A. S. M. Abdul Awal

THE EFFECTIVENESS OF PALM OIL FUEL ASH IN PREVENTING EXPANSION DUE TO ALKALI-SILICA REACTION

Abstract Laboratory tests were conducted to evaluate the performance of palm oil fuel ash (POFA), a recently identified pozzolanic material, in reducing the expansion of mortar bars containing Tuff as a reactive aggregate where ordinary Portland cement (OPC) was replaced, mass for mass, by 0, 10, 30 and 50% POFA. The South African NBRI Accelerated Test method was used in the experimental investigation, which revealed that palm oil fuel ash has a good potential in suppressing expansion due to alkali-silica reaction.

Mechanical Properties of Concrete Incorporating High Volume Palm Oil Fuel Ash

The use of pozzolanic materials in the production of concrete for structural purposes is increasing, and this trend is expected to continue, due to technological advancement and the desire for basic structural infrastructure. This paper describes a study undertaken to examine the use of high volume palm oil fuel ash (HVPOFA) as a cement replacement material in concrete, beyond the optimized level of 30%. For this purpose, concrete mixes with 100% ordinary Portland cement (OPC) as control were made, while high volume palm oil fuel ash concrete mixtures were prepared by substituting 50, 60 and 70% of cement by ash at 0.45 water-binder ratio. Mechanical properties of concrete such as compressive, splitting tensile and flexural strength of HVPOFA concrete were studied and compared with that with 100% OPC. The results indicate that palm oil fuel ash of up to 70% by mass can be combined with Portland cement to produce normal strength concrete.

STRENGTH, MODULUS OF ELASTICITY AND SHRINKAGE BEHAVIOUR OF CONCRETE CONTAINING WASTE CARPET FIBER

This paper presents test results on some physical and mechanical properties of concrete containing fiber from recycled carpet waste. Five concrete mixes namely plain concrete (PC) i.e. concrete without carpet fiber, as control and carpet fiber reinforced concrete (CFRC) mixes containing 0.5%, 1.0%, 1.5% and 2.0% polypropylene (PP) waste carpet fibers were made and tested for compressive, tensile and flexural strengths, modulus of elasticity and shrinkage at curing periods of 1, 7 and 28 days. It has been found that the addition of carpet fiber reduced the workability and density of concrete. Concrete containing carpet fiber exhibited lower compressive strength and modulus of elasticity than plain concrete. The carpet fibers, however, effectively improved the splitting tensile and flexural strengths of concrete. The obtained values of shrinkage revealed that the shrinkage strain of carpet fiber reinforced concrete was higher than that of plain concrete. On the basis of short-term investigation, the one-year shrinkage values of both plain concrete and concrete containing carpet fiber were also predicted by extrapolating the data obtained during this period. The results obtained in this study indicate that waste carpet fiber can suitably be used as fiber reinforcement in concrete with satisfactory performance.

SOME ASPECTS OF PHYSICAL AND MECHANICAL PROPERTIES OF SAWDUST CONCRETE

This paper presents experimental results on some physical and mechanical properties of concrete containing sawdust. Concrete specimens having various cement to sawdust ratios of 1:1, 1:2 and 1:3 by volume were made and tested for workability, density, water absorption, strength and modulus of elasticity at different curing periods of 7, 14 and 28 days. It has been found that with the increase in the amount of sawdust, the workability and density of concrete decreased; the water absorption capacity of concrete, however, increased with the increase in volume. Although the strength of sawdust concrete increased with curing period, the strength and the corresponding modulus of elasticity decreased with the increasing amount of sawdust in the mix. The results obtained and the observation made in the short-term investigation suggests that sawdust concrete can suitably be used as a building material in construction.

Mechanical Properties and Thermal Resistance of High Volume Fly Ash Concrete for Energy Efficiency in Building Construction

The utilization of waste materials in concrete is one of the best value added solutions to the construction industry. With the aim of sustability development, high volume fly ash (HVFA) were tested in concrete by substituting 40, 50 and 60% of OPC with fly ash. Properties studied in this research includes fresh concrete properties, mechanical properties and the resistance of concrete exposed to high temperature. The test result indicates that HVFA concrete positively influenced the workability; however, the setting times of the concrete were longer. It has been found that the development of strength of high volume fly ash concrete was relatively slower, but ahigher strength development at later ages was observed in concrete containing HVFA. The performance of concrete at elevated temperatures reveals that concrete without any fly ash has better resistance than HVFA concrete at high temperature. The use of high volume fly ash results in an acceptable concrete performance, which grants high potential for energy saving in the building construction.

Mechanical properties and thermal behaviour of two-stage concrete containing palm oil fuel ash

Two-stage concrete (TSC) is a special type of concrete which is made by placing coarse aggregate in a formwork and injecting a grout either by pump or under the gravity force to fill the voids. Over the decades, the application of supplementary cementing materials in conventional concrete has become widespread, and this trend is expected to continue in TSC as well. Palm oil fuel ash (POFA) is one of the ashes which has been recognized as a good pozzolanic material. This paper presents the experimental results on the performance behaviour of POFA in developing physical and mechanical properties of two-stage concrete. Four concrete mixes namely, TSC with 100% OPC as a control, and TSC with 10, 20 and 30% POFA were cast, and the temperature growth due to heat of hydration and heat transfer in the mixes was recorded. It has been found that POFA significantly reduced the temperature rise in two-stage aggregate concrete and delayed the transfer of heat to the mass of concrete. The compressive and tensile strengths, however, increased with the replacement of up to 20% POFA. The results obtained and the observation made in this study suggest that the substitution of OPC by POFA is beneficial, particularly for prepacked mass concrete where thermal cracking due to extreme heat rise is of great importance.

Deformation Characteristics of Concrete Containing High Volume Palm Oil Fuel Ash

With the increasing building activities in both developed and developing countries, the utilization of supplementary cementing materials will continue to increase in the years to come because of their technical, economical and ecological advantages. One of such pozzolanic materials is palm oil fuel ash (POFA) which has been identified to be a good cement substitute in mortar and concrete mixes. This paper highlights some laboratory test results on the deformation characteristics of concrete containing high volume palm oil fuel ash. Concrete specimens containing 50% POFA were made and tested for compressive strength, modulus of elasticity, shrinkage and creep. The results were compared with that of control specimen i.e. concrete made with 100% ordinary Portland cement (OPC). It has been observed that POFA concrete had lower compressive strength compared to OPC concrete. Along with lower strength development, the modulus of elasticity of concrete containing 50% ash was found to be lower. Although a relatively higher creep strain was been recorded in POFA concrete, there has been no significant difference of drying shrinkage in concrete with or without palm oil fuel ash.

Strength and Deformation Behaviour of Concrete Incorporating Steel Fibre from Recycled Tyre

This paper presents experimental results on strength and deformation behaviour of concrete reinforced with steel fibre from recycled tyre. Various concrete mixes were made where steel fibres were used at volume fractions ranging from 0 to 2 % by volume of concrete mix. Test specimens comprising of cube, cylinder and prism were prepared and tested for strength after 28 days of curing in water. It has been found that the compressive strength of concrete was slightly increased by the incorporation of recycled steel fibre. However, the tensile and flexural strength of concrete was remarkably improved with the increase of fibre content. Laboratory investigation further revealed that the addition of steel fibre had no influence on drying shrinkage; the creep of concrete, however, was found to be lower in concrete with fibre reinforcement than that in the control specimen.

Modification of grout properties in prepacked aggregate concrete incorporating palm oil fuel ash

Prepacked aggregate concrete (PAC) is a type of concrete that is placed in two stages where the coarse aggregates are first placed inside the formworks and then the grout is pumped from underneath through a manual pump. Grout properties including density, grout consistency, bleeding, and compressive strength are of great importance in PAC. Such properties could be improved by application of pozzolanic materials like palm oil fuel ash. This paper is aimed at finding the most optimum percentage of POFA replacement by weight of cement. It was concluded that 30% POFA replacement yielded the most optimum results.

Finite Element Modelling of Reinforced Concrete Slab at Elevated Temperature Using ABAQUS

This paper investigates the finite element modelling of the temperature distributions of reinforced concrete slab using a general purpose non-linear finite-element program, ABAQUS. The reinforced concrete slab is tested under exposure to designed fire in order to validate the shell element in in the ABAQUS program. The modelling results showed agreement with the fire test and it demonstrated that the ABAQUS shell element can be used to predict fire behaviour within reinforced concrete slab in elevated temperature conditions.