Showing papers on "Cement published in 2009"
TL;DR: In this article, the authors evaluated the environmental impact of four cement manufacturing processes: (1) the production of traditional Portland cement, (2) blended cement (natural pozzolans), (3) cement where 100% of waste cement kiln dust is recycled into the kiln process, and (4) Portland cement produced when CKD is used to sequester a portion of the process related CO2 emissions.
994 citations
TL;DR: In this paper, a composite cement material is prepared from cement material and carbon nanotubes, wherein the carbon-nanotubes are present from about 002 wt % to about 1 0 % based on the weight of the cement material.
624 citations
TL;DR: In this paper, an overview of the use of metakaolin as partial replacement of cement in mortar and concrete is presented, and properties reported in this paper are the fresh mortar/concrete properties, mechanical and durability properties.
623 citations
TL;DR: In this article, the performance of concrete mixtures incorporating 5%, 7.5% and 10% of discarded tyre rubber as aggregate and cement replacements was investigated, and the results showed that with up to 5% replacement, in each set, no major changes on concrete characteristics would occur, however, with further increase in replacement ratios considerable changes were observed.
591 citations
TL;DR: It is concluded that further research on the phase development during cement hydration in the presence of heavy metals and thermodynamic modelling is needed to improve effectiveness of cement-based s/s and extend this waste management technique.
496 citations
TL;DR: In this article, the authors employed Diffuse Reflectance Infrared DR-FTIR spectroscopy to monitor chemical transformations in pastes of Portland limestone cement and concluded that the setting is caused by interparticle coalescence of C-S-H.
489 citations
TL;DR: In this article, the suitability of using more sustainable concrete for wind turbine foundations and other applications involving large quantities of concrete was investigated, which was accomplished by partial replacement of cement with large volumes of fly ash or blast furnace slag and by using recycled concrete aggregate.
470 citations
TL;DR: Puertas et al. as mentioned in this paper investigated the feasibility of using and alkaline activated ground Turkish slag to produce a mortar without Portland cement (PC) by using three different activators: liquid sodium silicate (LSS), sodium hydroxide (SH) and sodium carbonate (SC) at different sodium concentrations.
467 citations
TL;DR: It was observed thatSteel slag used as a coarse aggregate improved the mechanical properties of asphalt mixtures and volume resistivity values demonstrated that the electrical conductivity of steel slag mixtures were better than that of limestone mixtures.
405 citations
TL;DR: The fly ashes contained significant levels of chloride and sulphate and it is suggested that the performance of fly ash-cement binders could be improved by the removal or control of these chemical species.
368 citations
TL;DR: In this article, the authors evaluated the properties of concrete made with crushed bricks replacing natural aggregates and found that the results indicated that ceramic residuals could be used as partial replacement of natural aggregate without reduction of concrete properties for 15% replacement and with reductions up to 20% for 30% replacement.
TL;DR: Results indicate that PET-filled concrete, when volume proportion and particle size of PET increased, showed a decrease in compressive strength, splitting tensile strength, modulus of elasticity and ultrasonic pulse velocity; however, the water absorption increased.
TL;DR: In this paper, experimental results on the use of Portland cement in the modification and stabilization of soils in the state of Washington, USA, were presented, which showed significant improvement in drying rate, workability, unconfined compressive strength, and shear strength.
TL;DR: In this paper, the effect of the presence of water-soluble polymers on the cement hydration reactions is investigated by means of isothermal calorimetry, thermal analysis, FT-IR spectroscopy and SEM investigation.
TL;DR: In this article, the authors describe laboratory drained standard triaxial tests conducted on artificially cemented Osorio sand specimens reinforced with randomly oriented discrete extensible polypropylene fibers, showing that fiber reinforcement increases peak strength, increases ultimate strength, decreases stiffness and changes the cemented sand brittle behavior to a more ductile one.
TL;DR: In this article, the authors presented a study which assessed the technologies that could be used for CO2 capture in cement plants, their costs, and barriers to their use, and the work covered new-build cement plants with postcombustion and oxy-combustions CO2 Capture and Storage (CCS) technologies.
TL;DR: In this article, the physical properties of concrete containing ground bagasse ash (BA) including compressive strength, water permeability, and heat evolution, were investigated, and it was shown that concrete samples containing 10-30% ground basse ash by weight of binder had greater compressive strengths than the control concrete.
TL;DR: In this article, an extensive experimental study on the compressive and splitting tensile strength of high-strength concrete with and without polypropylene (PP) fibers after heating to 600°C was presented.
TL;DR: In this article, the influence of SLWA volume and type on the internal humidity, autogenous shrinkage, and restrained shrinkage cracking behavior of concrete was examined under sealed and unsealed conditions, and the performance of each system was related to the cavitation of vapor-filled space in the paste, the SLWA spacing, and pore structure of the paste in relation to the LWA.
Abstract: Low water to cement ratio (w/c) concrete exhibits increased occurrences of early-age shrinkage cracking. These occurrences have spawned innovative developments in concrete mixture design that reduce the risk of cracking. One such development is internal curing, which utilizes the inclusion of saturated lightweight aggregate (SLWA). The SLWA supplies additional moisture to cement paste as it hydrates thereby counteracting the effects of self-desiccation. This paper presents results from a study that examined mortar systems with different volumes of SLWA under sealed and unsealed conditions. Specifically, the results indicate the influence of SLWA volume and type on the internal humidity, autogenous shrinkage, and restrained shrinkage cracking behavior. The performance of each system is shown to be related to the cavitation of vapor-filled space in the paste, the SLWA spacing, and the pore structure of the paste in relation to the LWA.
TL;DR: The results showed that ANN can be an alternative approach for the predicting the compressive strength of ground granulated blast furnace slag concrete using concrete ingredients as input parameters.
TL;DR: In this article, a 30-year old well from a natural CO2 production reservoir was investigated and the results were used as part of the CO2 Capture Project's effort to assess wellbore integrity performance in CO2 storage sites.
TL;DR: In this paper, two sets of experiments on typical Class G well cement were carried out in the laboratory to understand better the potential processes involved in well leakage in the presence of CO2.
TL;DR: In this paper, the authors examined the relative influences of ITZ and micro-cracking on the oxygen diffusivity, oxygen permeability and water sorptivity of cement-based materials.
Abstract: Available experimental investigations on the effect of the aggregate–paste ‘interfacial transition zone' (ITZ) on mass transport properties of cement-based materials appear to be ambiguous. While some studies have found a deleterious effect of the ITZ, results from others seem to suggest otherwise. The present study examines the relative influences of ITZ and microcracking on the oxygen diffusivity, oxygen permeability and water sorptivity, to further enhance understanding of the links between microstructure and transport properties. Specimens of several neat cement pastes, mortars and concretes were prepared and tested. Variables include water/cement (w/c) ratio (0·3 and 0·5), binder type (CEM I and CEM II with 8% silica fume), curing period (3 and 90 days), aggregate volume fraction (0–70%) and preconditioning temperature (50°C and 105°C). 105°C drying was adapted to induce microcracking. Backscattered electron microscopy and image analysis were applied to characterise the microstructure, in particular ...
TL;DR: A new type of steel slag-fly ash-phosphogypsum solidified material totally composed with solid wastes to be utilized as road base material that has higher early strength and long-term strength is much higher than cement stabilized granular materials.
TL;DR: In this article, a hydration kinetics model for Portland cement is formulated based on thermodynamics of multiphase porous media, and the mechanism of cement hydration is discussed based on literature review.
TL;DR: In this article, the consequences of external sulfate attack were investigated by traditional test methods, including length and mass change, as well as by a newly developed, surface sensitive ultrasonic method, using Leaky Rayleigh waves (1 MHz).
TL;DR: In this paper, the authors used bacteria induced calcium carbonate precipitation as a novel and environmentally friendly approach to produce a protective layer on the surface of cement-based materials in the study, where physical and chemical properties of the obtained layer were examined.
TL;DR: The study shows that the unconfined compressive strength of specimens with the ISSA/cement addition was improved to approximately 3-7 times better than that of the untreated soil; furthermore, the swelling behavior was also effectively reduced as much as 10-60% for those samples.
TL;DR: In this paper, the effect of various amounts of limestone on compressive strength, water penetration, sorptivity, electrical resistivity and rapid chloride permeability on concretes produced by using a combination of Portland limestone and limestone at 28, 90 and 180 days.
Abstract: The benefits of limestone as a partial replacement for Portland Cement (PC) are well established. Economic and environmental advantages by reducing CO2 emissions are well known. The paper describes the effect of various amounts of limestone on compressive strength, water penetration, sorptivity, electrical resistivity and rapid chloride permeability on concretes produced by using a combination of PC and limestone at 28, 90 and 180 days. The percentages of limestone that replace PC in this research are 0%, 5%, 10%, 15% and 20% by mass. The water/(clinker + limestone) or (w/b) ratios are 0.37, 0.45 and 0.55 having a constant total binder content of 350 kg/m3. Generally, results show that the Portland limestone cement (PLC) concretes having up to 10% limestone provide competitive properties with PC concretes.
TL;DR: In this article, the influence of binder type and dosage on the mechanical properties and microstructure of CPB was investigated using ordinary Portland cement (OPC), Portland composite cement (PCC), and sulphate resistant cement (SRC).
Abstract: In this study, the influence of binder type and dosage on the mechanical properties and microstructure of cemented paste backfill (CPB) was investigated using ordinary Portland cement (OPC), Portland composite cement (PCC) and sulphate resistant cement (SRC). The CPB samples of OPC and PCC were observed to lose their unconfined compressive strengths (UCSs) after 56 days. This could be associated with the sulphide moiety of the tailings, i.e. the attack on hydration products by sulphate and acid internally generated via the oxidation of pyrite present. In this respect, those CPB samples of sulphate resistant-based cements (SRC and a mix of OPC and SRC) maintained good long-term strengths and stability (i.e. no loss of strength). Increasing binder dosage (5–7 wt.%) improved the UCSs of CPB samples up to 1.9-fold with no loss of strength at >5 wt.%. Decreasing water-to-cement ratio appeared to produce a beneficial effect on the UCSs of CPB samples. SEM studies have provided further insight into the microstucture of CPB and confirmed the deleterious formation of gypsum as the expansive phase. These findings have demonstrated the practical importance of binder type/dosage and water-to-cement ratio for the short- and long-term mechanical performance of CPB.