Hilmi Mahmud | University of Malaya, Malaysia (original) (raw)

Papers by Hilmi Mahmud

Electronic Journal of Structural Engineering

This study focuses on the possibility of using rice husk ash (RHA) to produce high performance mo... more This study focuses on the possibility of using rice husk ash (RHA) to produce high performance mortar of 100 MPa. The variables of study include effect of grinding and level of cement replacement with RHA. The fine aggregate used was mining sand instead of silica sand which is frequently used in producing high performance concrete (HPC). The average particle size of the RHA used was 13.50 μm, 20.43 μm and 29.92 μm and level of cement replacement was at 0%, 10 %, 15 % and 20 %. The results show that the use of 10 % RHA with the average particle size of 20.43 μm gave better compressive strength from 3 days onwards compared to control OPC and silica fume and the use of 20% of RHA with the average particle size of 13.50 μm at 28 days gave better compressive strength compared to other concrete.

Renovation explicit dynamic procedures by application

The merits of high-strength high performance concrete (HSHPC) depend on the quality of constituen... more 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 for concretes. The addition of high-range water reducer and air-entraining admixtures are also inevitable to achieve good workability and freeze-thaw durability, respectively. This paper discusses various aspects of the major component materials of HSHPC. It briefly describes the property requirements of the component materials and emphasizes their contents or dosages needed for good performance. This paper also delineates the key roles of the constituent materials on the fresh and hardened properties, and durability of HSHPC.

The high demand of high strength high performance concrete (HSHPC) in concrete industries attract... more The high demand of high strength high performance concrete (HSHPC) in concrete industries attracts researchers to be more focused on improving the performance characteristics of HSHPC: workability, mechanical properties and durability. Applying high strength concrete, one of the performance characteristics, is beneficial for high rise buildings to increase the space of occupation and save the cost of maintenance in the long term. There is a need to study on HSHPC incorporating rice husk ash (RHA) due to limited information on utilizing RHA in HSHPC with low w/b. The binder and w/b adopted in this study were 550 kg/m and 0.25, respectively. The results reported included fresh, hardened and durability properties of high performance 100 MPa concrete incorporating 0%, 10%, 15% and 20% RHA as well as 10% condensed silica fume (CSF). The results revealed that the compressive, flexure and tensile strengths, and modulus of elasticity of concrete incorporating 10 % RHA are better than that o...

IOP Conference Series: Materials Science and Engineering, 2019

Academic Journals, Mar 1, 2011

International Journal of the Physical Sciences, 2011

Materials & Design, 2014

ABSTRACT The aim of this study is to investigate the role of 0–2 mm fine aggregate on the compres... more ABSTRACT 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 keep the same slump value for all mixes, additional water or superplasticizer were used in the RCA concretes. The compressive and splitting tensile strengths were measured at 3, 7 and 28 days. Test results show that coarse and fine RCAs, which were achieved from a parent concrete with 30 MPa compressive strength, have about 11.5 and 3.5 times higher water absorption than normal coarse and fine aggregates, respectively. The density of RCAs was about 20% less than normal aggregates, and, hence, the density of RCA concrete was about 8–13.5% less than normal aggregate concrete. The use of RCA instead of normal aggregates reduced the compressive and splitting tensile strengths in both normal and high strength concrete. The reduction in the splitting tensile strength was more pronounced than for the compressive strength. However, both strengths could be improved by incorporating silica fume and/or normal fine aggregates of 0–2 mm size in the RCA concrete mixture. The positive effect of the contribution of normal sand of 0–2 mm in RCA concrete is more pronounced in the compressive strength of a normal strength concrete and in the splitting tensile strength of high strength concrete. In addition, some equation predictions of the splitting tensile strength from compressive strength are recommended for both normal and RCA concretes.

2010 2nd International Conference on Chemical, Biological and Environmental Engineering, 2010

Grouted Macadam composite pavement (GMCP) is generally a composite pavement which is manufactured... more 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

"It is a well known fact that hydraulic structures located in tropical climates are generall... more "It is a well known fact that hydraulic structures located in tropical climates are generally exposed to harsh environments which are detrimental to the service life of steel and concrete. Apart from the ability to cope with physical, thermal and chemical attack originating from the effluent source, hydraulic structures located in tropical environments should be durable enough to withstand adverse conditions such as high temperatures, humidity, cyclic wetting and drying and intense solar radiation. This paper highlights a review of some deterioration mechanisms threatening hydraulic structures in tropical environments, inspection and testing of deteriorated structures including rehabilitation strategies. In addition to these a case study highlighting the rehabilitation of irrigation control structures in Malaysia has also been included. © 2006 Taylor & Francis Group, London. http://www.scopus.com/inward/record.url?eid=2-s2.0-84857479915&partnerID=40&md5=96b605c85eb842bba63670629d1ac8f7 "

Materials and Structures, 2015

DESCRIPTION

Electronic Journal of Structural Engineering

This study focuses on the possibility of using rice husk ash (RHA) to produce high performance mo... more This study focuses on the possibility of using rice husk ash (RHA) to produce high performance mortar of 100 MPa. The variables of study include effect of grinding and level of cement replacement with RHA. The fine aggregate used was mining sand instead of silica sand which is frequently used in producing high performance concrete (HPC). The average particle size of the RHA used was 13.50 μm, 20.43 μm and 29.92 μm and level of cement replacement was at 0%, 10 %, 15 % and 20 %. The results show that the use of 10 % RHA with the average particle size of 20.43 μm gave better compressive strength from 3 days onwards compared to control OPC and silica fume and the use of 20% of RHA with the average particle size of 13.50 μm at 28 days gave better compressive strength compared to other concrete.

Renovation explicit dynamic procedures by application

The merits of high-strength high performance concrete (HSHPC) depend on the quality of constituen... more 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 for concretes. The addition of high-range water reducer and air-entraining admixtures are also inevitable to achieve good workability and freeze-thaw durability, respectively. This paper discusses various aspects of the major component materials of HSHPC. It briefly describes the property requirements of the component materials and emphasizes their contents or dosages needed for good performance. This paper also delineates the key roles of the constituent materials on the fresh and hardened properties, and durability of HSHPC.

The high demand of high strength high performance concrete (HSHPC) in concrete industries attract... more The high demand of high strength high performance concrete (HSHPC) in concrete industries attracts researchers to be more focused on improving the performance characteristics of HSHPC: workability, mechanical properties and durability. Applying high strength concrete, one of the performance characteristics, is beneficial for high rise buildings to increase the space of occupation and save the cost of maintenance in the long term. There is a need to study on HSHPC incorporating rice husk ash (RHA) due to limited information on utilizing RHA in HSHPC with low w/b. The binder and w/b adopted in this study were 550 kg/m and 0.25, respectively. The results reported included fresh, hardened and durability properties of high performance 100 MPa concrete incorporating 0%, 10%, 15% and 20% RHA as well as 10% condensed silica fume (CSF). The results revealed that the compressive, flexure and tensile strengths, and modulus of elasticity of concrete incorporating 10 % RHA are better than that o...

IOP Conference Series: Materials Science and Engineering, 2019

Academic Journals, Mar 1, 2011

International Journal of the Physical Sciences, 2011

Materials & Design, 2014

ABSTRACT The aim of this study is to investigate the role of 0–2 mm fine aggregate on the compres... more ABSTRACT 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 keep the same slump value for all mixes, additional water or superplasticizer were used in the RCA concretes. The compressive and splitting tensile strengths were measured at 3, 7 and 28 days. Test results show that coarse and fine RCAs, which were achieved from a parent concrete with 30 MPa compressive strength, have about 11.5 and 3.5 times higher water absorption than normal coarse and fine aggregates, respectively. The density of RCAs was about 20% less than normal aggregates, and, hence, the density of RCA concrete was about 8–13.5% less than normal aggregate concrete. The use of RCA instead of normal aggregates reduced the compressive and splitting tensile strengths in both normal and high strength concrete. The reduction in the splitting tensile strength was more pronounced than for the compressive strength. However, both strengths could be improved by incorporating silica fume and/or normal fine aggregates of 0–2 mm size in the RCA concrete mixture. The positive effect of the contribution of normal sand of 0–2 mm in RCA concrete is more pronounced in the compressive strength of a normal strength concrete and in the splitting tensile strength of high strength concrete. In addition, some equation predictions of the splitting tensile strength from compressive strength are recommended for both normal and RCA concretes.

2010 2nd International Conference on Chemical, Biological and Environmental Engineering, 2010

Grouted Macadam composite pavement (GMCP) is generally a composite pavement which is manufactured... more 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

"It is a well known fact that hydraulic structures located in tropical climates are generall... more "It is a well known fact that hydraulic structures located in tropical climates are generally exposed to harsh environments which are detrimental to the service life of steel and concrete. Apart from the ability to cope with physical, thermal and chemical attack originating from the effluent source, hydraulic structures located in tropical environments should be durable enough to withstand adverse conditions such as high temperatures, humidity, cyclic wetting and drying and intense solar radiation. This paper highlights a review of some deterioration mechanisms threatening hydraulic structures in tropical environments, inspection and testing of deteriorated structures including rehabilitation strategies. In addition to these a case study highlighting the rehabilitation of irrigation control structures in Malaysia has also been included. © 2006 Taylor & Francis Group, London. http://www.scopus.com/inward/record.url?eid=2-s2.0-84857479915&partnerID=40&md5=96b605c85eb842bba63670629d1ac8f7 "

Materials and Structures, 2015

DESCRIPTION