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Journal Cover American Journal of Civil Engineering and Architecture
  [25 followers]  Follow
    
  This is an Open Access Journal Open Access journal
   ISSN (Print) 2328-398X - ISSN (Online) 2328-3998
   Published by Science and Education Publishing Homepage  [72 journals]
  • Effect of Aggregate Content on the Concrete Compressive Strength -
           Ultrasonic Pulse Velocity Relationship

    • Pages: 1 - 5
      Abstract: This paper investigates the relationship between the ultrasonic pulse velocity (UPV) and the compressive strength of concrete. The specimens used in the study were made of concrete with varied aggregate contents from 1000 to 1400 kg/m3. The specimens were made and tested at the Hawler Construction Laboratories (HCLabs) in Erbil, Kurdistan Region of Iraq. The UPV measurement and compressive strength tests were carried out at the concrete age of 28 days. The experimental results show that the relationship between UPV and the compressive strength of concrete is significantly influenced by the coarse aggregate content. Relationships are established for the range of contents of coarse aggregates and discussed.
      PubDate: 2016-1-4
      Issue No: Vol. 4, No. 1 (2016)
       
  • Application of ZLD Automaticly Continuous Launching System in the
           Construction of Prestressed Concrete Composite Box-girder Bridge with
           Corrugated Steel Webs

    • Authors: Dou Yong-zhi; Sun Chang-jun, Wei Fu-tang
      Pages: 6 - 11
      Abstract: The incremental launching construction method firstly is applied to the prestressed concrete composite girder bridge with corrugated steel webs and the bridge belongs to Zhengzhou Longhai Road Fast Track Project at Chang-zhuang reservoir in domestic. Under this background, ZLD automaticly continuous launching system is applied to the prestressed concrete composite girder bridge with corrugated steel webs and the construction scheme design, related construction technology and key points is introduced. Engineering practice shows that the advantage is synchronous control, automation, flexible construction, the force of incremental launching can be adjusted according to level of reaction force and deformation at the pier top. The construction efficiency, safety and reliability is improved for launching engineering, and it has a wide application prospect.
      PubDate: 2016-1-4
      Issue No: Vol. 4, No. 1 (2016)
       
  • Profitability Optimization of Construction Project Using Genetic Algorithm
           Cash Flow Model

    • Authors: I.M. Basha; A.H. Ibrahim, A.N. Abd El-Azim
      Pages: 12 - 22
      Abstract: Cash issues are various and complicated. The contractor starts with a forecast for the flow of the cash through the lifetime of the project. Cash shortages can lead to project failure and business bankruptcy. Researchers have studied cash flow in the context of project delay, business failure, and forecasting. However, negative cash flow trends and patterns themselves are not closely examined despite the amount, duration and distribution of negative cash flow are critical factors in construction performance. This study investigates cash flow management and profit optimization by reducing the extent and amount of negative cash flow on the construction projects and completes the project as scheduled by rescheduling construction activities based on the minimum cash flow availability. The study utilizes genetic algorithm’s technique to devise finance-based schedules that minimize project negative cash flow and profit optimization by identifying the amount and timing of individual inflow or outflow at the end of each period. The study also presents a case study project to illustrate the capability of the proposed model and adopts various constraints, including project profit and due dates, for scenario analysis. The analysis result demonstrates that minimizing negative flow ensures smooth financial pressure by properly shifting activities, and assigning due dates for projects helps planners avoid project duration extension while maximizing overall project profit.
      PubDate: 2016-1-11
      Issue No: Vol. 4, No. 1 (2016)
       
  • Comparative Elemental Analysis of Rice Husk Ash Calcined at Different
           Temperatures Using X-ray Flourescence (XRF) Technique

    • Authors: Taku J. K; Amartey Y. D, Kassar T
      Pages: 23 - 26
      Abstract: In this study, the effect of the calcination temperature of rice husk on the pozzolanic properties of the resulting rice husk ash (RHA) especially its silica content was investigated. Rice husk was collected from a rice milling plant and washed to remove sand and other impurities, beneficiated using the water beneficiation method and calcined at temperatures of 400, 500, 600, 700and 800°C, respectively for three hours. Samples were taken for XRF analysis, setting time determination and specific gravity test. The result of XRF analysis revealed that RHA calcined at temperatures between 400°C and 800°C contains more than 70% silica as stipulated by ASTM C618 for pozzolanas. The silica content though varies slightly with different calcination temperature of the rice husk ash. Also, calcination removed impurities present in the rice husk. Besides that, the specific gravity of RHA decreases with increasing calcination temperature from 2.00 at 400°C to 1.05 at 800°C. Setting times of RHA mortars at 15% replacement of OPC with RHA shows no definite pattern with increasing temperature. However, the initial and final setting times of OPC-RHA mortars at all calcination temperatures were higher than that of OPC mortar. As a whole, calcination improves the silica content of rice husk ash for use as a pozzolana as well as removes mineral impurities that may affect the pozzolanic properties of the rice husk ash.
      PubDate: 2016-1-15
      Issue No: Vol. 4, No. 1 (2016)
       
  • A Review on Recycled Aggregates for the Construction Industry

    • Authors: Yasir Karim; Zubair Khan, Mohammad S. Alsoufi, Mohammed Yunus
      Pages: 27 - 33
      Abstract: The essence of modern development is closely linked with conservation of natural resources by preventing environmental degradation as construction materials are increasingly judged by their ecological characteristics. Concrete, the most versatile material for construction, is playing a significant role in the growth of infrastructural and industrial segments but it has been claimed that concrete is not an environmentally-friendly material due to its destructive resource consuming nature and the possibly severe environmental impact after its use. It will, however, remain the major construction material being used worldwide. In order to study closely and in brief related studies in the field of recycling of hardened concrete or the use of recycled aggregates this literature review was carried out. Recycled aggregates are still not conventionally used in the construction industry but still a lot of work has been done on recycling of hardened concrete and continuous improvements are required to optimize this. Some of the research studies on the properties, uses, shortcomings and behavior of recycled aggregate have also been highlighted.
      PubDate: 2016-1-29
      Issue No: Vol. 4, No. 1 (2016)
       
  • A Comparative Analysis of Codes Prediction of Shear Resistance in Beams
           without Shear Reinforcement

    • Authors: Ofonime A. Harry; Ifiok E. Ekop
      Pages: 34 - 38
      Abstract: Shear provisions in codes are based on empirical equations derived from experimental test results without any rational theory to explain its behavior. Some of these expressions, for example BS 8110, ACI 318 and Eurocode 2 takes into account the effect of reinforcement ratio, effective depth and concrete compressive strength while Canadian code considers the shear strength to be a function of concrete compressive strength only. The new Model code 2010 considers the shear strength of beams as a function of longitudinal strain in the web. This brings about disparity in shear strength prediction from different codes. This paper examines the accuracy of shear strength predictions in beams without shear reinforcement. The study involves a comparative analysis of shear strength predictions from five different codes: BS 8110, Eurocode 2, Canadian code, ACI code 318 and Model code 2010. A total of 435 experimental test results from database of shear critical beams in literature were used for the study. The results shows that Model code 2010 shear strength prediction is the most conservative among the five codes shear provisions considered in this study. This may be due to the assumed linear elastic state of the flexural reinforcement at the point of failure in shear. BS 8110 and Eurocode 2 predictions gave the least variation compared to other codes predictions. The highest number of unsafe shear strength predictions was obtained from Canadian code followed by prediction s from ACI 318.
      PubDate: 2016-2-2
      Issue No: Vol. 4, No. 1 (2016)
       
 
 
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