laboratory tests, etc. During the investigations, inquest by the Lagos state Government and the strong support of the Council for the Regulation of Engineers in Nigeria (COREN) made the report worthy of commendation as well as being a source of information to the general public.

Click to open pages 1-4

Report Summary Order
The collapse of the Abu Ni’ima Islamic School building, along Gero road at Bukuru, Jos South LGA, is the first significant major building collapse in Plateau State. This report presents the findings of the investigation into the cause of collapse of the structure. A team was set up to carry out the investigation which comprised of professionals from different backgrounds such as Civil Engineers, Builders, Architects and even Sociologists. The team observed that the major portion of the school building that collapsed were two classrooms at the first floor level, the general hall at ground floor level, the stair hall and a large portion of the roof after manifesting clear signs of structural botch within its fabric. There was also no project billboard or sign post hence no information was available on the identities of the client, consultant or contractor. Based on site observations, the Schmidt rebound measurements and the various laboratory tests carried out on the school building, the cause of the building collapse was ascertained. The structure was originally a bungalow but was converted to a storey building hence the structure collapsed due to a combination of factors that include; Lack of Working Drawings, No statutory approval/permission, lack of supervision by professionals, the use of substandard and inadequate materials, poor workmanship, inadequate foundation type for structure and failure of structural elements.

Click to open pages 1-4

Report Summary Order
Nigeria ranks amongst the countries with the highest Road Traffic Crash (RTC) rate globally. To reduce this trend, the Federal Government of Nigeria (FGN) proposed the National Road Safety Strategy (NRSS) 2014-2018. This document has the Road Safety Audit (RSA) as a strategy for providing safe infrastructure and mobility. RSA is a powerful, low-cost tool for the quality and safety assurance of road traffic systems, made up of human, vehicles and the road environment. RSA was carried out on a 5.3km section of the Nnamdi Azikiwe expressway – from the approach to Berger flyover (Utako District) from Mabushi to the roundabout before Area 1 (Garki District). The audit revealed significant challenges and peculiarities on the road. It was observed that basic Self Explaining Road (SER) features were not present and some were in need of repair or replacement. There were deficiencies with direction signs and design of the median on the expressway exposed the grating, lighting and other pole-mounted infrastructure to car crashes. Some of the lighting posts were unforgiving. The destruction and vandalism of gratings around the pedestrian bridge allowed for the observed crossing of the road by pedestrians without using the available pedestrian bridge. It was also observed that the posted speed limits were not enforced while some electronic warning signs and street lights were non-functional at night. From the results of the RSA, suggested improvements to the expressway were recommended in order to achieve the goals of safe infrastructure and mobility on the road stretch.

Click to open pages 1-4

Report Summary Order
This study investigates the quality of Ordinary Portland Cement brands available in the market with a view to assessing their conformity to specifications as stipulated in the Nigerian Industrial Standards (NIS). Eight brands of cement available in Nigeria were tested for standard consistency, setting times (initial and final), soundness, fineness and compressive strength. Test results analysed suggest that most cement brands comply with the NIS specifications for standard consistency, setting times and soundness. However, Cements 2 and 5 failed to meet requirements for fineness with percentage retention values of 11.55 and 13.85% respectively exceeding the required standard of a maximum 10%. Also, Cements 3 and 5 failed to meet requirements for compressive strengths at 28 days as Cement 3 failed by a 0.47 N/mm2 margin yielding 32.03 N/mm2 as against the required 32.50 N/mm2 while Cement 5 failed by a more significant difference of 16.73 N/mm2 yielding 25.77 N/mm2 against 42.50 N/mm2. It was also established that the fineness of cement influenced the compressive strength; Cement 1 was the finest and yielded the highest strength of 53.63N/mm2 in 28 days while Cement 5 was the least fine and yielded the lowest strength of 25.77N/mm2. A correlation between fineness and compressive strength at ages 2, 7 and 28 days respectively was also established and a linear regression analysis was done to further buttress this relationship. The results of this investigation conclude that most cement brands comply with NIS specifications but there is however the need for routine monitoring of cement brands to ensure that the manufacturers maintain a uniform and consistent production line in Nigeria.

Click to open pages 1-4

Report Summary Order
In Nigeria currently, the dynamics of housing shortage, cost of building materials, sustainability ideals, technology and competition have brought about the need to employ innovative and alternative building materials in construction that would reduce cost of building houses while maintaining a socio-economic and an eco-friendly impact on the society. Bamboo is a renewable, durable, energy-efficient and environmentally friendly raw material that has the potential to substitute timber applications and compete with existing building materials in the construction industry. The current utilization of bamboo in construction in Nigeria is only a minute fraction of its boundless potentials. The primary objective of this study is to explore the use of bamboo as walling and ceiling panels. It involved processing round bamboo culms to produce Laminated Bamboo Panels which, on the basis of its properties, will favourably compete with conventional ceiling panels presently used in the Nigerian construction industry.  Round Bamboo culms were sourced from within the federal Capital Territory (FCT) Nigeria, processed into strips round culms, treated using the traditional and chemical treatment methods to improve its durability and performance. Treated strips were dried and glued together in stacks to produce bamboo laminates that were used for production of Bamboo Ceiling panels of dimension 900 x 360 x 15mm interlocked together using the tongue and groove joint. This research has demonstrated the potentials of the utilization of processed bamboo for various applications in building construction. Laminated Bamboo Panels produced are aesthetically appealing and durable. Further investigation would however be required to establish its performance potential.

Click to open pages 1-4

Report Summary Order
This report summarizes the assessment carried out as a result of the public outcry of the degree of safety of the Tamburawa Bridge in Kano State. Visual inspection, survey assessment, soil samples, investigations on mining activities and concrete strength tests were carried out to ascertain the safety condition of Tamburawa Bridge. It was concluded that the soils in the river Challawa are predominantly sandy soils with little or no clay which contributes to scouring (washing away) of the river bed around the piles. The scouring of the river bed could also be attributed to the change of water course. Farming within the vicinity of the bridge embankment and mining activities downstream of the river also lead to scouring of the river bed thereby exposing the piers foundation. The compressive strength test result of all the bridge elements shows that they are satisfactory. The assessment recommended the lengthening of the drainage pipes to prevent further corrosion of the steel members. The use of sand blasting and repainting of the steel beams was also recommended to protect them from further corrosion. Maintenance of cracks on the wing wall, pile caps and the reinforced concrete pile should be carried out, the use of sheet piles filled with compacted sand or concrete apron around the exposed piles to protect the foundation was recommended. Laws guiding mining activities should be enforced in the area to restrict collection of sand. Shoreline protection measures should be used in protecting the bridge embankment. The original bridge design should be sought out from the government to know if it’s end bearing piles or skin friction piles or both which will strongly determine the overall safety of the bridge.

Click to open pages 1-4

Report Summary Order
The collapse of a major structure that was a combination of reinforced concrete frame supporting an auditorium roof of steel trusses freely spanning nearly 70.0m in some directions is disastrous even if only in economic terms. However, the fact that it occurred during a major activity when it was full, during service, made it a calamity. The sympathy of the Federal Government of Nigeria which supports our intervention therefore goes out to those whose relations and friends lost their lives or were injured at the Reigners Bible Church. Two reports were produced; first was a preliminary report while a second visit was approved by the commission of enquiry following complaints raised which informed a final report. This report presents the findings of both reports form the site visits, through detailed investigation of the structural elements to presentations to the Judicial Commission of Enquiry. Several subcommittees were set up to investigate the various parameters (both structural and legislative) associated with the building and make submissions accordingly. Following the analysis of all the results, it was concluded that the collapse was a case of improper management of all the processes involved in the building production. The two structural engineering drawings submitted for the steel roof were not eventually used for the actual construction. During construction, there was a disastrous mix up of the structural steel sections used to fabricate the trusses with weaker sections being used to construct the longer span trusses. The quality of work at the column heads was unprofessional. No professional engineer was engaged to supervise the project. This was clearly a case of disaster waiting to happen. Clients and development control offices of the government should do more to ensure that this does not happen again.

Click to open pages 1-4