Construction Technology and Management

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Modeling Raw Material Inventory Control and Delivery of Ready Mixed Concrete to Sites in Addis Ababa
(Addis Ababa University, 2023-06) Seyfe Yihenew; Abrham Assefa (PhD)
Due to the city's booming construction, ready-mixed concrete is gaining wide recognition and has a high demand in Addis Ababa. Since these operations are performed in a highly uncertain environment, making planning and operating difficult and complex. So a supply chain management system is needed to form a consumption pattern for the raw materials of RMC and delivery of RMC. Inventory and delivery are the most important among the several management plans and decisions in RMC batching plants, such a raw material inventory control system of RMC batching plants could be applied as an approach for optimal estimation of the reservoirs required for storage of raw materials and to reduce the effect of uncertainties on delivery operations. This research aims to develop an integrated raw materials inventory model with a simulation model for the delivery of RMC to sites in Addis Ababa. The data sources used in this research are observation and financial reports using a case study plant and delivery sites. A raw material inventory model was developed through Economic Order Quantity (EOQ) model and the developed models are predicted using Artificial Neural Network (ANN). As a result, the testing predictive analysis results confirmed that the ANN predictive had higher accuracy in the prediction of the optimal order quantity and reordering point (ROP) of raw materials with an accuracy measurement value of 0.98 R and 0.2935 MAE and 0.9998 R and 0.2935 MAE for EOQ and ROP of Aggregate, 0.9831 R and 0.418 MAE and 0.9999 R and 0.1673 MAE for EOQ and ROP of Sand, and 0.9951 R and 1.6512 MAE and 0.9828 R and 6.1731 MAE for EOQ and ROP of Cement. Additionally, 63.35%, 76.47%, and 11.27% reductions have been obtained in the estimation of the optimal size of the required reservoirs for aggregate, sand, and cement respectively. Discrete Event Simulation (DES) was used to develop RMC to site delivery model. The study involved close observation of 182 concrete truck delivery cycles taken from two sample projects, which cover 50.89% of the overall yearly (2014 E.C.) concrete delivery of the case study plant. And EOQ-based ANN predictive analysis maximum consumption output results were used to get the maximum delivered amount of concrete used for the analysis of DES, the predictive output result was 1307.33 m3. Finally, an overall simulation output result, which is optimal by assigning 8 numbers of trucks, with an overall production rate of 0.025 TL/min (10.74m3/hr.) and 0.032 TL/min. (13.75 m3/hr.) respectively for the truck and mixer are established.
Identification of Determinant Factors for Contract Administration in Ethiopian Roads Administration Gambella Area Projects Management Office
(Addis Ababa University, 2023-11) Yeshidinber Ketema; Abraham Assefa (PhD); Derese Birbirsa (Mr.) Co-Advisor
The objective of the study is to identify the Determinant Factors for Contract Administration in Ethiopian Roads Administration Gambella Area Projects Management Office. The study prepared five scale based questionnaires and distributed to 141 sample populations and was analyzed using descriptive statistics, correlation and regression analysis. The descriptive and frequency analysis, interview response, meta-analysis and case study showed that documentation, resources, claim and dispute management, risk management, project process management, communication, project closure and stake holders are important in contract administration. The correlation analysis also showed that at significance level of 0.000 contract administration has high positive correlation with claim and dispute management (.769), moderate positive correlation with documentation (.651), project closure (.622), Risk Management (0.616) and project process management (.543) and low positive correlation with communication (.488), resource (.398) and stakeholder management (0.052). The regression analysis on the other hand showed that documentation, project closure, claim and dispute management and project process management have significant effects on Contract Administration with significance value of 0.001, 0.000, 0.000 and 0.006 respectively and, the coefficient significance value of communication (.134), resource (.147) and stake holders (.101) are significant at above 10% significant level and that of Risk Management (0.416) at 41.60% in which the variables have a significant relation with contract administration. In addition the foregoing; meta-analysis has been carried out to identify the best suit study among the similar perspective studies. Finally, the study recommends that recently launched ERA‘s various Manuals, Guidelines and Reports shall be properly implemented by the parties in the contract, better Communication scheme shall be devised among the parties, timely certification of Payments, assignment of qualified personnel for the works, establishment of strong Workshop, deployment of proper machineries both in number and quality, proper Stakeholder Management, Proper Risk Management, due consideration shall be given for the road at the Design Stage notably Design shall be done in due consideration of the actual site scenario, and last Security issue shall be resolved in the project vicinities.
Application of Load Bearing Brick Wall for Low Rise Condominium Projects in Ethiopia and Assessment of Locally Produced Bricks
(Addis Ababa University, 2017-07) Betelhem Bayou; Abraham Assefa (PhD)
Bricks are one of the oldest building materials in construction. Application of bricks in construction of Ethiopia is not new. They are used for construction of internal and external walls in all over the country. Once more brick is commonly used building material; however, there is a tendency to use brick masonry more as cladding and in-fill material rather than as a structural material. In order to solve the housing problem in Ethiopia, saving-house condominium projects, realestates, and private residential buildings have been constructed in many regions of Ethiopia for the past decades, there is also a bigger plan set by the government for the next GTP. From the past experience of building projects, wastage of materials, unsafe construction process, poor quality of output, high time and cost overrun, and risk of failure due to structural errors and mistakes made during construction process have been observed. The objective of this study is to assess locally produced bricks quality and availability to recommend a load bearing brick wall construction for low rise residential building and compare the cost with concrete frame structure building of the same plan, form and story. Over centuries, the utilization of bricks in construction has evolved significantly. In developed nations, bricks have emerged as the primary load-bearing system for various types of buildings, spanning from modest single-story residences to relatively tall commercial and industrial structures. Extensive analysis conducted on developed countries showcases the cost-related benefits of employing bricks. Additionally, brick walls exhibit excellent thermal insulating properties, leading to reduced fuel consumption and manufacturing energy expenditure. The analysis establishes that a three-story load bearing building can be built from locally produced fired clay bricks. There is also overall saving in both materials and cost when using load bearing structure instead of reinforced concrete of the same selected apartment building. The encouragement of the load bearing structure will result in the establishing number of modern factories for brick and clay product in Ethiopia.
Web- Based Application for Activity-Based Construction Cost Control in Selected Building Projects in Addis Ababa
(Addis Ababa University, 2023-04) Hanna Hailemicheal; Abraham Assefa (PhD)
Managing cost is the most important aspect in a construction project as it is an integral and sensitive part of a construction. The activities of contractors, subcontractors, and suppliers are dependent on the consistency of cash flow management of a construction project as it helps in determining how much money is profited after a project completion. If not, it can induce financial constraint or may lead to subsequent claims. However, in Ethiopian Construction Industry, the cost estimation method is usually not linked to the cost management and control mechanisms. In addition the current practice does not offer insight how to value projects or predict price for future bids. Furthermore, it is limited in supporting decision-making and performance control during construction. Current construction projects are also characterized by cost overruns and delays due to inefficient cost controlling processes besides other factors. This study develops a web-based Activity-Based Cost Controlling System by recording actual costs of onsite activities, analyzing and comparing it with budgeted cost, throughout a construction project life cycle to improve the project cost performance. The system uses a centralized database system to store actual cost information collected for each activity using cost codes (of which many activities in building construction share, the system records the daily executed quantities, the material, labor, equipment, and subcontract costs of each activity and analyzes to calculate the direct costs). A backend program is developed using PHP (Hypertext Preprocessor) that integrates the cost information and the tender price (unit price) of each activity to compare it with the actual cost performance and finally provide performance reports that are automated for control of cost. The web-based application is tested using data from three building projects from different contractors and was found to be close to actual cost. Aside from creating performance reports, the web-based application can provide data on the activities’ start and finish dates, and cost information for activities including labor productivity and composition. The result of the study has shown that this web-based application facilitates automation, control, and follow-up of the cost controlling process for contractors.
Assessment on the Impacts of Material Management Practices in Addis Ababa Con-dominium Housing Projects Performance
(Addis Ababa University, 2023-05) Mahlet Abebe; Abebe Dinku (Prof.)
Numerous studies have revealed that the cost of building materials and equipment may ac-count for more than 70% of the overall cost of a typical construction project. As a result, good management of these two factors enhances a project's quality, on-time completion, and cost effectiveness. The main problem with condominium housing in Addis Ababa is poor project performance. Analyzing the effects of material management procedures in Addis Ababa condominium housing complexes was the goal of this study. A questionnaire survey, interview, site observation, and case study were carried out. In this research, a total of 74 questionnaires and 12 interview respondents participated. The data obtained from the questionnaire were analyzed using SPSS. The study indicated that there is poor material management practice in Addis Ababa condominium housing con-struction project sites. The study identified major causes of ineffective material management practices. And iden-tified measures for effective material management practices like using technologies to fa-cilitate material management on the projects, preparing material takeoff from drawing, preparing the detailed and accurate bill of quantity, preparing drawings in detail. The study also indicates that ineffective material management practice has a negative im-pact on the project performance of Addis Ababa condominium housing construction pro-ject sites. Some impacts identified are added costs over and above those initially agreed contract amount, fewer returns on investment, higher rental prices to the end user, loss of profits to the contractor, delay in the progress of the work, claims, and termination of pro-ject, failure and defects, loss of productivity of work and rework due to improper quality and mistakes.
Assessment On The Factors That Cause The Delay Of 40/60 Housing Project Constructions In Addis Ababa: A Case Study of Ayat Condominium Project
(Addis Ababa University, 2022-10) Melen Kassu; Abebe Dinku (Prof.)
In search of a greater standard of living , a big population is currently moving from the rural area to the urban city. The expense of life and price of land have consequently increased significantly. As a result, the government has started constructing affordable homes for those with low and intermediate incomes.Nevertheless, despite having a contract duration of 730 calendar days, a total of 33,316 homes are still being built (AAHDC, 2021), despite an average of 5000 days having passed since the anticipated completion date. Accordingly,due to the rising rate of inflation and price increases, as well as the time that could be used to build other types of public infrastructure, this delay causes a major loss for both the government and the end users. Hence, the primary goal of this study is to identify the elements that influence the timely completion of 40/60 housing projects by taking Addis Ababa's Ayat condominium site as case study. In particular, the study examines the link between the dependent variable (time overrun) and the independent variables (such as labor skill, monitoring & control subcontractor/ speciality scarcity, communication problems payment delays and subcontractor negligence).This was studied using a control,subcontractor/speciality scarcity, communication problems, payment delays, and subcontractor negligence). This was studied using a mixed-methods approach (quantitative and qualitative), with a casual and explanatory research design. Professionals from contractors, consultants, and clients of ongoing 40/60 condominium housing developments Ayat site in Addis Ababa are the study target groups. A total of eighty (80) samples were taken from which sixty three (63) were collected. A stratified sample technique was used to choose respondents. Both descriptive and inferential statistics were used to determine the variables influencing the timely completion of the housing projects. In the case study, manpower skill, monitoring and control, subcontractor shortage, communication problems, payment delays, and subcontractor negligence were found to be statistically significant after analysing the data using SPSS.As a result, it is anticipated that the results of this study will be of great significance to the housing development program and its stakeholders, enabling them to better understand the factors that influence the timely construction of housing and to identify measures and solutions that will improve the provision of housing in the required quantity and quality. Additionally, it will help home-owners and end users decide what elements to take into account when choosing affordable housing.
Study on the Application of Just-In-Time Philosophy to Construction: A Case Study of Reinforcement Bar Production and Delivery System
(Addis Ababa University, 2023-05) Ruhama Girma; Abraham Assefa (PhD)
In cities like Addis Ababa, storage and working space are usually inadequate for construction projects. Construction materials like rebar require a lot of space for storage and production. For the temporary storage and production of rebar, some firms had to pay extra to rent space. Also, some use the roadside for storage and production areas. Furthermore, most activities performed during the construction process do not add value to the project but incur unnecessary costs and time that affect the project's performance. Therefore, this study intends to analyze the rebar production practice and explore whether applying the just-in-time concept to the rebar production and delivery system would be advantageous from the perspective of value. To achieve the study objective, case studies were carried out on two contractors. The contractors were selected based on their approaches to rebar production. The first one uses the on-site rebar production method, while the other contractor uses off-site rebar production with JIT delivery. The data collected from case studies was analyzed using descriptive analysis and by developing a discrete event simulation model. Finally, the study's findings revealed that there is a considerable amount of non-value-added and necessary but non-value-adding activities on site during the production of rebars. According to the simulation analysis result, off-site rebar production with JIT delivery is shown to decrease rebar production time, increase productivity, and decrease idleness of labor and machines. Additionally, the study revealed the motivating and challenging factors for JIT implementation. In general, on the basis of value, applying JIT to rebar production and delivery is efficient. Thus, it is important for construction companies to start considering the benefits of this production and delivery system.
Assessment of Construction and Demolition Waste Recycling Practices on Selected Buildings in Addis Ababa
(Addis Ababa University, 2023-05) Semhal Gebremedhin; Abraham Assefa (PhD)
Construction and demolition waste accounts for a significant portion of global solid waste production, with the majority of it ending up in landfills. Parallel to the rise in environmental consciousness, there is a growing awareness of waste issues all over the world. As a result, developing some construction and demolishing waste management solutions has become important. The objectives of this study is on examining the major building construction and demolishing waste materials, current practice of building construction and demolishing waste recycling, and testing the identified major building construction and demolishing waste material on selected buildings in Addis Ababa. The quantitative data gathered from the questionnaire was analyzed by straight forward percentages and frequency using SPSS. All other categories of respondents' interviews and responses/opinions to open ended data have yielded qualitative data and were summarized. The findings of this research revealed that most contractors try to reuse materials before disposing them but do not consider recycling at the site as an option; in terms of recycling, 4% of contractors said they recycle the waste from building construction and demolishing. And as for the amount of wastage from building construction and demolishing, HCB and cement take the first and the second place with 30 and 26 percentages respectively. The study also carried out laboratory test to compare the density and compressive strength of HCB with 50% replacement of its course aggregate with recycled HCB and HCB with standard mix which the HCB with 50% replacement yielded approximately close result to the HCB with standard mix. The study also found that contractors believe that by raising awareness, building recycling plants, and providing government incentives, recycling building construction and demolishing waste could be taken as an option by most contractors also potentially attracting private investors to invest in recycling factories
Assessment of Physical Properties of Ambo and Jema Sand and Evaluation of Their Performance as Fine Aggregate in High Strength Concrete
(Addis Ababa University, 2023-06) Shimelis Gemechu; Biruktawit Taye (PhD)
In Ethiopia, the construction of high-rise buildings, long span bridges and complex concrete structures which make use of high strength concrete is becoming common in recent times. In order to meet the ever increasing demand for fine aggregate in concrete construction, an alternative to the river sand is inevitable as river sand is quickly depleting and its quality from time to time is becoming questionable. The use of sand stone as a replacement to the fine aggregate for the production of High strength concrete in Ethiopia is an important study area since sufficient research on detail engineering characteristics and performance is not yet fully investigated. In this research, the performance and rate of strength development of high strength concrete made from sand stone sampled from Ambo and Jema river basin is studied. In addition, a comparison of strength development of High Strength Concrete was made between the sandstone fine aggregates and river sand (control sand). The experimental concrete is prepared and mixed in two separate sizes of coarse aggregate, 19 mm and 12.5 mm nominal maximum. The corresponding water cement ratio for 19 mm coarse aggregate was 0.27 and for the 12.5 mm coarse aggregate it was 0.29. Chemical admixture was used for all the concrete mixes in proportion to the cement content. The control concrete mix has attained the target strength for C70, C80 and C90 when 520 kg, 550 kg and 580 kg of cement per metric cube of concrete used and when 19 mm coarse aggregate used whereas it has not attained the C90 strength when 12.5 mm aggregate used. Concrete made with Ambo sand has attained the target strength of C70, C80 but failed for C90 for both types of coarse aggregate when used in the mix. Concrete made with Jema sands has not attained the target strength of C70, C80 and C90 for same amount of cement and coarse aggregate sizes that was used for the control mix. For Ambo sand concrete, when 19 mm aggregate is used, the percent of the compressive strength against the control concrete is 96.4%, 96.6%, 96.1% for C70, C80, C90 and it is in order of 97.1%, 97.7%, 94.4% when 12.5 mm aggregate used. The percent of the compressive strength of Jema sand concrete against the control concrete when 19 mm aggregate is used is 90.8%, 87.6%, 85% for C70, C80, C90 and it is in order of 89.5%, 87.5%, 87.3% when 12.5 mm aggregate used. The flexural test values, the modulus of elasticity values and mortar strength test results of concrete made from Ambo and Jema sands have met the requirement while Ambo sand produces a concrete with marginal increment than Jema sand. From the cost computation, to produce a unit volume of high strength concrete, the cost of concrete made from Ambo sand is 3.26% cheaper than Jema sand and it is 1.16% cheaper than the control sand.
Utilization of Crushed Ceramic Waste Tiles as a Partial Replacement of Coarse Aggregate in Cement Concrete Making
(Addis Ababa University, 2023-02) Temesgen, Kassahun; Abebe, Dinku (Prof.)
The main goal of sustainable construction can be greatly advanced by using waste materials in the production of concrete. Ceramic materials are being used more frequently in new projects as electrical insulators, sanitary fitting, and tiles, among other things. However, ceramic materials produce a significant amount of waste during production, transportation, and installation due to their fragility. As a result, this research outlines an experimental investigation of utilization of crushed ceramic waste tiles in cement concrete making by substituting the coarse aggregate. Before undergoing the ceramic wastes through the fundamental physical tests, they were manually crushed with a Ball-peen hammer and sieved. As part of the research, concrete-making materials (coarse aggregate, fine aggregate and crushed ceramic tiles) were tested in the material laboratories. Concrete mix designs for the C-20 and C-25 grades of concrete were produced using the ACI 211.1 mix design procedure. Each concrete grade’s natural coarse aggregate was replaced with crushed waste ceramic tiles at weights of 10%, 20%, and 30%.To compare test results with those obtained by partial substitution. A control mix of 0% crushed and sieved ceramic tiles was made. For the C-20 and C-25 classes of concrete, a total of eight concrete mixes including the control samples were produced. Each grade of fresh concrete was subjected to a slump test and fresh concrete density. Compressive strength, conducted on the seventh, fourteenth and twenty-eighth day, whereas the flexural strength, and splitting tensile strength tests were done on the twenty- eighth day. The results of the partial replacement of ceramic waste tiles tests were obtained to be marginally higher than those obtained by the control mix. After examining the results, it was established that the percentage of residual ceramic tiles to incorporate into the concrete mix that results the highest strength is 20% for C20 and C25 concrete classes. The overall findings of the results showed that incorporating waste ceramic tiles partially as coarse aggregate improved the compressive strength, split tensile strength and flexural strength.
Influence of Mineral Fillers on Short Term Ageing Characteristics of Asphalt Mastics
(Addis Ababa University, 2022-02) Hizbawi, Sisay; Abubaker, Ahmed (PhD)
Asphalt pavements’ deterioration due to asphalt binder ageing has been a subject of many researches. Different aspects of ageing, its causes and prevention mechanisms were the main focus in this researches and asphalt mixtures, mastics and neat binders have been in use for these purposes. Among these material mixtures, asphalt mastics were found advantageous for they resemble asphalt mixtures better than neat binders and relatively cost less during production than asphalt mixtures. One way to reduce effect of ageing with mastics is to use appropriate mineral fillers with chemical properties to reduce chemical products of ageing or have physically capability to adsorb the molecules formed during ageing. In order to address this issue in more feasible way, this paper presents experimental tests conducted to investigate the effect of using unconventional and abundant filler materials (OPC, PPC, red brick powder and wood ash) as a substitute to a conventional (limestone) filler on the industry to lessen the effect of short-term ageing. Chemical, microscopic, mechanical and rheological tests are conducted on a 60/70 bitumen, the conventional and unconventional fillers as well as on mastics produced from the combination of bitumen and different filler proportions. The results are presented in terms of FTIR spectrums, microscopic images and complex shear modulus (G*) master curves. Consequently, the results suggest that all the fillers have a mitigating effect towards short-term ageing as the offsets in master curves of aged and unaged mastics are less significant than the neat binder. Furthermore, some of the fillers (red brick powder in an excellent way, OPC and PPC in a medium manner) have the desired characteristics to effectively replace the conventional filler used as reference while wood ash filler has relatively the worst characteristics to serve as a replacement for limestone filler.
A Study on Assessment and Comparison of Schmidt Rebound Hammer Test Result Against Uniaxial and Core Test of Concrete
(Addis Ababa University, 2022-06) Solomon, Tibebu; Abebe, Dinku (Prof.)
Concrete is a mixture of cement, coarse aggregate, sand and water. This mixture is expected to form a homogeneous material with predictable strength behavior. However, it is very difficult to develop a model to correctly evaluate its onsite strength properties. Common methods used in evaluating and estimating concrete structures are uniaxial compressive strength; core test; and rebound hammer test. This research presents the assessment of compressive strength of cocnrete using rebound hammer, core test and uniaxial compressive strength test to develop relationship between these methods. In this study, cube samples, rebound hammer reading and core samples were extracted from the concrete slabs casted both from two control mix slabs and from four selected project sites for this analysis. Rebound hammer reading and core drilling operations were performed from the casted slabs the same data were collected from rebound hammer versus the project sites under investigation. Descriptive statistical data analysis such as the mean and standard deviation were computed between hammer versus cube and core versus cube strength. The relationship obtained from the variables is expressed as compressive strength of core is 0.732844 times cube strength and compressive strength of rebound hammer 1.11612321 times cube strength and compressive strength estimated from rebound hammer is 1.5241 times compressive strength of core.
Review of Design and Construction of Rigid Pavement in Hot Weather Area: The Case of Ditchoto Galafi Junction-Ellidar-Belho Road Project, In Ethiopia.
(Addis Ababa University, 2022-06) Ermias, Fekadu; Abrham, Gebre (PhD)
Most major road networks in Ethiopia are constructed with flexible pavement, this type of pavement used as the only option considered during the pavement type selection process for many years. Rigid pavement structure which distributes loads to the subgrade having, as the main load bearing course, a Portland cement concrete slab of relatively high-bending resistance, is considered as an alternative option for the first time in Ethiopia with a total length of about 80Kms and a thickness of 40cms in hot weather area, Afar Region. The purpose of this thesis was to review the Design and construction of rigid pavement in hot weather area: The case of Ditchoto-Galafi Junction –Ellidar-Belho Road Project. Ditchoto Galafi Junction- Ellidar- Belho Road project 80kms long located in Afar Region is the first of its kind to be built with Rigid Pavement in Ethiopia, the maximum temperature will vary from 27oc to 52oc and the annual rainfall is about 500mm.The design of this Rigid pavement has been reviewed briefly against the standard of Ethiopian Roads Authority (ERA) Pavement Design Manual. The findings of construction of Rigid Pavement Road in hot climate area are: water is scarce and full of salt, long hauling distance of concrete from batching plant, how to minimize thermal crack and shrinkage in this hot climate, long hauling distance of concrete which affects setting time of concrete, the manpower is new for construction of rigid pavement having long distance. The recommendation includes provision of Special Equipment like water treatment plant, Chiller machine for cooling, Deep water well (>500m) drilling machines, large Concrete batching plants, 40cm thick Paver and Bulk Cement trucks. Modified cement and different admixtures including curing compound has been used in the mix design to withstand the hot weather and heat of hydration. Special construction methodology has been used like night time concrete paving. The design can be reviewed comparing the results obtained by ERA manual and AASHTO procedures, mix design optimization has to be made to incorporate the challenges, water treatment plant should be used to de-saline the water, and Chiller machines are required to reduce the temperature of water drilled out from wells of 500m depth in order to use for concrete. The study can be used for similar projects to be built in our country since it will be better to use local cement than importation of bitumen with foreign currency and also it has less maintenance cost with longer design life.
Building Performance Simulation in Design Phase: A Case for Construction Consultants in Addis Ababa
(Addis Ababa University, 2022-05) Michael, Teshome; Abraham, Assefa (PhD)
Building performance analysis at the design stage enables assessing the building's performance and the variables that influence it. Simulating the performance of a building by visualizing how the building will react in response to excitation in a virtual environment provides designers and respective stakeholders vital information in the decision-making of buildings. Nonetheless, a common practice in Ethiopia indicates that an emphasis is placed on how the building appears and is constructed in the project's design phase rather than how the building will accomplish its intended function and performance requirements. Despite the longevity of buildings, analysis of how the building will operate and perform its intended function is seldom. This research aims to study the existing practices of building performance simulation for buildings in the design stages for the case of consultants in the architecture, engineering, and construction industry of Addis Ababa. The research design employed a questionnaire as a data collection tool. It gathered information from consultants about their approach to design, their tools, use of building performance simulation tools, consideration of uncertainties in their design, and sustainability approaches. For further validation, semi-structured interviews and documentation reviews were used for the case study analysis. It is found that there is a disparity and underlying lack of understanding of building performance fundamentals and analysis methods. For existing simulation practices in building projects in Addis Ababa, it is found that local consultants do not do them. Moreover, with the infancy of BIM practices in the city’s consultants, capitalizing on the possible BIM-based building performance simulation of buildings is not foreseeable under current circumstances. As a result, this research recommends essential education and training regarding building performance to realize its potential in developing buildings with improved performance and applicable standards and rating systems for sustainability in the local context.
Experimental Study on Partial Replacement of Coarse Aggregate with Crushed Clay Brick to Produce C-25 Concrete
(Addis Ababa University, 2022-01) Wengelawi, Markos; Biruktawit, Taye (PhD)
Concrete is a material that is composed of 60-80% of aggregates by volume. Natural crushed basaltic rock is extensively used in Addis Ababa as a coarse aggregate in concrete production. Studies have shown that extensive production of coarse aggregate from natural resources has negative impact on the landscape, water and atmosphere. To alleviate this negative impact, the experimental research aims to partially replace the basaltic coarse aggregate with waste crushed clay brick obtained from brick factories located in and around Addis Ababa, in concrete production. The research studied the effect of replacing a C-25 grade concrete coarse aggregate with crushed clay brick by 10%, 20%, 30%, 40% and 100% by volume. The effect on workability, hardened density, compressive strength, flexural strength and water penetration depth were investigated. The clay bricks used as replacements were collected from four different brick factories that are found in and around Addis Ababa. A total of twenty one concrete mixes were made that include the control and the replacement mixes. A water/cement ratio of 0.49 was used for all the mixes. In all the mixes the crushed clay bricks were used in a saturated surface dry condition. The findings of the experimental study showed that all the crushed clay bricks obtained from representative four different brick factories can be used as partial replacement of coarse aggregate up to 30% with a water/cement ratio of 0.49. Full replacement of coarse aggregate with crushed clay brick was made possible with a water/cement ratio of 0.40 though that particular concrete mixture was found to be uneconomical compared with the unit cost of the control mix. It was found that the slump and flexural strength of the replacement mix decreased when the crushed clay aggregate replacement percentage increased. The hardened density of the concrete produced with 30% replacement amount decreased by 3% from the control mix. Based on the water penetration test, it was found that the water penetration depth of the concrete increased when the CCB aggregate replacement increased. The amount of cost reduced when using 30% of CCB aggregates in replacement of crushed basalt stone is very insignificant only by 0.98% per one meter cube of concrete.
Computer Aided Management of Construction Payment: For Clients with Multiple Building Projects
(Addis Ababa University, 2022-03) Alazare, Shiferaw; Abraham, Assefa (PhD)
Regular and on-time payment is critical for the successful completion of a construction project. However, the construction industry suffers from delayed payments due to an inefficient payment certification process. Payment delays affect material delivery, labor productivity, and project progress and induce financial and subsequent time claims. This study proposed the breakdown of contract conditions into a logic that can be converted into executable codes called smart contracts that are executed on a web-based application. The system uses a centralized database to store contract data and BOQ and a backend developed using PHP that integrates smart contracts to automate and control payment management. The web-based application was then tested using the data from three building projects and was found to be accurate, effective, and efficient. Aside from creating automated payment certificates the web-based application can check bill of quantities, update advance payment and performance guarantee amount and expiry dates, identify various contract limits, and provide documentation tools. The result of the study has shown that the use of smart contracts and web-based application facilitate automation, control, and follow-up of the payment management process for clients with multiple building projects.
Application of Multi-Criteria Decision-Making Based on Combined Analytic Hierarchy Process and Linear Programming as an Alternative for Project Selection: The Case of Ethiopian Road Authority Road Projects
(Addis Ababa University, 2022-06) Tewodros, Abere; Abraham, Assefa (PhD)
Resources are limited for pursuing and funding new projects hence the challenge is to prioritize, select and allocate optimally. Ethiopian public projects encountered challenges in selecting best projects, finishing in time and cost. The project selection methods commonly used are quantitative in nature and they lack to account for intangible factors which can affect the outcome of project appraisals. An integrated Analytic Hierarchy Process and Linear Programming model that considered both quantitative and qualitative factors in choosing capital project is presented. The combined model is applied in Ethiopian Roads Authority road projects with Planning and Development Commission and Ministry of Finance as prime stakeholders in project selections. Research surveys were conducted in those organizations and secondary documents were used for the analysis. The results indicated project characteristics, with 0.5 weight, were ranked higher than other criteria related to the firm characteristic and external factors with weights of 0.36 and 0.14 respectively. The most important project selection sub-criteria found to be profit, measure of worth, project risk, financial standing, and resources with the overall weight of 0.15, 0.13, 0.12, 0.10 and 0.09 respectively. Others are economic factors, experience, technical ability, size & complexity, duration, organization culture, environmental, location factors, social responsibility, and political factors with weights of 0.07, 0.07, 0.07, 0.06, 0.04, 0.03, 0.02, 0.02, 0.02, and 0.01 respectively. Four projects out of six total projects were selected to have the most use of resources under the available resource constraints. The study provides a simple framework that can be used by organizations to make these challenging decisions. The integrated model is recommended for its ability to capture all possible factors, optimality advantage and applicability in different situations with refining the selection criteria.
Application of Data Mining Techniques for Conceptual Cost Estimation of Selected Building Projects in Addis Ababa
(Addis Ababa University, 2021-12) Biruk, Lemlem; braham, Assefa (PhD)
For project managers and decision makers, developing an accurate cost estimate in the conceptual stage of a project is a crucial but challenging task. Different techniques and methods have been devised and researched to accurately estimate the cost of building projects at the preliminary stages. These methods can broadly be divided into two based on the approach they follow. The cost –based or parametric cost modeling approach uses historical cost data and different Data Mining techniques to develop a cost prediction model. The second method uses a bottom-up or quantity strategy, in which data on the quantity of works is utilized to construct quantity prediction models for each work item. These predicted quantities can then be multiplied by their current unit rates to determine the respective costs. In this study a parametric cost model is first developed to assess its accuracy in predicting the final cost of building projects based on historical data collected from selected building projects in Addis Ababa. This was then followed by doing a comparison between the cost based and quantity based approaches by developing models for structural cost prediction as well as quantity models for the different work items that make up the structural work (concrete, reinforcement, and formwork). Concurrently, the study explored the effectiveness of four data mining techniques, namely Linear Regression (LR), Decision Trees (DT), Neural Networks (ANN), and Gradient Boosted Trees (GBT) in estimating the final and structural cost of building projects. With a relative error of 37.05%, the ANN model was the most accurate in forecasting the final cost of a construction project, while the GBT model performed better in predicting structural costs with a relative error of 22.67%. For quantity estimation models, the NN model showed superior performance for concrete and reinforcement quantity estimation with a relative errors of 16.44% and 19.32% respectively. The GBT model on the other hand performed better in formwork quantity estimation with a relative error of 19.58%. Accordingly, the total slab area was identified to be the most important variable for all prediction. The study indicated the quantity based approach provides more accurate cost prediction as opposed to the cost based approach for the case of structural cost estimation.
Assessment on Selected Prefabricated Wall Construction Practices as an Alternative Materials and Technology in The Ethiopian Housing Sector
(Addis Ababa University, 2021-10) Mishame, Desalegn; Denamo, Addissie (PhD)
Provision of affordable housing to citizens is one of the biggest concerns of governments all across the world. The cost of housing in cities of Ethiopia is very high that it is impossible for most city to afford a quality house. The government is trying to provide affordable houses with good quality and in short period of time. But the houses provided by the government are mostly substandard and timely completion of housing projects has been a challenge. This research is about prefabricated wall construction materials and about the significance of implementing alternative prefabricated wall construction materials in the Ethiopian housing construction sector. The thesis discusses five selected wall construction materials, their property and suitability for the housing construction. The research briefly describes five selected wall construction materials, hollow concrete block, Agrostone panel, gypsum board, and Styrofoam concrete and light weight concrete by explaining about the properties and advantages of the materials for the housing construction sector. The research goes on to explore the housing construction sector of Ethiopia for the perception and extent of using prefabricated wall construction materials. Furthermore the research includes experimental analysis to examine the physical properties of alternative prefabricated wall construction materials and also conduct a brief preliminary cost analysis of the wall construction materials. The findings from questionnaire, and cost analysis shows that hollow concrete block is the most cost effective material and the most available wall construction material. The other materials can be explored for their other attributes like timely finish, better quality, aesthetic and ease of transportation.
Identification of Problems on Road Maintenance and Assessment of the Effects of Poor Road Maintenance on Road Function (in the case of Federal Roads of Ethiopia)
(Addis Ababa University, 2022-03) Ermias, Eyob; Abebe, Dinku (Prof.); Addis, Mesfin (Mr.) Co-Advisor
To facilitate the socio-economic growth of one’s country, the importance of well-conditioned road networks with the proper road maintenance practice is very significant. However, most of the federal roads are not in good condition, even more than one-third of the federal roads are in poor and very poor condition (not safe for driving). This study focused on the identification of the existing problems of road maintenance and assessment of the overall effects of poor road maintenance on road function. The objectives of the study were achieved through a literature review, desk study, interview and questionnaire survey to identify the most significant problems of road maintenance and the most frequent effects of poor road maintenance on road function. Accordingly, a total of thirty-seven (37) top-ranked problems are acknowledged as the most significant problems on road maintenance under four categories, namely client-related, consultant-related, contractor-related and other problems and a total of eleven (11) top-ranked effects are acknowledged as the most frequently occurring effects of poor road maintenance. Among them, the study finding indicated that procurement delay, insufficient road condition survey with lack of appropriate project prioritization mechanism and slow decision-making process under client-related problems; staff unavailability on the site, insufficient data collection and condition survey before road maintenance and delay in decision making under consultant-related problems; shortage of equipment, equipment allocation/ management problems and lack of acquiring new and recent technology equipment under contractor-related problems and people in power have a little understanding on the effects of poor road maintenance, road maintenance is politically unattractive and lack of interest by professionals to participate in road maintenance works under other problems are the top-ranked problems on road maintenance. On the other hand, reduce the riding comfort, shorten the service/design life of the roads and increase vehicle operating costs are the top-ranked frequently occurring effects of poor road maintenance on road function. Thus, all the concerning stakeholders are recommended to give all due attention towards the most significant (acknowledged) problems while undertaking any road maintenance to alleviate the problems and minimize their effects.

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