Showing papers in "Cement and Concrete Research in 2002"

TL;DR: Alkali activation of ground granulated blast furnace slag with sodium silicate gave clinker-free binders, with high strength and early strength development, although set times were short and somewhat variable as mentioned in this paper.

TL;DR: In this paper, a new concept for the prevention of self-desiccation in hardening cement-based materials is proposed based on using fine, superabsorbent polymer (hydrogel, SAP) particles as a concrete admixture.

TL;DR: In this article, a mathematical procedure using spherical harmonic functions is described to characterize concrete aggregate particles and other particles of the same nature in 3D X-ray tomography images, and three main consequences of this procedure are mathematical classification of the shape of aggregates from different sources, comparison of composite performance properties to precise morphological aspects of particles, and incorporation of random particles into manyparticle computational models.

TL;DR: In this paper, the experimental analysis of samples of recycled concrete (RC) with replacement of natural aggregate (NA) by recycled aggregate originating from concrete (RCA) is presented, and the results of the tests of mechanical properties of RC were used for comparison with tests of mercury intrusion porosimetry.

TL;DR: In this paper, the effect of various types of superplasticizers on portland cement component minerals was investigated and the value of the adsorption isotherm was calculated from the amount of the super plasticizer adsorbed on a cement component mineral in an equilibrated solution.

TL;DR: In this article, the results of calorimeter tests on Portland cement-silica fume-fly ash mixtures are presented, showing that the reactionivity of the fly ash is hampered and the hydration of the cementitious system is significantly retarded.

TL;DR: In this article, the fracture energy of concrete, as well as other fracture parameters such as the effective length of the fracture process zone, critical crack-tip opening displacement and the fracture toughness, can be approximately predicted from the standard compression strength, maximum aggregate size, water-cement ratio, and aggregate type (river or crushed).

TL;DR: In this paper, the concept of an efficiency factor is applied as a measure of the relative performance of supplementary cementing materials (SCM) compared with Portland cement, and a mix design strategy to fulfil any requirements for concrete strength and service lifetime was developed and it enables concrete performance to be accurately predicted.

TL;DR: In this paper, the experimental results of mechanical behavior under static and dynamic loads of specimens made of concrete filled with small volumetric fractions of crushed tyre rubber and polypropylene short fibres, at 7 and 28 days, are compared with results of concrete specimens of similar features without fibres or tyre.

TL;DR: In this article, the authors investigated the performance of concrete manufactured with recycled aggregate (RA) using durability indexes as indicators, such as chloride conductivity, oxygen permeability and water sorptivity.

TL;DR: In this article, the main parameters studied were evolution of compressive strength, products of degradation, and microstructural changes of AAS concrete in a sulfate environment, and two tests were used to determine resistance to sulfate attack, which involved immersion in 5% magnesium sulfate and 5% sodium sulfate solutions.

TL;DR: In this article, the authors investigated the relationship between porosity and compressive strength and presented mathematical models that have been developed to describe this relationship and concluded that the equation derived by Hoff could effectively be used to predict the compressive strengths of foamed concrete mixtures containing high percentages of ash.

TL;DR: In this article, the early hydration of alkali-activated blast furnace slag cements was studied using isothermal conduction calorimetry, and the cumulative heat of hydration increases by increasing the n modulus as well as the dosage of water glass, but is still lower than that of Portland cement.

TL;DR: In this article, the authors investigated the effects of sodium and magnesium sulfate solutions on expansion and microstructure of different types of Portland cement mortars and reported that the expansion of mortars in sodium sulfate solution follows a two-stage process.

TL;DR: In this paper, the effect of reinforcement corrosion on the bond properties between concrete and reinforcement was investigated using pullout tests using reinforcements embedded in concrete specimens, which were corroded by an accelerated electric corrosion method.

TL;DR: In this paper, the influence of fly ash in C-A-S-H gels has been investigated and the effect of Al on aluminous supplementary cementing materials such as fly ash into cement pastes has been quantified.

TL;DR: In this paper, the effects of inorganic salt addition towards the setting and rheological characteristics of the early pastes of fly ash-based concrete cements were examined using compressive strength, Fourier transform infrared spectroscopy (FTIR) and X-ray diffractograms.

TL;DR: In this article, the authors present a new approach to design concrete mixtures based upon a set of models relating composition and engineering properties of concrete, to be implemented into software, linked with a material database.

TL;DR: In this paper, the effect of elevated temperatures on the mineralogical changes occurring in the hydrated phases of concrete cubes were studied by measuring ultrasonic pulse velocity (UPV) and consequent deterioration in the compressive strength with increase in temperature.

TL;DR: X-ray diffraction (XRD) analysis of three ladle slag fine samples passing 100, 200 and 325 mesh indicates that the major mineral in the slag fines is γ-C 2 S, which does not show cementitious property in water as mentioned in this paper.

TL;DR: In this paper, the effects of binder type, binder proportion and tailings properties on compressive strength development of paste backfill during the course of curing time were investigated.

TL;DR: In this article, the effect of crushed sand on high-strength concrete has been analyzed using three different types of crushed sands (granite, limestone and dolomite) with similar grading.

TL;DR: In this article, a first-order kinetic model was used to obtain values for overall sorption rate constants and intraparticle diffusion constants, and the Frumkin isotherm was found to be the appropriate equation for modelling isotherms from the experimental adsorption data.

TL;DR: In this article, a micro-structural characterization of cement pastes modified with EVA copolymer was performed, where the pastes were submitted to two different curing conditions, and analyzed at 28 days old, and thermal analyses (differential thermal analysis [DTA] and thermogravimetric [TG] analysis), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) tests were performed, which permitted the evaluation of the EVA effects on the cement hydration.

TL;DR: In this paper, the usability of Basic Oxygen Process (BOP) slags of Kardemir Iron and Steel Plant, Karabuk, Turkey as an additive into cement was investigated.

TL;DR: In this article, the effect of chloride ions on passivity breakdown of steel in simulated concrete pore (SCP) solution was studied using electrochemical techniques, and the sensitivity of cyclic potentiodynamic parameters such as ΔE (difference between Epit and Erep), ipeak and AC-impedance parameters like Rct, Rf, Ci, Rad and Cad to chloride ion concentration was investigated.

TL;DR: In this article, an experimental study on the water permeability and chloride penetrability of high-strength lightweight concrete (LWC) in comparison to that of high strength normal-weight concrete (NWC) with or without silica fume was presented.

TL;DR: In this article, binary and ternary blended cementitious systems based on ordinary Portland cement (OPC), pulverised fuel ash (PFA), and silica fume (SF) were investigated.

TL;DR: In this paper, the differential impedance analysis (DIA) has been applied to the study of the dielectric properties of hardened Portland cement paste, and two time constants are found in the impedance spectra obtained in the frequency region form 100 kHz to 15 MHz.

TL;DR: In this article, aqueous citric acid solution was attempted to purify phosphogypsum and improve its quality to make it fit for manufacture of cement and gypsum plaster for the first time.