Hilmi Mahmud

• University of Malaya

This research focuses on achieving early strength of cement-based materials through the hybrid nucleation acceleration method. Through the study of various mortar mixtures, which incorporate components such as ordinary Portland cement (OPC), fine limestone powder (with a particle size of d50: 1 μm), coarse limestone powder (with a particle size of...

This review aims to provide an insight into concrete pavement repair materials by gathering the relevant research outcomes and specifications. It provides a systematic literature review that focuses on pavement repair and types of cementitious repair material. In general, conventional cementitious repair materials can be divided into 4 categories:...

Nowadays, more infrastructure projects require concrete to have a high durability in addition to high strength. High strength high performance concrete (HSHPC) was developed to solve those problems. The weaknesses of HSHPC are high cost of constituent material such as silica fume which is mostly used as supplementary cementitious material (SCM), hi...

Solidification and stabilization of coal bottom ash waste (CBA) using CEM1 as the binder have been evaluated in case of leaching as well as the possibility to use this mixture for the construction industry. For this, the CEM1/CBA mass ratio has been varied between 0.5 and 2 and heavy metals leaching of Cu, Cd, Ni and Pb evaluated. Two types of crus...

Solidification and stabilization of coal bottom ash waste (CBA) using CEM1 as the binder have been evaluated in case of leaching as well as the possibility to use this mixture for the construction industry. For this, the CEM1/CBA mass ratio has been varied between 0.5 and 2 and heavy metals leaching of Cu, Cd, Ni and Pb evaluated. Two types of crus...

The aim of the present study is to investigate the effects of utilizing different processings of normal rice husk ash (RHA) and black rice husk ash (BRHA) on the mechanical and durability properties of high-strength concrete (HSC). Mechanical and durability properties of HSC were evaluated on concrete mixes containing unground BRHA and RHA and grou...

Lightweight concrete offers numerous benefits compared to normal weight concrete such as reduction in dead load and construction costs. One of the most common methods of producing structural lightweight concrete is the use of lightweight aggregates. The application of waste substances as cement substitutes or aggregates in concrete can support a so...

This study compares the engineering properties of normal weight concrete with those of concrete with two types of lightweight aggregates, namely, oil-palm-boiler-clinker (OPBC) concrete and lightweight expanded clay aggregate (LECA) concrete. OPBC is a porous solid waste from the palm oil industry, while LECA is an artificial and impenetrable mater...

Coal Bottom Ash (CBA) is one of the widely-produced residues of coal incineration in thermal power plants. The annual extraction of such a huge amount of waste needs a massive transfer field, which constitutes a threat to the environment. However, the utilization of such residue as a fine aggregate in concrete can be an environmentally-friendly opp...

Oil-palm-boiler clinker (OPBC) is an agricultural solid waste sourced from the palm oil industry in tropical regions. This study investigates the use of OPBC as coarse aggregate instead of conventional coarse aggregates to produce a greener concrete, which will help in implementing sustainable construction practices by reducing the usage of raw mat...

Lightweight concrete (LAWC) has numerous advantages over normal weight concrete (NWC), such as less dead load and construction costs. Using lightweight aggregates (LWA) is one of the most typical methods of fabricating structural LWAC. This paper studies the possibility of LAWC production by agricultural solid waste, specifically oil palm shell (OP...

Oil-palm-boiler clinker (OPBC) is an agricultural solid waste from the incineration process of solid wastes in palm oil industry. The OPBC that is highly porous and lightweight in nature is suitable to be used as a lightweight aggregate. This paper presents a method to produce high-strength lightweight aggregate concrete using OPBC. The workability...

Lightweight concrete offers numerous benefits compared to normal weight concrete such as reduction in dead load and construction costs. One of the most common methods of producing structural lightweight concrete is the use of lightweight aggregates. The application of waste substances as cement substitutes or aggregates in concrete can support a so...

High strength lightweight aggregate concrete (HSLAC) provides many advantages to construction industry, especially in the reduction of structure’s dead load. Incorporating waste materials in HSLAC promotes to implement sustainable practice, minimize the negative impact to environment and reduce the cost of product. Oil-Palm-Boiler Clinker (OPBC) is...

Concrete industry is one of the major sources of consuming high volume of natural resources. On the other hand, cement industry is a significant point source of carbon dioxide emissions due to the decomposition of raw material and burning fuel during the manufacturing process. As the demand for concrete is growing, one of the effective way to minim...

The aim of this study was to produce a sustainable construction material by incorporating an agricultural solid waste, namely oil palm shell (OPS), in an artificial lightweight aggregate concrete. For this purpose, in a structural lightweight aggregate concrete made of expanded clay, the lightweight aggregate was substituted with OPS in 0, 25 and 5...

This research aims to utilize Coal Furnace Bottom ash (CBA) and Oil-Palm Boiler Clinker (OPBC) as fine aggregate in concrete mix proportions. They are solid wastes from power plant and Oil Palm industry, respectively. Since these by-products do not have any primary use and are pure waste, an opportunity to use them as aggregate in concrete industry...

Green roofs are an increasingly important component of water-sensitive urban design systems that can potentially improve the quality of urban runoff, reduce the energy consumption of buildings, and add esthetic value to the environment. The most important green roof abilities, which appear as a key feature in urban catchments are the ability of rai...

This paper presents the effects of low volume fraction of polyvinyl alcohol (PVA) fibers on the mechanical properties of oil palm shell (OPS) high strength lightweight concrete mixtures. The slump, density, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity under various curing conditions have been measur...

In this study, the effects of a new type of non-metallic fiber (polypropylene twisted bundle (PPTB)) on the slump and mechanical properties of oil palm shell (OPS) concrete have been investigated. The results showed that increasing the volume fraction of PPTB fibers, it slightly decreases the workability and density of the concrete. It has found th...

The aim of this study is to investigate the role of 0–2 mm fine aggregate on the compressive and splitting tensile strengths of recycled concrete aggregate (RCA) concrete with normal and high strengths. Normal coarse and fine aggregates were substituted with the same grading of RCAs in two normal and high strength concrete mixtures. In addition, to...

This research has been conducted to investigate the compressive strength of Flemish bond spent copper slag masonry wall. The spent copper slag was taken from a shipyard and repair company in Pasir Gudang, Johor, Malaysia. In total three (3) sets of brick wall were built based on different percentage of spent copper slag replacement in bricks. The f...

Semi-flexible pavement surfacing is a composite pavement that utilizes the porous pavement structure of the flexible bituminous pavement, which is grouted with an appropriate cementitious material. The main objective of this study is to investigate the mechanical properties of cement-bitumen composites as an alternative semi-flexible pavement surfa...

For making artificial lightweight aggregate, selected raw materials are fed into a rotary kiln at high temperature. Providing such a high temperature is costly and generally, the process of making artificial lightweight aggregate is not environmentally friendly. The use of natural lightweight aggregate for making lightweight concrete can lead to lo...

Petroleum sludge was solidified in ordinary Portland cement, and the leachability test was performed based on American Nuclear Society 16.1 to produce leachate. The organic in solidified sludge was extracted by micro solid extraction to determine the organic in the sample. Organic in the leachate sample was detected by solid phase micro extraction...

The objective of this study was to investigate the effects of different species of oil palm shell (OPS) coarse aggregates on the properties of high strength lightweight concrete (HSLWC). Original and crushed OPS coarse aggregates of different species and age categories were investigated in this study. The research focused on two OPS species (dura a...

The use of steel fibers is a good solution for compensating lower mechanical properties of lightweight concrete. However, due to the high specific gravity, the addition of steel fiber increases the density of lightweight concrete. Therefore, there is some reluctance regarding the use of this fiber in lightweight concrete. In this study, to prevent...

Concrete is the most widely used construction material. With the ever-increasing industrialization and urbanization, huge amounts of natural resources are required to make concrete. This, in turn, means that large volumes of natural resources and raw materials are being used for concrete production around the world. To eliminate or minimize the neg...

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 degrees C) and duration of heat treatment (0.5 and 1 h). The reduction in density is found to be within the...

This paper reported on an experimental program to research the effect of using blasted copper slag from shipyard repair and maintenance as replacement of fine aggregates in the sand-cement brick. 20 cubes of cement sand brick mixtures were produced with different blasted copper slag ratio ranging from 0% (for the control mixture) to 60%. All the sa...

Semiflexible pavement (SFP), a composite pavement, is formed by filling into a very open porous asphalt skeleton a specifically designed water consistency fluid mortar with a very high early and 28-day strength. The amalgamation of both components will produce a SFP where it will replace the conventional wearing course. The main goal of this invest...

Semi-flexible pavement surfacing is a composite pavement that utilizes the porous pavement structure of the flexible bituminous pavement, which is subsequently grouted with appropriate cementitious materials. This study aims to investigate the compressive strength, flexural strength, and workability performance of cementitious grout. The grout mixt...

The use of waste and by-product materials as aggregate or cement replacement in concrete can provide a solution to reducing the negative impact of the concrete industry. This paper reports an investigation to produce green concrete by using oil palm shell (OPS) as coarse lightweight aggregate as well as ground granulated blast furnace slag (GGBFS)...

Toxicity characteristic leaching procedure was executed on solidified petroleum sludge to investigate the metal ions release in leaching medium extractant fluid number 2, U.S.EPA SW-846 TCLP. Nine metal ions from solidified sludge in ordinary Portland cement were evaluated at water to cement ratio of 0.4 to 0.5 and incorporation of 5-15% cement rep...

The effect of cement replacement materials on hydration of solidified waste in ordinary Portland cement has been investigated based on initial setting time. Five cement replacement materials namely, rice husk ash, condensed silica fume, activated carbon, fly ash and meta kaolin were selected for solidified organic waste in the cement. The initial s...

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. T...

With the ever-increasing industrialization and urbanization, huge amounts of natural resources are required to make concrete. Green concrete can provide a solution to reducing the negative impact of the concrete industry. This paper presents the results of experiments conducted to produce green structural lightweight concrete by using oil palm shel...

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 re...

Oil palm shell (OPS) is a waste from the agricultural sector and is available in large quantities in the tropical regions. This paper investigates the effect of the replacement of normal weight coarse aggregate by oil palm shells on the compressive strength, density, modulus of elasticity, workability and water absorption. The gradation of substitu...

Crushed large oil palm shell (OPS) was used as a coarse aggregate in four different concrete mixtures. The stress-strain behavior and modulus of elasticity of OPS concrete were investigated and compared to granite normal weight concrete (NWC) and expanded clay lightweight concrete (LWC). The stress-strain curve of the OPS concrete showed that this...

Oil palm shell (OPS) is a waste lightweight aggregate originating from the palm oil industry, which is approximately 50% lighter than conventional aggregate. In this study, crushed old OPS was used as coarse aggregate. Compressive strength under different curing conditions and the splitting tensile and flexural strengths were compared with those of...

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 st...

The aim of this study was to compare the efficacy of three ASTM saturation techniques for measuring the water absorption of concrete. The water absorption of two ordinary concretes was determined based on the cold water, boiling water and vacuum saturation techniques. The concretes were produced with water to cement (w/c) ratios of 0.50 and 0.60 an...

This paper reports the results of a study conducted to investigate the effect of low volume content of steel fiber on the slump, density, compressive strength under different curing conditions, splitting tensile strength, flexural strength and modulus of elasticity of a grade 35 oil palm shell (OPS) lightweight concrete mixture. The results indicat...

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 60MPa and 70MPa at 2...

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/m3 was found 24% higher than the corresponding normal weight concrete (NWC). Good aggregate interlock in PKSC was evident as it produced...

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 compres...

In Malaysia, oil palm shell (OPS) is an agricultural solid waste originating from the palm oil industry. In this investigation old OPS was used for production of high strength lightweight concrete (HSLC). The density, air content, workability, cube compressive strength and water absorption were measured. The effect of five types of curing condition...

The assessment of magnesium sulphate attack on concretes containing rice husk ash (RHA, 20wt% of the cementitious materials) with various average particle sizes was investigated. The total cementitious materials were 390 kg and the water-to-binder ratio (W/B) was 0.53 for all mixtures. Specimens were initially cured in water for 7 d and then immers...

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 i...

Abstract-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 conduc...

The environmental impact from the concrete construction industry is quite alarming. The industry is embarking into improving the concrete performance and exploring into alternative materials to reduce such impact. An area which is lacking is improvement in the quality of concrete practice itself. By having good concrete practice, a good quality con...

Rice husk which is an agricultural waste, constitutes about one-fifth of the 500 million tonnes of rice produced annually worldwide. Normally, the residue is disposed off by burning at the mill sites and the resultant rice husk ash (RHA) is dumped on a waste land. This generates environmental, pollution and land dereliction problems. Under controll...

Grouted Macadam composite pavement (GMCP) is generally a composite pavement which is manufactured by preparing a highly workable fluid mortar which is specially designed with a very high early and 28 day strength (1 day - 45 MPa, 28 day - 105 MPa) by filling the flowing fluid mortar into a very open porous asphalt skeleton (25-32% Voids in Mix - VI...

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 cem...

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, miner...

This paper investigates the properties of rice husk ash (RHA) produced by using a ferro-cement furnace. The effect of grinding on the particle size and the surface area was first investigated, then the XRD analysis was conducted to verify the presence of amorphous silica in the ash. Furthermore, the effect of RHA average particle size and percentag...

Portland cement and rice husk ash were incorporated to stabilize and solidify the contaminant in petroleum sludge. Stabilization and solidification technique was chosen as an alternative treatment to reduce toxicity of the sludge prior to final disposal of the waste. The sludge has significant amount of organic material which normally interfere wit...

An experimental investigation was carried out to improve the mechanical properties of Palm Kernel Shell Concrete (PKSC) by varying sand content and incorporating mineral admixtures, to achieve strength of 35 MPa. The mineral admixtures included 10% silica fume as additional cementitious material and 5% class F fly ash as cement replacement material...

Four reinforced oil palm shell foamed concrete (OPSFC) beams were fabricated, and their shear behaviour was tested. The OPSFC has a target density of approximately 1600 kg/m(3) and a 28-day compressive strength of about 20 MPa. Two beams were cast with shear reinforcements while the other two were cast without such reinforcements. For comparison, f...

The merits of high-strength high performance concrete (HSHPC) depend on the quality of constituent materials. The constituent materials play the vital roles to improve the performance of HSHPC. In particular, the use of supplementary cementing materials is essential when high strength and durability become the most critical issues to be considered...

This paper reports an investigation on the strength properties, a time dependent property as well as durability characteristics of normal and water reduced high strength concrete (WRHSC), with or without rice husk ash (RHA), designed to produce Grade 60 at 28 days. RHA was 'added' or 'replaced' at/by 5% - 20% of the cement content. A PCE superplast...

This study reports the effect of cementitious materials, fine and coarse aggregates content on workability and compressive strength of palm kernel shell concrete. Palm kernel shells a by product of the production of palm oil, were used as lightweight aggregates. The following cementitious materials were added: 10% silica fume as additional cementit...

This paper presents the results on the structural behavior of palm kernel shell concrete and its comparison with normal weight concrete (NWC). The structural grade palm kernel shell concrete, a lightweight concrete (LWC) produced using palm kernel shell (PKS) an agricultural waste and by-product of the production of palm oil as lightweight aggregat...

Design of concrete mixtures is the process of selecting the most economical and practical proportions of all the ingredients to produce quality concrete. Because of the nature of the mix design process and all the heuristic knowledge that is associated with it, concrete mix design lends itself well to a knowledge-based application. This paper descr...

Semi-flexible pavement is a composite pavement that utilizes the porous pavement structure of the flexible bituminous pavement which is subsequently grouted with an appropriate cementitious material. The main purpose of this research is to investigate the influence of superplasticizer type and dosage on the flowability of cementitious grouts. The g...

This article gives an overview on the recent developments in the area of fibre reinforced concrete (FRC) and high performance fibre reinforced cementitious composites (HPFRCC). It is divided into two main sections. The first section focuses on the definition, fibre classification and applications of FRC, whereas the next section discusses the conce...

In this study, the strength development and lechability aspects of metal-contaminated soil treated with ordinary portland cement (OPC) were investigated. The soil was collected from a scrap metal yard within the outskirts of Kuala Lumpur, Malaysia. Metal composition analysis indicated that the predominant metals present in the soil were iron (42,19...

This paper presents the findings of a study on solidification/stabilization (S/S) of lead-contaminated soil using ordinary Portland cement (OPC) and rice husk ash (RHA). The effects of varying lead concentrations (in the form of nitrates) in soil samples on the physical properties of their stabilized forms, namely unconfined compressive strength (U...

The reduction in the sources of natural sand and the requirement for reduction in the cost of concrete production has resulted in the increased need to identify substitute material to sand as fine aggregates in the production of concretes. Quarry dust, a by-product from the crushing process during quarrying activities is one of the materials being...

This paper reports the experimental study undertaken to investigate the influence of partial replacement of sand with quarry dust, and cement with fly ash on the concrete compressive strength development. Two types of replacement proportion of sand with quarry dust, 20 % and 40 % were practiced in the concrete mixes except in the control concrete m...

Splitting tensile strength (STS) is one of the concrete mechanical properties that are used in structural design. It can be related to numerous parameters, which include compressive strength, water/binder (W/B) ratio and concrete age. Until now, most researchers estimated the STS directly from compressive strength data. This paper suggests formulae...

Silica fume and fly ash are used to replace 10% of cement by weight. They are used either separately or in combination with quarry dust in the concrete mixes. Quarry dust is incorporated to replace 20% and 40% of sand in the respective mixes. Superplasticizer and air entraining admixture are used as chemical admixtures to control the flowability of...

The aim of this study was to investigate the possibility of developing high performance concrete (HPC) using silica fume (SF) at relatively high water–binder ratios. For this purpose, water–binder ratios of 0.45 and 0.50 were considered. Test specimens were air and water cured and exposed to a medium temperature range of 20°C to 50°C. The compressi...

The strength properties of hybrid nylon-steel fibre-reinforced concrete were investigated in comparison to that of polypropylene-steel fibre-reinforced concrete, at the same volume fraction (0.5%). The content of the high performance macro structure steel fibres is at 0.4% volume fraction, and the content of micro nylon and polypropylene-fibres is...