Search results for: rail strength analysis
Commenced in January 2007
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Edition: International
Paper Count: 29784

Search results for: rail strength analysis

29424 Neural Network Based Path Loss Prediction for Global System for Mobile Communication in an Urban Environment

Authors: Danladi Ali

Abstract:

In this paper, we measured GSM signal strength in the Dnepropetrovsk city in order to predict path loss in study area using nonlinear autoregressive neural network prediction and we also, used neural network clustering to determine average GSM signal strength receive at the study area. The nonlinear auto-regressive neural network predicted that the GSM signal is attenuated with the mean square error (MSE) of 2.6748dB, this attenuation value is used to modify the COST 231 Hata and the Okumura-Hata models. The neural network clustering revealed that -75dB to -95dB is received more frequently. This means that the signal strength received at the study is mostly weak signal

Keywords: one-dimensional multilevel wavelets, path loss, GSM signal strength, propagation, urban environment and model

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29423 Design of a Vehicle Door Structure Based on Finite Element Method

Authors: Tawanda Mushiri, Charles Mbohwa

Abstract:

The performance of door assembly is very significant for the vehicle design. In the present paper, the finite element method is used in the development processes of the door assembly. The stiffness, strength, modal characteristic, and anti-extrusion of a newly developed passenger vehicle door assembly are calculated and evaluated by several finite element analysis commercial software. The structural problems discovered by FE analysis have been modified and finally achieved the expected door structure performance target of this new vehicle. The issue in focus is to predict the performance of the door assembly by powerful finite element analysis software, and optimize the structure to meet the design targets. It is observed that this method can be used to forecast the performance of vehicle door efficiently when it’s designed. In order to reduce lead time and cost in the product development of vehicles more development will be made virtually.

Keywords: vehicle door, structure, strength, stiffness, modal characteristic, anti-extrusion, Finite Element Method

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29422 Elastic Constants of Heat Treated Wood

Authors: Ergun Guntekin

Abstract:

Effects of heat treatment on elastic constants of Black pine (Pinus nigra) wood were investigated. Specimens were exposed to heat under atmospheric pressure at two different temperatures (180 and 210 °C) and three different time levels (2, 5, 8 hours). Three Young’s modulus in three anatomical directions, six Poisson’s ratios and three Shear modulus values associated with the main directions were evaluated by compression tests. Compression strength of the samples in three principal directions was also determined. All of the properties of the specimens tested were altered by heat treatment. The degree of alteration depends on the temperature as well as duration applied. Results indicate that EL and compression strength in L direction were not significantly influenced, compression strength in R direction significantly decreased, ER, ET and compression strength in T direction were increased for shorter periods, then dropped for 8-hour application of 180 ºC. ER was not significantly affected, compression strength in R direction and EL was significantly decreased, ET and compression strength in T direction were increased for shorter periods, then decreased for 8-hour application of 210 ºC. The shear modulus of the samples was decreased with application of treatment combinations. Most of the Poisson’s ratios were not affected by heat treatment.

Keywords: black pine, elastic constants, heat treatment, wood

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29421 Non-linear Model of Elasticity of Compressive Strength of Concrete

Authors: Charles Horace Ampong

Abstract:

Non-linear models have been found to be useful in modeling the elasticity (measure of degree of responsiveness) of a dependent variable with respect to a set of independent variables ceteris paribus. This constant elasticity principle was applied to the dependent variable (Compressive Strength of Concrete in MPa) which was found to be non-linearly related to the independent variable (Water-Cement ratio in kg/m3) for given Ages of Concrete in days (3, 7, 28) at different levels of admixtures Superplasticizer (in kg/m3), Blast Furnace Slag (in kg/m3) and Fly Ash (in kg/m3). The levels of the admixtures were categorized as: S1=Some Plasticizer added & S0=No Plasticizer added; B1=some Blast Furnace Slag added & B0=No Blast Furnace Slag added; F1=Some Fly Ash added & F0=No Fly Ash added. The number of observations (samples) used for the research was one-hundred and thirty-two (132) in all. For Superplasticizer, it was found that Compressive Strength of Concrete was more elastic with regards to Water-Cement ratio at S1 level than at S0 level for the given ages of concrete 3, 7and 28 days. For Blast Furnace Slag, Compressive Strength with regards to Water-Cement ratio was more elastic at B0 level than at B1 level for concrete ages 3, 7 and 28 days. For Fly Ash, Compressive Strength with regards to Water-Cement ratio was more elastic at B0 level than at B1 level for Ages 3, 7 and 28 days. The research also tested for different combinations of the levels of Superplasticizer, Blast Furnace Slag and Fly Ash. It was found that Compressive Strength elasticity with regards to Water-Cement ratio was lowest (Elasticity=-1.746) with a combination of S0, B0 and F0 for concrete age of 3 days. This was followed by Elasticity of -1.611 with a combination of S0, B0 and F0 for a concrete of age 7 days. Next, the highest was an Elasticity of -1.414 with combination of S0, B0 and F0 for a concrete age of 28 days. Based on preceding outcomes, three (3) non-linear model equations for predicting the output elasticity of Compressive Strength of Concrete (in %) or the value of Compressive Strength of Concrete (in MPa) with regards to Water to Cement was formulated. The model equations were based on the three different ages of concrete namely 3, 7 and 28 days under investigation. The three models showed that higher elasticity translates into higher compressive strength. And the models revealed a trend of increasing concrete strength from 3 to 28 days for a given amount of water to cement ratio. Using the models, an increasing modulus of elasticity from 3 to 28 days was deduced.

Keywords: concrete, compressive strength, elasticity, water-cement

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29420 Towards Sustainable Concrete: Maturity Method to Evaluate the Effect of Curing Conditions on the Strength Development in Concrete Structures under Kuwait Environmental Conditions

Authors: F. Al-Fahad, J. Chakkamalayath, A. Al-Aibani

Abstract:

Conventional methods of determination of concrete strength under controlled laboratory conditions will not accurately represent the actual strength of concrete developed under site curing conditions. This difference in strength measurement will be more in the extreme environment in Kuwait as it is characterized by hot marine environment with normal temperature in summer exceeding 50°C accompanied by dry wind in desert areas and salt laden wind on marine and on shore areas. Therefore, it is required to have test methods to measure the in-place properties of concrete for quality assurance and for the development of durable concrete structures. The maturity method, which defines the strength of a given concrete mix as a function of its age and temperature history, is an approach for quality control for the production of sustainable and durable concrete structures. The unique harsh environmental conditions in Kuwait make it impractical to adopt experiences and empirical equations developed from the maturity methods in other countries. Concrete curing, especially in the early age plays an important role in developing and improving the strength of the structure. This paper investigates the use of maturity method to assess the effectiveness of three different types of curing methods on the compressive and flexural strength development of one high strength concrete mix of 60 MPa produced with silica fume. This maturity approach was used to predict accurately, the concrete compressive and flexural strength at later ages under different curing conditions. Maturity curves were developed for compressive and flexure strengths for a commonly used concrete mix in Kuwait, which was cured using three different curing conditions, including water curing, external spray coating and the use of internal curing compound during concrete mixing. It was observed that the maturity curve developed for the same mix depends on the type of curing conditions. It can be used to predict the concrete strength under different exposure and curing conditions. This study showed that concrete curing with external spray curing method cannot be recommended to use as it failed to aid concrete in reaching accepted values of strength, especially for flexural strength. Using internal curing compound lead to accepted levels of strength when compared with water cuing. Utilization of the developed maturity curves will help contactors and engineers to determine the in-place concrete strength at any time, and under different curing conditions. This will help in deciding the appropriate time to remove the formwork. The reduction in construction time and cost has positive impacts towards sustainable construction.

Keywords: curing, durability, maturity, strength

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29419 Durability Aspects of Recycled Aggregate Concrete: An Experimental Study

Authors: Smitha Yadav, Snehal Pathak

Abstract:

Aggregate compositions in the construction and demolition (C&D) waste have potential to replace normal aggregates. However, to re-utilise these aggregates, the concrete produced with these recycled aggregates needs to provide the desired compressive strength and durability. This paper examines the performance of recycled aggregate concrete made up of 60% recycled aggregates of 20 mm size in terms of durability tests namely rapid chloride permeability, drying shrinkage, water permeability, modulus of elasticity and creep without compromising the compressive strength. The experimental outcome indicates that recycled aggregate concrete provides strength and durability same as controlled concrete when processed for removal of adhered mortar.

Keywords: compressive strength, recycled aggregate, shrinkage, rapid chloride permeation test, modulus of elasticity, water permeability

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29418 Effect of Addition Rate of Expansive Additive on Autogenous Shrinkage and Delayed Expansion of Ultra-High Strength Mortar

Authors: Yulu Zhang, Atushi Teramoto, Taka-Aki Ohkubo

Abstract:

In this study, the effect of expansive additives on autogenous shrinkage and delayed expansion of ultra-high strength mortar was explored. The specimens made for the study were composed of ultra-high strength mortar, which was mixed with ettringite-lime composite type expansive additive. Two series of experiments were conducted with the specimens. The experimental results confirmed that the autogenous shrinkage of specimens was effectively decreased by increasing the proportion of the expansive additive. On the other hand, for the specimens, which had 7% expansive additive, and were cured for seven days at a constant temperature of 20°C, and then cured for a long time in either in an underwater, moist (Relative humidity: 100%) or dry air (Relative humidity: 60%) environment, excessively large expansion strain occurred. Specifically, typical turtle shell-like swelling expansion cracks were confirmed in the specimens that underwent long-term curing in an underwater and moist environment. According to the result of hydration analysis, the formation of expansive substances, calcium hydroxide and alumina, ferric oxide, tri-sulfate contribute to the occurrence of delayed expansion.

Keywords: ultra-high strength mortar, expansive additive, autogenous shrinkage, delayed expansion

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29417 Comparison of Physical and Chemical Properties of Micro-Silica and Locally Produced Metakaolin and Effect on the Properties of Concrete

Authors: S. U. Khan, T. Ayub, N. Shafiq

Abstract:

The properties of locally produced metakaolin (MK) as cement replacing material and the comparison of reactivity with commercially available micro-silica have been investigated. Compressive strength, splitting tensile strength, and load-deflection behaviour under bending are the properties that have been studied. The amorphous phase of MK with micro-silica was compared through X-ray diffraction (XRD) pattern. Further, interfacial transition zone of concrete with micro-silica and MK was observed through Field Emission Scanning Electron Microscopy (FESEM). Three mixes of concrete were prepared. One of the mix is without cement replacement as control mix, and the remaining two mixes are 10% cement replacement with micro-silica and MK. It has been found that MK, due to its irregular structure and amorphous phase, has high reactivity with portlandite in concrete. The compressive strength at early age is higher with MK as compared to micro-silica. MK concrete showed higher splitting tensile strength and higher load carrying capacity as compared to control and micro-silica concrete at all ages respectively.

Keywords: metakaolin, compressive strength, splitting tensile strength, load deflection, interfacial transition zone

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29416 The Impact of Alumina Cement on Properties of Portland Cement Slurries and Mortars

Authors: Krzysztof Zieliński, Dariusz Kierzek

Abstract:

The addition of a small amount of alumina cement to Portland cement results in immediate setting, a rapid increase in the compressive strength and a clear increase of the adhesion to concrete substrate. This phenomenon is used, among others, for the production of liquid floor self-levelling compounds. Alumina cement is several times more expensive than Portland cement and is a component having a significant impact on prices of products manufactured with its use. For the production of liquid floor self-levelling compounds, low-alumina cement containing approximately 40% Al2O3 is normally used. The aim of the study was to determine the impact of Portland cement with the addition of alumina cement on the basic physical and mechanical properties of cement slurries and mortars. CEM I 42.5R and three types of alumina cement containing 40%, 50% and 70% of Al2O3 were used for the tests. Mixes containing 4%, 6%, 8%, 10% and 12% of different varieties of alumina cement were prepared; for which, the time of initial and final setting, compressive and flexural strength and adhesion to concrete substrate were determined. The analysis of the obtained test results showed that a similar immediate setting effect and clearly better adhesion strength can be obtained using the addition of 6% of high-alumina cement than 12% of low-alumina cement. As the prices of these cements are similar, this can give significant financial savings in the production of liquid floor self-levelling compounds.

Keywords: alumina cement, immediate setting, compression strength, adhesion to substrate

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29415 Anisotropic Shear Strength of Sand Containing Plastic Fine Materials

Authors: Alaa H. J. Al-Rkaby, A. Chegenizadeh, H. R. Nikraz

Abstract:

Anisotropy is one of the major aspects that affect soil behavior, and extensive efforts have investigated its effect on the mechanical properties of soil. However, very little attention has been given to the combined effect of anisotropy and fine contents. Therefore, in this paper, the anisotropic strength of sand containing different fine content (F) of 5%, 10%, 15%, and 20%, was investigated using hollow cylinder tests under different principal stress directions of α = 0° and α = 90°. For a given principal stress direction (α), it was found that increasing fine content resulted in decreasing deviator stress (q). Moreover, results revealed that all fine contents showed anisotropic strength where there is a clear difference between the strength under 0° and the strength under 90°. This anisotropy was greatest under F = 5% while it decreased with increasing fine contents, particularly at F = 10%. Mixtures with low fine content show low contractive behavior and tended to show more dilation. Moreover, all sand-clay mixtures exhibited less dilation and more compression at α = 90° compared with that at α = 0°.

Keywords: anisotropy, principal stress direction, fine content, hollow cylinder sample

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29414 An Experimental Study of the Effectiveness of Lubricants in Reducing the Sidewall Friction

Authors: Jian Zheng, Li Li, Maxime Daviault

Abstract:

In several cases, one needs apply lubrication materials in laboratory tests to reduce the friction (shear strength) along the interfaces between a tested soil and the side walls of container. Several types of lubricants are available. Their effectiveness had been tested mostly through direct shear tests. These testing conditions are quite different than those when the tested soil is placed in the container. Thus, the shear strengths measured from direct shear tests may not be totally representative of those of interfaces between the tested soil and the sidewalls of container. In this paper, the effectiveness of different lubricants used to reduce the friction (shear strength) of soil-structure interfaces has been studied. Results show that the selected lubricants do not significantly reduce the sidewall friction (shear strength). Rather, the application of wax, graphite, grease or lubricant oil has effect to increase the sidewall shear strength due probably to the high viscosity of such materials. Subsequently, the application of lubricants between tested soil and sidewall and neglecting the friction (shear strength) along the sidewalls may lead to inaccurate test results.

Keywords: arching, friction, laboratory tests, lubricants

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29413 The Effect of Soil Fractal Dimension on the Performance of Cement Stabilized Soil

Authors: Nkiru I. Ibeakuzie, Paul D. J. Watson, John F. Pescatore

Abstract:

In roadway construction, the cost of soil-cement stabilization per unit area is significantly influenced by the binder content, hence the need to optimise cement usage. This research work will characterize the influence of soil fractal geometry on properties of cement-stabilized soil, and strive to determine a correlation between mechanical proprieties of cement-stabilized soil and the mass fractal dimension Dₘ indicated by particle size distribution (PSD) of aggregate mixtures. Since strength development in cemented soil relies not only on cement content but also on soil PSD, this study will investigate the possibility of reducing cement content by changing the PSD of soil, without compromising on strength, reduced permeability, and compressibility. A series of soil aggregate mixes will be prepared in the laboratory. The mass fractal dimension Dₘ of each mix will be determined from sieve analysis data prior to stabilization with cement. Stabilized soil samples will be tested for strength, permeability, and compressibility.

Keywords: fractal dimension, particle size distribution, cement stabilization, cement content

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29412 Investigating the Mechanical Properties of Geopolymer Concrete Containing Microencapsulated Phase Change Materials

Authors: Shima Pilehvar, Vinh Duy Cao, Anna M. Szczotok, Anna-Lena Kjøniksen

Abstract:

Micro encapsulated phase change materials (MPCM) may be utilized to increase the energy efficiency of buildings by the addition of MPCM to concrete structures. However, addition of MPCM to Portland cement concrete is known to reduce the compressive strength of the concrete. Accordingly, it is interesting to also examine the effect of adding MPCM to geopolymer concrete. Geopolymer binder is synthesized by mixing aluminosilicate materials in amorphous form with a strong alkali activator, and have a much lower CO2 footprint than Portland cement concrete. In this study, the mechanical properties of fly ash-based geopolymer concrete with different types and contents of MPCM were investigated at different curing temperatures. The aim was to find the optimum amount of MPCM which still maintain the workability and compressive strength at an acceptable level. The results revealed that both workability and compressive strength of geopolymer concrete decrease after adding MPCM. Also, the percentage of strength reduction can be variable by different types of MPCM.

Keywords: compressive strength, concrete, curing, geopolymer, micro-encapsulated PCM

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29411 Nonlinear Finite Element Modeling of Unbonded Steel Reinforced Concrete Beams

Authors: Fares Jnaid, Riyad Aboutaha

Abstract:

In this paper, a nonlinear Finite Element Analysis (FEA) was carried out using ANSYS software to build a model able of predicting the behavior of Reinforced Concrete (RC) beams with unbonded reinforcement. The FEA model was compared to existing experimental data by other researchers. The existing experimental data consisted of 16 beams that varied from structurally sound beams to beams with unbonded reinforcement with different unbonded lengths and reinforcement ratios. The model was able to predict the ultimate flexural strength, load-deflection curve, and crack pattern of concrete beams with unbonded reinforcement. It was concluded that when the when the unbonded length is less than 45% of the span, there will be no decrease in the ultimate flexural strength due to the loss of bond between the steel reinforcement and the surrounding concrete regardless of the reinforcement ratio. Moreover, when the reinforcement ratio is relatively low, there will be no decrease in ultimate flexural strength regardless of the length of unbond.

Keywords: FEA, ANSYS, unbond, strain

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29410 Shear Strength Parameters of an Unsaturated Lateritic Soil

Authors: Jeferson Brito Fernades, Breno Padovezi Rocha, Roger Augusto Rodrigues, Heraldo Luiz Giacheti

Abstract:

The geotechnical projects demand the appropriate knowledge of soil characteristics and parameters. The determination of geotechnical soil parameters can be done by means of laboratory or in situ tests. In countries with tropical weather, like Brazil, unsaturated soils are very usual. In these soils, the soil suction has been recognized as an important stress state variable, which commands the geo-mechanical behavior. Triaxial and direct shear tests on saturated soils samples allow determine only the minimal soil shear strength, in other words, no suction contribution. This paper briefly describes the triaxial test with controlled suction as well as discusses the influence of suction on the shear strength parameters of a lateritic tropical sandy soil from a Brazilian research site. In this site, a sample pit was excavated to retrieve disturbed and undisturbed soil blocks. The samples extracted from these blocks were tested in laboratory to represent the soil from 1.5, 3.0 and 5.0 m depth. The stress curves and shear strength envelopes determined by triaxial tests varying suction and confining pressure are presented and discussed. The water retention characteristics on this soil complement this analysis. In situ CPT tests were also carried out at this site in different seasons of the year. In this case, the soil suction profile was determined by means of the soil water retention. This extra information allowed assessing how soil suction also affected the CPT data and the shear strength parameters estimative via correlation. The major conclusions of this paper are: the undisturbed soil samples contracted before shearing and the soil shear strength increased hyperbolically with suction; and it was possible to assess how soil suction also influenced CPT test data based on the water content soil profile as well as the water retention curve. This study contributed with a better understanding of the shear strength parameters and the soil variability of a typical unsaturated tropical soil.

Keywords: site characterization, triaxial test, CPT, suction, variability

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29409 The Role of the Stud’s Configuration in the Structural Response of Composite Bridges

Authors: Mohammad Mahdi Mohammadi Dehnavi, Alessandra De Angelis, Maria Rosaria Pecce

Abstract:

This paper deals with the role of studs in the structural response of steel-concrete composite beams. A tri-linear slip-shear strength law is assumed according to literature and codes provisions for developing a finite element (FE) model of a case study of a composite deck. The variation of the strength and ductility of the connection is implemented in the numerical model carrying out nonlinear analyses. The results confirm the utility of the model to evaluate the importance of the studs capacity, ductility and strength on the global response (ductility and strength) of the structures but also to analyze the trend of slip and shear at interface along the beams.

Keywords: stud connectors, finite element method, slip, shear load, steel-concrete composite bridge

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29408 Mechanical Properties of a Soil Stabilized With a Portland Cement

Authors: Ahmed Emad Ahmed, Mostafa El Abd, Ahmed Wakeb, Moahmmed Eissa

Abstract:

Soil modification and reinforcing aims to increase soil shear strength and stiffness. In this report, different amounts of cement were added to the soil to explore its effect on shear strength and penetration using 3 tests. The first test is proctor compaction test which was conducted to determine the optimal moisture content and maximum dry density. The second test was direct shear test which was conducted to measure shear strength of soil. The third experiment was California bearing ratio test which was done to measure the penetration in soil. Each test was done different amount of times using different amounts of cement. The results from every test show that cement improve soil shear strength properties and stiffness.

Keywords: soil stabilized, soil, mechanical properties of soil, soil stabilized with a portland cement

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29407 Effects of Rice Husk Ash on the Properties of Scrap Tyre Steel Fiber Reinforced High Performance Concrete (RHA-STSFRHAC)

Authors: Isyaka Abdulkadir, Egbe-Ngu Ntui Ogork

Abstract:

This research aims to investigate the effect of Rice Husk Ash (RHA) on Scrap Tyre Steel Fiber Reinforced High Performance Concrete (STSFRHPC). RHA was obtained by control burning of rice husk in a kiln to a temperature of 650-700oC and when cooled sieved through 75µm sieve and characterized. The effect of RHA were investigated on grade 50 STSFRHPC of 1:1.28:1.92 with water cement ratio of 0.39 at additions of Scrap Tyre Steel Fiber (STSF) of 1.5% by volume of concrete and partial replacement of cement with RHA at percentages of 0, 5, 10, 15 and 20. The fresh concrete was tested for slump while the hardened concrete was tested for compressive and splitting tensile strengths respectively at curing ages of 3, 7, 28 and 56 days in accordance with standard procedure. Results of RHA-STSFRHPC indicated a reduction in slump and compressive strength with increase in RHA content, while splitting tensile strength increased with RHA replacement up to 10% and reduction in strength above 10% RHA content. The 28 days compressive strength of RHA-STSFRHPC with up to 10% RHA attained the desired characteristic strength of 50N/mm2 and therefore up to 10% RHA is considered as the optimum replacement dosage in STSFRHPC-RHA.

Keywords: compressive strength, high performance concrete, rice husk ash, scrap tyre steel fibers

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29406 Suitability of Quarry Dust as Replacement of Sand in Medium Grade Concrete

Authors: Popoola M. Oyenola

Abstract:

Concrete plays the important role and a huge percentage of concrete is being utilized in every construction practices. Natural river sand is one of the major ingredients of concrete, is becoming expensive due to excessive cost of accessibility from sources. Also large scale depletion of sources creates environmental problems. Therefore, there is a need of economic alternative materials. Quarry dust is a waste obtained during quarrying process. It has been rampantly used in different construction practices and could be used as an effective fine aggregate instead of river sand. Partial and total replacement of fine aggregate in conventional concrete with quarry dust has been empirically conducted with the view to examining primarily the compressive strength of the resulting composite and possible total utilization of quarry dust as fine aggregate in the production of medium grade concrete. The results of the study showed that its specific gravity, porosity and water absorption showed satisfactory performance. The percentage replacement of natural river sand with quarry dust for a designed strength of 25N/mm2 varied at intervals of 10% up to a maximum value of 100%. A total of 132 cubes of 150 x 150 x 150mm were cast and tested at 7, 14 and 28 days of hydration. Compressive strength increases with curing age in all the mixes. Compressive strength decreases with increase in percentage of quarry dust. Generally the compressive strength of concrete incorporating quarry dust attained strength of 22.47 N/mm2 after 28 days which makes it a suitable aggregate for the production medium grade concrete.

Keywords: quarry dust, concrete, aggregates, compressive strength

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29405 Differential Effect of Technique Majors on Isokinetic Strength in Youth Judoka Athletes

Authors: Chungyu Chen, Yi-Cheng Chen, Po-Hsian Hsu, Hsin-Ying Chen, Yen-Po Hsiao

Abstract:

The purpose of this study was to assess the muscular strength performance of upper and lower extremity in isokinetic system for the youth judo players, and also to compare the strength difference between major techniques. Sixteen male and 20 female judo players (age: 16.7 ± 1.6 years old, training age: 4.5 ± 0.8 years) were served as the volunteers for this study. There were 21 players major hand techniques and 15 players major foot techniques. The Biodex S4 Pro was used to assess the strength performance of extensor and flexor of concentric action under the load condition of 30 degree/sec, 60 degree/sec, and 120 degree/sec for elbow joints and knee joints. The strength parameters were included the maximal torque, the normalized maximal torque, the average power, and the average maximal torque. A t test for independent groups was used to evaluate whether hand major and foot major differ significantly with an alpha level of .05. The result showed the maximal torque of left knee extensor in foot major players (243.5 ± 36.3 Nm) was higher significantly than hand major (210.7 ± 21.0 Nm) under the load of 30 degree/sec (p < .05). There were no differences in upper extremity strength between the hand and foot techniques major in three loads (ps < .05). It indicated that the judo player is required to develop the upper extremity strength overall to secure the execution of major techniques.

Keywords: knee, elbow, power, judo

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29404 The Development of a Low Carbon Cementitious Material Produced from Cement, Ground Granulated Blast Furnace Slag and High Calcium Fly Ash

Authors: Ali Shubbar, Hassnen M. Jafer, Anmar Dulaimi, William Atherton, Ali Al-Rifaie

Abstract:

This research represents experimental work for investigation of the influence of utilising Ground Granulated Blast Furnace Slag (GGBS) and High Calcium Fly Ash (HCFA) as a partial replacement for Ordinary Portland Cement (OPC) and produce a low carbon cementitious material with comparable compressive strength to OPC. Firstly, GGBS was used as a partial replacement to OPC to produce a binary blended cementitious material (BBCM); the replacements were 0, 10, 15, 20, 25, 30, 35, 40, 45 and 50% by the dry mass of OPC. The optimum BBCM was mixed with HCFA to produce a ternary blended cementitious material (TBCM). The replacements were 0, 10, 15, 20, 25, 30, 35, 40, 45 and 50% by the dry mass of BBCM. The compressive strength at ages of 7 and 28 days was utilised for assessing the performance of the test specimens in comparison to the reference mixture using 100% OPC as a binder. The results showed that the optimum BBCM was the mix produced from 25% GGBS and 75% OPC with compressive strength of 32.2 MPa at the age of 28 days. In addition, the results of the TBCM have shown that the addition of 10, 15, 20 and 25% of HCFA to the optimum BBCM improved the compressive strength by 22.7, 11.3, 5.2 and 2.1% respectively at 28 days. However, the replacement of optimum BBCM with more than 25% HCFA have showed a gradual drop in the compressive strength in comparison to the control mix. TBCM with 25% HCFA was considered to be the optimum as it showed better compressive strength than the control mix and at the same time reduced the amount of cement to 56%. Reducing the cement content to 56% will contribute to decrease the cost of construction materials, provide better compressive strength and also reduce the CO2 emissions into the atmosphere.

Keywords: cementitious material, compressive strength, GGBS, HCFA, OPC

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29403 Improvement of Compressive and Tensile Strengths of Concrete Using Polypropylene Fibers

Authors: Omar Asad Ahmad, Mohammed Awwad

Abstract:

Concrete is one of the essential elements that used in different types of construction these days, but it has many problems when interacts with environmental elements such as water, air, temperature, dust, and humidity. Also concrete made with Portland cement has certain characteristics: it is relatively strong in compression but weak in tension and tends to be brittle. These disadvantages make concrete limited to use in certain conditions. The most common problems appears on concrete are manifested by tearing, cracking, corrosion and spalling, which will lead to do some defect in concrete then in the whole construction, The fundamental objective of this research was to provide information about the hardened properties of concrete achieved by using easily available local raw materials in Jordan to support the practical work with partners in assessing the practicability of the mixes with polypropylene, and to facilitate the introduction of polypropylene fiber concrete (PFC) technology into general construction practice. Investigate the effect of the polypropylene fibers in PCC mixtures and on materials properties such as compressive strength, and tensile strength. Also to investigate the use of polypropylene fibers in plain cubes and cylindrical concrete to improve its compressive and tensile strengths to reduce early cracking and inhibit later crack growth. Increasing the hardness of concrete in this research is the main purpose to measure the deference of compressive strength and tensile strength between plain concrete and concrete mixture with polypropylene fibers different additions and to investigate its effect on reducing the early and later cracking problem. To achieve the goals of research 225 concrete test sample were prepared to measure it’s compressive strength and tensile strength, the concrete test sample were three classes (A,B,C), sub-classified to standard , and polypropylene fibers added by the volume of concrete (5%, 10%, 15%, and 20%). The investigation of polypropylene fibers mixture with concrete shows that the strengths of the cement are increased and the cracking decreased. The results show that for class A the recommended addition were 5% of polypropylene fibers additions for compressive strength and 10 % for tensile strength revels the best compressive strength that reach 26.67 Mpa and tensile strength that reach 2.548 Mpa records. Achieved results show that for classes B and C the recommend additions were 10 % polypropylene fibers revels the best compressive strength records where they reach 21.11 and 33.78 Mpa, records reach for tensile strength 2.707 and 2.65 Mpa respectively.

Keywords: polypropylene, effects, compressive, tensile, strengths, concrete, construction

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29402 Relationship between Interfacial Instabilities and Mechanical Strength of Multilayer Symmetric Polymer Melts

Authors: Mohammad Ranjbaran Madiseh

Abstract:

In this research, an experimental apparatus has been developed for observing interfacial stability and deformation of multilayer pressure-driven channel flows. The interface instability of the co-extrusion flow of polyethylene and polypropylene is studied experimentally in a slit geometry. By investigating the growing interfacial wave (IW) and tensile stress of extrudate samples, a relationship between interfacial instability (II) and mechanical properties of polypropylene (PP) and high-density polyethylene (HDPE) has been established. It is shown that the mechanism of interfacial strength is related to interfacial instabilities as well as interfacial strength. It is shown that there is an ability to forecast the quality of final products in the co-extrusion process. In this study, it is found that the instability is controlled by its dominant wave number, which is associated with maximum tensile stress at the interface.

Keywords: interfacial instability, interfacial strength, wave number, interfacial wave

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29401 Characterization of Erodibility Using Soil Strength and Stress-Strain Indices for Soils in Some Selected Sites in Enugu State

Authors: C. C. Egwuonwu, N. A. A. Okereke, K. O. Chilakpu, S. O. Ohanyere

Abstract:

In this study, initial soil strength indices (qu) and stress-strain characteristics, namely failure strain (ϵf), area under the stress-strain curve up to failure (Is) and stress-strain modulus between no load and failure (Es) were investigated as potential indicators for characterizing the erosion resistance of two compacted soils, namely sandy clay loam (SCL) and clay loam (CL) in some selected sites in Enugu State, Nigeria. The unconfined compressive strength (used in obtaining strength indices) and stress-strain measurements were obtained as a function of moisture content in percentage (mc %) and dry density (γd). Test were conducted over a range of 8% to 30% moisture content and 1.0 g/cm3 to 2.0 g/cm3 dry density at applied loads of 20, 40, 80, 160 and 320 kPa. Based on the results, it was found out that initial soil strength alone was not a good indicator of erosion resistance. For instance, in the comparison of exponents of mc% and γd for jet index or erosion resistance index (Ji) and the strength measurements, qu and Es agree in signs for mc%, but are opposite in signs for γd. Therefore, there is an inconsistency in exponents making it difficult to develop a relationship between the strength parameters and Ji for this data set. In contrast, the exponents of mc% and γd for Ji and ϵf and Is are opposite in signs, there is potential for an inverse relationship. The measured stress-strain characteristics, however, appeared to have potential in providing useful information on erosion resistance. The models developed for the prediction of the extent or the susceptibility of soils to erosion and subjected to sensitivity test on some selected sites achieved over 90% efficiency in their functions.

Keywords: characterization of erodibility, selected sites in Enugu state, soil strength, stress-strain indices

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29400 The Effect of Mineral Addition (Natural Pozzolana) on the Capillary Absorption and Compressive Strength of Environmental Mortar

Authors: W. Deboucha, M. N. Oudjit, A. Bouzid, L. Belagraa, A.Noui

Abstract:

The cement manufacturing is the one of the factors that pollutes the atmosphere in the industrial sector. The common way to reduce this pollution is using mineral additions as partial replacement of Portland cement. Particularly, natural pozzolana (NP) is component in which they can be used to decrease the rate of pollution. The main objective of this experimental work is the study of the effect of mineral addition (natural pozzolana) on the capillary water absorption and compressive-flexural strength of cement mortar. The results obtained in the present research showed that the higher dosages of natural pozzolana added could be the principal parameter of such decrease in strength at early and medium term. Further, this increase of incorporated addition has been believed to reduce the capillary water absorption.

Keywords: Natural pozzolana, mortar, strength, capillary absorption

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29399 Analytical Evaluation on Hysteresis Performance of Circular Shear Panel Damper

Authors: Daniel Y. Abebe, Jaehyouk Choi

Abstract:

The idea of adding metallic energy dissipaters to a structure to absorb a large part of the seismic energy began four decades ago. There are several types of metal-based devices conceived as dampers for the seismic energy absorber whereby damages to the major structural components could be minimized for both new and existing structures. This paper aimed to develop and evaluate structural performance of both stiffened and non stiffened circular shear panel damper for passive seismic energy protection by inelastic deformation. Structural evaluation was done using commercially available nonlinear FE simulation program. Diameter-to-thickness ratio is employed as main parameter to investigate the hysteresis performance of stiffened and unstiffened circular shear panel. Depending on these parameters three different buckling mode and hysteretic behavior was found: yielding prior to buckling without strength degradation, yielding prior to buckling with strength degradation and yielding with buckling and strength degradation which forms pinching at initial displacement. Hence, the hysteresis behavior is identified, specimens which deform without strength degradation so it will be used as passive energy dissipating device in civil engineering structures.

Keywords: circular shear panel damper, FE analysis, hysteretic behavior, large deformation

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29398 Study on the Strength and Durability Properties of Ternary Blended Concrete

Authors: Athira Babu, M. Nazeer

Abstract:

Concrete is the most common and versatile construction material used in any type of civil engineering structure. The durability and strength characteristics of concrete make it more desirable among any other construction materials. The manufacture and use of concrete produces wide range of environmental and social consequences. The major component in concrete, cement accounts for roughly 5 % of global CO2 emissions. In order to improve the environmental friendliness of concrete, suitable substitutes are added to concrete. The present study deals with GGBS and silica fume as supplementary cementitious materials. The strength and durability studies were conducted in this ternary blended concrete. Several mixes were adopted with varying percentages of Silica Fume i.e., 5%, 10% and 15%. Binary mix with 50% GGBS was also prepared. GGBS content has been kept constant for the rest of mixes. There is an improvement in compressive strength with addition of Silica Fume.Maximum workability, split tensile strength, modulus of elasticity, flexural strength and impact resistance are obtained for GGBS binary blend. For durability studies, maximum sulphate resistance,carbonation resistance andresistance to chloride ion penetration are obtained for ternary blended concrete. Partial replacement of GGBS and Silica Fume reduces the environmental effects, produces economical and eco-friendly concrete. The study showed that for strength characteristics, binary blended concrete showed better performance while for durability study ternary blend performed better.

Keywords: concrete, GGBS, silica fume, ternary blend

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29397 Development of Light-Weight Refractory Bricks

Authors: Liaqat Ali, Furqan Ahmad

Abstract:

The heat losses should be controlled during the high temperature processes from energy conservation point of view. For this purpose, refractories with low thermal conductivity, high porosity and good mechanical strength along with low price are desirable. In this work, various combinations of naturally occurring, locally available, cheap raw materials, namely, clay, rice husk and saw dust were used. Locally produced insulating firebricks (IFBs) cannot be used at higher than a few hundred °C and possess low strength as well. Various process parameters were studied and the refractories with desirable properties were produced, which can be used up to 1200 °C.

Keywords: firebricks, mechanical strength, thermal conductivity, refractory bricks

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29396 Particle Size Effect on Shear Strength of Granular Materials in Direct Shear Test

Authors: R. Alias, A. Kasa, M. R. Taha

Abstract:

The effect of particle size on shear strength of granular materials are investigated using direct shear tests. Small direct shear test (60 mm by 60 mm by 24 mm deep) were conducted for particles passing the sieves with opening size of 2.36 mm. Meanwhile, particles passing the standard 20 mm sieves were tested using large direct shear test (300 mm by 300 mm by 200 mm deep). The large direct shear tests and the small direct shear tests carried out using the same shearing rate of 0.09 mm/min and similar normal stresses of 100, 200, and 300 kPa. The results show that the peak and residual shear strength decreases as particle size increases.

Keywords: particle size, shear strength, granular material, direct shear test

Procedia PDF Downloads 467
29395 Effects of Potential Chloride-Free Admixtures on Selected Mechanical Properties of Kenya Clay-Based Cement Mortars

Authors: Joseph Mwiti Marangu, Joseph Karanja Thiong'o, Jackson Muthengia Wachira

Abstract:

The mechanical performance of hydrated cements mortars mainly depends on its compressive strength and setting time. These properties are crucial in the construction industry. Pozzolana based cements are mostly characterized by low 28 day compressive strength and long setting times. These are some of the major impediments to their production and diverse uses despite numerous technological and environmental benefits associated with them. The study investigated the effects of potential chemical activators on calcined clay- Portland cement blends with an aim to achieve high early compressive strength and shorter setting times in cement mortar. In addition, standard consistency, soundness and insoluble residue of all cement categories was determined. The test cement was made by blending calcined clays with Ordinary Portland Cement (OPC) at replacement levels from 35 to 50 percent by mass of the OPC to make test cement labeled PCC for the purposes of this study. Mortar prisms measuring 40mmx40mmx160mm were prepared and cured in accordance with KS EAS 148-3:2000 standard. Solutions of Na2SO4, NaOH, Na2SiO3 and Na2CO3 containing 0.5- 2.5M were separately added during casting. Compressive strength was determined at 2rd, 7th, 28th and 90th day of curing. For comparison purposes, commercial Portland Pozzolana cement (PPC) and Ordinary Portland Cement (OPC) were also investigated without activators under similar conditions. X-Ray Florescence (XRF) was used for chemical analysis while X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) were used for mineralogical analysis of the test samples. The results indicated that addition of activators significantly increased the 2nd and 7th day compressive strength but minimal increase on the 28th and 90th day compressive strength. A relatively linear relationship was observed between compressive strength and concentration of activator solutions up to 28th of curing. Addition of the said activators significantly reduced both initial and final setting time. Standard consistency and soundness varied with increased amount of clay in the test cement and concentration of activators. Amount of insoluble residues increased with increased replacement of OPC with calcined clays. Mineralogical studies showed that N-A-S-H is formed in addition to C-S-H. In conclusion, the concentration of 2 molar for all activator solutions produced the optimum compressive strength and greatly reduced the setting times for all cement mortars.

Keywords: activators, admixture, cement, clay, pozzolana

Procedia PDF Downloads 241