Showing papers in "Cement and Concrete Research in 2005"

TL;DR: In this paper, the effects of ground granulated blast furnace slag (GGBFS) on the microstructure and mechanical properties of metakaolin (MK) based geopolymers were studied.

TL;DR: In this paper, the relationship between the mineralogical and microstructural characteristics of activated fly ash mortars and its mechanical properties has been established, and the results of the investigation show that in all cases (whatever the activator used) the main reaction product formed is an alkaline aluminosilicate gel, with low-ordered crystalline structure.

TL;DR: In this article, the degradation of geopolymer materials using a class F fly ash (FA) and alkaline activators when exposed to 5% solutions of acetic and sulfuric acids was studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).

TL;DR: In this article, the compressive strength and the stress-strain curve (SSC) of recycled aggregate concrete (RAC) with different replacement percentages of recycled coarse aggregate (RCA) are investigated experimentally.

TL;DR: In this article, the effect of storing at room temperature before the application of heat on phase composition and phase composition was studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and SEM.

TL;DR: In this article, the effect of temperature in the mineralogical composition of cement hydration products has been studied using thermogravimetric analysis (TGA) and DTG curves, which can be used to determine fire conditions and the consequent deterioration expected in the cement paste.

TL;DR: In this paper, a two-stage mixing approach (TSMA) is proposed to improve the compressive strength for recycled aggregate concrete and hence lower its strength variability, which can fill up some pores and cracks, resulting in a denser concrete, an improved interfacial zone around recycled aggregate and thus a higher strength when compared with the traditional mixing approach.

TL;DR: In this paper, the properties of concrete containing fine recycled aggregate are investigated, and the results show that fine aggregate in concrete was replaced with 0, 25, 50% and 100% crushed concrete (CC) or crushed brick (CB).

TL;DR: In this paper, the microscopic study of a set of alkali-activated and thermally cured fly ash samples enabled the authors to establish a descriptive model for the microstructural development of fly ash-based cementitious geopolymers.

TL;DR: In this article, a water permeability resistant behavior and microstructure of concrete with nano-SiO2 were experimentally studied and it was shown that the micro-structured concrete with SiO2 is more uniform and compact than that of normal concrete.

TL;DR: In this paper, the authors investigated the durability of geopolymer materials manufactured using class F fly ash and alkaline activators when exposed to a sulfate environment and found that the most significant deterioration was observed in the sodium sulfate solution and it appeared to be connected to migration of alkalies into solution.

TL;DR: In this paper, the authors used differential thermal analysis, thermogravimetric analysis (DTA/TGA) and isothermal calorimetry to determine the degree of hydration of blended cements and pozzolan reaction.

TL;DR: In this paper, the morphology, fineness and pozzolanic activity of four glass powders (GP-fine and GP-dust) were investigated from the screening of crushed waste glasses, one from a dust collector for the glass crushing process and two from further grinding of the powder from the dust collector in a ball mill.

TL;DR: In this paper, the strength potential of nylon-fiber-reinforced concrete was investigated versus that of polypropylene fiber reinforced concrete, at a fiber content of 0.6 kg/m 3.

TL;DR: In this paper, experiments and theories on self-compacting concrete are discussed, where the packing behavior of the powders (cement, fly ash, stone powder) and aggregates (three sands and gravel) used are analyzed in detail.

TL;DR: In this paper, the surface microstructure of waste polyethylene terephthalate (PET) bottles lightweight aggregate (WPLA) was investigated to examine the effect of granulated blast-furnace slag (GBFS) on WPLA.

TL;DR: In this paper, the authors synthesize available literature and field experience and provide a framework for understanding the fundamental aspects of air entrainment in concrete, such as concrete temperature, the physical and chemical characteristics of constituent materials, and mixing and placing techniques.

TL;DR: In this article, the effect of test methods on bond strength between concrete substrate and repair material was investigated, and four test methods with cementitious or modified-cementitious repair materials, and two surface roughnesses were studied.

TL;DR: In this paper, a thermophilic anaerobic microorganism is incorporated at different cell concentrations with the mixing water, and a 25% increase in 28 day compressive strength of cement mortar was achieved with the addition of about 105 cell/ml of mixing water.

TL;DR: The authors used finite element procedures combined with knowledge of individual phase moduli, in combination with a cement paste microstructure development model, to predict elastic moduli as a function of degree of hydration, as measured by loss on ignition.

TL;DR: In this article, the flow induced by a smaller cone test for cement pastes and grouts is studied and a modified relation allows the prediction of the plastic yield value from the measured spread.

TL;DR: In this paper, the rheological properties of fine particles, such as mineral admixtures (MA), were investigated using a Rotovisco RT 20 rheometer (Haake) with a cylindrical spindle.

TL;DR: In this article, a study of the hydration of fly ash cement was conducted, in which the influences of the glass content and the basicity of glass phase were clarified and hydration over a long curing time was characterized.

TL;DR: In this paper, the isolated contribution of silica fume on the tensile strengths of high performance concrete (HPC) is investigated. But the results indicate that the optimum replacement percentage is not a constant one but depends on the water-cementitious material (w/cm) ratio of the mix.

TL;DR: In this paper, several superplasticizers (polycarboxylates, vinyl copolymers, melamine and naphthalene-based) and shrinkage-reducing (polypropylenglycol derivatives) admixtures were used to affect the mechanical and rheological properties and setting times of alkali-activated slag pastes and mortars.

TL;DR: Magnesium silicate hydrate gels (M-S-H) have been prepared by precipitation and the range of gel compositions lie between Mg/Si molar ratios 0.67-1.0 as mentioned in this paper.

TL;DR: In this paper, a thixotropic model is presented to predict the trends of the fresh behaviour of cement pastes in various flow situations, and its four parameters are identified experimentally for tested cement paste using coaxial viscometer test.

TL;DR: The contribution of hybrid fibers to the workability, mechanical and shrinkage properties of lightweight concrete (LWC) with high strength and workability was investigated in this paper, which showed that adding fiber to the lightweight concrete mixture greatly reduces the sedimentation of aggregates during mixing and improves the uniformity of the mix; however, the slump value is reduced.

TL;DR: In this article, two different filler types, limestone and quartzite, are considered in combination with different Portland cements, and an existing hydration model for blended cement is modified for these systems.

TL;DR: In this paper, the use of expanded polystyrene (EPS) beads as lightweight aggregate, both in concrete and mortar, has been investigated, and the compressive strength of the EPS concretes containing fly ash showed a continuous gain even up to 90 days.