This research aimed to clarify the role of by-product materials, such as CKD with SF as partial replacement by weight of cement in concrete manufacturing and inclusion on different characteristics of concrete. Concret...This research aimed to clarify the role of by-product materials, such as CKD with SF as partial replacement by weight of cement in concrete manufacturing and inclusion on different characteristics of concrete. Concrete test specimens were mixed with 0%, 5%, 10%, 15%, 20% and 25% (CKD) with 15% (SF) as partial replacement by weight of Cement (CEM I-52.5N). Fresh concrete properties have been evaluated by workability measurement slump test. While hardened concrete properties have been evaluated by compressive, split tensile and flexural strengths tests at ages 7, 28 and 56 days, but evaluated for bond strength, modulus of elasticity and chemical composition measurement with X-Ray Fluorescence at age of 28 days. The test results have revealed that the increase of CKD amount with fixed amount of SF in concrete mixtures as partial replacement by weight of cement leads to gradual decrease of fresh concrete workability. In concrete mixtures, 20% CKD in the presence of 15% SF as partial replacement by the weight of cement are the optimum ratios which can be used without any negative effect on mechanical properties compressive, indirect tensile, flexural and bond strength at all the ages of concrete. Also modulus of elasticity and bond strength increased by 8.81% and 0.69% respectively at the age 28 days compared with control mixture.展开更多
X-ray fluorescence (XRF) analysis utilizes particle size which is resulted from milling of a material. The milling ensures uniform and fine grained powder. The finer and more uniform the particle size is, the better t...X-ray fluorescence (XRF) analysis utilizes particle size which is resulted from milling of a material. The milling ensures uniform and fine grained powder. The finer and more uniform the particle size is, the better the result and easier it is for material quality control. To ensure uniformity in particle size and finer powder, a comparative analysis was conducted with different grinding aids and pressed pellet method was used in obtaining analysis results. Pressed pellets of cement raw meal sample milled with different grinding aids (graphite, aspirin and lithium borate) were subjected to XRF. Graphite produced better particle size uniformity with a corresponding standard deviation that made quality control of raw meal easier and better than aspirin and lithium borate.展开更多
Polymethylmethacrylate(PMMA) bone cement technology has progressed from industrial Plexiglass administration in the 1950 s to the recent advent of nanoparticle additives. Additives have been trialed to address problem...Polymethylmethacrylate(PMMA) bone cement technology has progressed from industrial Plexiglass administration in the 1950 s to the recent advent of nanoparticle additives. Additives have been trialed to address problems with modern bone cements such as the loosening of prosthesis, high post-operative infection rates, and inflammatory reduction in interface integrity. This review aims to assess current additives used in PMMA bone cements and offer an insight regarding future directions for this biomaterial. Low index(< 15%) vitamin E and low index(< 5 g) antibiotic impregnated additives significantly address infection and inflammatory problems, with only modest reductions in mechanical strength. Chitosan(15% w/w PMMA) and silver(1% w/w PMMA) nanoparticles have strong antibacterial activity with no significant reduction in mechanical strength. Future work on PMMA bone cements should focus on trialing combinations of these additives as this may enhance favourable properties.展开更多
The aim of this work was to examine the microstructural changes of CEM I standardised cement mortar caused by accelerated carbonation (20% CO2 concentration) using porosity accessible to water and nitrogen adsorption....The aim of this work was to examine the microstructural changes of CEM I standardised cement mortar caused by accelerated carbonation (20% CO2 concentration) using porosity accessible to water and nitrogen adsorption. The conflicted results obtained by these two techniques showed the differences in porous domains explored, while the pore size distributions calculated from nitrogen adsorption provided evolution of the micro and meso pores during carbonation. The porosity accessible to water showed changes in all three porous domains: macro, meso and micro pores. This is because of difference in the molecular sizes between water and nitrogen molecules. Although these two techniques are different, they help to complementarily evaluate the effects of carbonation. The results also indicated the influence of type of cement on microstructural evolutions and the correlation between variations of mesopores volume and specific surface area. Changes in microstructure induce changes in macroscopic properties that we also examined such as the solid phase volume using helium pycnometry, the gas permeability, the thermal conductivity, the thermal diffusivity, and the longitudinal and transverse ultrasonic velocities.展开更多
The influences of nano silica (NS) on the hydration and microstructure development of steam cured cement high volume fly ash (40 wt%, CHVFA) system were investigated. The compressive strength of mortars was tested wit...The influences of nano silica (NS) on the hydration and microstructure development of steam cured cement high volume fly ash (40 wt%, CHVFA) system were investigated. The compressive strength of mortars was tested with different NS dosage from 0 to 4%. Results show that the compressive strength is dramatically improved with the increase of NS content up to 3%, and decreases with further increase of NS content (e g, at 4%). Then X?ray diffraction (XRD), differential scanning calorimetry-thermogravimetry (DSCTG), scanning electron microscope (SEM), energy disperse spectroscopy (EDS), mercury intrusion porosimeter (MIP) and nuclear magnetic resonance (NMR) were used to analyze the mechanism. The results reveal that the addition of NS accelerates the hydration of cement and fly ash, decreases the porosity and the content of calcium hydroxide (CH) and increases the polymerization degree of C-S-H thus enhancing the compressive strength of mortars. The interfacial transition zone (ITZ) of CHVFA mortars is also significantly improved by the addition ofNS, embodying in the decrease of Ca/Si ratio and CH enrichment of ITZ.展开更多
Quartz cement as syntaxial overgrowths is one of the most abundant cements in sandstones. Distribution of quartz cement in time and space indicates that the more younger the stratigraphy is, the more smaller the amoun...Quartz cement as syntaxial overgrowths is one of the most abundant cements in sandstones. Distribution of quartz cement in time and space indicates that the more younger the stratigraphy is, the more smaller the amount of quartz cement, and the amount of quartz cement increases with increasing of depth and basin type also is a factor which controls the amount of quartz cement. The sources of silica for quartz cement have many different opinions, but there is one or more dominant sources. Temperature and pH of fluid are major factors which influence the precipitation of quartz cement. There exist three hypotheses on the flow of pore fluid and transport and precipitation of silica, that is, the hypothesis of cycle of shallow underground water, the hypothesis of high concentration of fluid driven by compaction and the hypothesis of diffusion and recycle of local fluid. The research of quartz cement is significant for the timing of paleotemperature, heterogeneity of reservoir, physical property of reservoir and the timing of oil immersion, etc.展开更多
文摘This research aimed to clarify the role of by-product materials, such as CKD with SF as partial replacement by weight of cement in concrete manufacturing and inclusion on different characteristics of concrete. Concrete test specimens were mixed with 0%, 5%, 10%, 15%, 20% and 25% (CKD) with 15% (SF) as partial replacement by weight of Cement (CEM I-52.5N). Fresh concrete properties have been evaluated by workability measurement slump test. While hardened concrete properties have been evaluated by compressive, split tensile and flexural strengths tests at ages 7, 28 and 56 days, but evaluated for bond strength, modulus of elasticity and chemical composition measurement with X-Ray Fluorescence at age of 28 days. The test results have revealed that the increase of CKD amount with fixed amount of SF in concrete mixtures as partial replacement by weight of cement leads to gradual decrease of fresh concrete workability. In concrete mixtures, 20% CKD in the presence of 15% SF as partial replacement by the weight of cement are the optimum ratios which can be used without any negative effect on mechanical properties compressive, indirect tensile, flexural and bond strength at all the ages of concrete. Also modulus of elasticity and bond strength increased by 8.81% and 0.69% respectively at the age 28 days compared with control mixture.
文摘X-ray fluorescence (XRF) analysis utilizes particle size which is resulted from milling of a material. The milling ensures uniform and fine grained powder. The finer and more uniform the particle size is, the better the result and easier it is for material quality control. To ensure uniformity in particle size and finer powder, a comparative analysis was conducted with different grinding aids and pressed pellet method was used in obtaining analysis results. Pressed pellets of cement raw meal sample milled with different grinding aids (graphite, aspirin and lithium borate) were subjected to XRF. Graphite produced better particle size uniformity with a corresponding standard deviation that made quality control of raw meal easier and better than aspirin and lithium borate.
文摘Polymethylmethacrylate(PMMA) bone cement technology has progressed from industrial Plexiglass administration in the 1950 s to the recent advent of nanoparticle additives. Additives have been trialed to address problems with modern bone cements such as the loosening of prosthesis, high post-operative infection rates, and inflammatory reduction in interface integrity. This review aims to assess current additives used in PMMA bone cements and offer an insight regarding future directions for this biomaterial. Low index(< 15%) vitamin E and low index(< 5 g) antibiotic impregnated additives significantly address infection and inflammatory problems, with only modest reductions in mechanical strength. Chitosan(15% w/w PMMA) and silver(1% w/w PMMA) nanoparticles have strong antibacterial activity with no significant reduction in mechanical strength. Future work on PMMA bone cements should focus on trialing combinations of these additives as this may enhance favourable properties.
文摘The aim of this work was to examine the microstructural changes of CEM I standardised cement mortar caused by accelerated carbonation (20% CO2 concentration) using porosity accessible to water and nitrogen adsorption. The conflicted results obtained by these two techniques showed the differences in porous domains explored, while the pore size distributions calculated from nitrogen adsorption provided evolution of the micro and meso pores during carbonation. The porosity accessible to water showed changes in all three porous domains: macro, meso and micro pores. This is because of difference in the molecular sizes between water and nitrogen molecules. Although these two techniques are different, they help to complementarily evaluate the effects of carbonation. The results also indicated the influence of type of cement on microstructural evolutions and the correlation between variations of mesopores volume and specific surface area. Changes in microstructure induce changes in macroscopic properties that we also examined such as the solid phase volume using helium pycnometry, the gas permeability, the thermal conductivity, the thermal diffusivity, and the longitudinal and transverse ultrasonic velocities.
基金Funded by the “13th Five-Year” National Science and Technology Support Program of China(No.2016YFC0701003–05)the Science and Technology Support Program of Hubei Province(No.2015BAA084)the National Natural Science Foundation of China(No.51378408)
文摘The influences of nano silica (NS) on the hydration and microstructure development of steam cured cement high volume fly ash (40 wt%, CHVFA) system were investigated. The compressive strength of mortars was tested with different NS dosage from 0 to 4%. Results show that the compressive strength is dramatically improved with the increase of NS content up to 3%, and decreases with further increase of NS content (e g, at 4%). Then X?ray diffraction (XRD), differential scanning calorimetry-thermogravimetry (DSCTG), scanning electron microscope (SEM), energy disperse spectroscopy (EDS), mercury intrusion porosimeter (MIP) and nuclear magnetic resonance (NMR) were used to analyze the mechanism. The results reveal that the addition of NS accelerates the hydration of cement and fly ash, decreases the porosity and the content of calcium hydroxide (CH) and increases the polymerization degree of C-S-H thus enhancing the compressive strength of mortars. The interfacial transition zone (ITZ) of CHVFA mortars is also significantly improved by the addition ofNS, embodying in the decrease of Ca/Si ratio and CH enrichment of ITZ.
文摘Quartz cement as syntaxial overgrowths is one of the most abundant cements in sandstones. Distribution of quartz cement in time and space indicates that the more younger the stratigraphy is, the more smaller the amount of quartz cement, and the amount of quartz cement increases with increasing of depth and basin type also is a factor which controls the amount of quartz cement. The sources of silica for quartz cement have many different opinions, but there is one or more dominant sources. Temperature and pH of fluid are major factors which influence the precipitation of quartz cement. There exist three hypotheses on the flow of pore fluid and transport and precipitation of silica, that is, the hypothesis of cycle of shallow underground water, the hypothesis of high concentration of fluid driven by compaction and the hypothesis of diffusion and recycle of local fluid. The research of quartz cement is significant for the timing of paleotemperature, heterogeneity of reservoir, physical property of reservoir and the timing of oil immersion, etc.