Roller compacted concrete (RCC) is a concrete compacted by roller compaction. The concrete mixture in its unhardened state must support a roller while being compacted. The aim of this research work was to investigate the behavior and properties of roller compacted concrete when constructed in the laboratory using roller compactor manufactured in local market to simulate the field conditions. The roller compaction was conducts in three stages; each stage has different loading and number of passes of the roller. For the first stage, a load of (24) kg and (5) passes in each direction had been employed. For the second stage, a load of (104) kg and (10) passes in each direction were conducted. Finally, at the third stage, a load of (183) kg and (15) passes were adopted. Such procedure was in accordance to previous work conducted by the author. The effects of the type of coarse aggregate (crushed and rounded), fine aggregate (river and natural) and cement type (OPC and SRPC) on the mechanical properties of RCC were investigated. The effect of compaction method on compressive strength and indirect tensile strength was also discussed. A total of (26) roller compacted concrete slab samples of (380×380×100 mm) were prepared in the laboratory, Then, the slab specimens are taken out of the molds and immersed in the curing tank for (28) days. Core and Beam specimens were obtained from the slab samples for the determination of mechanical properties. Such properties include compressive, indirect tensile, flexural strengths using one point loading. It was concluded that the compressive strength of RCC using crushed aggregate is higher than that when using rounded aggregate in a range of (15-66) % for core specimens, while the compressive strength of RCC when using river sand is higher than that when using natural sand in a range of (9-26)% for core specimens. When river sand is implemented, RCC samples show higher indirect tensile strength than those with natural sand, such variation is within (7-8) %
This study discusses risk management strategies caused by pandemic-related (Covid-19) suspensions in thirty-six engineering projects of different types and sizes selected from countries in the middle east and especially Iraq. The primary data collection method was a survey and questionnaire completed by selected project crew and laborers. Data were processed using Microsoft Excel to construct models to help decision-makers find solutions to the scheduling problems that may be expected to occur during a pandemic. A theoretical and practical concept for project risk management that addresses a range of global and local issues that affect schedule and cost is presented and results indicate that the most significant delays are due to a
... Show MoreThis study discusses risk management strategies caused by pandemic-related (Covid-19) suspensions in thirty-six engineering projects of different types and sizes selected from countries in the middle east and especially Iraq. The primary data collection method was a survey and questionnaire completed by selected project crew and laborers. Data were processed using Microsoft Excel to construct models to help decision-makers find solutions to the scheduling problems that may be expected to occur during a pandemic. A theoretical and practical concept for project risk management that addresses a range of global and local issues that affect schedule and cost is presented and results indicate that the most significant delays are due to a
... Show MoreThe present study has examined the spatiotemporal varieties of the demographics of the Shatt Al-Arab River fishes and their relation to some ecological components. The aim is to forecast these groups in the unexplored parts of the waterway with an emphasis on environmental indices of diversity. Three sites in the river were selected as an observation and study of these species, which lasted from March 2019 to February 2020, the study dealt with factors affecting fishes, as Water Temperature (WT), Dissolved Oxygen (DO), Potential Hydrogen Ion (pH), Salinity (Sal), and Transparency (Tra). Gill nets, cast nets, hooks, and hand nets were adopted to collecting fish. The results indicated that the fish population comprises 60 species represent
... Show MoreThe aim of this study is to propose reliable equations to estimate the in-situ concrete compressive strength from the non-destructive test. Three equations were proposed: the first equation considers the number of rebound hummer only, the second equation consider the ultrasonic pulse velocity only, and the third equation combines the number of rebound hummer and the ultrasonic pulse velocity. The proposed equations were derived from non-linear regression analysis and they were calibrated with the test results of 372 concrete specimens compiled from the literature. The performance of the proposed equations was tested by comparing their strength estimations with those of related existing equations from literature. Comparis
... Show MoreCommunication and media technologies have seen several changes in the last two decades. These changes put the basis for the emergence of communicative and media practices on several levels including political, economic, technological and artistic. And these, in turn, led to the emergence of new media trends and phenomena in various areas of media worthily to be studied and researched for example online advertisings. Online advert
... Show Moreان الرأسمالية ليست بناءً هندسياً يتم انتظامه وفقاً للنظريات الهندسية والمعادلات الرياضية والفنون المعمارية، لأنها ببساطة نظاماً اجتماعياً يقوم على تشكيلة اقتصادية معينة، والأخيرة تقوم على مستوى معين لتطور قوى الانتاج (التكنولوجيا) والذي يقوم عليه مستوىً معين لعلاقات الإنتاج، ويقوم على التشكيلة الاقتصادية/ نمط الإنتاج نظاماً سياسياً، هو جزء من البناء الفوقي، ولأنها نظاماً اجتماعياً بالمواصفات انفة
... Show MoreThe specialist researcher fined the relations between economic ideas with economic facts in his theory which called humanity building it is appeared clearly ( in Ibn Khalduons’ Muqaddimah) in a clothe of economic social phenomenon's as a systematical analysis in all fifty chapters of al Muqaddimah ,therefore this paper deal with Ibn Khalduon economic thoughts as important says which describe the society building in its economic subjective and examine the relationship between The dissert and the city within economic says which are cover the social analysis ,and determinate the analysis objects which clearly in this dualism model ,between the state and economic bas
... Show MoreThis essay aims to highlight the most important issues and difficulties facing implementing large projects that follow the turn-key method, considered one of the types of contractual methods in Iraq, especially for large and complex projects requiring speedy completion. The projects implemented in this way face delays and delays in completion, which led to the lack of benefit from the projects for which they were implemented, especially those affecting the lives of citizens within the health sector. The case study dealt with the construction of hospitals with multi-bed capacities within multiple governorates in Iraq, With large financial allocations within the federal budget of the Government of Iraq over several years.
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