Hilmi Bin Mahmud

Study on Properties of Rice Husk Ash and Its Use as Cement Replacement Material

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 percentage on concrete workability, fresh density, superplasticizer (SP) content and the compressive strength were also investigated. Although grinding RHA would reduce its average particle size (APS), it was not the main factor controlling the surface area and it is thus resulted from RHAs multilayered, angular and microporous surface. Incorporation of RHA in concrete increased water demand. RHA concrete gave excellent improvement in strength for 10% replacement (30.8% increment compared to the control mix), and up to 20% of cement could be valuably replaced with RHA without adversely affecting the strength. Increasing RHA fineness enhanced the strength of blended concrete compared to coarser RHA and control OPC mixtures.

Prediction of splitting tensile strength of high-performance concrete

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 that relate STS with that of compressive strength, W/B ratio and concrete age. The predicted STS can be obtained accurately using these formulae. It is proposed that the equation with the concrete age (t) parameter be used in predicting the STS of high-performance concrete (HPC).

Development of high performance concrete using silica fume at relatively high water-binder ratios

Abstract 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 compressive strength, modulus of elasticity and initial surface absorption (ISA) of hardened concrete were determined in the laboratory. Test results indicated that concrete under water curing offers the best results. The highest level of compressive strength and modulus of elasticity and the lowest level of ISA were produced by SF concrete under water curing and at temperature of 35°C. Data collected also revealed that, under controlled curing conditions, it is possible to produce HPC at relatively high water–binder ratios.

Effects of oil palm shell coarse aggregate species on high strength lightweight concrete.

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 and tenera), in which the coarse aggregates were taken from oil palm trees of the following age categories (3–5, 6–9, and 10–15 years old). The results showed that the workability and dry density of the oil palm shell concrete (OPSC) increase with an increase in age category of OPS species. The compressive strength of specimen CD3 increases significantly compared to specimen CT3 by 21.8%. The maximum achievable 28-day and 90-day compressive strength is 54 and 56 MPa, respectively, which is within the range for 10–15-year-old crushed dura OPS. The water absorption was determined to be within the range for good concrete for the different species of OPSC. In addition, the ultrasonic pulse velocity (UPV) results showed that the OPS HSLWC attain good condition at the age of 3 days.

Development of lightweight concrete using industrial waste material, palm kernel shell as lightweight aggregate and its properties

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/m3. 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 properties of normal weight concrete (NWC) of grade 30 produced using crushed granite aggregates. The fresh and hardened concrete properties such as density, workability, compressive strength of PKSC and NWC were compared. Further, structural behavior through flexural test was investigated. It has been found that PKSC has produced workable concrete and compressive strength of about 35MPa was obtained within 90 days. The addition of 10% silica fume has effect on both workability and strength. The as-cured density of PKSC was found 22% lower than the NWC. Further, the moment capacity of PKSC beams was found higher than NWC beams. In addition, the mode of failure observed in PKSC was ductile compared to the brittle failure of NWC beams.

Immobilization of Petroleum Sludge Incorporating Portland Cement and Rice Husk Ash

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 with the cement hydration process. A way to improve is by incorporation of cement replacement material. Mixture proportioning was conducted to find optimum water to cement ratio, sludge to cement ratio and cement replacement percentage. The solidified sludge performance was measured by compressive strength and permeable porosity. The optimum ratio of water to cement was found at 0.45 and cement to sludge of 8. Rice husk ash (RHA) was added at 5, 10 and 15 % cement replacement. 5 % RHA exhibited the best performance with regards to unconfined compressive of 24.9 N/mm 2 . The strength was better than the sludge cement of 19.2 N/mm 2 . Permeable porosity has inverse relationship with strength at water to cement ratio of 0.4. However at water to cement ratio of 0.45, the relationship showed different trend where increase in porosity cause increase in strength. Porosity was found to increase with increasing RHA content. The surface morphology of solidified cement with voids was found to be in the range of 10 to 15 μm for 15 % RHA.

Effects of using silica fume and polycarboxylate-type superplasticizer on physical properties of cementitious grout mixtures for semiflexible pavement surfacing

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 mixtures are designed to achieve high strength and maintain flow properties in order to allow the cement slurries to infiltrate easily through unfilled compacted skeletons. A paired-sample t-test was carried out to find out whether water/cement ratio, SP percentages, and use of silica fume influence the cementitious grout performance. The findings showed that the replacement of 5% silica fume with an adequate amount of superplasticizer and water/cement ratio was beneficial in improving the properties of the cementitious grout.

Effects of Aggregate Gradation on the Physical Properties of Semiflexible Pavement

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 investigation is to study the effect of various aggregate gradations towards producing SFP. These include determining the optimum binder, volumetric properties, and durability and strength of each aggregate gradation. The final results were statistically analyzed and two factor variance analyses (ANOVA) were performed to check on the significance at certain confidence limits. The results confirmed that different aggregate gradations significantly affect the properties mentioned.

Strength, Durability and Shrinkage of High-Strength Rice Husk Ash Concrete

This paper reports on an investigation on strength, durability and shrinkage of high strength rice husk ash concrete (HSRHAC) with w/b ratio of 0.27. Rice husk ash (RHA) was incorporated either as 10% ‘addition’ or 10% ‘replacement’ of cement. Specimens were subjected to water curing or air-drying and tested up to 180 days. For comparison purposes, concrete containing 10% condensed silica fume (CSF) and concrete containing superplasticizer alone (SpOPC) were also cast. Results shows that with the aid of a polycarboxylic hyperplasticizer, high workability RHA concrete mixtures in the range of 200-250 mm slump ad having 28 days strengths of 80 MPa can be routinely produced. In general, strengths of RHA concrete are higher than the control superplasticized concrete but marginally lower than CSF. Durability of concrete with regards to initial surface absorption (ISA) shows that RHA concrete exhibit similar ISA values compared to CSF concrete. After 3 cycles of wetting in magnesium sulphate solution for 30 days followed by 7 days air-drying, RHA concrete produced similar expansion compared to the CSF concrete but lower expansion than the SpOPC concrete. At 180 days, shrinkage of HSRHAC is similar to that of CSF. Based on the current study, it can be concluded that RHA is just as good as CSF in producing high strength concrete of Grade 80. Since RHA can be produced at a much lower cost than CSF, it is an attractive alternative material in the production of HSC.

Effects of Low Volume Fraction of Polyvinyl Alcohol Fibers on the Mechanical Properties of Oil Palm Shell Lightweight Concrete

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 measured and evaluated. The results indicate that an increase in PVA fibers decreases the workability of the concrete and decreases the density slightly. The 28-day compressive strength of oil palm shell fiber-reinforced concrete (OPSFRC) high strength lightweight concrete (HSLWC) subject to continuous moist curing was within the range of 43–49 MPa. The average modulus of elasticity () value is found to be 16.1 GPa for all mixes, which is higher than that reported in previous studies and is within the range of normal weight concrete. Hence, the findings of this study revealed that the PVA fibers can be used as an alternative material to enhance the properties of OPS HSLWC for building and construction applications.