Journal Cover Challenge Journal of Concrete Research Letters
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  This is an Open Access Journal Open Access journal
   ISSN (Online) 2548-0928
   Published by TULPAR Academic Publishing Homepage  [2 journals]
  • Cover & Contents Vol.8 No.3

    • Authors: CJCRL Journal Management
      PubDate: 2017-09-12
      Issue No: Vol. 8, No. 3 (2017)
       
  • Feasibility of using self-compacting concrete in civil engineering
           applications

    • Authors: Zeinab A. Etman, Mounir M. Kamal, Mohamed R. Afify, Tamer I. Ahmaed
      Pages: 70 - 83
      Abstract: This research aimed to investigate the feasibility of using self-compacting concrete in civil engineering applications as a producing a precast hollow unit. The behavior of the hollow sections cast with self-compacted concrete beneath line-load was evaluated. An experimental work was carried out and a finite element model with ANSYS (version 15) was adopted. A total of fourteen hollow beams were cast and tested. The most variables taken into thought were; the types of reinforcement (reinforced steel bar and steel wire meshes), the types of steel wire meshes (expanded and welded steel wire mesh), number of layers of steel meshes (one layer and two layers), cross section thickness of concrete (40 mm and 60mm), concrete cover thickness (15mm and 20 mm) and also the shapes of cross section (square or circular). Special attention to initial cracking load, ultimate load, deflection, cracking pattern, energy absorption and ductility index were investigated. Good agreement was found compared with the experimental results. Out of this research; this paper presents applications of self-compacted concrete for casting skinny structural hollow members. These members can be used as precast units within the construction of the tunnel to decrease the problems in highway roads due to the difficulty of using crossing bridges particularly for kids and old people which are very useful for developing countries with great economic advantages.
      PubDate: 2017-09-12
      DOI: 10.20528/cjcrl.2017.03.001
      Issue No: Vol. 8, No. 3 (2017)
       
  • Study on partial replacement of groundnut shell ash with cement

    • Authors: Nadiminti Venkata Lakshmi, Polinati Satya Sagar
      Pages: 84 - 90
      Abstract: Concrete plays a prominent role in the construction industry. In the present scenario, there is a shortage of this material so there is a need to find alternatives to replace it in the concrete. In order to overcome this situation; many waste products which are available freely like a paper waste, red mud, rice husk and plastic waste can be used.  Among all of these, Ground nut shell ash is one of the good waste materials available from the oil industry. It can be used widely for the replacement of cement. The ground net shell contains CaO, SiO2, Al2O3, and Fe2O3. This experimental investigation was carried out to evaluate the strength of concrete, in which cement was replaced with ground nut shell ash for cubes, cylinders, and Prisms with different percentages which vary from 0% to 30% at an interval of 5% were performed. Concrete was batched by weight on adopting a ratio of 1:2:4 with water–cement ratio of 0.6. Concrete cubes of 150*150*150 mm in dimensions, cylinders of 150*300 mm in dimensions and 100*150 mm prisms are used. These Cubes, cylinders, and prisms were tested for 7, 14 and 28 days for compression, flexural and split tensile strengths. It is observed that 10% replacement of ground nut shell ash shown the highest strength values when compared with other percentages and for 15% replacement of ground nut shell ash the compressive and split tensile strength obtained the highest strength rather than other flexural strength.
      PubDate: 2017-09-12
      DOI: 10.20528/cjcrl.2017.03.002
      Issue No: Vol. 8, No. 3 (2017)
       
  • Effectiveness of crack repairing measures in Tabuk City, Saudi Arabia

    • Authors: Yazan Issa
      Pages: 91 - 95
      Abstract: Concrete cracking and defect patterns can often indicate its causes. In this research paper, detailed description of cracks types, causes, and proper solutions is identified. The main objective of the paper is to measure the response of specialists about the probability of certain cracks causes and solutions, and to evaluate the effect of using epoxy materials in repairing concrete cracks. The present study shows that about 50% of responders indicated that cracks due to steel corrosion represent between 10-20% of building cracks. And about 80% of the responders indicated that crack due to load increasing is rarely occurred in the site. The interviewed specialists ensured that using epoxy materials are effective in solving most cracks’ problems. The experimental work results show that the flexural strength of epoxy repaired samples exceeded that of original samples. And the increase in flexural strength is inversely proportioned with sample depth.
      PubDate: 2017-09-12
      DOI: 10.20528/cjcrl.2017.03.003
      Issue No: Vol. 8, No. 3 (2017)
       
  • Cover & Contents Vol.8 No.2

    • Authors: CJCRL Journal Management
      PubDate: 2017-07-01
      Issue No: Vol. 8, No. 2 (2017)
       
  • Effectiveness of high performance mortar reinforced with fibers as a
           repair material

    • Authors: Eethar Thanon Dawood, Tamara Waleed Ghanim
      Pages: 29 - 47
      Abstract: The present work deals with engineering properties of high performance mortar (HPM) to be used as a repair material. The experimental study was conducted on HPM reinforced with mono steel fibers and hybrid fibers consist of steel and polypropylene fibers. The economical efficiency of the designed mono and hybrid fibers reinforced mortar were presented. The results indicate that the hybridization of 1.8% steel fibers and 0.2% polypropylene fibers is very beneficial to decrease the production cost of fiber reinforced mortar for large scale construction project applications. The combined system of substrate concrete with different mixes of HPM was used to study its bond strength properties. The experimental tests are: two-part bond strength tests in additional to three part-bond strength tests. It was found that HPM reinforced by hybrid fibers has the best performance when two-part bond strength is required. On the other hand, in three parts bonding, the combined system of NC with epoxy has the best bond strength while HPM reinforced fibers show a better failure mode.
      PubDate: 2017-07-01
      DOI: 10.20528/cjcrl.2017.02.001
      Issue No: Vol. 8, No. 2 (2017)
       
  • Structural behaviour of ferrocement channels slabs for low cost housing

    • Authors: Yousry B. I. Shaheen, Essam A. Eltehawy
      Pages: 48 - 64
      Abstract: This paper presents a new pre cast U-shape ferrocement forms reinforced with various types of metallic and non-metallic mesh reinforcement. This research was designed to investigate the feasibility and effectiveness of employing various types of reinforcing meshes in the construction of structural slabs incorporating permanent U-shape ferrocement forms as a viable alternative for conventional reinforced concrete slabs. Fiber glass meshes reinforcement was used for durability and protection against corrosion of reinforcing steel. To accomplish this objective, an experimental program was conducted. The experimental program comprised casting and testing ten slabs having the total dimensions of 500x100x2500 mm incorporating 40 mm thick U-shape permanent ferrocement forms. Series A consists of two conventionally reinforced concrete slabs were cast and tested and used as control slab without fibers and with fibers, volume fraction, 2.05 % and 2.177 %. Series B comprises of two slabs reinforced with one and two layers of expanded steel mesh, volume fraction 2.09 and 2.42% respectively. Series C comprises two slabs reinforced with two and four layers of welded galvanized steel mesh, having volume fraction 2.05 and 2.189% respectively. Series D Consists of two slabs reinforced with one layer and two layers of fiber glass meshes, having volume fraction 2.107 and 2.277% respectively. Series E comprises two slabs reinforced with 2 layers expanded steel mesh and one layer expanded steel mesh, having volume fraction 1.357 and 2.750 % respectively. The test specimens were tested as simple slabs under four-line loadings condition on a span of 2300mm. The performance of the test slabs in terms of strength, stiffness, strains, cracking behavior, ductility, and energy absorption properties was investigated. The behavior of the developed slabs was compared to that of the control slabs. The experimental results showed that high ultimate and serviceability loads, better crack resistance control, high ductility, and good energy absorption properties could be achieved by using the proposed slabs and low cost compared with control specimen.
      PubDate: 2017-07-01
      DOI: 10.20528/cjcrl.2017.02.002
      Issue No: Vol. 8, No. 2 (2017)
       
  • Evaluation of initial setting time due to superplasticizers

    • Authors: Abhishek Singh, Shobha Ram, Alok Verma
      Pages: 65 - 69
      Abstract: This paper shows how polycarboxylate based superplasticizer affects the initial setting time of cement paste. Three superplasticizers are used in this study with different properties and aiming to determine the delay in initial setting time due to superplasticizer. Initial setting time is calculated as per IS: 4031-PART 5-1988 with different SP dosages (0.5%, 0.75%, 1.0% and 1.5% of weight of cement). Superplasticizer is an admixture which reduces the water-cement ratio or increase the workability at the same water content. This paper deals with the evaluation of initial setting time due to superplasticizers.
      PubDate: 2017-07-01
      DOI: 10.20528/cjcrl.2017.02.003
      Issue No: Vol. 8, No. 2 (2017)
       
  • Cover & Contents Vol.8 No.1

    • Authors: Journal Management CJCRL
      PubDate: 2017-04-04
      Issue No: Vol. 8, No. 1 (2017)
       
  • Non-destructive techniques for early damage detection for highway bridges
           using dynamic response

    • Authors: Ahmed A. Elshafey
      Abstract: Nondestructive techniques are based on the comparison of the static and dynamic behaviors of intact structures and their behavior in later times. The techniques are based on detection of any damage or deterioration through the structural behavior. One of the effective methods used in damage detection is based on the dynamic response of the structure to random excitation. The random decrement method is used to extract the free vibration response of structural systems subjected to Gaussian random loads with zero mean. The free vibration of the system depends on the mass and stiffness matrices of the system. When the mass and/or stiffness matrices change, the free response will also be changed. The random decrement method identifies the damage through the change of the system properties. The random decrement is usually used for single channel readings. However, in this work it is extended to use multi-channel to extract multi-signature for the structure from the dynamic response of the multi-degree-of-freedom systems. The proposed research aims to apply the random decrement technique as a nondestructive method in identifying the damage existence and location in concrete bridges. Moreover, one of the successfully used methods on data taken from finite element analysis is the modified mode shape difference method. The method can be used to extract the mode shapes of the structure without knowing the exciting force under the condition that excitation force should be stationary with zero-mean Gaussian process. The proposed work will include three models; single span, two-span simply supported bridges and a slab type bridge.  Since bridges are subject to moving dynamic loads, the models will be tested by using different locations to inspect the best places to excite the structures. 
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Environmental Safety Of Natural And Manufactured Building Materials

    • Authors: M.K. Kamal, A. A. Nasser, N. A. Hassan
      Abstract: Natural radioactivity was estimated in building materials using γ-spectroscopic method. Samples of granite, bricks, concrete and ceramic were collected from different places in Egypt. Samples were prepared for physical and mechanical properties measurements as well as the radioactive content. Gamma spectrometer composed of NaI crystal connected to ORTEC analyser was used for radioactive measurements. Standard sample was prepared with the same geometry factor in NIS using a standard source traceable to NIST. Data of 238U, 232Th and 40K activities were collected, where the effective dose was calculated by the aid of UNSCEAR. Diffusion equation was used to estimate Radon emissions rate from building materials used in proposed model rooms.It was found that the average concentrations of 238U, 232Th and 40K in the studied materials were for granite 63.4, 2.42, 1010.91 Bq/kg, for bricks   20.12, 3.75, 27.25 Bq/kg and for concrete 34.23, 2.36, 506.36Bq/kg. In spite of using materials with permissible activity concentration, the radon emission in model rooms was beyond the safe limits for inhabitants. The maximum dose from Rn concentration was 1.23 mSv/y. This concentration was affected by the space dimension, passing elapsed time and building material radioactivity as well as ventilation. It was also found that the most powerful factor affecting radon concentration is the ventilation
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Effect of nano-SiO2 particles on properties of cement mortar applicable
           for ferrocement elements

    • Authors: Abbas Booshehrian, Payam Hosseini
      Abstract: In this study the mechanical properties (by compressive and flexural strength tests), durability (by water absorption test), and microstructural properties of interfacial transition zone (ITZ) (by Scanning Electron Microscopy and Atomic Force Microscopy tests) of mortars applicable for the casting of ferrocement elements reinforced with nano-SiO2 particles are investigated. The parameters of this study include the low replacement  ratio of nano-SiO2 particles respect to cementin Ordinary Portland Cement (OPC) mortar mixture (including 1%, 2% and 3%), water to binder ratio (including 0.35, 0.4 and 0.5), and also sand to binder ratio (including 2 and 2.5).The results have shown that the cement mortars containing nano-particles have reasonably higher strength, low water absorption and denser ITZ compared to those of the OPC ferrocement mortars. Furthermore, along with increasing the W/CM, the performance of silica nano-particles has been reduced. Besides, using higher S/CM was followed by strength loss in both categories of mixtures including with and without silica nano-particles. However, distinctive strengthening trend was not observed in mixtures with different S/CM (by holding the other variables constant such as silica nano-particles).
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Effective thermal conductivity of foamcrete of different densities

    • Authors: Md Azree Othuman Mydin
      Abstract: The main purpose of this study is to investigate the thermal conductivity of foamed concrete. Various densities of foamed concrete samples ranging from 650, 700, 800, 900, 1000, 1100 and 1200 kg/m3 with constant cement-sand ratio of 2:1 and water-cement ratio of 0.5 were produced. This study was limited to the effect of density, porosity and pore size on thermal conductivity of foamed concrete. Hot-guarded Plate method was used to obtain the thermal conductivity of foamed concrete at different densities. The porosity value of foamed concrete was determined through the Vacuum Saturation Apparatus. In turn to examine the effect of pore size on thermal conductivity of foamed concrete, pore size measurements were made under a microscope with a magnification of 60x. Lower density foamed concrete translates to lower thermal conductivity. The density of foamed concrete is controlled by the porosity where lower density foamed concrete indicates greater porosity. Therefore, thermal conductivity changes considerably with the porosity of foamed concrete because air is the poorest conductor compared to solid and liquid due to its molecular structure.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Potential of Using Lightweight Foamed Concrete in Composite Load-Bearing
           Wall Panels In Low-Rise Construction

    • Authors: Md Azree Othuman Mydin
      Abstract: This paper will look at the potential of using lightweight foamed concrete (LFC) in composite load-bearing wall panels in low-rise construction. From the experimental verification, as expected the mechanical properties of LFC were reasonably low when compared to normal strength concrete. Nonetheless there was a potential of using LFC as fire resistant partition or as load-bearing walls in low-rise residential construction. In order to demonstrate the feasibility of this proposal, this paper presents a preliminary feasibility study on its fire resistance and structural performance of LFC based system. The objectives of this feasibility is two-fold; to investigate the fire resistance performance of LFC panels of different densities when exposed to fire on one side for different fire resistance ratings based on insulation requirement and to examine whether the composite walling system had sufficient load carrying capacity, based on compression resistance at ambient temperature.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Comparative Study Between Flowable High Strength Mortar and Flowing High
           Strength Concrete

    • Authors: Mahyuddin Ramli, Eethar Thanon Dawood
      Abstract: This paper presents the results of an investigation aimed to evaluate the comparison between high strength flowing concrete (HSFC) and high strength flowable mortar (HSFM) from the view of density, compressive strength and flexural strength at the age of 7 and 28 days. The results illustrate that the use of Silica fume (10 % as a partial replacement of cement) and superplasticizer (1.6- 2.2% of cementitious materials) gives the properties of high flowability with the high strength for each of concrete and mortar mixes. Besides, the compressive strength and flexural strength for each of mortar and concrete have been enhanced by the inclusion of silica fume.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Phenomenological Model of Corrosion Process in Reinforced Concrete
           identified by AE

    • Authors: Y. Tomoda, M. Ohtsu
      Abstract: Corrosion of reinforcing steel is modelled phenomenologically as corrosion losses of three phases.   In order to identify the corrosion process in reinforced concrete based on the model, continuous AE monitoring in reinforced concrete specimens was conducted in an accelerated corrosion test and a cyclic wet and dry test.   It is demonstrated that two periods of high AE activities are observed.  The 1st AE activity corresponds to the onset of the corrosion in rebar of the 1st phase in the phenomenological model.  At the 2nd period of high activity AE events result from concrete cracking, corresponding to the 3rd phase in the model.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Damage of Reinforced Concrete qualified by AE

    • Authors: M. Uchida, T. Okamoto, M. Ohtsu
      Abstract: In order to assess the damage levels of the structures, one criterion based on the Kaiser effect of acoustic emission (AE) is proposed.  AE parameters of load ratio and calm ratio are defined for qualification of the damages.   Accordingly, the feasibility of the damage qualification is experimentally examined by using reinforced concrete beams which are damaged under incremental-cyclic loading.   It is found that the damages qualified by the two ratios are in good agreement with actual damages of the beams.  This suggests that the damages of such reinforced concrete structures in service as bridges, docks and buildings are quantitatively assessed, by simply applying cyclic loading and monitoring AE activity
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Detection of Thermal Cracks in Early-Age Concrete by AE

    • Authors: T. Watanabe, T. Ohno, C. Hashimoto
      Abstract: Early-age cracking after casting is a fundamental problem for the durability of concrete structures.   Recently, thermal cracks and early-age cracks have been observed in concrete containing Portland cement with blast-furnace slag in Japan.  In order to reduce the number of these cracks, fly ash is substituted for cement or sand.  Fly ash is one of the popular admixtures as a waste material from coal-fired power plants.  To evaluate the effect of fly ash on early-age cracks, experimental studieswere performed.  In order to detect micro-cracking in concrete, acoustic emission (AE) measurement was applied.   In experiments, two types of fly ash, typeⅡ and Ⅳ categorized by JIS were employed. The ratio to substitute cement and sand was 10% and 20%.  As a result, micro-cracks in concrete were detected by the AE method.   Resultsshow that substitution of fly ash for cement and sand is effective to reduce micro-cracking due to thermal changes which occurs from 20 to 30 hours elapsed after casting of concrete.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Failure Detection of High-Strength Tendons in Prestressed Concrete Bridges
           by AE

    • Authors: S. Yuyama, M. Ohtsu
      Abstract: Three types of beams post-tensioned by steel bar, strand, and parallel wire cable with three different grout conditions (unbonded, partially grouted and fully grouted) were tested in a laboratory.  Failure was introduced by artificial corrosion, charging anodic current to tendons.  It is found that acoustic emission (AE) signals with extremely high amplitudes are generated by ruptures of high-strength tendons.  Detectability of failure is demonstrated to be 82-86%.  Then, continuous AE monitoring was carried out in two highway bridges in service.  The analysis of detected AE signals proves that meaningful AE events due to tendon failure are clearly discriminated from other signalsof traffic noises and hammering.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Effect of Blended Fly Ash on the Compressive Strength of Cement Paste

    • Authors: S. K. Agarwal, L. P. Singh, V. Sood, G. Mishra, S. Ahalawat
      Abstract: In this paper, the effect of fly ash percentage of different fields or hoppers on the compressive strength of cement paste with and without superplasticizer has been studied. The accelerated pozzolanic activity of fly ash of each field and their blending has been evaluated with and without superplasticizer. The pozzolanic activity increases from field I to V as expected, the noticeable observation is that with the use of superplasticizer, the pozzolanic activity of the first field is comparable to control value of 340 kg/cm2. Further, the pozzolanic activity of blended fly ash of first field with fly ash of other fields, the pozzolanic reactivity is comparable to control value. In case of 50-50 blending of first field and second field fly ash the pozzolanic activity is approx 7% more than control
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Comparative Study of The Effects of Wind and Earthquake Loads on High-rise
           Buildings

    • Authors: Khaled Mohamed Heiza, Magdy A. Tayel
      Abstract: It is very essential to consider the effects of lateral loads induced from wind and earthquakes in the design of reinforced concrete structures, especially for high-rise buildings. The Egyptian Code of Practice for Calculating Loads and Forces in Structural and Building Works, 1993 and 2003 gives simplified methods for calculating such loads. In some cases effects of earthquakes are found to be dominant and more critical than wind effects. This depends on some factors defined by codes. In this research the both effects will be studied and compared according to the Egyptian Code 1993 and 2003. The codes are reviewed for wind and earthquake analysis and discussed to show all factors affecting the design. A computer program is developed to analyze the structural buildings behavior under wind pressure defined as well as equivalent static loads for earthquakes considering all factors in the codes. Application examples for buildings with different heights, floor weights and boundary conditions for both winds and earthquakes such as the intensity of the wind pressure, the seismic zone coefficient, the importance factor, structural system factor and the soil coefficient are analyzed and discussed for the purpose of comparison. Some recommendations are suggested to improve the resistance of the structural and environmental systems of the buildings with respect to lateral loads. Finally Egyptian seismic map, tables of different shape effect and structural systems are provided to help structural designers and researches during design process.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Finite Element Modelling of Strengthened Simple Beams using FRP
           Techniques: A parametric Study

    • Authors: F. A. Fathelbab, M. S. Ramadan, A. Al-Tantawy
      Abstract: The main objective of this paper is to study analytically the strengthening of a simple
      reinforced concrete beams due to excessive uniform loads in flexure, shear and a
      combination of flexure and shear, using externally bonded FRP sheets technique. A
      commercial finite element computer program ANSYS has been used to perform a structural
      linear and non-linear analysis for several models using several schemes of FRP sheets. A
      parametric study has been performed for a lot of strengthened beams. FE models studies a
      main parameter of different schemes of FRP sheets in flexure, shear and combination
      flexure/shear. Comparing the results with a control beam model – simple reinforced
      concrete beam without strengthening – it is obvious that all strengthened beams have a
      greater ultimate capacity than the control beam and noticeable enhancement in member
      ductility. The increasing level differs as a result of the strengthening scheme. The
      strengthened beam in both flexure and shear gives a higher ultimate load capacity, delay the
      failure and prevent debonding failure up to a level at which debonding occurs in both
      longitudinal and wrapped jackets CFRP sheets.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Air Permeability of Hardener-Free Epoxy-Modified Mortars Using NDT

    • Authors: Aamer rafique bhutta
      Abstract: The purpose of this study is to investigate the airpermeability of hardener-free epoxy-modified mortars by applyinga non destructive testing method developed by RILEM Technical Committee 189-NEC. Considering intelligent patch materials for the repair work of deteriorated reinforced concrete structures, hardener-free epoxy-modified mortars using a bisphenol A-type epoxy resin without any hardener are prepared with various polymer-cement ratios, and tested for moisture content, air permeability and strength. As a result, although there is no significant strength improvement, the coefficient of air permeability of the hardener-free epoxy-modified mortars is markedly decreased with an increase in the polymer-cement ratio.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • AE-SiGMA Analysis in Brazilian Test of Concrete

    • Authors: M. Mondoringin, S. Nozaki, M. Ohtsu
      Abstract: The moment tensor analysis of AE waveforms has been developed and is now available for identifying crack kinematics of a location, a crack-type and a crack orientation in a material.   The procedure has been implemented as the SiGMA analysis.  Mechanisms of cracking can be visually and quantitatively studied at the meso-scale in concrete. Since the tensile strength of concrete is normally evaluated by the Brazilian test.  Mechanisms of macro-scale tensile failure in concrete are clarified as the cracking process at the meso-scale determined by the SiGMA analysis.  Evolution of the fracture process zone under the combination of tensile and compressive stresses is discussed.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Mechanisms of Corrosion-Induced Cracks in Concrete

    • Authors: M. Ohtsu, F. A. K. M. Uddin
      Abstract: Corrosion-induced cracks was simulated in expansion tests.   Kinematical mechanisms of micro-cracks were identified by theSiGMA analysis of acoustic emission (AE).   By applying the boundary element method (BEM), extension of the corrosion-induced crack in an arbitrary direction was analyzed.   It is demonstrated that extension of the corrosion-induced crack is governed by the mode-I failure, although all kinds of micro-cracks are observed  in results of AE analysis.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Damage Evaluation of Core Concrete by AE

    • Authors: Tetsuya Suzuki, Masayasu Ohtsu
      Abstract: For a detailed inspection of a concrete structure, core samples are usually drilled out and then their physical properties are measured.  In this study, damage evaluationmethod for concrete materials is studied,applying acoustic emission (AE) method and computerized tomography (CT) scanning procedure.   We have proposed a quantitative damage evaluation of concrete, based on AE measurement anddamage mechanics in the compression test.  The procedure is named DeCAT (Damage Estimation of Concrete by Acoustic Emission Technique), which is based on estimating an intact modulus of elasticity in concrete.  Concrete-core samples were taken from reinforced concrete walls in a canal.  These samples are strongly damaged by a freezing and thawing process.  Crack distributions in the samples were inspected with helical CT scans, which were undertaken at one-millimetre interval.  After the helical CT scan, damage of freeze-thawed samples was evaluated by applying the DeCAT analysis. These results demonstrate that the decrease in physical properties could be evaluated by comparing the averaged CT number with the durability index by AE.The both values clearly reflect amount of internal cracks in core samples.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Porosity and Strength of Pozzolan Modified Cement Systems

    • Authors: C M. Sutan, Sinin Hamdan, Habibur Rahman Sobuz, Vincent Laja, Md. Saiful Islam
      Abstract: Porosity is one of the important properties that determine the durability of concrete and mortar. Porosity represents the amount of voids inside the concrete, which is dimensionless quantity, usually expressed as a percentage value. This aim of this study is to determine the effect of pozzolans such as pulverized fly ash (PFA) silica fume (SF) on the porosity and strength of mortars. The mix proportion with and without pulverized fly ash (PFA) and silica fume (SF) are tested with two properties such as strength and porosity in order to understand the effect against performance of the mortar. In addition, curing condition also does affect the strength and porosity of the modified mortar. The results from this study shows that the pozzolan modified mortar which is the sample with pozzolan replacement, has low in durability and higher porosity compared with non-modified mortar when it is cured under air curing, which is the method of curing that usually been applied at the construction site.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Behavior and Analysis of Cracked Self-Compacted Reinforced Concrete Beams

    • Authors: Khaled Mohamed Heiza, A. T. Attwa, Y. B. Shaheen
      Abstract: The objectives of this paper are to compare between the fracture parameters of self compacting concrete (SCC) and normal vibrating concrete (NVC). The fracture behavior of both the plain and reinforced concrete beam specimens under three point bending (3PB) was investigated. It was found that the values of fracture toughness in reinforced concrete beams increased with increasing the notch – depth ratio, increasing the area of steel bars in cross section and with using dolomite as coarse aggregate in the mix. The self compacting concrete beams exhibit good fracture toughness than those of normal concrete at all the used variables. A model of Hillerborg was used to predict the fracture toughness of notched concrete beams.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Statistical Modelling and Prediction of Compressive Strength of Concrete

    • Authors: Mahmoud Shaaban Sayed Ahmed
      Abstract: The matrix mixture of concrete can be made to have high compressive strength. In the present paper, statistical model was built-up to predict the compressive strength of concrete containing different matrix mixtures at fixed age or at different age of 1, 3, 7, 28, 56, 90 and 180 days. The model examines eight different parameters for the matrix mixture that includes: time, water, cement, metakaolin (MK), silica fume (SF), sand (S), aggregate (A) and superplasticizer (SP). This research addresses the effect of the matrix mixture of concrete on the compressive strength, where this information will help the cement industry in producing the required concrete strength. The results from the predicted model have high correlation to the experimental results for the concrete compressive strength.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Corrosion Damage in Reinforced Concrete identified by AE

    • Authors: Yuma Kawasaki, Misuzu Kitaura, Tomoe Kobarai, Masayasu Ohtsu
      Abstract: Deterioration and damage in reinforced concrete (RC) have been reported world-wide.   One of critical causes is a salt attack.  Thus, monitoring against corrosion damageis a key issue.  To identify the onset of corrosion and the nucleation of corrosion-induced cracks due to expansion of corrosion products, continuous acoustic emission (AE) monitoring is available.   SiGMA (Simplified Green’s functions for Moment tensor Analysis) procedure is applied to AE waveforms to identify source kinematics of micro-cracks in the corrosion process.  Results show that the onset of corrosion and the nucleation of corrosion-induced cracks in RC are visually located.  Further, corrosion damage due to the expansion of corrosion products is quantitatively identified.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Shear Strength of Self-compacting Concrete Containing Different Fillers
           and Coarse Aggregates

    • Authors: Mohamed Abd Elaziz Safan
      Abstract: An experimental investigation was conducted to evaluate the shear strength provided by different self-compacting concrete mixes proportioned using different fillers and coarse aggregates. A total of 28 simple beams without web reinforcement were tested in flexure. The test parameters included the use of gravel versus crushed dolomite as coarse aggregates, the amount of longitudinal reinforcement and the composition and percentage of fillers. Dolomite stone powder with either silica fume or fly ash were used as fillers replacing cement aiming at reducing the cost of the mix and obtaining better performance. The test results indicated that the overall structural performance in terms of cracking pattern and shear strength was comparable in all mixes. The potentials of developing shear strength and post cracking shear resistance were better when gravel was used as coarse aggregate and when relatively high fractions of dolomite powder were used as cement replacement.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Properties of High Strength Flowable Mortar Reinforced With Different
           Fibers

    • Authors: Eethar T. Dawood, Mahyuddin Ramli
      Abstract: An experimental study was conducted on the high-strength flowable mortar (HSFM) reinforced by the different percentages of palm Fiber (0, 0.5& 1%), steel fiber (0, 0.5, 1.0& 2%), and the hybridization of these two fibers with 2% volumetric fractions.  Different tests have been done to determine some aspects namely the density, compressive strength, splitting tensile strength, static modulus of elasticity, flexural strength, toughness and ultrasonic pulse velocity.  The results show that the use of hybridization of steel fiber with palm fiber gives an unambiguous improvement in these properties and thus the optimum percentages for these two fibers have been taken into consideration. The use of low volume fraction of palm fiber in hybrid fiber mixes was found to be a promising concept in HSFM mixes
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Behaviour of Fiber Reinforced Concrete Beams with Spliced Tension Steel
           Reinforcement

    • Authors: Mohamed Abd Elaziz Safan
      Abstract: The aim of the current work is to describe the flexural and bond behaviour of simply supported concrete beams with tension reinforcement spliced at mid-span. The parameters included in the study were the type of the concrete, the splice length and the configuration of the hooked splice. Fifteen beams were cast using an ordinary concrete mix and two fiber reinforced concrete mixes incorporating steel and polypropylene fibers. Each concrete mix was used to cast five beams with continuous, spliced and hooked spliced tension steel bars. A test beam was reinforced on the tension side with two 12-mm bars with a splice length of 20 and 40 times the bar diameter. The hooked bars were spliced along 20 times the bar diameter and provided with 45-degree and 90-degree hooks. The test results in terms of cracking and ultimate loads, cracking patterns, ductility, and failure modes are reported. The results demonstrated the consequences due to short splices and the improvement in the structural behaviour due to the use of hooks and the confinement provided by the steel and polypropylene fibers.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Reinforced Concrete Corrosion and Protection

    • Authors: Zeinab A. Etman
      Abstract: This paper reports result of a study conducted to assess the effect of some locally produced materials on the protection of reinforcing steel against corrosion. Also the effect of period and the main consequences on mechanical properties of steel and concrete are evaluated. Reinforcing steel bars, 10 mm in diameter, that were corroded in reinforced concrete specimens were removed and tested in tension. Twenty seven concrete cylinders with dimensions (15 × 30 cm) provided with central steel bar were cast and tested after 28 days to demonstrate the effect of the protective materials on the bond strength. A total of ten reinforced concrete beams (10 × 15 × 100 cm) were cast using a self-compacted concrete mix. All beams were tested in flexure. The results of the tested beams are analyzed in terms of; cracking pattern, load deflection, ductility. The failure mode of each specimen was recorded. The tests recommended determining the mechanical properties of mix were; the compressive test, the splitting tensile test, and flexural strength test. Results cleared that with increasing duration of exposure to a corrosive environment, the steel mass loss increases appreciably. This leads to a significant increase of the applied stress. In addition, a reduction of the tensile ductility of the material was observed. The main result from the accelerated corrosion tests in bare steel bars, that the important ductility property of the elongation to failure is very sensitive to mass loss due to corrosion, it is valid and in real structures. Coating with epoxy resin increases the protective from the corrosion more cement-based resin by 15 %.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Biofilm Formation and Thermographic evaluation of Fly Ash concrete in sea
           water

    • Authors: Vinita Vishwakarma
      Abstract: Nuclear industry is opting for fly ash modified concrete structures to increase their resistance to seawater and microbial induced deterioration. This study focuses on comparative studies on biodeterioration of three types of concrete; control (unmodified concrete), fly ash and superplasticizer modified concrete exposed for 10 months in seawater environments. Biodeterioration of concrete specimens was evaluated by characterization of biofilm parameters like total bacteria density, density of anaerobic sulfate reducing bacteria (SRB) and aerobic sulfur oxidizing bacteria (SOB). Epifluorescence microscopy was used to visualize the biofilms on these concrete specimens. pH reduction on the exposed concrete specimen surface and the total concrete specimen was evaluated.  Using Lock-in thermography (LT) phase angles and amplitude images were compared between unexposed and exposed concrete specimens to characterize deterioration under biofilms. Fly ash modified concrete showed least pH reduction and least density of total heterotrophic bacteria, SRB and SOB in the biofilms. Epifluorescence micrographs confirmed the delay in the onset of biofilm formation on fly ash modified concrete.  LT study supported and confirmed that there is very little change in the phase angle and amplitude between one year seawater exposed and unexposed fly ash modified concrete indicating least deterioration even after 10 month exposure in seawater.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Experimental Evaluation of Steel–Concrete bond Strength in Low-cost
           Self-compacting Concrete

    • Authors: Mohamed Abd Elaziz Safan, Mounir M Kamal, Mohamed A Al-gazzar
      Abstract: The main objective of this research was to evaluate the potentials of self-compacting concrete (SCC) mixes to develop bond strength. The investigated mixes incorporated relatively high contents of dolomite powder replacing Portland cement. Either silica fume or fly ash was used along with the dolomite powder in some mixes. Seven mixes were proportioned and cast without vibration in long beams with 10 mm and 16 mm steel dowels fixed vertically along the concrete flow path. The beams were then broken into discrete test specimens. A push-out configuration was adopted for conducting the bond test. The variation of the bond strength along the flowing path for the different mixes was evaluated. The steel-concrete bond adequacy was evaluated based on normalized bond strength. The results showed that the bond strength was reduced due to Portland cement replacement with dolomite powder. The addition of either silica fume or fly ash positively hindered further degradation as the dolomite powder content increased. However, all SCC mixes containing up to 30% dolomite powder still yielded bond strengths that were adequate for design purpose. The test results demonstrated inconsistent normalized bond strength in the case of the larger bar diameter compared to the smaller one.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Structural Behavior of Composite Reinforced Ferrocement Plates

    • Authors: Yousry B. I. Shaheen, Mohamed Abd El-Aziz Saa'fan, Abdalla El-Mohamady
      Abstract: The results of an experimental investigation to examine the structural behavior of composite reinforced ferrocement concrete plates are presented in this paper. The precast permanent ferrocement forms are proposed as a viable alternative to the steel panels in some of its uses. The experimental program comprised casting and testing of eighteen reinforced ferrocement plates having the dimensions of 550mm width, 1100mm length and different thicknesses (60, 80,100) mm. Each control plate was reinforced with four steel bars of 6mm diameter at the bottom of the plate and six steel bars of 6mm diameter at the transverse direction. Two types of steel mesh were used to reinforce the ferrocement plates. These types are: galvanized welded wire mesh of size of opening 12.5x12.5mm, and (33 X 16.5mm) expanded metal wire mesh of diamond size 33x16.5mm. Single layer, double layers and three layers of each type of the steel mesh were employed. All specimens were tested under 3-lines flexural loadings. The flexural performances of the all tested plates in terms of strength, stiffness, cracking behavior, ductility and energy absorption properties were investigated. The results showed that high serviceability and ultimate loads, crack resistance control, and good energy absorption properties could be achieved by using the developed ferrocement plates. 
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Current understanding and Future Approaches for Controlling Microbially
           Influenced Concrete Corrosion: A Review

    • Authors: Rani P George
      Abstract: The microbes colonize the concrete surface and its pores, capillaries and micro-cracks and cause damage through biodeterioration. Though the biodeterioration of concrete in sewage pipes is extensively studied, the problems in constructions such as maritime structures, bridges, tanks, pipelines and cooling towers have received lesser attention. In nuclear industry future power plants will be designed for 100 years to make available operation of nuclear power plants for more periods. Therefore, integrity of the concrete structures in nuclear power plants has to be maintained for this long duration specially those exposed to aggressive seawater environment. Nuclear industry is looking at various options including modified concrete with special admixtures and fly ash to achieve this goal. A direction for future approaches like using nanophase modification to get stronger and flexible concrete is given in this paper.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Performance of Self-Compacted Concrete Exposed To Fire or Aggressive Media

    • Authors: Khaled Mohamed Heiza
      Abstract: Fires and aggressive environment affect the durability of different types of concretes, so experimental investigation of concrete deterioration is very essential. The production of self – compacted concrete (SCC) mixes with two different types of mineral admixtures (silica fume and fly ash) are included in this research. The workability of fresh concrete mixes was investigated using five different international specified techniques. The properties of hardened concrete samples were determined under the exposure of different temperatures, which ranges between 25ºC and 600ºC. The effects of the methods of treatment for concrete samples after being exposed to fire on there, physical and mechanical properties were investigated. On the other hand the effects of some aggressive and corrosive mediums on the hardened mechanical properties and deterioration of the different mixes of (SCC) in comparison with normal concrete (NC) was also investigated. Both (MgSo4) and (MgCl2) were used to investigate the corrosion of reinforcing steel bars and deterioration of SCC mixes. Self-compacted concrete containing fly ashes has a good durability performance rather than self compacting concrete containing silica fume.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Pre- and Post-Fire Strength Assessment of Ferrocement beams

    • Authors: Yousry B. I Shaheen, Zeinab A. Etman, Ahmed G. Ramadan
      Abstract: The results of an experimental investigation on the behavior of ferrocement beams after exposed to fire are presented in this paper. Different types of steel meshes are used compared with conventional reinforcement. The experimental program comprised casting and testing of eighteen beams having the dimensions of 100mm×100mm×1000mm. Three beams were reinforced as a conventional reinforcement. Each control beam was reinforced with two steel bars of diameter 8 mm in tension, two steel bar of diameter 6mm in compression and stirrups of 6 mm diameter placed at 200 mm intervals. The ferrocement beams were reinforced with steel meshes without any stirrups. Two types of steel meshes were used to reinforce the ferrocement laminate. These types are: square welded wire fabric, and expanded wire mesh. Single layer, double layers and three layers of square welded wire mesh were employed. Single layer and double layers of expanded wire mesh were employed. The experimental program was classified into three groups. First group was tested without exposure to fire, the second group was tested after exposure to fire for six hours and the last group was tested after exposure to fire under loading. All specimens were tested under 4-points flexural loadings. The performance of the test beams in terms of strength, stiffness, cracking behavior and energy absorption was investigated. The results showed that high serviceability and ultimate loads, crack resistance control, and better deformation characteristics could be achieved by using the proposed ferrocement forms.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Influence of Silica Fume, Fly Ash, Super Pozz, and High Slag Cement on
           Water Permeability and Strength of Concrete

    • Authors: Adham A Elsayed
      Abstract: In this study, effects of mineral admixtures on the water permeability and compressive strength of concretes containing silica fume (SF) and fly ash (FA), super pozz (SP) were experimentally investigated. Permeability of concrete was determined through DIN 1048 (Part 5). The research variables included cement type, ordinary Portland cement (OPC) or high slag cement (HSC), and mineral admixtures content were used as a partial cement replacement. They were incorporated into concrete at the levels of 5%, 10%, and15% for silica fume and 10%, 20%, 30% for fly ash, or super pozz by weight of cement. Water- cement ratio of 0.40 was used and tests were carried out at 28 days. From the tests, the lowest measured water permeability was for the 10% super pozz and 10% silica fume or 20% fly ash mixes. Although the highest compressive strengths of concretes determined was 10% silica fume mix for ordinary Portland cement and were reduced as the increase in the replacement ratios for other mineral admixtures than ordinary Portland cement concrete.The main objective of this research was to study the water permeability and compressive strength of concrete containing silica fume, fly ash, and super pozz and high slag cement to achieve the best concrete mixture have lowest permeability. The results were compared to the control concrete ordinary Portland cement concrete without admixtures. The optimum cement replacement by FA, SP and SF in this experiment is 10% SP. The knowledge on the strength and permeability of concrete containing silica fume and fly ash, super pozz and high slag cement could be beneficial on the utilization of these waste materials in concrete work, especially on the topic of durability.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Effect of Admixture on the Compressive Strength of Composite Cement Mortar

    • Authors: Suresh Kumar Agarwal, Vivek Sood, Ajay Dwivedi
      Abstract: The effect of superplasticizer on the development of composite cement based on flyash/limestone powder as per EN-197-2000 has been studied. Various mixes of fly ash and limestone up to 40% has been blended. The results have been compared with clinker of 43 grade ordinary portland cement used in the present study. 1 day strength of mixes with 5% and 10% limestone powder has been found to be is comparable to control. Further, it has been found that 28 days strength of mix with 15% lime stone powder and 25% fly ash gives more than 32.5 R required for composite cement. With the use of superplasticizer, strength has been found comparable or more in all the mixes at 1day to 43 grade OPC. X-ray diffraction (XRD) analysis of various mixes at different hydration times has also been evaluated. 
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Performance of Fly Ash and Stone Dust Blended Concrete in Acidic
           Environment

    • Authors: Alok Verma, Anıl Kumar Sahu, Mukesh Shukla
      Abstract: Large scale housing construction activities require a huge amount of resources. Out of the total cost in a construction project the component of material cost has a major share. Therefore, the need of the hour is the replacement of costly and scarce conventional building materials by innovative, cost effective and environmental friendly alternatives. Fly ash and stone dust, generated as waste products in coal based thermal power plants and stone crusher industry respectively have been found appropriate for this purpose. The objective of this study was to investigate the performance of concrete mixes blended with fly ash and stone dust in chemically aggressive environmental conditions. The results indicate that a judicious selection of these waste products as ingredients in concrete shall further enhance benefits under aggressive environmental conditions of exposure.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Damage Detection of Ferrocement Tanks Using Experimental Modal Analysis
           and Finite Element Analysis

    • Authors: Yousry B.I. Shaheen, Boshra Eltaly
      Abstract: In the recent years, structural health monitoring for civil structures using experimental modal analysis has been developed. Experimental modal analysis is the process of determining the dynamic parameters (frequencies, damping factors, modal vectors and modal scaling) of a linear, time invariant system by way of an experimental approach. It began in 1940’s in aircraft then it used in civil structures since the advent of the digital mini-computers and the digital Fast Fourier Transformation (FFT) spectrum analyzer in the early 1970’s. In this paper, the damage in ferrocement tank is detected experimentally by changing in its dynamic parameters due to two damages that were manufactured in its wall. Also in the current paper, theoretical models using ANSYS finite element software were developed to find the modal parameters of the healthy and damage tank. The current results showed that the theoretical models give accurate results in comparing with the theoretical results. Also the experimental modal analysis is quick, easy and inexpensive method to detect the damage in the ferrocement tank.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Study of Sorptivity of Self-Compacting Concrete with Different Chemical
           Admixtures

    • Authors: Saeed Ahmed Alsheikh
      Abstract: The influence of chemical admixtures on the properties of Self-Compacting Concrete (SCC) was investigated. All types of used admixtures were the same percentage of 1.4% according technical data. The water – cement ratio was maintained at 0.36 for all mixes [8] [9].The paper presents test results for acceptance characteristics of flow ability, resistance against segregation, and passing ability of self-compacting concrete in fresh state. Further, mechanical properties of hardened concrete such as compressive, tensile and flexural strength at the ages of 7 and 28 were also determined, and results of Absorption and sorptivity result are included here.The results indicate that Sika ViscoCrete 3425 and AddiCrete BVS 100 give better results for all tests.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • The Stability of Fresh Zero-Slump Concrete

    • Authors: Christian Otto Sørensen
      Abstract: This report focuses upon the effects of cement-substitution in part by two potash feldspar powders, and by silica-fume, on the fresh concrete strength of newly compacted cylinder samples. The water/cement-ratio was kept constant at 0.31. An Intensive Compaction Tester (abbrev: IC-Tester) which exerts a slow kneading action under pressure on the sample in a cylindrical mold, was utilized. It was found that the fresh cylinder compressive strength increased with decreasing water-content and more than doubled with each of the 3 fillers replacing 30 % of the cement-volume. A tradeoff was a loss in 28-day compressive strength for both of the feldspars, while the 28-day strength of the silica-samples remained virtually unaffected.
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Shear Strengthening of Self-Compacting Reinforced Concrete Deep Beams With
           External Bonded Layers

    • Authors: Khaled M. Heiza, N N Meleka, N Y Elwkad
      Abstract: Self-compacting concrete (SCC) is a stable and highly flowable concrete. In this study, a new shear strengthening technique for reinforced self-compacting concrete (RSCC) deep beams was suggested and compared with some traditional techniques. An experimental test program consists of sixteen specimens of RSCC deep beams strengthened by different materials such as steel, glass and carbon fiber reinforced polymers (GFRP and CFRP) was executed. Externally bonded layers (EBL) and near surface mounted reinforcement (NSMR) were used as two different techniques. The effects of the new technique which depends on using intertwined roving NSM GFRP rods saturated with epoxy were compared with the other models. The new technique for shear strengthening increases the load capacity from 36% to 55% depending on the anchorage length of GFRP rods. Two dimensional nonlinear isoperimetric degenerated layered finite elements (FE) analysis was used to represent the SCC, reinforcement and strengthening layers of the tested models. The analytical results have been very close to the experimental results.    
      PubDate: 2017-01-15
      Issue No: Vol. 8, No. 1 (2017)
       
  • Comparative study on the using of PEG and PAM as curing agents for
           self-curing concrete

    • Authors: Alaa A. Bashandy, Nageh N. Meleka, Mohamed M. Hamad
      Pages: 1 - 10
      Abstract: There are many factors, which may affect on concrete quality. One of those is concrete curing. Self-curing concrete is the solution. It may produce by using chemical curing agents. The concept of those agents is to reduce the water evaporation from concrete. This research aims to study the effect of chemical curing agents on the behavior of self-curing concrete. Two different chemical curing agents were used to study the main mechanical properties of concrete. The main variables are; the type of curing agent (Polyethylene glycol "PEG400"–Poly Acrylamide "PAM") and its dosages. The results obtained in terms of compressive, tensile and flexure strength values. Test results showed that the self-curing concrete cured by each agent performed better in hardened properties compared to none cured concrete. Also, curing using the both agents together perform better than using each one individually.
      PubDate: 2017-04-04
      DOI: 10.20528/cjcrl.2017.01.001
      Issue No: Vol. 8, No. 1 (2017)
       
  • Effect of reinforcement in perforated brick arrangement for determining
           flexural strength and corrosion loss

    • Authors: Mosfeka Mahabuba Akter, Atique Shahariar, Md. Shafiqul Islam
      Pages: 11 - 16
      Abstract: Brick masonry walls consist of the main elements that responsible for the global stability of brick masonry buildings when subjected to lateral loads such as wind and seismic forces. These elements are subjected to gravity forces, bending moments and shear forces due to the horizontal loading. The application of reinforcement increases the deformation capacity, controls the crack opening and allows a better distribution of stresses. Longitudinal reinforcements increase the flexural strength, even if they seem not to influence the shear behavior. Effectiveness of reinforcement on the increase of the resistance of brick masonry wall is highly related to the failure mode of the element. This paper shows the flexural strength of reinforced perforated brick masonry wall and weight loss of reinforcements for corrosion after a certain period of time. Several reinforce bar arrangements into the perforated brick masonry walls show the variety of possible applications.
      PubDate: 2017-04-04
      DOI: 10.20528/cjcrl.2017.01.002
      Issue No: Vol. 8, No. 1 (2017)
       
  • Structural behavior of recycled aggregates concrete filled steel tubular
           columns

    • Authors: Boshra Eltaly, Ahmed Bembawy, Nageh Meleka, Kameel Kandil
      Pages: 17 - 28
      Abstract: This paper presents an experimental and numerical investigation to determine the behavior of steel tubular columns filled with recycled aggregates concrete up to failure under constant axial compression loads. The experimental program included two steel tube columns, four recycled concrete columns and eight composite columns filled with different types of recycled coarse aggregates (granite and ceramic). Different percentages of recycled coarse aggregates: 0, 25 and 50 of the percentage of the coarse aggregates (dolomite) were used. The results of the numerical model that was employed by the finite element program, ANSYS, were compared with the experimental results. The results of the experimental study and the finite element analysis were compared with the design equations using different national building codes: AISC1999, AISC2005 and EC4. The results indicated that the recycled aggregates concrete infill columns have slightly lower but comparable ultimate capacities compared with the specimens filled with normal concrete.
      PubDate: 2017-04-04
      DOI: 10.20528/cjcrl.2017.01.003
      Issue No: Vol. 8, No. 1 (2017)
       
 
 
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