Hashim Abdul Razak - Profile on Academia.edu (original) (raw)
Papers by Hashim Abdul Razak
Cement and Concrete Research, 2005
The concept of efficiency can be used for comparing the relative performance of various pozzolans... more The concept of efficiency can be used for comparing the relative performance of various pozzolans when incorporated into concrete. In this paper, an alternative approach for the evaluation of efficiency factor k of a pozzolanic material has been introduced. The method, developed following Abram's strength-W/C ratio rule, calculates efficiency in terms of relative strength and cementitious materials content. The advantage of this method is that only two mixtures are required to determine the k factor of a specific mixture. A laboratory investigation on silica fume (SF) and metakaolin (MK) concrete found that the computed efficiency factors varied with pozzolan type, replacement level and age. At 28 days, the k values ranged from 1.6 to 2.3 for MK and 2.1 to 3.1 for SF mixtures, while at 180 days, the k values varied from 1.8 to 4.0 for MK and 2.4 to 3.3 for SF mixtures. Generally, the k factors increased with age but declined with higher pozzolanic content. It was also observed that change in W/CM ratio from 0.33 to 0.27 did not significantly affect the resultant efficiency factors. © 2004 Elsevier Ltd. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S000888460400242X
http://ac.els-cdn.com/S000888460400242X/1-s2.0-S000888460400242X-main.pdf?_tid=bd7a69b8-7820-11e3-868e-00000aacb360&acdnat=1389156956_b3c258306027f97b5631be2a0618449f
Response Prediction of Offshore Floating Structure Using Artificial Neural Network
Advanced Science Letters, 2012
For deep-water oil and gas exploration, spar platform is considered to be the most economic and s... more For deep-water oil and gas exploration, spar platform is considered to be the most economic and suitable floating offshore structure. Analysis of spar platform is complex due to various nonlinearities such as geometric, variable submergence, varying pretention, etc. The Finite Element Method (FEM) is an important technique to deal with this type of analysis. However, FEM is computationally very expensive and highly time-consuming process. Artificial Neural Network (ANNs) can provide meaningful solutions and can process information in extremely rapid mode ensuring high accuracy of prediction. This paper presents dynamic response prediction of spar mooring line using ANN. FEM-based time domain response of spar platform such as surge, heave and pitch is trained by ANN. Mooring line top tension is predicted after 7200 sec (2 hours) of wave loading. The response obtained using ANN is validated by conventional FEM analysis. Results show that ANN approach is found to be very efficient and it significantly reduces the time for predicting long response time histories. Thus ANN approach is recommended for efficient designing of floating structures. © 2012 American Scientific Publishers. All rights reserved.
www.ingentaconnect.com/content/asp/asl/2012/00000014/00000001/art00033
http://www.ingentaconnect.com/content/asp/asl/2012/00000014/00000001/art00033?token=0055134ed587e2a46762c6b795d76766c25443a2b5f7b673f7b2f267738703375686f492388928b81ab5d
12th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC12, 2011
The effects of far distant earthquakes felt in regions with low and moderate seismicity has incre... more The effects of far distant earthquakes felt in regions with low and moderate seismicity has increased markedly over the last decade. Henceforth fragility curves in this study are to indicate whether buildings are safe to enter or not after an earthquake event occurring more than 300km away. The probability of light, moderate and severe damage states occurring on two and four storey reinforced concrete buildings up to a peak ground acceleration of 0.2g were predicted. The building models were constructed using finite element software based on eight node brick elements with three degrees of freedom at each node. The analysis was carried out using a dynamic response spectrum to calculate the peak inter-storey drift ratios. For the development of fragility curves, the results were collated following a log-normal mean distribution. The results showed that light damage is likely to occur with a probability of over 10% within a 50 year period, while the existing record is unlikely to cause structural damage. The fragility curves were comparable to those for RC moment resisting frames obtained by (Rossetto and Elnashai 2003) at a lower drift limit, with approximately 2% of inter-storey drift ratio.
http://www.sciencedirect.com/science/article/pii/S1877705811013531
Construction and Building Materials, Jan 1, 2011
This paper compares three methods for activation of OPC-slag mortars (OSM): (1) prolonged grindin... more This paper compares three methods for activation of OPC-slag mortars (OSM): (1) prolonged grinding of binders (mechanical method), (2) elevated temperature curing of mortars (thermal method), and (3) use of chemical activators such as NaOH, KOH, and Na2SiO3, 9.35H2O (chemical method). The proper reactivity of OSM was evaluated using a mixture of 50% OPC and 50% slag. Early and ultimate strengths were compared. All three activation methods accelerated both the slag reaction and strength development rates. However, the chemical method did not show a significant effect on the ultimate strength, while thermal activation increased the early strength by 3 days. Mechanical activation increased the early strengths of the mortar significantly, but about 6% strength loss occurred in the ultimate strength. Although, the application of mechanical and thermal activation methods needs extra equipment and energy, due to more significant of strength improvement; based on current test results, it can be said that mechanical activation is the most efficient and feasible method for the activation of OSMs. © 2010 Elsevier Ltd. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0950061810003090
http://ac.els-cdn.com/S0950061810003090/1-s2.0-S0950061810003090-main.pdf?_tid=1f70136c-7820-11e3-8df9-00000aacb362&acdnat=1389156691_598fed59ba988ef24a61b55479cb6ea7
Construction and Building Materials, Oct 1, 2010
Although the use of slag has many benefits, its low hydration at early stages causes the strength... more Although the use of slag has many benefits, its low hydration at early stages causes the strength to be low. Hence, the uses of slag are restricted, even before it needs to be activated. In this investigation, a chemical method was used to activate the ordinary Portland cement-slag mortars (OSM). 37 OSM were used, 4 of them as control. All mix designs were made by W/B = 0.33, S/B = 2.25, and with 0%, 30%, 40%, 50%, and 60% levels of slag. The activators; sodium hydroxide, potassium hydroxide, and sodium silicate have been used. Whenever the activators were used alone, the highest effect was obtained by sodium silicate and the lowest for sodium hydroxide. It was determined that the effects of the combined activators are better than that of an individual one. It was observed that strength loss for some mixes, at long ages, is determined by some factors, such as level of slag used, type and dosage of alkali activators, and curing regimes. © 2010 Elsevier Ltd. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0950061810001261
http://ac.els-cdn.com/S0950061810001261/1-s2.0-S0950061810001261-main.pdf?_tid=037aee7a-7820-11e3-91fd-00000aab0f26&acdnat=1389156644_0a6299272577efa3436bc0823103770b
Asian Journal of Civil Engineering, 2010
The use of high strength concrete (HSC) has been studied for many years in developed and developi... more The use of high strength concrete (HSC) has been studied for many years in developed and developing countries. Although, HSC has a few disadvantages, it has many advantages. The concrete with compressive strength (CS) levels in the range of 50 to100 MPa, is called HSC. The most important property of HSC is 28-day CS as a criterion. Sometimes due to time limitations and construction project problems, estimation of 28-day CS based on 7-day CS can be useful. Based on many experimental tests and analysis of the results, three sets of equations are determined with ANN and Regression techniques are compared and the best is recommended. © 2009 by DotNetNuke Corporation.
www.bhrc.ac.ir/portal/Portals/2/pdf/asian%20jornal/APRIL%202010/Sajedi-5.pdf
Arabian Journal for Science and Engineering, Oct 1, 2010
This paper reports the details of investigations carried out to study the performance of industri... more This paper reports the details of investigations carried out to study the performance of industrial waste incineration bottom ash and refined kaolin to produce controlled low-strength material (CLSM). CLSM mixes were designed with varying amounts of incineration bottom ash, refined kaolin, and cement. Water content was adjusted to get sufficient flowability. Tests for density, stiffening time, bleed, settlement, sorptivity, water absorption, moisture content, California bearing ratio, initial surface absorption, and compressive strength were carried out on the CLSM mixtures. Study for corrosivity and leaching of heavy metals and salts on the bleed and leachate were also performed. The compressive strength of CLSM tested ranged from 0.36 to 4.40 MPa. CBR values ranged from 10 to 46 and ISAT values at 1 hour from 0.56 to 4.76 ml/m2/s. None of the heavy metals tested exceeded the threshold limits in leachate. Addition of kaolin controls the compressive strength development, and reduces initial surface absorption, California bearing ratio, and water absorption values. It is shown that the incineration bottom ash, along with refined kaolin, can be successfully employed in CLSM, thereby contributing to sustainability in civil engineering practice.
ajse.kfupm.edu.sa/articles/352B%20p.05.pdf
Journal of Hazardous Materials, Dec 30, 2009
Controlled low-strength material (CLSM) is slurry made by mixing sand, cement, ash, and water. It... more Controlled low-strength material (CLSM) is slurry made by mixing sand, cement, ash, and water. It is primarily used as a replacement for soil and structural fillings. This paper presents the findings of a preliminary investigation carried out on the performance of industrial waste incineration bottom ash as CLSM. CLSM mixes were designed using industrial waste incineration bottom ash, and cement. Tests for density, setting time, bleed, and compressive strength on cubes under various curing conditions, corrosivity, and leaching of heavy metals and salts were carried out on the CLSM mixtures, and the results discussed. Compressive strength for the designed CLSM mixtures ranged from 0.1 to 1.7 MPa. It is shown that the variations in curing conditions have less influence on the compressive strength of CLSM at high values of water to cement ratio (w/c), but low values of w/c influences the strength of CLSM. The CLSM produced does not exhibit corrosive characters as evidenced by pH. Leaching of heavy metals and salts is higher in bleed than in leachate collected from hardened CLSM. Cement reduces the leaching of Boron in bleed. It is concluded that there is good potential for the use of industrial waste incineration bottom ash in CLSM. © 2009 Elsevier B.V. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0304389409011893
http://ac.els-cdn.com/S0304389409011893/1-s2.0-S0304389409011893-main.pdf?_tid=be4739c6-781f-11e3-9f12-00000aab0f6b&acdnat=1389156528_7d710042bbe701383e9f7279f1e70f17
Chemical cellulation technique for lightweight clay bricks
British Ceramic Transactions, Aug 1, 2002
Lightweight clay bricks were produced using a chemical cellulation technique from a residual soil... more Lightweight clay bricks were produced using a chemical cellulation technique from a residual soil of high clay content, mostly non-crystalling. The cellulation technique introduces cells into the material during the mixing stage as a result of the chemical reaction between aluminium powder and quicklime, which liberates hydrogen gas. The technique also requires the use of sodium silicate to achieve a proper cellulated structure. The mechanisms of reaction of the abovementioned chemicals with each other as well as with the raw material were investigated. Engineering properties of the fired product, namely compressive strength, bulk density, water absorption, and volumetric shrinkage, were determined and compared with solid bricks prepared in the laboratory. Based on the results of the study, a mechanism for the cellulation process, though complex, is postulated. The process is a combination of chemical reaction between the chemical additives used and the response of the soil to the chemicals or to the reaction products. The study also reveals the possibility of producing lightweight clay bricks, mostly of loadbearing performance, using the residual soil.
http://www.maneyonline.com/doi/abs/10.1179/096797802225003352
Building and Environment, Jan 1, 2004
The weatherability of PTFE- and PVC-coated fabrics under tropical climate was evaluated based on ... more The weatherability of PTFE- and PVC-coated fabrics under tropical climate was evaluated based on outdoor exposure test for a period of 2 years. This study is confined to the examination of the surface characteristics of 10 different types of fabric which include dirt repellency, discolouration and coating condition. The results indicate that the dirt repellency of PTFE-coated fabrics is generally more superior. However, the surface treatment for some of the PVC-coated fabrics, do provide excellent dirt repellency as well. Morphological examinations using the scanning electron microscope revealed that cracking and peeling of the coating were more evident on the PVC-coated as compared to the PTFE-coated fabrics. The hot and humid conditions prevalent in a tropical environment were very conducive for the growth of fungi, which adhered on the surface of some of the PVC-coated fabrics. Generally the degree of surface degradation on all the fabrics was more severe due to the much harsher tropical climate in comparison with other exposure tests conducted in the past. © 2003 Elsevier Ltd. All rights reserved.
www.sciencedirect.com/science/article/pii/S0360132303001586
http://ac.els-cdn.com/S0360132303001586/1-s2.0-S0360132303001586-main.pdf?_tid=68dc113c-781f-11e3-8ead-00000aab0f6b&acdnat=1389156385_2e118ad95309b4cec2c4f107a09dd05a
Engineering Structures, 2001
An experimental investigation to study the effect of general corrosion on the modal parameters of... more An experimental investigation to study the effect of general corrosion on the modal parameters of reinforced concrete beams was conducted. The full scale beams were subjected to reinforcement corrosion until an appreciable amount of steel corrosion damage was introduced. The states of damage in the test beams were assessed through measurement of crack width and spalling. Modal tests were performed on the test beams after corrosion damage and the modal parameters extracted were compared against that from a control beam. The results obtained showed changes in the modal parameters especially natural frequencies and damping ratio. The trend in the measured natural frequencies was sensitive to the deterioration state of the beams. Changes in modal damping ratio for the transfer function method and the normal mode method were also observed. However, the changes were inconsistent with the changes in natural frequencies, as concluded by previous researchers, but a trend was obsedved which was rather mode dependent. Furthermore, the load carrying capacity of the beams was determined through static load test and the results were correlated with the state of corrosion damage and changes in the modal parameters. This investigation provides further insight on the use of modal parameters to detect damage in structural concrete elements which can be useful for structural appraisal and assessment purposes when applied to full scale structures. © 2001 Elsevier Science Ltd. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0141029601000050
http://ac.els-cdn.com/S0141029601000050/1-s2.0-S0141029601000050-main.pdf?_tid=6f59f448-781f-11e3-8709-00000aacb35d&acdnat=1389156395_fe9cc521987889353e8edfd6467acda4
Concrete performance using locally produced kaolin
Proceedings of Institution of Civil Engineers: Construction Materials, 2010
This study presents the effect of incorporating local calcined kaolin on the engineering properti... more This study presents the effect of incorporating local calcined kaolin on the engineering properties and durability of concrete with water/binder ratios in the range of 0·40-0·60. Blended mixtures with cement replacement of 5, 10, 15 and 20% were designed with a target slump of 150±25 mm. From this investigation, it was found that a 10% replacement level was the optimum level in terms of compressive strength. Beyond 10% replacement levels, the strength was decreased but remained higher than the control mixtures with the exception of water/binder ratio of 0·60. With respect to the durability test, the initial surface absorption at 10 min (ISA-10), the sorptivity and the water absorption were enhanced with higher replacement level regardless of water/binder ratio. A linear equation was developed to determine the superplasticiser dosage for a desired workability based on the obtained results. This investigation has shown that the local kaolin has a potential to be incorporated as blended cement as it improves the durability/permeability and compressive strength in comparison with ordinary Portland cement mixtures.
http://www.icevirtuallibrary.com/content/article/10.1680/coma.900021
Journal of Environmental Management, 2013
This paper reports the corrosivity and leaching behavior of CLSM made using two different industr... more This paper reports the corrosivity and leaching behavior of CLSM made using two different industrial wastes i.e. bottom ash from an incineration facility and quarry dust. The leachate samples were derived from fresh and hardened CLSM mixtures, and studied for leaching and electrical resistivity. The release of various contaminants and the consequent environmental impact caused by the contaminants were studied by the measurement of contaminants in the bleed, in the leachate at 28 days, and on the leachate derived from crushed block and whole block leaching done over a period of 126 days. Results indicated that the CLSM mixtures are non corrosive; diffusion was the leaching mechanism; and the contaminants were found to be moderate to low mobility. © 2013 Elsevier Ltd.
Corrosivity and leaching behavior of controlled low-strength material (CLSM) made using bottom ash and quarry dust
Journal of Environmental Management, 2013
This paper reports the corrosivity and leaching behavior of CLSM made using two different industr... more This paper reports the corrosivity and leaching behavior of CLSM made using two different industrial wastes i.e. bottom ash from an incineration facility and quarry dust. The leachate samples were derived from fresh and hardened CLSM mixtures, and studied for leaching and electrical resistivity. The release of various contaminants and the consequent environmental impact caused by the contaminants were studied by the measurement of contaminants in the bleed, in the leachate at 28 days, and on the leachate derived from crushed block and whole block leaching done over a period of 126 days. Results indicated that the CLSM mixtures are non corrosive; diffusion was the leaching mechanism; and the contaminants were found to be moderate to low mobility. © 2013 Elsevier Ltd.
Effect of kaolin addition on the performance of controlled low-strength material using industrial waste incineration bottom ash
Waste Management & Research, 2010
Incineration of industrial waste produces large quantities of bottom ash which are normally sent ... more Incineration of industrial waste produces large quantities of bottom ash which are normally sent to secured landfill, but is not a sustainable solution. Use of bottom ash in engineering applications will contribute to sustainability and generate revenue. One way of using the industrial waste incineration bottom ash is in controlled low-strength material (CLSM). Use of bottom ash in CLSM has problems related to bleeding and excessive strength development and so an additive has to be used to control bleeding and strength development. The main objective of this research is to study the effect of kaolin addition on the performance of CLSM made using industrial waste incineration bottom ash. CLSM mixes were made with bottom ash, cement, and refined kaolin. Various tests were performed on the CLSM in fresh and hardened states including compressive strength, water absorption, California bearing ratio (CBR) and the tests for concentration of leachable substances on the bleed and leachate. The compressive strength of CLSM tested ranged from 0.11 to 9.86 MPa. CBR values ranged from 6 to 46, and water absorption values from 12 to 36%. It was shown that the addition of kaolin delayed the initial setting time of CLSM mixtures, reduced bleeding, lowered the compressive strength, and increased the values of water absorption, sorption, and initial surface absorption. The CLSM tested did not have corrosivity. It was shown that the hardened CLSM was non hazardous, and the addition of kaolin increased the concentration of heavy metals and salts in the bleed and leachate. © The Author(s), 2010.
http://wmr.sagepub.com/content/28/9/848.short
11th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC-11, 2008
The main purpose of this paper is to study the effect of kaolin addition on the performance of Co... more The main purpose of this paper is to study the effect of kaolin addition on the performance of Controlled Low-Strength Material (CLSM) made using industrial hazardous waste incinerator bottom slag. Various mix formulatiuons of CLSM were made with the incinerator bottom slag, kaolin, and cement. Amount of cement added varied from 0 to 40 percent of weight of slag. Amount of kaolin added were 25, 50, 75, and 100 percent of weight of cement. Water content was adjusted to get sufficient flowability. The CLSM mixes prepared were tested for setting time, bleeding, and corrosivity in fresh state. Tests like compressive strength, California Bearing Ratio (CBR), Initial Surface Absorption (ISAT), settlement, and water absorption, were conducted on the hardened CLSM. Compressive strength tests were conducted at 7, 14, and 28 days on 70.7 mm cubes. Heavy metals analysis for bleed and leachate water was also conducted on the CLSM mixes. The 28 days compressive strength of CLSM tested ranged from 0.36 to 4.40 MPa. CBR values ranged from 10% to 46%, and ISAT values at 1 hour from 0.56 to 4.76 mL/m2/s. None of the twelve heavy metals tested exceeded the threshold limits. It is concluded that the kaolin addition in CLSM using incinerator slag showed reduction in the compressive strength, but improved performance with regard to ISAT, CBR, and water absorption. It is concluded that the incinerator slag can be developed as a new sustainable construction material in CLSM.
ajse.kfupm.edu.sa/articles/352B%20p.05.pdf
30th IMAC, A Conference on Structural Dynamics, 2012, 2012
The use of dynamically measured flexibility matrix to indicate and locate damage is reported in m... more The use of dynamically measured flexibility matrix to indicate and locate damage is reported in many studies. However their focus is mostly on structures like beams or slabs that each node has one degree of freedom and all DOFs are in the same direction. For a structure with degrees of freedoms in three directions e.g. frame structures, both modal testing and damage detection become more complicated. It is because each DOF in the stiffness matrix is influenced by all the members connected to it. When it comes to flexibility matrix, another problem arises. Since flexibility matrix is more global, damage does not only affect the related DOFs, but others too. This article aims to address these problems in order to develop a reliable damage detection method for frame structures. The modal parameters of a four story frame structure are calculated for intact and damage cases. Changes in the flexibility matrix were analyzed for different damage scenarios when the damage member is known. It was suggested that there are some patterns that relate DOFs and members which can be used to locate the damage member. © The Society for Experimental Mechanics, Inc. 2012.
http://link.springer.com/chapter/10.1007/978-1-4614-2419-2_37
Applied Mathematics and Computation, 2013
In this paper, an explicit time integration scheme is proposed for structural vibration analysis ... more In this paper, an explicit time integration scheme is proposed for structural vibration analysis by using wavelet functions. Initially, the differential equation of vibration governing SDOF (single-degree of freedom) systems has been solved by wavelet operators, and later the proposed approach has been generalized for MDOF (multi-degrees of freedom) systems. For this purpose, two different types of wavelet functions have been exemplified including, complex Chebyshev wavelet functions and simple Haar wavelet functions. In the proposed approach, a straightforward formulation has been derived from the numerical approximation of response through the wavelet definition. Emphasizing on frequency-domain approximation, a simple step-by-step algorithm has been implemented and improved to calculate the response of MDOF systems. Moreover, stability and accuracy of results have been evaluated. The effectiveness of the proposed approach is demonstrated using three examples compared with some of the existing numerical integration schemes such as family of Newmark-β, Wilson-θ and central difference method. In all the procedures, computation time involved has also been considered. Finally, it is concluded that the vibration analysis of structures is improved by lesser computation time and high accuracy of proposed approach, particularly, in large-scaled systems. © 2013 Elsevier Inc. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0096300313006395
12th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC12, 2011
Self Compacting Concrete (SCC) is new type of concrete that posse's property of high flow ability... more Self Compacting Concrete (SCC) is new type of concrete that posse's property of high flow ability, passing ability and stability. To achieve SCC, many factors must be investigated. Coarse aggregate is one of these factors that have a significant influence on SCC. This paper presents the coarse aggregate properties such as maximum size, texture and type of coarse aggregate that have a direct effect on achieving SCC. Three types of coarse aggregate are used, namely crush gravel, uncrushed gravel and crush limestone. To determine the workability, different test methods are adopted such as slump flow, V-funnel, L-box and U-box test. It was found that by increasing the maximum size of coarse aggregate, flowability and passing ability reduced. In addition it was observed that when uncrushed gravel was used in the concrete mixture, flow ability, passing ability and segregation resistance increased as compared to concrete with crushed gravel. Furthermore, the inclusion of 10% HRM as a partial replacement by weight of cement leads to reduce flow ability and increase viscosity. The compressive and flexural strengths and modulus of elasticity was measured. It was noticed that concrete mixes prepared with crushed limestone showed higher strengths and modulus of elasticity than concrete mixes prepared with crushed and uncrushed gravel. In addition, lower maximum size of coarse aggregate leads to higher strengths compared to higher maximum size of coarse aggregate in SCC mixes.
http://www.sciencedirect.com/science/article/pii/S1877705811011799
Materials & Design, Jan 1, 2014
This study deals with a proposed mix design method for SCC utilizing different properties of coar... more This study deals with a proposed mix design method for SCC utilizing different properties of coarse aggregate. The work was conducted in three phases, i.e. paste, mortar and concrete to facilitate the mix design process. Initial investigation on cement paste determined the basis for water cement ratio and superplasticizer dosage for the concrete. For the study on mortar, metakaolin (MK) as pozzolan was used at replacement levels of 5%, 10%, 15%, and 20% by weight of cement. Self compactability of mortars was obtained by adding suitable materials such as mineral admixtures and superplasticizer which provided a sufficient balance between flowability and viscosity of the mix. The optimum MK replacement level for cement was 10% from the viewpoint of workability and strength. Flowability of mortar decreased with the use of metakaolin. Moreover, strength of mortar increased when the optimum replacement level of pozzolan was used. Different fresh concrete tests were adopted. The results obtained for fresh concrete properties showed that flowability of concrete increased with increase flowability of mortar. The mixes which contained coarse aggregate with lower volume, small size, and continuous grading affected positively the fresh properties of SCC. Finally, the mix design method used was successful in producing SCC with different coarse aggregate properties. © 2013 Elsevier Ltd.
http://www.sciencedirect.com/science/article/pii/S0261306913007000
Cement and Concrete Research, 2005
The concept of efficiency can be used for comparing the relative performance of various pozzolans... more The concept of efficiency can be used for comparing the relative performance of various pozzolans when incorporated into concrete. In this paper, an alternative approach for the evaluation of efficiency factor k of a pozzolanic material has been introduced. The method, developed following Abram's strength-W/C ratio rule, calculates efficiency in terms of relative strength and cementitious materials content. The advantage of this method is that only two mixtures are required to determine the k factor of a specific mixture. A laboratory investigation on silica fume (SF) and metakaolin (MK) concrete found that the computed efficiency factors varied with pozzolan type, replacement level and age. At 28 days, the k values ranged from 1.6 to 2.3 for MK and 2.1 to 3.1 for SF mixtures, while at 180 days, the k values varied from 1.8 to 4.0 for MK and 2.4 to 3.3 for SF mixtures. Generally, the k factors increased with age but declined with higher pozzolanic content. It was also observed that change in W/CM ratio from 0.33 to 0.27 did not significantly affect the resultant efficiency factors. © 2004 Elsevier Ltd. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S000888460400242X
http://ac.els-cdn.com/S000888460400242X/1-s2.0-S000888460400242X-main.pdf?_tid=bd7a69b8-7820-11e3-868e-00000aacb360&acdnat=1389156956_b3c258306027f97b5631be2a0618449f
Response Prediction of Offshore Floating Structure Using Artificial Neural Network
Advanced Science Letters, 2012
For deep-water oil and gas exploration, spar platform is considered to be the most economic and s... more For deep-water oil and gas exploration, spar platform is considered to be the most economic and suitable floating offshore structure. Analysis of spar platform is complex due to various nonlinearities such as geometric, variable submergence, varying pretention, etc. The Finite Element Method (FEM) is an important technique to deal with this type of analysis. However, FEM is computationally very expensive and highly time-consuming process. Artificial Neural Network (ANNs) can provide meaningful solutions and can process information in extremely rapid mode ensuring high accuracy of prediction. This paper presents dynamic response prediction of spar mooring line using ANN. FEM-based time domain response of spar platform such as surge, heave and pitch is trained by ANN. Mooring line top tension is predicted after 7200 sec (2 hours) of wave loading. The response obtained using ANN is validated by conventional FEM analysis. Results show that ANN approach is found to be very efficient and it significantly reduces the time for predicting long response time histories. Thus ANN approach is recommended for efficient designing of floating structures. © 2012 American Scientific Publishers. All rights reserved.
www.ingentaconnect.com/content/asp/asl/2012/00000014/00000001/art00033
http://www.ingentaconnect.com/content/asp/asl/2012/00000014/00000001/art00033?token=0055134ed587e2a46762c6b795d76766c25443a2b5f7b673f7b2f267738703375686f492388928b81ab5d
12th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC12, 2011
The effects of far distant earthquakes felt in regions with low and moderate seismicity has incre... more The effects of far distant earthquakes felt in regions with low and moderate seismicity has increased markedly over the last decade. Henceforth fragility curves in this study are to indicate whether buildings are safe to enter or not after an earthquake event occurring more than 300km away. The probability of light, moderate and severe damage states occurring on two and four storey reinforced concrete buildings up to a peak ground acceleration of 0.2g were predicted. The building models were constructed using finite element software based on eight node brick elements with three degrees of freedom at each node. The analysis was carried out using a dynamic response spectrum to calculate the peak inter-storey drift ratios. For the development of fragility curves, the results were collated following a log-normal mean distribution. The results showed that light damage is likely to occur with a probability of over 10% within a 50 year period, while the existing record is unlikely to cause structural damage. The fragility curves were comparable to those for RC moment resisting frames obtained by (Rossetto and Elnashai 2003) at a lower drift limit, with approximately 2% of inter-storey drift ratio.
http://www.sciencedirect.com/science/article/pii/S1877705811013531
Construction and Building Materials, Jan 1, 2011
This paper compares three methods for activation of OPC-slag mortars (OSM): (1) prolonged grindin... more This paper compares three methods for activation of OPC-slag mortars (OSM): (1) prolonged grinding of binders (mechanical method), (2) elevated temperature curing of mortars (thermal method), and (3) use of chemical activators such as NaOH, KOH, and Na2SiO3, 9.35H2O (chemical method). The proper reactivity of OSM was evaluated using a mixture of 50% OPC and 50% slag. Early and ultimate strengths were compared. All three activation methods accelerated both the slag reaction and strength development rates. However, the chemical method did not show a significant effect on the ultimate strength, while thermal activation increased the early strength by 3 days. Mechanical activation increased the early strengths of the mortar significantly, but about 6% strength loss occurred in the ultimate strength. Although, the application of mechanical and thermal activation methods needs extra equipment and energy, due to more significant of strength improvement; based on current test results, it can be said that mechanical activation is the most efficient and feasible method for the activation of OSMs. © 2010 Elsevier Ltd. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0950061810003090
http://ac.els-cdn.com/S0950061810003090/1-s2.0-S0950061810003090-main.pdf?_tid=1f70136c-7820-11e3-8df9-00000aacb362&acdnat=1389156691_598fed59ba988ef24a61b55479cb6ea7
Construction and Building Materials, Oct 1, 2010
Although the use of slag has many benefits, its low hydration at early stages causes the strength... more Although the use of slag has many benefits, its low hydration at early stages causes the strength to be low. Hence, the uses of slag are restricted, even before it needs to be activated. In this investigation, a chemical method was used to activate the ordinary Portland cement-slag mortars (OSM). 37 OSM were used, 4 of them as control. All mix designs were made by W/B = 0.33, S/B = 2.25, and with 0%, 30%, 40%, 50%, and 60% levels of slag. The activators; sodium hydroxide, potassium hydroxide, and sodium silicate have been used. Whenever the activators were used alone, the highest effect was obtained by sodium silicate and the lowest for sodium hydroxide. It was determined that the effects of the combined activators are better than that of an individual one. It was observed that strength loss for some mixes, at long ages, is determined by some factors, such as level of slag used, type and dosage of alkali activators, and curing regimes. © 2010 Elsevier Ltd. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0950061810001261
http://ac.els-cdn.com/S0950061810001261/1-s2.0-S0950061810001261-main.pdf?_tid=037aee7a-7820-11e3-91fd-00000aab0f26&acdnat=1389156644_0a6299272577efa3436bc0823103770b
Asian Journal of Civil Engineering, 2010
The use of high strength concrete (HSC) has been studied for many years in developed and developi... more The use of high strength concrete (HSC) has been studied for many years in developed and developing countries. Although, HSC has a few disadvantages, it has many advantages. The concrete with compressive strength (CS) levels in the range of 50 to100 MPa, is called HSC. The most important property of HSC is 28-day CS as a criterion. Sometimes due to time limitations and construction project problems, estimation of 28-day CS based on 7-day CS can be useful. Based on many experimental tests and analysis of the results, three sets of equations are determined with ANN and Regression techniques are compared and the best is recommended. © 2009 by DotNetNuke Corporation.
www.bhrc.ac.ir/portal/Portals/2/pdf/asian%20jornal/APRIL%202010/Sajedi-5.pdf
Arabian Journal for Science and Engineering, Oct 1, 2010
This paper reports the details of investigations carried out to study the performance of industri... more This paper reports the details of investigations carried out to study the performance of industrial waste incineration bottom ash and refined kaolin to produce controlled low-strength material (CLSM). CLSM mixes were designed with varying amounts of incineration bottom ash, refined kaolin, and cement. Water content was adjusted to get sufficient flowability. Tests for density, stiffening time, bleed, settlement, sorptivity, water absorption, moisture content, California bearing ratio, initial surface absorption, and compressive strength were carried out on the CLSM mixtures. Study for corrosivity and leaching of heavy metals and salts on the bleed and leachate were also performed. The compressive strength of CLSM tested ranged from 0.36 to 4.40 MPa. CBR values ranged from 10 to 46 and ISAT values at 1 hour from 0.56 to 4.76 ml/m2/s. None of the heavy metals tested exceeded the threshold limits in leachate. Addition of kaolin controls the compressive strength development, and reduces initial surface absorption, California bearing ratio, and water absorption values. It is shown that the incineration bottom ash, along with refined kaolin, can be successfully employed in CLSM, thereby contributing to sustainability in civil engineering practice.
ajse.kfupm.edu.sa/articles/352B%20p.05.pdf
Journal of Hazardous Materials, Dec 30, 2009
Controlled low-strength material (CLSM) is slurry made by mixing sand, cement, ash, and water. It... more Controlled low-strength material (CLSM) is slurry made by mixing sand, cement, ash, and water. It is primarily used as a replacement for soil and structural fillings. This paper presents the findings of a preliminary investigation carried out on the performance of industrial waste incineration bottom ash as CLSM. CLSM mixes were designed using industrial waste incineration bottom ash, and cement. Tests for density, setting time, bleed, and compressive strength on cubes under various curing conditions, corrosivity, and leaching of heavy metals and salts were carried out on the CLSM mixtures, and the results discussed. Compressive strength for the designed CLSM mixtures ranged from 0.1 to 1.7 MPa. It is shown that the variations in curing conditions have less influence on the compressive strength of CLSM at high values of water to cement ratio (w/c), but low values of w/c influences the strength of CLSM. The CLSM produced does not exhibit corrosive characters as evidenced by pH. Leaching of heavy metals and salts is higher in bleed than in leachate collected from hardened CLSM. Cement reduces the leaching of Boron in bleed. It is concluded that there is good potential for the use of industrial waste incineration bottom ash in CLSM. © 2009 Elsevier B.V. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0304389409011893
http://ac.els-cdn.com/S0304389409011893/1-s2.0-S0304389409011893-main.pdf?_tid=be4739c6-781f-11e3-9f12-00000aab0f6b&acdnat=1389156528_7d710042bbe701383e9f7279f1e70f17
Chemical cellulation technique for lightweight clay bricks
British Ceramic Transactions, Aug 1, 2002
Lightweight clay bricks were produced using a chemical cellulation technique from a residual soil... more Lightweight clay bricks were produced using a chemical cellulation technique from a residual soil of high clay content, mostly non-crystalling. The cellulation technique introduces cells into the material during the mixing stage as a result of the chemical reaction between aluminium powder and quicklime, which liberates hydrogen gas. The technique also requires the use of sodium silicate to achieve a proper cellulated structure. The mechanisms of reaction of the abovementioned chemicals with each other as well as with the raw material were investigated. Engineering properties of the fired product, namely compressive strength, bulk density, water absorption, and volumetric shrinkage, were determined and compared with solid bricks prepared in the laboratory. Based on the results of the study, a mechanism for the cellulation process, though complex, is postulated. The process is a combination of chemical reaction between the chemical additives used and the response of the soil to the chemicals or to the reaction products. The study also reveals the possibility of producing lightweight clay bricks, mostly of loadbearing performance, using the residual soil.
http://www.maneyonline.com/doi/abs/10.1179/096797802225003352
Building and Environment, Jan 1, 2004
The weatherability of PTFE- and PVC-coated fabrics under tropical climate was evaluated based on ... more The weatherability of PTFE- and PVC-coated fabrics under tropical climate was evaluated based on outdoor exposure test for a period of 2 years. This study is confined to the examination of the surface characteristics of 10 different types of fabric which include dirt repellency, discolouration and coating condition. The results indicate that the dirt repellency of PTFE-coated fabrics is generally more superior. However, the surface treatment for some of the PVC-coated fabrics, do provide excellent dirt repellency as well. Morphological examinations using the scanning electron microscope revealed that cracking and peeling of the coating were more evident on the PVC-coated as compared to the PTFE-coated fabrics. The hot and humid conditions prevalent in a tropical environment were very conducive for the growth of fungi, which adhered on the surface of some of the PVC-coated fabrics. Generally the degree of surface degradation on all the fabrics was more severe due to the much harsher tropical climate in comparison with other exposure tests conducted in the past. © 2003 Elsevier Ltd. All rights reserved.
www.sciencedirect.com/science/article/pii/S0360132303001586
http://ac.els-cdn.com/S0360132303001586/1-s2.0-S0360132303001586-main.pdf?_tid=68dc113c-781f-11e3-8ead-00000aab0f6b&acdnat=1389156385_2e118ad95309b4cec2c4f107a09dd05a
Engineering Structures, 2001
An experimental investigation to study the effect of general corrosion on the modal parameters of... more An experimental investigation to study the effect of general corrosion on the modal parameters of reinforced concrete beams was conducted. The full scale beams were subjected to reinforcement corrosion until an appreciable amount of steel corrosion damage was introduced. The states of damage in the test beams were assessed through measurement of crack width and spalling. Modal tests were performed on the test beams after corrosion damage and the modal parameters extracted were compared against that from a control beam. The results obtained showed changes in the modal parameters especially natural frequencies and damping ratio. The trend in the measured natural frequencies was sensitive to the deterioration state of the beams. Changes in modal damping ratio for the transfer function method and the normal mode method were also observed. However, the changes were inconsistent with the changes in natural frequencies, as concluded by previous researchers, but a trend was obsedved which was rather mode dependent. Furthermore, the load carrying capacity of the beams was determined through static load test and the results were correlated with the state of corrosion damage and changes in the modal parameters. This investigation provides further insight on the use of modal parameters to detect damage in structural concrete elements which can be useful for structural appraisal and assessment purposes when applied to full scale structures. © 2001 Elsevier Science Ltd. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0141029601000050
http://ac.els-cdn.com/S0141029601000050/1-s2.0-S0141029601000050-main.pdf?_tid=6f59f448-781f-11e3-8709-00000aacb35d&acdnat=1389156395_fe9cc521987889353e8edfd6467acda4
Concrete performance using locally produced kaolin
Proceedings of Institution of Civil Engineers: Construction Materials, 2010
This study presents the effect of incorporating local calcined kaolin on the engineering properti... more This study presents the effect of incorporating local calcined kaolin on the engineering properties and durability of concrete with water/binder ratios in the range of 0·40-0·60. Blended mixtures with cement replacement of 5, 10, 15 and 20% were designed with a target slump of 150±25 mm. From this investigation, it was found that a 10% replacement level was the optimum level in terms of compressive strength. Beyond 10% replacement levels, the strength was decreased but remained higher than the control mixtures with the exception of water/binder ratio of 0·60. With respect to the durability test, the initial surface absorption at 10 min (ISA-10), the sorptivity and the water absorption were enhanced with higher replacement level regardless of water/binder ratio. A linear equation was developed to determine the superplasticiser dosage for a desired workability based on the obtained results. This investigation has shown that the local kaolin has a potential to be incorporated as blended cement as it improves the durability/permeability and compressive strength in comparison with ordinary Portland cement mixtures.
http://www.icevirtuallibrary.com/content/article/10.1680/coma.900021
Journal of Environmental Management, 2013
This paper reports the corrosivity and leaching behavior of CLSM made using two different industr... more This paper reports the corrosivity and leaching behavior of CLSM made using two different industrial wastes i.e. bottom ash from an incineration facility and quarry dust. The leachate samples were derived from fresh and hardened CLSM mixtures, and studied for leaching and electrical resistivity. The release of various contaminants and the consequent environmental impact caused by the contaminants were studied by the measurement of contaminants in the bleed, in the leachate at 28 days, and on the leachate derived from crushed block and whole block leaching done over a period of 126 days. Results indicated that the CLSM mixtures are non corrosive; diffusion was the leaching mechanism; and the contaminants were found to be moderate to low mobility. © 2013 Elsevier Ltd.
Corrosivity and leaching behavior of controlled low-strength material (CLSM) made using bottom ash and quarry dust
Journal of Environmental Management, 2013
This paper reports the corrosivity and leaching behavior of CLSM made using two different industr... more This paper reports the corrosivity and leaching behavior of CLSM made using two different industrial wastes i.e. bottom ash from an incineration facility and quarry dust. The leachate samples were derived from fresh and hardened CLSM mixtures, and studied for leaching and electrical resistivity. The release of various contaminants and the consequent environmental impact caused by the contaminants were studied by the measurement of contaminants in the bleed, in the leachate at 28 days, and on the leachate derived from crushed block and whole block leaching done over a period of 126 days. Results indicated that the CLSM mixtures are non corrosive; diffusion was the leaching mechanism; and the contaminants were found to be moderate to low mobility. © 2013 Elsevier Ltd.
Effect of kaolin addition on the performance of controlled low-strength material using industrial waste incineration bottom ash
Waste Management & Research, 2010
Incineration of industrial waste produces large quantities of bottom ash which are normally sent ... more Incineration of industrial waste produces large quantities of bottom ash which are normally sent to secured landfill, but is not a sustainable solution. Use of bottom ash in engineering applications will contribute to sustainability and generate revenue. One way of using the industrial waste incineration bottom ash is in controlled low-strength material (CLSM). Use of bottom ash in CLSM has problems related to bleeding and excessive strength development and so an additive has to be used to control bleeding and strength development. The main objective of this research is to study the effect of kaolin addition on the performance of CLSM made using industrial waste incineration bottom ash. CLSM mixes were made with bottom ash, cement, and refined kaolin. Various tests were performed on the CLSM in fresh and hardened states including compressive strength, water absorption, California bearing ratio (CBR) and the tests for concentration of leachable substances on the bleed and leachate. The compressive strength of CLSM tested ranged from 0.11 to 9.86 MPa. CBR values ranged from 6 to 46, and water absorption values from 12 to 36%. It was shown that the addition of kaolin delayed the initial setting time of CLSM mixtures, reduced bleeding, lowered the compressive strength, and increased the values of water absorption, sorption, and initial surface absorption. The CLSM tested did not have corrosivity. It was shown that the hardened CLSM was non hazardous, and the addition of kaolin increased the concentration of heavy metals and salts in the bleed and leachate. © The Author(s), 2010.
http://wmr.sagepub.com/content/28/9/848.short
11th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC-11, 2008
The main purpose of this paper is to study the effect of kaolin addition on the performance of Co... more The main purpose of this paper is to study the effect of kaolin addition on the performance of Controlled Low-Strength Material (CLSM) made using industrial hazardous waste incinerator bottom slag. Various mix formulatiuons of CLSM were made with the incinerator bottom slag, kaolin, and cement. Amount of cement added varied from 0 to 40 percent of weight of slag. Amount of kaolin added were 25, 50, 75, and 100 percent of weight of cement. Water content was adjusted to get sufficient flowability. The CLSM mixes prepared were tested for setting time, bleeding, and corrosivity in fresh state. Tests like compressive strength, California Bearing Ratio (CBR), Initial Surface Absorption (ISAT), settlement, and water absorption, were conducted on the hardened CLSM. Compressive strength tests were conducted at 7, 14, and 28 days on 70.7 mm cubes. Heavy metals analysis for bleed and leachate water was also conducted on the CLSM mixes. The 28 days compressive strength of CLSM tested ranged from 0.36 to 4.40 MPa. CBR values ranged from 10% to 46%, and ISAT values at 1 hour from 0.56 to 4.76 mL/m2/s. None of the twelve heavy metals tested exceeded the threshold limits. It is concluded that the kaolin addition in CLSM using incinerator slag showed reduction in the compressive strength, but improved performance with regard to ISAT, CBR, and water absorption. It is concluded that the incinerator slag can be developed as a new sustainable construction material in CLSM.
ajse.kfupm.edu.sa/articles/352B%20p.05.pdf
30th IMAC, A Conference on Structural Dynamics, 2012, 2012
The use of dynamically measured flexibility matrix to indicate and locate damage is reported in m... more The use of dynamically measured flexibility matrix to indicate and locate damage is reported in many studies. However their focus is mostly on structures like beams or slabs that each node has one degree of freedom and all DOFs are in the same direction. For a structure with degrees of freedoms in three directions e.g. frame structures, both modal testing and damage detection become more complicated. It is because each DOF in the stiffness matrix is influenced by all the members connected to it. When it comes to flexibility matrix, another problem arises. Since flexibility matrix is more global, damage does not only affect the related DOFs, but others too. This article aims to address these problems in order to develop a reliable damage detection method for frame structures. The modal parameters of a four story frame structure are calculated for intact and damage cases. Changes in the flexibility matrix were analyzed for different damage scenarios when the damage member is known. It was suggested that there are some patterns that relate DOFs and members which can be used to locate the damage member. © The Society for Experimental Mechanics, Inc. 2012.
http://link.springer.com/chapter/10.1007/978-1-4614-2419-2_37
Applied Mathematics and Computation, 2013
In this paper, an explicit time integration scheme is proposed for structural vibration analysis ... more In this paper, an explicit time integration scheme is proposed for structural vibration analysis by using wavelet functions. Initially, the differential equation of vibration governing SDOF (single-degree of freedom) systems has been solved by wavelet operators, and later the proposed approach has been generalized for MDOF (multi-degrees of freedom) systems. For this purpose, two different types of wavelet functions have been exemplified including, complex Chebyshev wavelet functions and simple Haar wavelet functions. In the proposed approach, a straightforward formulation has been derived from the numerical approximation of response through the wavelet definition. Emphasizing on frequency-domain approximation, a simple step-by-step algorithm has been implemented and improved to calculate the response of MDOF systems. Moreover, stability and accuracy of results have been evaluated. The effectiveness of the proposed approach is demonstrated using three examples compared with some of the existing numerical integration schemes such as family of Newmark-β, Wilson-θ and central difference method. In all the procedures, computation time involved has also been considered. Finally, it is concluded that the vibration analysis of structures is improved by lesser computation time and high accuracy of proposed approach, particularly, in large-scaled systems. © 2013 Elsevier Inc. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0096300313006395
12th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC12, 2011
Self Compacting Concrete (SCC) is new type of concrete that posse's property of high flow ability... more Self Compacting Concrete (SCC) is new type of concrete that posse's property of high flow ability, passing ability and stability. To achieve SCC, many factors must be investigated. Coarse aggregate is one of these factors that have a significant influence on SCC. This paper presents the coarse aggregate properties such as maximum size, texture and type of coarse aggregate that have a direct effect on achieving SCC. Three types of coarse aggregate are used, namely crush gravel, uncrushed gravel and crush limestone. To determine the workability, different test methods are adopted such as slump flow, V-funnel, L-box and U-box test. It was found that by increasing the maximum size of coarse aggregate, flowability and passing ability reduced. In addition it was observed that when uncrushed gravel was used in the concrete mixture, flow ability, passing ability and segregation resistance increased as compared to concrete with crushed gravel. Furthermore, the inclusion of 10% HRM as a partial replacement by weight of cement leads to reduce flow ability and increase viscosity. The compressive and flexural strengths and modulus of elasticity was measured. It was noticed that concrete mixes prepared with crushed limestone showed higher strengths and modulus of elasticity than concrete mixes prepared with crushed and uncrushed gravel. In addition, lower maximum size of coarse aggregate leads to higher strengths compared to higher maximum size of coarse aggregate in SCC mixes.
http://www.sciencedirect.com/science/article/pii/S1877705811011799
Materials & Design, Jan 1, 2014
This study deals with a proposed mix design method for SCC utilizing different properties of coar... more This study deals with a proposed mix design method for SCC utilizing different properties of coarse aggregate. The work was conducted in three phases, i.e. paste, mortar and concrete to facilitate the mix design process. Initial investigation on cement paste determined the basis for water cement ratio and superplasticizer dosage for the concrete. For the study on mortar, metakaolin (MK) as pozzolan was used at replacement levels of 5%, 10%, 15%, and 20% by weight of cement. Self compactability of mortars was obtained by adding suitable materials such as mineral admixtures and superplasticizer which provided a sufficient balance between flowability and viscosity of the mix. The optimum MK replacement level for cement was 10% from the viewpoint of workability and strength. Flowability of mortar decreased with the use of metakaolin. Moreover, strength of mortar increased when the optimum replacement level of pozzolan was used. Different fresh concrete tests were adopted. The results obtained for fresh concrete properties showed that flowability of concrete increased with increase flowability of mortar. The mixes which contained coarse aggregate with lower volume, small size, and continuous grading affected positively the fresh properties of SCC. Finally, the mix design method used was successful in producing SCC with different coarse aggregate properties. © 2013 Elsevier Ltd.
http://www.sciencedirect.com/science/article/pii/S0261306913007000