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Full-Text Articles in Engineering

Numerical Analysis Of Free-Edge Effect On Size-Influenced Mechanical Properties Of Single-Layer Triaxially Braided Composites, Chao Zhang, Wieslaw Binienda Sep 2015

Numerical Analysis Of Free-Edge Effect On Size-Influenced Mechanical Properties Of Single-Layer Triaxially Braided Composites, Chao Zhang, Wieslaw Binienda

Wieslaw K. Binienda

The mechanical properties of triaxially braided composites under transverse loads are found to be size-dependent, due to the presence of free-edge effect. Numerical studies of the mechanical behaviors of straight-sided coupon specimens and an infinitely large plate under both axial and transverse tension loads were conducted using a meso-scale finite element model. The numerical model correlates well with experimental results, successfully capturing the free-edge warping phenomena under transverse tension. Free-edge effect is observed as out-of-plane warping, and it can be correlated to the premature damage initiation in the affected area. The numerical results characterize the impact of free-edge effects on …


Enhancement Of The Mechanical Properties Of Lightweight Oil Palm Shell Concrete Using Rice Husk Ash And Manufactured Sand Jan 2015

Enhancement Of The Mechanical Properties Of Lightweight Oil Palm Shell Concrete Using Rice Husk Ash And Manufactured Sand

Faculty of Engineering University of Malaya

This study explores the use of rice husk ash (RHA) and manufactured sand (M-sand) as replacements for cement and fine aggregate, respectively, in lightweight oil palm shell concrete (OPSC). In the first stage of this study, the effect of various cement replacement levels, with RHA (5%, 10%, 15%, and 20%) and 100% sand replacement with M-sand and quarry dust (QD), on the compressive strength of OPSC was investigated. The results showed that the highest compressive strength of OPSC of about 51.49 MPa was achieved with the use of 15% RHA and M-sand. In the second stage of the work, the …


Conductive Concrete Overlay For Bridge Deck Deicing: Mixture Proportioning, Optimization, And Properties, Sherif Yehia, Christopher Tuan Mar 2014

Conductive Concrete Overlay For Bridge Deck Deicing: Mixture Proportioning, Optimization, And Properties, Sherif Yehia, Christopher Tuan

Christopher Y. Tuan

Bridge pavement surfaces are prone to ice accumulation, making winter travel hazardous. Current practice is to use road salt and deicing chemicals, that cause damage to concrete and corrosion of reinforcing steel. A thin conductive concrete overlay can generate enough heat to prevent ice formation on a bridge deck. Conductive concrete is a cementitious admixture containing electrically conductive components that attain stable and high electrical conductivity. Due to the electrical resistance and impedance in conductive concrete, heat is generated when connected to a power source, and can be used for deicing or anti-icing. Conductive concrete is a relatively new material …


Effects Of Heat Treatment On Oil Palm Shell Coarse Aggregates For High Strength Lightweight Concrete, Hilmi Mahmud Feb 2014

Effects Of Heat Treatment On Oil Palm Shell Coarse Aggregates For High Strength Lightweight Concrete, Hilmi Mahmud

Hilmi Mahmud

In this study, the effects of heat treatment on oil palm shell (OPS) coarse aggregates are evaluated for high strength lightweight concrete (HSLWC). OPS coarse aggregates are subjected to heat treatment at two temperature settings (60 and 150. °C) and duration of heat treatment (0.5 and 1. h). The reduction in density is found to be within the range of HSLWC when heat-treated OPS aggregates are added into the oil palm shell concrete (OPSC). The results reveal that workability of the OPSC increases with an increase in temperature and duration of heat treatment of the OPS aggregates. It is found …


Engineering Properties Of Oil Palm Shell Lightweight Concrete Containing Fly Ash, Hilmi Mahmud Aug 2013

Engineering Properties Of Oil Palm Shell Lightweight Concrete Containing Fly Ash, Hilmi Mahmud

Hilmi Mahmud

The effect of cement replacement with type F fly ash at 0%, 10%, 30% and 50% on some engineering properties of an oil palm shell (OPS) high strength lightweight concrete was investigated. The properties studied include workability, density, compressive strength, splitting tensile strength, flexural strength, water absorption and drying shrinkage. The effect of initial water curing periods of 2, 4 and 6. days after demoulding and air drying environment on the 28-day compressive strength was also investigated. The test results showed that even with 50% substitution of cement with fly ash, a low cost grade 30 OPS lightweight concrete can …


Lightweight Aggregate Concrete Fiber Reinforcement - A Review, Hilmi Mahmud Jan 2012

Lightweight Aggregate Concrete Fiber Reinforcement - A Review, Hilmi Mahmud

Hilmi Mahmud

The higher brittleness and lower mechanical properties of lightweight aggregate concrete (LWAC) compared to normal weight concrete (NWC) at the same compressive strength has prevented it from being widely used in the construction industry despite its many advantages. Studies have shown that the use of fibers in LWAC is an appropriate solution to resolve such problems. This paper reviews the influence of the addition of fibers on the properties of different types of LWAC. These properties include the workability, compressive strength, stress-strain behavior, tensile strength, modulus of elasticity, and compressive and flexural toughness. Generally, the inclusion of fibers in LWAC, …


A New Method Of Producing High Strength Oil Palm Shell Lightweight Concrete, Hilmi Mahmud Dec 2011

A New Method Of Producing High Strength Oil Palm Shell Lightweight Concrete, Hilmi Mahmud

Hilmi Mahmud

This paper presents a new method to produce high strength lightweight aggregate concrete (HSLWAC) using an agricultural solid waste, namely oil palm shell (OPS). This method is based on crushing large old OPS. Crushed OPS are hard and have a strong physical bond with hydrated cement paste. The 28 and 56. days compressive strength achieved in this study were about 53 and 56. MPa, respectively. Furthermore, it was observed that it was possible to produce grade 30 OPS concrete without the addition of any cementitious materials. Compared to previous studies, significantly lower cement content was used to produce this grade …


Shear Behaviour Of Reinforced Palm Kernel Shell Concrete Beams, Hilmi Mahmud Jun 2011

Shear Behaviour Of Reinforced Palm Kernel Shell Concrete Beams, Hilmi Mahmud

Hilmi Mahmud

The shear behaviour of palm kernel shell concrete (PKSC) beams prepared using palm kernel shell (PKS) as lightweight aggregate (LWA) is reported here. The shear strength of grade 30 PKSC with a density of 1850 kg/m(3) was found 24% higher than the corresponding normal weight concrete (NWC). Good aggregate interlock in PKSC was evident as it produced shorter jagged cracks compared to longer plain cracks of NWC. Further, PKSC was able to produce twice as many flexural and shear cracks compared to NWC. Tension stiffening between the tensile cracks of PKSC enhanced flexural rigidity and dowel action. The non-linear numerical …


Enhancement And Prediction Of Modulus Of Elasticity Of Palm Kernel Shell Concrete, Hilmi Mahmud Apr 2011

Enhancement And Prediction Of Modulus Of Elasticity Of Palm Kernel Shell Concrete, Hilmi Mahmud

Hilmi Mahmud

This paper presents results of an investigation conducted to enhance and predict the modulus of elasticity (MOE) of palm kernel shell concrete (PKSC). Scanning electron microscopic (SEM) analysis on palm kernel shell (PKS) was conducted. Further, the effect of varying sand and PKS contents and mineral admixtures (silica fume and fly ash) on compressive strength and MOE was investigated. The variables include water-to-binder (w/. b) and sand-to-cement (s/. c) ratios. Nine concrete mixes were prepared, and tests on static and dynamic moduli of elasticity and compressive strength were conducted. The SEM result showed presence of large number of micro-pores on …


High-Strength Rice Husk Ash Concrete Incorporating Quarry Dust As A Partial Substitute For Sand, Hilmi Mahmud Jan 2011

High-Strength Rice Husk Ash Concrete Incorporating Quarry Dust As A Partial Substitute For Sand, Hilmi Mahmud

Hilmi Mahmud

Quarry dust is a by-product from the granite crushing process in quarrying activities. This paper presents the findings from experimental work undertaken to evaluate the suitability of quarry dust as a partial substitute for sand in high-strength concrete (HSC) containing rice husk ash (RHA). Two grades of HSC mixes, to achieve 60 MPa and 70 MPa at 28 days, were designed with and without the incorporation of RHA. Quarry dust was then used in the mixes containing RHA as a partial substitute for sand, in quantities ranging from 10% to 40%. The slump of the fresh concrete and the compressive …


A New Method Of Producing High Strength Oil Palm Shell Lightweight Concrete, Zamin Jumaat Dec 2010

A New Method Of Producing High Strength Oil Palm Shell Lightweight Concrete, Zamin Jumaat

Zamin Jumaat

This paper presents a new method to produce high strength lightweight aggregate concrete (HSLWAC) using an agricultural solid waste, namely oil palm shell (OPS). This method is based on crushing large old OPS. Crushed OPS are hard and have a strong physical bond with hydrated cement paste. The 28 and 56 days compressive strength achieved in this study were about 53 and 56 MPa, respectively. Furthermore, it was observed that it was possible to produce grade 30 OPS concrete without the addition of any cementitious materials. Compared to previous studies, significantly lower cement content was used to produce this grade …


Mix Design And Mechanical Properties Of Oil Palm Shell Lightweight Aggregate Concrete: A Review, Hilmi Mahmud Nov 2010

Mix Design And Mechanical Properties Of Oil Palm Shell Lightweight Aggregate Concrete: A Review, Hilmi Mahmud

Hilmi Mahmud

To build environmentally sustainable structures, especially in developing countries, the possibility of using some agricultural wastes and industrial by-products from different industries as construction materials will be highly desirable and has several practical and economic advantages. Oil palm shell (OPS) is a form of agricultural solid waste in the tropical regimes. Research over the last two decades shows that OPS can be used as a lightweight aggregate for producing structural lightweight aggregate concrete. The density of OPS concrete is around 20 - 25% lower than normal weight concrete. Generally, mechanical properties of OPS concrete are slightly lower than the other …


Effect Of Aggregate Size And Proportion On Strength Properties Of Palm Kernel Shell Concrete, Hilmi Mahmud Jan 2010

Effect Of Aggregate Size And Proportion On Strength Properties Of Palm Kernel Shell Concrete, Hilmi Mahmud

Hilmi Mahmud

This paper presents information on the physical and mechanical properties of different sizes of palm kernel shells (PKS) used here as lightweight aggregates (LWA) and their influence on mechanical properties of palm kernel shell concrete (PKSC). Silica fume and fly ash were used as cementitious materials and all mixes had 1% superplasticizer on cement weight. It has been found that PKS consists of about 65 to 70% of medium size particles in the range of 5 to 10 mm. The other two sizes, namely, small (0-5 mm) and large (10-15 mm) sizes were found to influence the mechanical properties of …


Development Of Lightweight Concrete Using Industrial Waste Material, Palm Kernel Shell As Lightweight Aggregate And Its Properties, Hilmi Mahmud Jan 2010

Development Of Lightweight Concrete Using Industrial Waste Material, Palm Kernel Shell As Lightweight Aggregate And Its Properties, Hilmi Mahmud

Hilmi Mahmud

Agricultural industrial wastes produced after extracting palm oil from palm fruits known as palm kernel shell (PKS) are available in large quantities in Indonesia, Malaysia, Nigeria and other tropical countries. Malaysia is the second largest palm oil producing country in the world. This paper reports the results of an investigation conducted to utilize the PKS as lightweight aggregate to produce grade30 concrete with density of about 1850kg/m 3. The properties of both PKS and crushed granite aggregates were compared. The concrete produced using PKS referred to here after as palm kernel shell concrete (PKSC) and its properties were compared with …


Effect Of Aggregate Size And Proportion On Strength Properties Of Palm Kernel Shell Concrete, Zamin Jumaat Jan 2010

Effect Of Aggregate Size And Proportion On Strength Properties Of Palm Kernel Shell Concrete, Zamin Jumaat

Zamin Jumaat

This paper presents information on the physical and mechanical properties of different sizes of palm kernel shells (PKS) used here as lightweight aggregates (LWA) and their influence on mechanical properties of palm kernel shell concrete (PKSC). Silica fume and fly ash were used as cementitious materials and all mixes had 1% superplasticizer on cement weight. It has been found that PKS consists of about 65 to 70% of medium size particles in the range of 5 to 10 mm. The other two sizes, namely, small (0-5 mm) and large (10-15 mm) sizes were found to influence the mechanical properties of …


Comparison Of Mechanical And Bond Properties Of Oil Palm Kernel Shell Concrete With Normal Weight Concrete, Zamin Jumaat Dec 2009

Comparison Of Mechanical And Bond Properties Of Oil Palm Kernel Shell Concrete With Normal Weight Concrete, Zamin Jumaat

Zamin Jumaat

The comparison of the fresh, mechanical and bond properties of grade 30 lightweight concrete, namely oil palm kernel shell concrete (OPKSC) with normal weight concrete (NWC) of similar strength is presented in this paper. Oil palm kernel shell (OPKS), an industrial waste has been used as lightweight aggregates (LWA) in the OPKSC. In addition, mineral admixtures, 10% of silica fume and 5% fly ash have been used. The OPKSC produced a density reduction of about 20% compared to NWC. The addition of silica fume enhanced the compressive strength and thus OPKSC produced 28-day compressive strength up to 37 MPa. The …