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J M Khatib - One of the best experts on this subject based on the ideXlab platform.
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factors influencing Strength Development of concrete containing silica fume
Cement and Concrete Research, 1995Co-Authors: S. Wild, B.b. Sabir, J M KhatibAbstract:Existing data on the relationships between temperature, pozzolanic activity and cement hydration are reviewed with particular emphasis on condensed silica fume (CSF)-ordinary Portland cement blends. CSF concrete with a range of fume contents has been cured at two temperatures (20 °C and 50 °C) for periods up to 91 days. Strength Development and relative Strength are considered in relation to temperature, cement hydration and pozzolanic action. The observed results establish that relative Strength varies directly with CSF content and that the Strength enhancement at early curing periods, which is achieved by increase in curing temperature, is a result of increased reaction rate between Ca(OH)2 and CSF.
Suksun Horpibulsuk - One of the best experts on this subject based on the ideXlab platform.
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Impact of field conditions on the Strength Development of a geopolymer stabilized marine clay
Applied Clay Science, 2018Co-Authors: Mohammadjavad Yaghoubi, Suksun Horpibulsuk, Arul Arulrajah, M. Disfani, Stephen Darmawan, James WangAbstract:Abstract A soft marine clay was stabilized with fly-ash (FA) and slag (S) based geopolymers. FA and S with combined contents of 10, 20 and 30% were added to the soft clay and activated with a liquid alkaline activator (L) at various contents. The clay was a marine clay which was dominated by quartz, illite and feldspar. The effect of a number of preparation and curing factors including water content and temperature variation, wetting-drying cycles and mixing time and method were evaluated. The objective of this research was to evaluate the effect of these factors that are likely to occur in ground improvement applications, such as deep soil mixing, on the unconfined compressive Strength (UCS), microstructure and mineralogy of the mixtures. Results showed that increasing the FA + S content increased the UCS values significantly through the geopolymerization process, which was evident when increasing the FA + S content from 10% to 20%. Moreover, higher UCS values were achieved when the curing temperature was increased and the Strength Development was accelerated as a result of accelerated precipitation of FA and S. Furthermore, Strength Development was enhanced when the L/(FA + S) ratio was increased from 0.75 to 1.0, followed by a decrease at L/(FA + S) ratio of 1.25. Similar trends of Strength Development were observed by varying the water contents of 0.75, 1.0 and 1.25 liquid limit (LL) of the soil. The increased amount of liquid, L and water, caused less favorable environment, such as lower L molarity and less particle contact, for proper Strength Development. The UCS values decreased for up to 6 cycles of wetting and drying, where the geopolymeric network was not sufficiently stable, and remained almost constant afterwards. Increasing the mixing time caused more dissolution of FA and S, which resulted in enhancement of the UCS values. Adding FA + S and L to the soil separately resulted in higher UCS values compared to when FA + S and L were mixed together initially and then added to the soil. The microstructure and mineralogy analyses indicated that increasing the curing temperature, as well as the L/(FA + S) ratio resulted in more dissolution of FA and S and formation of calcium sodium aluminum silicate hydrate (CNASH) products.
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Strength Development in clay fly ash geopolymer
Construction and Building Materials, 2013Co-Authors: Patimapon Sukmak, Suksun Horpibulsuk, Shuilong ShenAbstract:Abstract This paper presents the role of influential factors on the Strength Development in a clay–fly ash geopolymer that a silty clay is used as fine aggregates and fly ash, FA is used as a pozzolanic material. A liquid alkaline activator, L is a mixture of sodium silicate solution (Na 2 SiO 3 ) and sodium hydroxide solution (NaOH). The studied influential factors are Na 2 SiO 3 /NaOH ratio, L/FA ratio and heat conditions. The optimum ingredient for the clay–FA geopolymer is the Na 2 SiO 3 /NaOH ratio of 0.7 and the L/FA ratio of 0.6. The Na 2 SiO 3 /NaOH ratio required for the clay–FA geopolymer is less than that of the FA geopolymer because the clay has high cation absorption ability and then absorbs some of the input NaOH. For a given Na 2 SiO 3 /NaOH content, the Strength increases with increasing the liquid alkaline activator. The excess input alkaline activator causes the precipitation at very early stage before the condensation process in geopolymerization and results in the cracks on the FA particles. The overheating (very high temperature) and excess heat duration cause the micro-cracks on the specimens. The relationship between the Strength and heat energy is proposed to integrate the role of heat temperature and duration on the geopolymerization. The compressive Strength increases with increasing heat energy up to a certain level. Beyond this level, the specimens shrink and crack due to the reduction in pore fluid, which results in the Strength reduction. The relationship between Strength and heat energy can be used as fundamental for further study on the Strength Development and the mix design method for the clay–FA geopolymer with different specimen dimensions, clay minerals, liquid alkaline activators, pozzolanic materials and clay:FA ratios.
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Strength Development in clay–fly ash geopolymer
Construction and Building Materials, 2013Co-Authors: Patimapon Sukmak, Suksun Horpibulsuk, Shuilong ShenAbstract:Abstract This paper presents the role of influential factors on the Strength Development in a clay–fly ash geopolymer that a silty clay is used as fine aggregates and fly ash, FA is used as a pozzolanic material. A liquid alkaline activator, L is a mixture of sodium silicate solution (Na 2 SiO 3 ) and sodium hydroxide solution (NaOH). The studied influential factors are Na 2 SiO 3 /NaOH ratio, L/FA ratio and heat conditions. The optimum ingredient for the clay–FA geopolymer is the Na 2 SiO 3 /NaOH ratio of 0.7 and the L/FA ratio of 0.6. The Na 2 SiO 3 /NaOH ratio required for the clay–FA geopolymer is less than that of the FA geopolymer because the clay has high cation absorption ability and then absorbs some of the input NaOH. For a given Na 2 SiO 3 /NaOH content, the Strength increases with increasing the liquid alkaline activator. The excess input alkaline activator causes the precipitation at very early stage before the condensation process in geopolymerization and results in the cracks on the FA particles. The overheating (very high temperature) and excess heat duration cause the micro-cracks on the specimens. The relationship between the Strength and heat energy is proposed to integrate the role of heat temperature and duration on the geopolymerization. The compressive Strength increases with increasing heat energy up to a certain level. Beyond this level, the specimens shrink and crack due to the reduction in pore fluid, which results in the Strength reduction. The relationship between Strength and heat energy can be used as fundamental for further study on the Strength Development and the mix design method for the clay–FA geopolymer with different specimen dimensions, clay minerals, liquid alkaline activators, pozzolanic materials and clay:FA ratios.
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Field Strength Development of repaired pavement using the recycling technique
Quarterly Journal of Engineering Geology and Hydrogeology, 2012Co-Authors: Avirut Chinkulkijniwat, Suksun HorpibulsukAbstract:The pavement recycling technique is a way to effectively repair damaged pavements. In this study, statistical analysis shows that the field Strength is significantly lower than the laboratory Strength. The mixing process used in the pavement recycling technique does not significantly affect the field Strength reduction, as indicated by the small variation of the field hand-compacted Strength ( q ufh ) and the laboratory Strength ( q u1 ). The curing conditions do significantly control the field Strength Development. A factor of safety of 2.0 is recommended for design. The Strength Development mainly depends on the soil-water/cement ratio ( w / C ) and curing time regardless of the level of compaction energy. A general Strength Development model as a function of w / C and curing time is introduced. Only two laboratory Strength data from the specimens cured at two different curing times are required in the proposed model. A high accuracy of the Strength prediction is reported. This proposed model is a very powerful tool that determines the Strength Development of cement-stabilized coarse-grained soil after 7 days of curing. It can also be used to determine the correct quantity of cement to be stabilized for different field mixing water contents, compaction energies and curing times.
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Strength Development in blended cement admixed saline clay
Applied Clay Science, 2012Co-Authors: Suksun Horpibulsuk, Apichat Suddeepong, Worawit Phojan, Avirut ChinkulkijniwatAbstract:This present paper investigates influential factors (water content, cement content, fly ash content andcuring time) on Strength Development in saline soil admixed with cement and fly ash. It is found that for aparticular cement content, the Strength of admixed saline clay increases with fly ash content and the highestStrength is attained at 25% fly ash. Fly ash disperses the soil-cement clusters into smaller clusters andincreases the reactive surface, hence Strength improvement. Based on the clay-water/cement ratio and theparameter equivalent cement content, the Strength prediction equation for the cement admixed saline soil isintroduced. For fly ash content less than 25%, fly ash content is equivalent to 0.75 cement content for allcombinations of water content, cement content and fly ash content.
S. Wild - One of the best experts on this subject based on the ideXlab platform.
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Accelerating Early Strength Development of Concrete Using Metakaolin as an Admixture
2004Co-Authors: J. Bai, S. Wild, Albinas GailiusAbstract:A study of metakaolin (MK) as an early Strength accelerator for Portland cement (PC) and Portland Cement-Pulverised Fuel Ash (PFA) concrete (PC-PFA) has been carried out. This paper reports Strength Development, particularly at early curing ages, to evaluate the effectiveness of MK as an accelerating admixture. This is supported by analysis of the heat evolution using a calorimeter. The Portland cement concrete covering five different addition levels of MK (1 % – 5 %) to binder and with four water to cement ratios of 0.3, 0.4, 0.5 and 0.6 (0.4 and 0.5 for PC 60 % – PFA 40 % concrete) were cured in water up to 28 days. The compressive Strengths were evaluated at 1, 3, 7, 14 and 28 days. The compressive Strength Development of the concrete at various curing times is compared with control concrete (PC only). It is found that MK contributes significantly to early Strength Development as an accelerating admixture for PC and PC-PFA concrete.
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Strength Development in concrete incorporating PFA and metakaolin
Magazine of Concrete Research, 2000Co-Authors: J. Bai, S. Wild, B.b. Sabir, John KinuthiaAbstract:The work presented in this paper forms part of an ongoing investigation examining the potential of using metakaolin pulverized fuel ash (MK–PFA) blends for cements in concrete. The programme of research involves the examination of the effects of the blends on the workability, Strength Development and factors affecting durability, including chloride penetration, carbonation and water transport properties. The influence on the workability was reported previously and this paper gives the results for compressive-Strength Development. Several blend compositions were employed at water : binder ratios of 0·4, 0·5 and 0·6 to produce concretes, the compressive Strengths of which were evaluated at 7, 28 and 90 days. It is found that the contrasting influences on the Strength, particularly at early curing times, effected by PFA and MK when used in isolation as blends for cement can be combined effectively by the employment of various ratios of MK and PFA. Early Strengths surpassing that of the control are obtained w...
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factors influencing Strength Development of concrete containing silica fume
Cement and Concrete Research, 1995Co-Authors: S. Wild, B.b. Sabir, J M KhatibAbstract:Existing data on the relationships between temperature, pozzolanic activity and cement hydration are reviewed with particular emphasis on condensed silica fume (CSF)-ordinary Portland cement blends. CSF concrete with a range of fume contents has been cured at two temperatures (20 °C and 50 °C) for periods up to 91 days. Strength Development and relative Strength are considered in relation to temperature, cement hydration and pozzolanic action. The observed results establish that relative Strength varies directly with CSF content and that the Strength enhancement at early curing periods, which is achieved by increase in curing temperature, is a result of increased reaction rate between Ca(OH)2 and CSF.
Rajender Gupta - One of the best experts on this subject based on the ideXlab platform.
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hydration reaction and Strength Development of calcium sulfoaluminate cement based mortar cured at cold temperatures
Construction and Building Materials, 2019Co-Authors: Guangping Huang, Deepak Pudasainee, Rajender GuptaAbstract:Abstract The objective of this paper is to investigate the hydration reaction and Strength Development of calcium sulfoaluminate (CSA) cement mortar cured in various cold temperatures (i.e., 5 °C, 0 °C, −5 °C and −10 °C). In this study, both CSA cement-based and GU (General Use) cement-based mortar samples were cured in wet sands at temperatures of 5 °C, 0 °C, −5 °C and −10 °C. During the investigation, the temperature profiles in both sands and the centers of mortar samples were recorded. In addition, thermogravimetric analysis (TGA) and unconfined compressive Strength (UCS) tests were conducted on the samples at 1, 3, 7 and 28 days. The TGA results showed that the hydration reaction rate of GU cement was slow at cold temperatures and decreased with a drop in the curing temperature. However, the hydration reaction of CSA cement was very fast—it was mostly completed within the first 24 h—regardless of the curing temperatures. The UCS test results indicated that the Strength Development of CSA-based mortar was much faster than that of GU-based mortar. The CSA-based mortar achieved rapid Strength Development even cured in frozen sands with temperatures at −5 °C and −10 °C. In conclusion, CSA cement can be substituted for GU cement to accelerate the Strength Development of cement-based materials constructed in cold temperatures.
Ian Mccarthy - One of the best experts on this subject based on the ideXlab platform.
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The effect of crystallinity on Strength Development of α-TCP bone substitutes
Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2020Co-Authors: Christopher Camire, Pernilla Nevsten, Lars Lidgren, Ian MccarthyAbstract:Alpha phase tricalcium phosphates (alpha-TCP) were produced using a solid-state reaction method and milled for various periods of time. The resulting four materials were alpha-TCPs, ranging in crystalline content. Powders were exposed to X-ray diffraction for material identification as well as for use in crystallinity and purity calculations. Powder particle size was investigated using laser diffraction. Materials were mixed with 2.5% Na2HPO4 solution to initiate the hydration of alpha-TCP to calcium-deficient hydroxyapatite (CDHA). Isothermal calorimetry was performed to observe thermal response of the powders over a period of time. During the reaction process, at various time points up to 216 h, the material was compression tested to observe Strength Development. Materials proved to be predominantly alpha phase, while amorphous content determined by XRD varied. Reactivity, as measured by isothermal calorimetry, varied with crystallinity of the alpha-TCP powder. Speed of Strength Development did not change except for the most finely ground powder. In addition, crystal size of the CDHA was changed only in the product formed from the most highly ground material. It is proposed that increasing reactivity of alpha-TCP cements does not result in a corresponding increase in rate of Strength Development until there is sufficient supersaturation to produce significant crystal nucleation
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The effect of crystallinity on Strength Development of alpha-TCP bone substitutes.
Journal of Biomedical Materials Research Part B, 2006Co-Authors: Christopher Camire, Pernilla Nevsten, Lars Lidgren, Ian MccarthyAbstract:Alpha phase tricalcium phosphates (alpha-TCP) were produced using a solid-state reaction method and milled for various periods of time. The resulting four materials were alpha-TCPs, ranging in crystalline content. Powders were exposed to X-ray diffraction for material identification as well as for use in crystallinity and purity calculations. Powder particle size was investigated using laser diffraction. Materials were mixed with 2.5% Na2HPO4 solution to initiate the hydration of alpha-TCP to calcium-deficient hydroxyapatite (CDHA). Isothermal calorimetry was performed to observe thermal response of the powders over a period of time. During the reaction process, at various time points up to 216 h, the material was compression tested to observe Strength Development. Materials proved to be predominantly alpha phase, while amorphous content determined by XRD varied. Reactivity, as measured by isothermal calorimetry, varied with crystallinity of the alpha-TCP powder. Speed of Strength Development did not change except for the most finely ground powder. In addition, crystal size of the CDHA was changed only in the product formed from the most highly ground material. It is proposed that increasing reactivity of alpha-TCP cements does not result in a corresponding increase in rate of Strength Development until there is sufficient supersaturation to produce significant crystal nucleation. (Less)
