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This paper aims to study the effect of adding horsehair (HH), polypropylene (PF), carbon (CF), basalt (BF) and glass fibers (GF) on the physico-mechanical durability and microstructure properties of natural hydraulic lime-based mortars (NHL). The studied fibers were added to the mixture at 0.3 %, 0.6 %, and 1.2 % by weight of NHL and compared with plain NHL mortar. The workability (flow diameter test), physical (dry bulk density and water absorption), compressive strength (fc) and flexural strength (ff) (at 7 and 28 days) were tested. The durability was tested by water penetration depth (Wd), NaCl and Na2SO4 salt crystallization and exposure to the wetting-drying (W-D) cycles in Na2SO4, as proved by XRD. Scanning electron microscopy (SEM) of samples after 28 days of curing. From the results, it can be concluded that HH3 (0.3 % fiber) has the highest dry density (1794 kg/m3), fc and ff at 28-days (13.3 and 4.2 MPa), and resistance of all salt crystallization tested, smallest water absorption percentage (16.2 %), and water penetration depth (38.23 mm) of all mortars. On the other hand, it can be noted that adding synthetic types of fibers reduced the dry density and increased water absorption. The XRD explained that immersion or exposure to (W-D) cycles of Na2SO4 has a worse effect on hydration than NaCl exposure. The SEM shows that fiber-filled lime mortar's mechanical properties and durability are improved through the conductive network, especially HH, which had a large diameter with a rough surface and indicated a sufficient level of adhesion with the matrix.

This experimental study aims to investigate the properties of sand concrete (SC) by using sisal fibres and latex in various fields in construction. Sisal fibres were applied at four ratios of 0.05%, 0.10%, 0.15% and 0.20%, while liquid latex was replaced with three ratios of 15%, 25% and 35%. In this context, ideal percentages of sisal fibre (0.1% F) and latex (35% L) were combined in a single cement matrix. For each percentage, tests on flow, density, compressive strength, flexural strength, ultrasonic pulse velocity, modulus of elasticity, water accessible porosity, water absorption and shrinkage were performed on fresh and hardened SC. Scanning electron microscopy (SEM) was also conducted for microstructure analysis. Results indicate that adding latex emulsion to SC containing sisal fibres increased the adhesion of the fibres to the cement matrix, which contributed to the increase in flexural strength and the decrease in shrinkage. This condition also helped reduce the porosity and water absorption of latex-modified SC with sisal fibres compared with SC that contained fibres. The improvement occurred in the properties that constitute an obstacle to the widespread use of SC. Thus this improvement has practical implications. This experimental study aims to investigate the properties of sand concrete (SC) by using sisal fibres and latex in various fields in construction. Sisal fibres were applied at four ratios of 0.05%, 0.10%, 0.15% and 0.20%, while liquid latex was replaced with three ratios of 15%, 25% and 35%. In this context, ideal percentages of sisal fibre (0.1% F) and latex (35% L) were combined in a single cement matrix. For each percentage, tests on flow, density, compressive strength, flexural strength, ultrasonic pulse velocity, modulus of elasticity, water accessible porosity, water absorption and shrinkage were performed on fresh and hardened SC. Scanning electron microscopy (SEM) was also conducted for microstructure analysis. Results indicate that adding latex emulsion to SC containing sisal fibres increased the adhesion of the fibres to the cement matrix, which contributed to the increase in flexural strength and the decrease in shrinkage. This condition also helped reduce the porosity and water absorption of latex-modified SC with sisal fibres compared with SC that contained fibres. The improvement occurred in the properties that constitute an obstacle to the widespread use of SC. Thus this improvement has practical implications.

This research aims to study factors affecting the strength of adhesion between old concrete and new concrete. Among the factors that have been studied in this research are the type of bonding material and the roughness of the surface adhesion, four types of bonding materials (EPICHOR-1768, C-Latex, SikaBond-T21, EPICHOR-500) have been selected because they are available in local markets. A wire brush is used in order to increase the roughness of sample surfaces. The pull-off and slant shear tests have been adopted to assess the bonding strength between the test the old and new concrete. 30 cylindrical samples (7 cm diameter) have been examined by pull-off test, also slant shear test was conducted on 40 samples (10 cm×10 cm×30 cm). The obtained results showed that there is an active role for the bonding material as well as the surface roughness to increase the strength of adhesion between the old and new concrete. Also, it showed that the best of these bonding materials is EPICHOR-1768 because of its significant impact in increasing the strength of the adhesion between the old and new concrete where the percentage of increase 124% in the pull-off test and 48% in slant shear test, compared to the reference sample for each test. As well, as a result of roughening the surface by brush, the strength of adhesion reaches 4% increase in the pull-off test and 23% in the slant shear test compared with the reference sample for each test, which demonstrates the importance of surface roughness to increase the bonding strength between the old and new concrete. This research aims to study factors affecting the strength of adhesion between old concrete and new concrete. Among the factors that have been studied in this research are the type of bonding material and the roughness of the surface adhesion, four types of bonding materials (EPICHOR-1768, C-Latex, SikaBond-T21, EPICHOR-500) have been selected because they are available in local markets. A wire brush is used in order to increase the roughness of sample surfaces. The pull-off and slant shear tests have been adopted to assess the bonding strength between the test the old and new concrete. 30 cylindrical samples (7 cm diameter) have been examined by pull-off test, also slant shear test was conducted on 40 samples (10 cm×10 cm×30 cm). The obtained results showed that there is an active role for the bonding material as well as the surface roughness to increase the strength of adhesion between the old and new concrete. Also, it showed that the best of these bonding materials is EPICHOR-1768 because of its significant impact in increasing the strength of the adhesion between the old and new concrete where the percentage of increase 124% in the pull-off test and 48% in slant shear test, compared to the reference sample for each test. As well, as a result of roughening the surface by brush, the strength of adhesion reaches 4% increase in the pull-off test and 23% in the slant shear test compared with the reference sample for each test, which demonstrates the importance of surface roughness to increase the bonding strength between the old and new concrete.

The review of the literature and design guidelines indicates a lack of design codes governing the shear strength of reinforced concrete (RC) beams strengthened with ultrahigh-performance fiber-reinforced concrete (UHPFRC). This study uses the results of a 3D finite element model constructed previously by the authors and verified against an experimental programme to gain a clear understanding of the shear strength of RC beams strengthened with UHPFRC by using different schemes. Experimental results found in the literature along with the numerical results for shear capacities of normal-strength RC and UHPFRC beams without stirrups are compared with available code design guidelines and empirical models found in the literature. The results show variance between the empirical models and the experimental results. Accordingly, proposed equations derived based on empirical models found in the literature were set to estimate the shear capacity of normal-strength RC beams without stirrups. In addition, the term 'shear span-to-depth ratio' is not considered in the equations for design guidelines found in the literature regarding the shear capacity of UHPFRC beams without stirrups. Consequently, a formula estimating the shear strength of UHPFRC and RC beams strengthened with UHPFRC plates and considering the effect of shear span-to-depth ratio is proposed and validated against an experimental programme previously conducted by the authors. The review of the literature and design guidelines indicates a lack of design codes governing the shear strength of reinforced concrete (RC) beams strengthened with ultrahigh-performance fiber-reinforced concrete (UHPFRC). This study uses the results of a 3D finite element model constructed previously by the authors and verified against an experimental programme to gain a clear understanding of the shear strength of RC beams strengthened with UHPFRC by using different schemes. Experimental results found in the literature along with the numerical results for shear capacities of normal-strength RC and UHPFRC beams without stirrups are compared with available code design guidelines and empirical models found in the literature. The results show variance between the empirical models and the experimental results. Accordingly, proposed equations derived based on empirical models found in the literature were set to estimate the shear capacity of normal-strength RC beams without stirrups. In addition, the term 'shear span-to-depth ratio' is not considered in the equations for design guidelines found in the literature regarding the shear capacity of UHPFRC beams without stirrups. Consequently, a formula estimating the shear strength of UHPFRC and RC beams strengthened with UHPFRC plates and considering the effect of shear span-to-depth ratio is proposed and validated against an experimental programme previously conducted by the authors.

Investigations on the dynamic behavior of concrete members, incorporating steel fibers with different aspect ratios, are limited so far and do not covered comprehensively in prior studies. Present endeavor is devoted to examine the dynamic response of the steel fibrous concrete beams and slabs under the influence of impact loading. These members were reinforced with steel fibers in different length of 25 mm and 50 mm. Four concrete mixes were designed and used based on the proportion of long and short fibers. Twenty-four slabs and beams were fabricated with respect to the concrete mix and these specimens were tested in impact load experiment. Testing observations revealed that the maximum dynamic deflection or ductility of the member can be achieved with increasing the fiber length. Structural behavior of the tested structures was predicted using nonlinear finite element analysis with specific material constitutive relationships. Eight nodes plate elements have been considered in the present dynamic analysis. Dynamic fracture energy of the members was calculated and agreement ratio, of more than 70%, was noticed between the experimental and analysis outcomes. Investigations on the dynamic behavior of concrete members, incorporating steel fibers with different aspect ratios, are limited so far and do not covered comprehensively in prior studies. Present endeavor is devoted to examine the dynamic response of the steel fibrous concrete beams and slabs under the influence of impact loading. These members were reinforced with steel fibers in different length of 25 mm and 50 mm. Four concrete mixes were designed and used based on the proportion of long and short fibers. Twenty-four slabs and beams were fabricated with respect to the concrete mix and these specimens were tested in impact load experiment. Testing observations revealed that the maximum dynamic deflection or ductility of the member can be achieved with increasing the fiber length. Structural behavior of the tested structures was predicted using nonlinear finite element analysis with specific material constitutive relationships. Eight nodes plate elements have been considered in the present dynamic analysis. Dynamic fracture energy of the members was calculated and agreement ratio, of more than 70%, was noticed between the experimental and analysis outcomes.

This research aims to study the utilization of olive waste ash (OWA) in the production of concrete as a partial substitute for cement. Effects of using OWA on the physical and mechanical properties of concrete mixtures have been investigated. This is done by carrying out tests involving the addition of various percentages of OWA to cement (0%, 5%, 10% and 15%). For each percentage, tests were performed on both fresh and hardened concrete; these included slump test, unit weight test and compressive strength test after 7, 28 and 90 days. Durability tests were investigated in solutions containing 5% NaOH and MgSO4 by weight of water. In addition, resistance to high temperatures was tested by subjecting the cubes to high temperatures of up to 170oC. The results of this research indicate that a higher percentage of OWA gives a lower compressive strength and lower workability but higher performance in terms of durability against both different weather conditions and high temperatures. This research aims to study the utilization of olive waste ash (OWA) in the production of concrete as a partial substitute for cement. Effects of using OWA on the physical and mechanical properties of concrete mixtures have been investigated. This is done by carrying out tests involving the addition of various percentages of OWA to cement (0%, 5%, 10% and 15%). For each percentage, tests were performed on both fresh and hardened concrete; these included slump test, unit weight test and compressive strength test after 7, 28 and 90 days. Durability tests were investigated in solutions containing 5% NaOH and MgSO4 by weight of water. In addition, resistance to high temperatures was tested by subjecting the cubes to high temperatures of up to 170oC. The results of this research indicate that a higher percentage of OWA gives a lower compressive strength and lower workability but higher performance in terms of durability against both different weather conditions and high temperatures.

The strength of concrete structures deteriorates after exposure to fire. Strength loss varies with elevated temperature, fire duration, and the mechanical properties of concrete. Repairing and strengthening affected structures are important to improve their performances. Fire-damaged concrete has been repaired using fiber-reinforcing polymer. The superior properties of ultrahigh performance fiber-reinforced concrete (UHPFRC) make it suitable as a repair material. Furthermore, an excellent repair material should be able to bond properly with the substrate and maintain its structural integrity. The aim of this paper is to review the potential use of UHPFRRC as a repair material for fire-damaged concrete in terms of bond strength. Previous studies showed that developing efficient rehabilitation techniques that enable fire-damaged structures to be restored has some challenges. Whether UHPFRC can be used as a repair material particularly for fire-damaged concrete structure is recommended to be proven in future studies. The strength of concrete structures deteriorates after exposure to fire. Strength loss varies with elevated temperature, fire duration, and the mechanical properties of concrete. Repairing and strengthening affected structures are important to improve their performances. Fire-damaged concrete has been repaired using fiber-reinforcing polymer. The superior properties of ultrahigh performance fiber-reinforced concrete (UHPFRC) make it suitable as a repair material. Furthermore, an excellent repair material should be able to bond properly with the substrate and maintain its structural integrity. The aim of this paper is to review the potential use of UHPFRRC as a repair material for fire-damaged concrete in terms of bond strength. Previous studies showed that developing efficient rehabilitation techniques that enable fire-damaged structures to be restored has some challenges. Whether UHPFRC can be used as a repair material particularly for fire-damaged concrete structure is recommended to be proven in future studies.

Exterior walls in buildings are exposed to various forms of thermal loads, which depend on the positions of walls. Therefore, one of the efficient methods for improving the energy competence of buildings is improving the thermal properties of insulation plaster mortar. In this study, lightweight fine aggregate (LWFA) and micro rubber ash (MRA) from recycled tires were used as partial replacements for sand. The flow ability, unit weight, compressive strength, tensile strength, thermal conductivity (K-value), drying shrinkage and microstructure scan of lightweight rubberized mortar (LWRM) were investigated. Ten mixtures of LWRM were prepared as follows: traditional cement mortar (control mixture); three mixes with different percentages of LWFA (25%, 50% and 75%); three mixes with different percentages of MRA (2.5%, 5% and 7.5%); and three mixes consisting both types with determined ratios (25% LWFA+5% MRA, 50% LWFA+5% MRA and 75% LWFA+5% MRA). The flow ability of the mortars was 22+-2 cm, and LWRM contained LWFA and MRA. The compressive and tensile strength decreased by approximately 64% and 57%, respectively, when 75% LWFA was used compared with those when the control mix was used. The compressive and tensile strength decreased when 5% MRA was used. By contrast, mixes with determined ratios of LWFA and MRA affected reduced unit weight, K-value and dry shrinkage. Exterior walls in buildings are exposed to various forms of thermal loads, which depend on the positions of walls. Therefore, one of the efficient methods for improving the energy competence of buildings is improving the thermal properties of insulation plaster mortar. In this study, lightweight fine aggregate (LWFA) and micro rubber ash (MRA) from recycled tires were used as partial replacements for sand. The flow ability, unit weight, compressive strength, tensile strength, thermal conductivity (K-value), drying shrinkage and microstructure scan of lightweight rubberized mortar (LWRM) were investigated. Ten mixtures of LWRM were prepared as follows: traditional cement mortar (control mixture); three mixes with different percentages of LWFA (25%, 50% and 75%); three mixes with different percentages of MRA (2.5%, 5% and 7.5%); and three mixes consisting both types with determined ratios (25% LWFA+5% MRA, 50% LWFA+5% MRA and 75% LWFA+5% MRA). The flow ability of the mortars was 22+-2 cm, and LWRM contained LWFA and MRA. The compressive and tensile strength decreased by approximately 64% and 57%, respectively, when 75% LWFA was used compared with those when the control mix was used. The compressive and tensile strength decreased when 5% MRA was used. By contrast, mixes with determined ratios of LWFA and MRA affected reduced unit weight, K-value and dry shrinkage.

This study investigated the structural behaviour of reinforced reactive powder concrete (RPC) beams under service load and fire exposure. The beams were composed of hybrid fibres (50% polypropylene fibres and 50% steel fibres) at different volume fractions relative to nonfibrous-reinforced RPC beams. The bottom and both sides of the beams which were simply supported and loaded with two-point loads were exposed to a controlled fire for 120 min in accordance with ASTM E 119 standard time–temperature curve. The midspan deflection was recorded every 5 min. The experiment also included loading tests on fire-damaged beams after cooling. The nonfibrous-reinforced RPC beams failed during the fire test after 38 min because of the spalling of the reinforcement cover which directly exposed the reinforcing steel to elevated temperatures. By contrast, the beams with hybrid fibres could resist failure during the entire test period. The rate of increase in deflection during fire exposure declined with an increase in hybrid fibre content. Increases in fibre volume fraction from 0.25% to 0.75% and 1.25% decreased the midspan deflection of the reinforced RPC beams by 33% and 36%, respectively. Adding hybrid fibres could considerably improve the residual stiffness of fire-damaged beams. This study investigated the structural behaviour of reinforced reactive powder concrete (RPC) beams under service load and fire exposure. The beams were composed of hybrid fibres (50% polypropylene fibres and 50% steel fibres) at different volume fractions relative to nonfibrous-reinforced RPC beams. The bottom and both sides of the beams which were simply supported and loaded with two-point loads were exposed to a controlled fire for 120 min in accordance with ASTM E 119 standard time–temperature curve. The midspan deflection was recorded every 5 min. The experiment also included loading tests on fire-damaged beams after cooling. The nonfibrous-reinforced RPC beams failed during the fire test after 38 min because of the spalling of the reinforcement cover which directly exposed the reinforcing steel to elevated temperatures. By contrast, the beams with hybrid fibres could resist failure during the entire test period. The rate of increase in deflection during fire exposure declined with an increase in hybrid fibre content. Increases in fibre volume fraction from 0.25% to 0.75% and 1.25% decreased the midspan deflection of the reinforced RPC beams by 33% and 36%, respectively. Adding hybrid fibres could considerably improve the residual stiffness of fire-damaged beams.

Disposal of waste polycarbonate plastic is a serious environmental issue all around the globe, on account of its health hazard and difficulty in land filling. As a possible solution to the problem of polycarbonate plastic waste, an experimental study was conducted to examine the potential of using it as sand replacement in the concrete. This paper examines impact strength properties of concrete in which different amounts 2.5%, 5% and 10% of polycarbonate plastic waste particles were used as sand replacement. For each amount, six beams of 100 mm ×100 mm × 500mm were subjected to 4.5 kg hammer from 480mm height. The number of blows of the hammer required to induce the ultimate failure of the beams were recorded. The results are presented in terms of impact energy required for the ultimate failure. The concrete mixtures exhibited ability to absorb a large amount of impact energy. The polycarbonate plastic waste increased the ultimate failure impact energy of concrete. Disposal of waste polycarbonate plastic is a serious environmental issue all around the globe, on account of its health hazard and difficulty in land filling. As a possible solution to the problem of polycarbonate plastic waste, an experimental study was conducted to examine the potential of using it as sand replacement in the concrete. This paper examines impact strength properties of concrete in which different amounts 2.5%, 5% and 10% of polycarbonate plastic waste particles were used as sand replacement. For each amount, six beams of 100 mm ×100 mm × 500mm were subjected to 4.5 kg hammer from 480mm height. The number of blows of the hammer required to induce the ultimate failure of the beams were recorded. The results are presented in terms of impact energy required for the ultimate failure. The concrete mixtures exhibited ability to absorb a large amount of impact energy. The polycarbonate plastic waste increased the ultimate failure impact energy of concrete.

Palm oil ash wastes are normally used as fuel to heat up boiler for electricity generation in palm oil mills. This process leads to the production of unwanted ash residue which is known as palm oil fuel ash (POFA). The sufficiently amorphous POFA contains a high amount of silica, which makes it possible to be used as a pozzolanic material in concrete. POFA was treated to lower the unburned carbon and to reduce the particle size and then used in the production of high strength concrete by partially substituting ordinary Portland cement (OPC) at replacement levels of 0%, 10%, 20%, 30%, 40%, 50 and 60% on the mass-for-mass basis. The results show that the high strength green concrete containing POFA has superior workability, strength and transport properties when compared with the control OPC high strength concrete even at high POFA content of 60%. Hence, the treated POFA has promising potential to be utilized in the production of high strength green concrete with superior strength and transport properties. This could directly contribute to the sustainability of the concrete industry, via the utilization of agro-industry by-product in high strength green concrete with lower cement consumption and potentially superior durability performance. Palm oil ash wastes are normally used as fuel to heat up boiler for electricity generation in palm oil mills. This process leads to the production of unwanted ash residue which is known as palm oil fuel ash (POFA). The sufficiently amorphous POFA contains a high amount of silica, which makes it possible to be used as a pozzolanic material in concrete. POFA was treated to lower the unburned carbon and to reduce the particle size and then used in the production of high strength concrete by partially substituting ordinary Portland cement (OPC) at replacement levels of 0%, 10%, 20%, 30%, 40%, 50 and 60% on the mass-for-mass basis. The results show that the high strength green concrete containing POFA has superior workability, strength and transport properties when compared with the control OPC high strength concrete even at high POFA content of 60%. Hence, the treated POFA has promising potential to be utilized in the production of high strength green concrete with superior strength and transport properties. This could directly contribute to the sustainability of the concrete industry, via the utilization of agro-industry by-product in high strength green concrete with lower cement consumption and potentially superior durability performance.

No contract type is perfect; one type may be better suited than another based on the unique requirements of a particular project. All of the contract types have distinct advantages and disadvantages with the best choice being governed by the requirements of the specific project. This research aimed at facilitating the owners' and contractors' need to select the appropriate contract type. Ten criteria were used to select the appropriate contract type between the lump sum, unit price and cost-plus types using one of the most popular multi-criteria decision making (MCDM) processes. This approach was the analytical hierarchy process (AHP). Pre-questionnaires interviews, structured questionnaires were applied through the research methodology steps to reach the best contract type. Excel sheet was prepared for applying AHP procedure. The research determined the most appropriate contract type that was preferred selected by owners. The main findings of this research were the best contract type was the unit price contract. There were differences in the type of contract that achieves each criterion separately. The most effective criterion for selecting the appropriate contract type for owners was the achievement of best value for their money. No contract type is perfect; one type may be better suited than another based on the unique requirements of a particular project. All of the contract types have distinct advantages and disadvantages with the best choice being governed by the requirements of the specific project. This research aimed at facilitating the owners' and contractors' need to select the appropriate contract type. Ten criteria were used to select the appropriate contract type between the lump sum, unit price and cost-plus types using one of the most popular multi-criteria decision making (MCDM) processes. This approach was the analytical hierarchy process (AHP). Pre-questionnaires interviews, structured questionnaires were applied through the research methodology steps to reach the best contract type. Excel sheet was prepared for applying AHP procedure. The research determined the most appropriate contract type that was preferred selected by owners. The main findings of this research were the best contract type was the unit price contract. There were differences in the type of contract that achieves each criterion separately. The most effective criterion for selecting the appropriate contract type for owners was the achievement of best value for their money.

The construction industry is complex, fragmented, dynamic and involves many parties in an adversarial relationship. This makes disputes almost inevitable in any construction project. This paper aims to provide a comprehensive review of the adopted methodologies in resolving disputes that arise in the construction projects. The paper evaluates and classifies the different methods of disputes resolution. A comparison was conducted between the advantages and disadvantages of each method. The paper distinguishes between the traditional method of disputes resolution; litigation and Alternative Dispute Resolution (ADR) methods such as arbitration, mediation, med/arb, mini-trial and dispute review board. In conclusion there is no best way to solve all kind of disputes in construction projects, however, a general step by step process of how disputes should be addressed is finally presented. The construction industry is complex, fragmented, dynamic and involves many parties in an adversarial relationship. This makes disputes almost inevitable in any construction project. This paper aims to provide a comprehensive review of the adopted methodologies in resolving disputes that arise in the construction projects. The paper evaluates and classifies the different methods of disputes resolution. A comparison was conducted between the advantages and disadvantages of each method. The paper distinguishes between the traditional method of disputes resolution; litigation and Alternative Dispute Resolution (ADR) methods such as arbitration, mediation, med/arb, mini-trial and dispute review board. In conclusion there is no best way to solve all kind of disputes in construction projects, however, a general step by step process of how disputes should be addressed is finally presented.

This paper reports about the use of recycled iron powder (IP) in producing cement mortar under normal conditions. Flow table test was performed on fresh mortar. Destructive tests were conducted on cubes of the hardened mortar to obtain the compressive and flexural strengths of the cement mortar. The effects of adding 10%, 20%, 30%, and 40% of waste IP as a natural sand replacement were assessed and compared. Waste iron are of two types: iron IP, which shows a similar particle size distribution to that of the sand used in making the samples, and fine iron powder (FIP), which contains fine particles. The compressive strength decreased with the increased amount of added IP in the mixtures, but it increased with the addition of 10% FIP and decreased gradually with the increased FIP level. By contrast, the flexural strength significantly increased with increased FIP in the mixtures. Recommendations regarding the applications of recycling to conserve resources and raw materials and prevent environmental pollution are provided.

Despite of different definitions of organizational culture, shared meanings, assumptions, beliefs and understandings held by a team are considered as the basic component of the organizational culture definition. Organizational culture gives identity to an organization. Nowadays with the increasing of the internationalization of the construction industry, the organizational culture become more importance than any other times. The aim of this research is to investigate the importance of the organizational culture for Gaza Strip construction companies. The study used a questionnaire that was administered by contracting companies classified at the Palestinian Contractors Union. Out of 134 questionnaires were distributed, only 74 questionnaires were received. The research found out that the existence of the organizational cultural in the organization is very important for its survival and continuity, where the organizational cultural help in achieving the organization goals, the organizational cultural help the organization to take right actions and decisions, the organizational cultural help in creating policies and assignments to increase profitability, growth, and respond to market demands, the organizational cultural help the individuals and teams to do the assigned work efficiently, and the organizational cultural play basic role in sharing of information rapidly inside the organization

Demands for construction materials and for steel in particular are globally increasing. In 2008, the construction sector consumed 56% of the total 1088 million tons of steel demand. Steel production is a major contributor to greenhouse emissions with an estimated 25% of total CO2 emissions. Therefore, reusing and recycling steel could be beneficial in lowering the global levels of CO2 emissions. This paper examines the possibility of using steel form the debris of damaged buildings during the 2014 war on Gaza, Palestine. The lack of steel bars and their uprising prices in Gaza strip encouraged the trend of using used steel in new constructions. The paper examines the properties of used steel in comparison with the standards. It also compares between steel of known and unknown extraction sources and between steel extracted under an expert supervision and steel extracted by local residents. The validity of reused steel is examined through a process of Re-certification. The process includes applying a tensile and bend and re-bend test to used steel bars. The results indicate that some reused steel bars meet the specification for new constructions. The results also show that steel bars extracted under a specialist supervision shows better performance than those extracted by local steel collectors in Gaza.

Palm oil fuel ash (POFA) was utilized as a pozzolanic material in varied quantities to produce high-strength concretes (HSCx) of above 90 MPa, with significant improvement in its engineering and fluid transport properties. The chemical and physical characteristics of ultrafine POFA (U-POFA) utilized in HSCx were investigated along with its concomitant fresh, strength and durability characteristics compared to ordinary Portland cement based type (OPC-HSC). The U-POFA had high surface area of (1.136 m2/g-Blaine), mean particle size (2.06 μm), and glassy phase (70.59%). The HSCx that had replacement level of 0, 20, 40 and 60% of U-POFA recorded the 90-day strength of 100.5, 105.2, 109.0 and 108.5 MPa. Utilizing high volume of POFA in HSCx is possible with improved fineness and heat-treatment at 500 ± 50 °C, and could retard water absorption/permeability, setting and chloride penetration/migration rates …

Ultra-High Performance Fiber Concrete (UHPFC) is one of the breakthroughs in the 21st century in the field of concrete technology where this composite material providing an important improvement in strength, workability, ductility and durability when compared with normal concrete. This paper discusses the influence of different curing conditions on the mechanical properties of UHPFC and the bonding between UHPFC and bar of 12 mm in diameter. An experimental program was performed to study the mechanical properties of UHPFC which were cured under six different curing conditions. Test results indicated that steam and boil curing methods showed a promising performance particularly at early age of curing compared to other type of curing. The results of pull out test showed that the failure was in bar (bar rapture failure) in all type of curing regimes.

The development of concrete technology shows a variety of admixtures in concrete to produce special concrete. This includes the production of self-compacting concrete which is able to fill up all spaces, take formwork shapes and pass through congested reinforcement bars without vibrating or needing any external energy. In this study, the main objective is to compare the physical and mechanical properties of self-compacting concrete containing metakaolin with normal concrete. Four types of samples were produced to study the effect of metakaolin towards the physical and mechanical properties of self-compacting concrete where 0%, 5%, 10% and 15% of metakaolin were used as cement replacement. The physical properties were investigated using slump test for normal concrete and slump flow test for self-compacting concrete. The mechanical properties were tested for compressive strength and tensile strength …

The performance of any repaired concrete structure, depends on the quality of the interfacial transition zone of the composite system formed by the repair material and the existing concrete substrate. The main aim of this paper is to evaluate the bonding behavior between normal strength concrete (NSC) substrate as an old concrete and Ultra High Performance Concrete (UHPC) as a repair material. In order to assess the bond behavior, standard slant shear test and splitting tensile test were carried out. The relation between surface roughness and bond strength in shear and indirect tension for different surfaces roughness has been assessed. The old concrete surfaces were roughened by mechanical wire brush, scarifying using an electrical grinder, scabbling by a mechanical drill and as cast without roughening. Analysis of the results indicates that bond strength increases when UHPC is used for shear and tension alike. For the scabbling technique, the shear strength yields values 251.8% higher than the those for as cast surface and 153% for tension strength. In addition, UHPC show advantages that qualify it for repairing and strengthening techniques including adding a new concrete to the existing concrete substrate. In general, rough surface preparation leads to a higher bond strength. R a coefficient is a representative parameter and related to the bond strength, particularly, for shear strength. Finally, the results showed that tension strength is less sensitive to the surface roughness level and more proportional to the repair material strength.

This study investigated the effectiveness of several types of adhesives used in post-installed rebar connections as a bonding agent between steel reinforcement bars and old concrete under pull-out test. The cylindrical samples (96 + 24 Nos) of 15 dia. × 30 cm with anchors rebar of varying diameter (8, 10, 12 mm) with different embedded length (10, 15 and 20 × rebar diameter). The control (24 Nos) was the cast in-place rebar concrete specimens while other samples (96 Nos) were post rebar-installed concrete specimen of varied bonding agents-chemical adhesives (Sikadure-31CF and EPICHOR 1786) or cement-based binders (mortar, ultra-high performance self-compacting concrete (UHPSCC). The findings showed that the use of the adhesives and UHPCC pull-out load values were in close proximity while they all outperformed mortar bonded specimens. The pull-out load (bond strength) increases with …

The primary focus of this work was to utilize the waste of palm oil industry as a supplementary binder for producing high strength concrete (HSC) whose strength reached 116 MPa. The treatment of ground POFA (GPOFA) to produce ultrafine or treated POFA (UPOFA) changed its fineness, unburned carbon composition and percentage of pozzolanic minerals (SiO2 + Al2O3 + Fe2O3) and led to the production of high strength concrete dubbed HSCg and HSCu, respectively. The characteristics of HSCu indicated UPOFA positive contributions towards workability, strength and permeability (gas and water, chloride penetration and migrations). At the age of 180 days, HSCu containing 20, 40 and 60% of UPOFA resulted in the compressive strength of 108.6, 114.4 and 112.4 MPa, respectively as against the maximum of 106.5 MPa and 105.1 MPa in HSCg and POFA-free high strength concrete (HSC-OPC), respectively …

The aim of this paper is to identify and rank the design phase faults/errors affecting on the maintenance of the United Nations Relief and Works Agency (UNRWA)'s school’s buildings in Gaza Strip, and to propose recommendations for minimizing the future maintenance problem related to the school buildings at Gaza Strip. A survey was conducted to collect the required data were adopted in this study. This study reveals the important factors that leading to defects in the design stage which includes: lack of workshops to discuss construction problems between project parts, Inadequate QA/QC programs during design stage, Lack of auditing and archiving of approved as-built drawing documents electronically after the completion the project. The study recommends several actions to improve maintenance performance of UNRWA's schools in Gaza Strip. The designer must take into account maintenance considerations during the design and supervision stages by choosing of durable materials. The UNRWA should conduct workshops or training courses for designers, supervisor, and maintenance engineers.

This paper presents a study that aims to explore the reality of the strategic planning in the construction companies in Gaza Strip. The clarity of the scientific concept of strategic planning has been investigated, in addition its significance, the degree of implementation and use, also the participation involvement in setting strategic plans and ability to adapt with their internal and external changing environment to be considered. This study relied mainly on the field study methods, where a special questionnaire was designed and distributed on a sample of "149" construction company, therefore, a full comprehensive survey was adopted. A "66" questionnaire out of "90' were retrieved and were processed and analyzed. The results of the study recommended the necessity of starting up with the use of strategic planning as an administrative tool to help these companies to adapt with their internal and external environments, also to provide more training courses for top management on strategic management and planning, and to emphasize on the sharing principle when setting strategic plans, where different administrative levels are involved

Article Preview Article Preview The number of existing structures under repair and rehabilitation has extensively increased over the past two decades; these structures typically require performance enhancements including durable and safe repair and strengthening. The experimental program aimed to investigate the bond strength at the joint surfaces between conventional concrete substrate as existing concrete and reactive powder concrete RPC as new overlay concrete. Pull off test was used to quantify the direct tension of the bond strength. Different surfaces roughness were used for existing concrete. The obtained results, clearly showed that, RPC could be linked excellent to the existing concrete at early age; as a result, all failures occurred through the existing concrete, regardless of the surface roughness of existing concrete. RPC could be used as an excellent overlay concrete for increasing the durability at …

This paper presents a study that aims to explore the reality of the strategic planning in the construction companies in Gaza Strip. The clarity of the scientific concept of strategic planning has been investigated, in addition its significance, the degree of implementation and use, also the participation involvement in setting strategic plans and ability to adapt with their internal and external changing environment to be considered. This study relied mainly on the field study methods, where a special questionnaire was designed and distributed on a sample of "149" construction company, therefore, a full comprehensive survey was adopted. A "66" questionnaire out of "90' were retrieved and were processed and analyzed. The results of the study recommended the necessity of starting up with the use of strategic planning as an administrative tool to help these companies to adapt with their internal and external environments, also to provide more training courses for top management on strategic management and planning, and to emphasize on the sharing principle when setting strategic plans, where different administrative levels are involved

Ground treated ultrafine-POFA obtained from palm oil industry was heat-treated to remove excess carbon. The varied proportion (17%, 30% and 40%) of UPOFA was incorporated into the ultra-high strength concrete (UHSC) to study its effects on the UPOFA-UHSC (U x-UHSC) in comparison with OPC-UHSC (U 0-UHSC) engineering and transport properties. The U x-UHSC has an increasing workability tendency with a retarded setting times as compared to U 0-UHSC. Besides, U x-UHSC registered higher compressive strength than the U 0-UHSC. The 90-d strength of 156 MPa was achieved in U 17-UHSC which was 4.7%, 7.5% and 12.2% higher than the values obtained for U 30-UHSC, U 40-UHSC and U 0-UHSC, respectively. The U 40-UHSC exhibited the greatest improvement at 90 days in transport properties such as porosity, water absorption, initial surface absorption, rapid chloride permeability, gas permeability and water permeability while the highest strength was recorded with U 17-UHSC. Thus, the pozzolanic UPOFA is capable of improving the engineering and transport properties of UHSC.

The performance of any repaired concrete structure, and thus its service life, depends on the quality of the interfacial transition zone of the composite system formed by the repair material and the existing concrete substrate. In this work, the properties of the interfacial transition zone between normal concrete (NC) substrate as an old concrete and ultra-high performance fiber-reinforced concrete (UHPFC) as a repair material was investigated. Pull-off and splitting cylinder tensile tests were performed to quantify the bond strength in direct and indirect tensions, respectively. The microstructure of the interfacial transition zone was also studied using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS). Different types of NC substrate surface preparation methods were used. An optical three-dimensional surface metrology device was used to estimate the substrate roughness parameters …

The bonding that exists between the old concrete and the new concrete depends largely on the quality of substrate surface preparation. The accurate representation of substrate surface roughness can help determine very precisely the correct bonding behavior. In this work, an experimental investigation was carried out to quantify the normal concrete (NC) substrate roughness parameters and evaluate their relationship with the bonding performance of ultra high-performance fiber concrete (UHPFC), used as a repair material. The bond strength was quantified based on the results of the pull-off test, splitting cylinder tensile test, and the slant shear test. Three types of NC substrate surface preparation were used: as-cast (without surface preparation) as reference, wire-brushed, and sand-blasted (SB); the roughness of which was determined using an optical three-dimensional (3D) surface metrology device (Alicona …

Article Preview Article Preview Ultra high performance fiber concrete (UHPFC) is an advanced formula concrete that is proven to be more superior than conventional concrete because it embrace the qualities of steel and concrete. Therefore UHPFC properties which include high durability and strength are fully exploited in the research of rehabilitation and strengthening in concrete and even non-concrete structures. This article presents the findings of an experimental study carried out to examine the bonding strength behaviour between normal concrete (NC) substrate and UHPFC as a repair material, under flexural strength test by using third-point loading beam test method. Three types of NC substrate surface preparation were used: as-cast (without surface preparation) as a reference, wire-brushed, and sand-blasted. The flexural test results clearly indicated that all failures occurred through the NC substrate and no …

The interfacial bond characteristics between normal concrete substrate as old concrete and ultra high performance fiber concrete as repair material have been investigated. Normal concrete substrates were first subjected to different surface preparation methods prior to bonding the ultra high performance fiber concrete to form repair composites. The interfacial mechanical bond of the composites was assessed using slant shear and tensile splitting strength tests. In addition, rapid chloride permeability test was performed to ascertain the potential chloride resistance of the composites. The microstructure of the transition zone between the normal concrete and ultra high performance fiber concrete was also studied using scanning electron microscope. The results generally indicate that surface preparation of the substrate is very much required to obtain superior mechanical bond of the composites; whereby the …

The deterioration of reinforced concrete structures is a major social problem. To minimize this problem and ensure effective structural management, the number and extent of repair interventions must be kept at the lowest probable level. Good bond is one of the main requirements for successful repair. The main aim of this study was to investigate the compressive stress-strain behaviour of the composite specimens consist of ordinary concrete (OC) substrate as old concrete and reactive powder concrete (RPC) as a retrofitting material, by using different types of OC substrate surface preparation methods. The results showed that the composite OC/RPC specimens were able to behave closely to individual OC, in the case of using OC substrate with surface prepared by sand blasted.

Under normal circumstances, reinforced concrete structures (RCS) show excellent performance in terms of durability and structural behaviour except for the zones that are subjected to severe mechanical or cyclic loading and aggressive environmental conditions. Therefore the methods of rehabilitation or strengthening of these zones should be reliable, effective and economical. Today, many scientists, academics and engineers understood the extremely low porosity and low permeability characteristics of ultra high performance fibre concrete (UHPFC) giving its enhanced durability over high performance concrete (HPC), thus making it potentially suitable for rehabilitation and retrofitting problematic RCS. The advantages of utilising the technology of UHPFC in repairing works includes (i) decrease the working time needed for the rehabilitation works; and (ii) increase the serviceability and durability to an extent where …

In recent years premature deterioration of concrete structures due to salt damage has become a serious social problem. Repair and strengthening in order to improve the durability of these structures has become critical. Therefore ultra high performance concrete (UHPFC) properties in terms of durability and strength are fully exploited in rehabilitation and strengthening. This study was performed to evaluate the bond strength between UHPFC and Normal Concrete (NC) substrate; Slant shear tests were performed to quantify the bond strength in shear, split tests conducted to evaluate the bond strength in indirect tension. The results showed that UHPFC has excellent interlocking with the surface of NC substrate, and then gives bond strength greater than the strength of NC substrate.

As a rule of thumb, the interfacial bonding between deteriorated concrete structures with a newly overlay repair material is one of the most important factors for structural functionality and safety as well as durability performance. In order to acquire an enhanced resistance against penetration of harmful substances, a good and effective bonding is necessary at the concrete interfaces. The objective of this study is to examine experimentally the mechanical properties and permeability characteristics of the interface between normal concrete (NC) substrate which represents old concrete structures and an overlay of ultra high performance fiber concrete (UHPFC) as a repair material. The mechanical interfacial bond characteristics were assessed using the slant shear and splitting tensile tests to quantify the influence of the differently roughened substrate surfaces. On the other hand, the permeability characteristics were …

The uniqueness of Ultra-High Performance Fiber Concrete (UHPFC) is its extremely low porosity gives its low permeability and high durability, making it potentially suitable for rehabilitation and retrofitting reinforced concrete structures or for use as a new construction material. This experimental study was performed to assess the bond strength between UHPFC as a repair material and Normal Concrete (NC) substrate as an old material; split tensile strength and slant shear tests were performed to quantify the bond strength in indirect tension and shear respectively, also the correlation between split tensile strength and slant shear were studied. The result showed that UHPFC has been cured by steam, gives high bond strength at the early age of the repair process, and interacts well with the surface of NC, as a result the failure occurred mostly in the NC substrate. A good correlation between the slant shear test results and the split tensile test results has been observed.

The construction industry is one of the main sectors of the Palestinian economy. The contracting companies carry out important construction projects in cooperation with subcontractors. The majority of works in construction projects (such as shuttering, building, plastering, painting, carpentry, and ironmongery works) are implemented by subcontractors through the main contractors[1]. This study aimed at investigating the relationship between the main contractors and their subcontractors. The study used a questionnaire that was administered by contracting companies classified at the Palestinian Contractors Union (in 1st, 2nd and 3rd class building categories) and their subcontractors. The study included the following main topics: 1) Factors used by general contractors for selection of suitable subcontractors. 2) Factors leading to the contractor- subcontractor interface problems. 3) Relationship between the main contractor and the subcontractor related to (Contractual relationship – safety - productivity improvement). The study revealed the important factors used by general contractors for selection of suitable subcontractors include: "adherence of the subcontractor to the contract terms, adherence to time schedule, commitment to prices, good reputation, specialty in certain type of work, commitment to quality and the existence of required equipment and machinery". The study found out that the important factors that cause interface problems include: "Assigning part of the works to new sub contractor without informing the original sub contractor, main contractor's financial problems, delay in contract progress payments, non-adherence to the conditions of the contract, non- adherence of the subcontractor to the time schedule, and lack of construction quality work" The study found that the majority of contracts are written contracts that are usually prepared by the main contractor then shown to the subcontractor, and include a penalty condition to end the contract in case that one of the parties doesn’t comply. Also, the study found out that the responsibility for safety and security is common between the contractor and the subcontractor. The contractor usually considers the previous performance of the subcontractor related to safety issues before selecting him for a project. Finally, the study found out that to improve the productivity, the main contractor should provide all requirements for the subcontractor and prepare the materials and shop-drawings early, while the subcontractor shall be aware of the modern managerial techniques and shall motivate the labors. The study recommended several actions to improve the relations between the contractors and their subcontractors. For example, the contractor should select the subcontractor according to his experience, capabilities, resources and reputation. On the other hand, the subcontractor should do his best to complete the works on time, adhere to all contract terms and conditions and to keep the best quality of work. [1] The terms: “Contractor”, “Main Contractor”, “General Contractor” and “Prime Contractor” shall have the same meaning whenever they are used.

This research aimed at studying the effect of sulfate attack on the compressive concrete strength with various percentages of recycled aggregate replacements (0%, 30%, 60% and 100%). Water cement ratio (0.42) are used, MgSO4 solution was used with two concentration (6% and 9 %) to represent the effect of sulfate attack on the concrete compressive strength. The experimental tests focused on physical properties of recycled aggregate; density, unit weight, sieve analysis, Los Angles test and specific gravity. Tests have also been performed on 108 concrete cubes samples at 7 days, 14 days and 28 days for compressive strength. The results of compressive strength at 28 days using (0%, 30%, 60% and 100%) recycled aggregate are (330, 280, 266 and 244) Kg/cm2 respectively, with reduction in compressive strength was (15.2%, 19.4% and 26%) for replacement ratio (30%, 60% and 100%) respectively. MgSO4 solution has an effect on compressive strength after 90 days of immersion in 6% and 9% concentrated of MgSO4 solution. The results of this study show that the reduction in compressive strength using recycled aggregate is more sensitive against the sulfate attack compared with natural aggregate.

In this study, the behaviour of eco-friendly concrete (Eco-Con) reinforced slabs was investigated by testing the structural behaviour of two-way slabs under punching shear, and by testing the performance of Eco-Con when used as a simulated repair material for one-way slabs under 4-point bending. Four Eco-Con mixes with the same target compressive strength of 32 MPa were used. The mixes consisted of one Portland cement concrete (CC) as the control mix, and three Eco-Con mixes namely: geopolymer rubber (GR), geopolymer lightweight expanded clay aggregate “LECA” (GL), and rubber engineered cementitious composite (RECC). The results for slabs subjected to punching shear showed 32 %, and 37 % less strength and 9 %, and 23 % less deflection when using Eco-Con concrete mixes GR and GL, respectively compared with the CC mix. The strength of Eco-Con RECC slab slightly decreased by 7 %, but its deflection capacity increased by 20 %, compared with the CC slab. The bending tests of ‘repaired’ slabs showed comparable slab bending strength capacity and ultimate deflection with the CC slab when using GR or GL mixes as the slab repair material. However, using RECC showed an increase in the slab bending strength capacity by 14 % and doubled the ultimate deflection, compared with the CC mix. Refereed/Peer-reviewed

Foam concretes (FCs) have stronger matrix structure than lightweight concretes. The porosity of foam and lightweight concretes reduces as the density of the material increases. In addition, the porosity of lightweight concrete is highly affected by the aggregates’ pore features, and that of FC is totally affected by the pore structure of the matrix. Addition of ground calcium carbonate (GCC) and glass fibre (GF) to FC was investigated in this study. The effects of ingredients, namely, GCC, GF, cement and water on flexural and compressive strengths and the thermal conductivity properties were also studied. Test results were optimised in a proposed hybrid model. The optimisation results were also validated with laboratory tests. GCC incorporation increases compressive strength and thermal conductivity because of the filling effect. Furthermore, GF inclusion in the concrete mixtures contributes to the flexural strength of concrete. Foam concretes (FCs) have stronger matrix structure than lightweight concretes. The porosity of foam and lightweight concretes reduces as the density of the material increases. In addition, the porosity of lightweight concrete is highly affected by the aggregates’ pore features, and that of FC is totally affected by the pore structure of the matrix. Addition of ground calcium carbonate (GCC) and glass fibre (GF) to FC was investigated in this study. The effects of ingredients, namely, GCC, GF, cement and water on flexural and compressive strengths and the thermal conductivity properties were also studied. Test results were optimised in a proposed hybrid model. The optimisation results were also validated with laboratory tests. GCC incorporation increases compressive strength and thermal conductivity because of the filling effect. Furthermore, GF inclusion in the concrete mixtures contributes to the flexural strength of concrete.

Purpose: Studying the factors affecting on the tender pricing for construction projects, especially the infrastructure projects in the Gaza Strip, throughout (1)studying the main factors affecting on tender pricing by considering the project parties (The owner, the consultant, the contractor and the donor), in addition to the market and the project, and (2) Identification of the most important problems that the contractor deals with in pricing the tender. Research Methodology: A number of researches and scientific papers related to the field of study were studied. A questionnaire was designed according to the quantitative scale methodology in this research. The final version of the questionnaire was obtained by (1) Arbitration of the questionnaire by 12 experts in construction especially in infrastructure sector in the Gaza Strip, where they were used to revise and measure the clarity and ease of understanding of the factors included in the questionnaire, and 122 questionnaires were distributed to the parties involved (construction companies and consulting offices). The questionnaire results: Throughout previous studies and arbitration of the questionnaire, 61 indicators were collected, divided into six sections, as follows: Factors affecting on tender pricing which are related to the owner, consultant, contractor, donor, market, and the project. The highest factors in the group of owners were the financial performance of the owner, and the accuracy in estimation the work to be implemented, The highest factors were the accuracy of the quantities listed by the consultant in the Bill of quantities, and the quality and accuracy of the tender documents provided by the consultant. Theoretical and practical implications of the research: The research unravels about an important concept and paves the path for future research in this particular area. It is concerned with construction professionals working in infrastructure construction firms. The questionnaire survey did not include all collected factors from literature review, since it was generalized that adopted to Gaza Strip. Recommendations were made for owners, consultants and contractors respectively in order to optimize the their infrastructure sector tenders pricing.

The construction sector is considered as one of the main pillars in the construction sector and the Qatari grant projects are considered as one of the largest projects spent in the Gaza Strip. The aim of this research is to improve the performance of all parties involved in the Qatari project by focusing on the factors of success and correcting the factors of failure, by exploring the present situation of the construction projects in Gaza strip, and identifying the most significant ones. This study was carried out through the distribution of ninety three questionnaires to the contracting companies working in Qatari projects, the consulting offices supervising Qatari projects. In addition, the Ministry of Public Works and Housing, and Qatari committee also throughout holding an interviews with some of construction companies that implemented the project of (city of his Highness Sheikh Hamad in the second phase in KhanYounis). This research revealed the most important factors that affecting the success of Qatari construction project in Gaza Strip which are : clear scope of the project, experience of the designer and his team, experience of contractor, closure of crossing points, presence of highly qualified technical staff, availability of funding of contractor to carryout business, regular mechanism of payments, reputation of the contractor, delay in obtaining fund and sufficient time given to design and . The results of this study have led to several recommendations aimed to the success of construction projects in general and Qatari projects in the Gaza Strip in particular: The need to give sufficient time to design, study all proposals in advance, inclusion of all parties in the design phase and set goals in advance in addition to studying all the surrounding circumstances, in addition to work on identifying alternatives to materials that may be used instead of materials, that are difficult to enter by the occupation, also need to pay attention to the technical staff of the project through employing a highly experienced technical team and conducting training courses. In addition to the contractor's interest in the quality of work to obtain the satisfaction of all related parties. The study also recommended the need to pay attention to the work of technical evaluation of contractors on the basis of experience and financial ability and performance and provide all the necessary facilities for work and find a quick mechanism in the disbursement of contractors' receivables in addition to the work of the contractor to include all the basic materials at the beginning of the project to ensure the work in the fastest time and avoid the delay caused by closing crossings .