Mohd Zamin Jumaat

Utilization of palm oil fuel ash in concrete: a review

Abstract Uncontrolled dumping of palm oil fuel ash (POFA) not only occupies valuable land but also creates environmental pollution and health hazard. These problems can be reduced to a large extent by using POFA in concrete. A number of research works have been carried out to investigate the potential of POFA for use as a supplementary cementing material in normal, high strength, high performance, and aerated concretes. This paper presents a review on the use of POFA in different types of concrete. It firstly discusses the physical and chemical properties of POFA. Then the emphasis has been given on the effects of POFA on the fresh and hardened properties, and durability of concrete. This paper shows that both ground and unground POFA increase the water demand and thus decrease the workability of concrete. However, ground POFA has shown a good potential for improving the hardened properties and durability of concrete due to its satisfactory micro-filling ability and pozzolanic activity. In addition to dis...

Properties of high-workability concrete with recycled concrete aggregate

This study presents the effects of recycled concrete aggregate (RCA) on the key fresh and hardened properties of concrete. RCA was used to produce high-workability concrete substituting 0-100% natural coarse aggregate (NCA) by weight. The slump and slump flow of fresh concretes were determined to ensure high workability. In addition, the compressive, flexural and splitting tensile strengths, modulus of elasticity, and permeable voids of hardened concretes were determined. The test results revealed that RCA significantly decreased the workability of concrete. RCA also affected the compressive strength, modulus of elasticity, and permeable voids of concrete. At the age of 28 days, the concrete with 100% RCA provided 12.2% lower compressive strength and 17.7% lesser modulus of elasticity than the control concrete. Also, 100% RCA increased the permeable voids of 28-day old concrete by 8.2%. However, no significant negative impact of RCA was observed on the flexural and splitting tensile strengths of concrete.

FLEXURAL BEHAVIOUR OF REINFORCED CONCRETE SLABS WITH FERROCEMENT TENSION ZONE COVER

Abstract This paper presents a study of the flexural behaviour of reinforced concrete slabs with ferrocement tension zone cover. The results of tests on 12 simply supported slabs are presented. The effect of the following parameters: percentage of wire mesh reinforcement in the ferrocement cover layer, thickness of the ferrocement layer and the type of connection between the ferrocement layer and the reinforced concrete slab on the ultimate flexural load, first crack load, crack width and spacing, and the load–deflection relationship were examined. The results indicate that the use of ferrocement cover slightly increases the ultimate flexural load and increases in the first crack load. The first crack load increased with the increase in the percentage of mesh reinforcement and the ferrocement layer thickness. Considerable reduction in cracks width and spacing (64–84%) was observed for specimens with a ferrocement layer. The presence of a cold joint between the reinforced concrete slab and the ferrocement layer lowered the ultimate flexural load by 34%, however, cracks width and spacing were reduced. Specimens cast without structural connection, provided that concrete was cast within 1–1.5 h of casting the ferrocement cover, behaved in a very similar manner to those with structural connection. The deflections at service load and near ultimate load were smaller for specimens with ferrocement layer. The ferrocement layer thickness and the connection type influenced the reduction in deflection.

Effects of recycled concrete aggregate on the fresh properties of self-consolidating concrete

Concrete wastes are generally delivered to the landfill sites for disposal. Due to increasing charges of landfill and scarcity of natural coarse aggregate (NCA), recycled concrete aggregate (RCA) derived from concrete wastes is growing interest in construction industry. In the present study, RCA was used as partial and full replacements of NCA to produce self-consolidating concrete (SCC). Different SCC mixes were produced with RCA substituting 0%, 30%, 50%, 70%, and 100% NCA by weight. The water to cement (W/C) ratio and high-range water reducer (HRWR) dosage were kept the same for all concretes. The effects of RCA on the key fresh properties such as filling ability, passing ability, and segregation resistance of SCC were investigated. The test results revealed that the filling ability and passing ability of SCC were improved for 30% and 50% RCA. The SCC mixes with 30% and 50% RCA also possessed adequate segregation resistance. In addition, strong correlations were observed for filling ability, passing ability, and segregation resistance. The overall test results suggest that RCA can be used to produce SCC substituting up to 50% NCA without affecting the key fresh properties of concrete.

Reinforced steel I-beams: A comparison between 2D and 3D simulation

This study reports the accuracies of Finite Element (FE) simulations, based on two and three dimensional (2D and 3D) modelling of strengthened steel I-beams in static linear and non-linear analyses. To investigate the effects of simulation modelling methods on the accuracy of the results, 28 computer and laboratory specimens were used. To strengthen the beams, Carbon Fibre Reinforced Polymer (CFRP) and steel plates were applied, and to simulate the specimens, ANSYS software was utilized. All specimens were modelled by using shell elements or solid elements in the 2D and 3D modelling cases, respectively. The results show that non-linear and 3D simulation methods predicted the experimental results appropriately.

Incorporating residual strains in the flexural rigidity of RC members with varying degrees of prestress and cracking

The deformation of reinforced concrete columns and beams is controlled by the variation of the flexural rigidity (EI) both along the member and with applied loads and time. Currently, the moment-curvature (M/χ) approach is used to quantify EI. Prior to cracking, the M/χ approach provides a pure mechanics based solution for EI; that is, the only components of the model that have to be determined empirically are the material stress-strain relationships. However after cracking, the M/χ approach has to be semi-empirical, that is EI has to be determined empirically because the M/χ approach cannot simulate the mechanics of tension-stiffening. An alternative approach for quantifying EI using a moment-rotation (M/θ) approach is described in this paper. It is shown that the M/θ approach gives exactly the same results as the M/χ approach prior to cracking but after cracking has an advantage over the M/χ approach in that it can quantify the mechanics of tension-stiffening, that is allow for bond slip and its effect on crack spacing and crack widths. This paper deals with the mechanics of incorporating creep, shrinkage, prestress, relaxation and thermal gradients (broadly referred to as residual strains) on the flexural rigidity of RC beams and columns at all levels of loading prior to concrete softening.

A Comprehensive Study of the Polypropylene Fiber Reinforced Fly Ash Based Geopolymer

As a cementitious material, geopolymers show a high quasi-brittle behavior and a relatively low fracture energy. To overcome such a weakness, incorporation of fibers to a brittle matrix is a well-known technique to enhance the flexural properties. This study comprehensively evaluates the short and long term impacts of different volume percentages of polypropylene fiber (PPF) reinforcement on fly ash based geopolymer composites. Different characteristics of the composite were compared at fresh state by flow measurement and hardened state by variation of shrinkage over time to assess the response of composites under flexural and compressive load conditions. The fiber-matrix interface, fiber surface and toughening mechanisms were assessed using field emission scan electron microscopy (FESEM) and atomic force microscopy (AFM). The results show that incorporation of PPF up to 3 wt % into the geopolymer paste reduces the shrinkage and enhances the energy absorption of the composites. While, it might reduce the ultimate flexural and compressive strength of the material depending on fiber content.

Utilization of Palm Oil Fuel Ash as Binder in Lightweight Oil Palm Shell Geopolymer Concrete

Traditionally fly ash (FA) has been used to replace cement as binder in the geopolymer concrete. The utilization of palm oil industrial waste materials known as palm oil fuel ash (POFA) and oil palm shell (OPS) that are abundantly available in South East Asia as binder and coarse aggregate in geopolymer concrete would give an added advantage in both the environmental and economic aspects. The mechanical properties of the OPS geopolymer concrete (OPSGC) through the use of POFA, FA, and OPS are investigated and reported. A total of ten OPSGC mixtures were prepared with varying percentages of POFA and FA such as 0, 10, 20, 40, and 100%. The specimens prepared with two alkaline solution to binder (AK/B) ratios of 0.35 and 0.55 were oven cured at 65°C for 48 hours. The experimental results showed that the highest compressive strength of 30 MPa was obtained for the mix with 20% replacement of FA by POFA and AK/B ratio of 0.55, which underwent oven curing. Further, the mix of up to 20% POFA (with AK/B ratio of 0.55) can be categorized as structural lightweight concrete. An increase of the POFA content beyond 20% decreases the mechanical properties, and hence this mix is recommended to be used.

Oil and Gas Energy Potential at Malaysian Seabed and Spar Platform for Deepwater Installation

Offshore sedimentary basins of Malaysian region indicate abundant sources of energy at its seabed. Furthermore, depletion of oil and gas reserves in its onshore land and shallow water depth has accelerated the exploration toward these deeper waters. Frequent increasing demand requires precise investigation to acquire these energies in optimum custom. A competent exploration structure is also desired for energy extraction from the deep water. In this study, oil and gas status in Malaysian scenario is reconnoitered. As the sea wave influences greatly on offshore structures, approaches for collecting wave data are sightseen. The structural configuration and characteristics of compliant floating spar platform for energy extraction are addressed. The study reveals that the continental shelf offshore of Malaysian waters is divided into seven sedimentary basins, among which three basins have major ongoing oil and gas extraction activity. Around 68% oil and 86% natural gas of the countrys reserves are located in East Malaysia at offshore Sabah and Sarawak. Except the Kebabangan field, all the other offshore energy reserves are located at more than 1000 m depth. In lieu of a fixed platform, a floating platform will be a competent energy extraction structure in this deeper water. The deep water wave data can be appropriately obtained in satellite altimetry approach for its extent of accuracy. The first installed spar at Kikeh field denotes bright possibilities of incorporating spar platform in Malaysian sedimentary basins. If spar platforms are installed at these deeper vicinities, all the basins will certainly climb in optimum operation yielding a huge usable energy.

A Review on the Use of Agriculture Waste Material as Lightweight Aggregate for Reinforced Concrete Structural Members

The agriculture industry is one of the main industries in the Southeast Asia region due to its favourable conditions for plantations. In fact, Southeast Asia region is the world’s largest producer of palm oil and coconut. Nevertheless, vast plantation of these agriculture products leads to equally large amount of waste materials emanating from these industries. Previously, researchers have attempted to utilize the resulting waste materials such as oil palm shell, palm oil clinker, and coconut shell from these industries as lightweight aggregate to produce structural grade lightweight aggregate concrete. In order to promote the concept of using such concrete for actual structural applications, this paper reviews the use of such agriculture-based lightweight aggregate concrete in reinforced concrete structural members such as beam and slab, which were carried out by researchers in the past. The behaviour of the structural members under flexural, shear, and torsional load was also summarized. It is hoped that the knowledge attained from the paper will provide design engineers with better idea and proper application of design criteria for structural members using such agriculture waste as lightweight aggregate.