Showing papers in "Cement and Concrete Research in 1995"

TL;DR: In this paper, the authors developed an ultra-high strength ductile concrete designated RPC (Reactive Powder Concrete), which was made possible by the application of a certain number of basic principles relating to the composition, mixing and post set heat curing of the concrete.

TL;DR: In this article, the changes of the properties for the rubberized concretes were investigated in terms of both size and amount of the rubber chips, and it was observed that plastic energy capacities began to increase when the high elastic energy capacity of normal concrete was reduced by adding rubber.

TL;DR: In this paper, the effect of the sand content on the development of pore structure, the permeability to water, and the diffusivity of chloride ions was studied on portland cement mortars.

TL;DR: In this paper, the compressive strength of mortars based on the raw clays is affected by structure of clays, and a close correlation exists between the clays' pozzolanic activity and the particle size distribution of dehydroxylated clays.

TL;DR: In this paper, the maximum penetration of localized attack on steel embedded in concrete containing chlorides was found to be about four to eight times the average general penetration of the deepest pits.

TL;DR: In this paper, the authors examined the early hydration of alkali-slag cements activated by different sodium compounds, such as NaOH, NaCO3, Na2SiO3 and NaF, at 25 and 50 °C.

TL;DR: In this article, a study of several RPC compositions by Mercury Porosimetry, Thermogravimetric Analysis and X-ray diffraction made it possible to better understand their microstructural properties depending on their heat treatment.

TL;DR: In this article, influences of cement, chemical admixture, mineral admixture and water-cement ratio on the autogenous shrinkage of cement paste were experimentally studied, and some admixtures which were able to reduce autogeneous shrinkage were found.

TL;DR: In this paper, the suitability of a particular binder system for an application based on fresh concrete properties and mechanical properties was evaluated for concrete mixes having a fixed waterbinder ratio of 0.35 and a constant total binder content of 430 kg/m3.

TL;DR: In this article, the authors focus on the evolution of the heat of hydration of hardening concrete or cement based materials and propose a new general hydration model based on isothermal and adiabatic hydration tests, valid for portland cement and blast furnace slag cement.

TL;DR: In this article, a computer-based numerical model is presented, with which hydration and microstructural development in Portland cement-based materials can be simulated, enabling the prediction of hydration curves as a function of the particle size distribution and chemical composition of the cement, the water/cement ratio and actual reaction temperature.

TL;DR: In this article, the physical and chemical properties of thermally activated alumino-silicate material (MK) were investigated for fresh and hardened concrete incorporating this material, and the results indicated that the material is highly pozzolanic and can be used as a supplementary cementing material to produce high-performance concrete.

TL;DR: In this article, various mechanical properties of concretes were examined and it was observed that as the amount of WCA increases, density, compressive strength, modulus of elasticity and value of toughness decrease.

TL;DR: In this paper, chemical shrinkage of cement was calculated from chemical equation of hydration, it was compared with observed one and relationship between them was clearly described and defined by definition of chemical shrinkages and autogenous shrinkage was made.

TL;DR: In this paper, a macroscopic stress due to the capillary depression and characterisation of the viscoelastic aging behavior of the material was introduced, and the result was in satisfactory agreement with measurements.

TL;DR: In this article, a new mechanism has been proposed to explain the delayed expansions due to the presence of dead-burnt CaO or MgO, of Portland cement based materials, based on the crystal growth pressure, the solubility of hydroxide crystals, their growth habits and diffusion of Ca2+ and Mg2+ through the electrical double layer which forms round cement hydration products.

TL;DR: In this paper, the authors measured the fluidity, setting time and time dependency of fluidity using fresh cement paste prepared with four kinds of organic admixtures, polycar-ylic acid-based, aminosulfonic acid based, β-naphthalenesulfonic acids-based and lignin sulfonic acidbased, by two different methods of addition, together with mixing water (simultaneous addition) and specified time after mixing with water (later addition).

TL;DR: Chloride binding and its influence on the rate of reinforcement corrosion has been investigated in a range of mixes by pore solution analysis and measuring the galvanic current in macro corrosion cells formed by embedding mild steel bars in two layers of concrete as discussed by the authors.

TL;DR: In this article, a set of high performance concrete mixes, of low water cement ratio and fixed mortar composition, containing six different types of aggregates of constant volume fraction, has been used to check moduli of elasticity at 7, 28 and 91 days.

TL;DR: In this article, the composite mechanism of polymer modified cement (PMC) and mortar has been studied by using particle dispersion of polymer and the formation of polymer films as a composite mechanism.

TL;DR: In this article, the authors present a constitutive macromechanical model for concrete in compression, named the Compressive Damage Zone (CDZ) model, based on the hypothesis of compressive failure within a zone of limited length.

TL;DR: In this article, three cements with variable C3A contents were mixed with different levels of chloride, alkali and sulfate contents to study the effect of these parameters on pore solution composition.

TL;DR: The microcracking and self-healing mechanisms of concrete exposed to rapid freezing and thawing in water and subsequently kept in water have been investigated by Scanning Electron Microscopy (SEM) as mentioned in this paper.

TL;DR: In this paper, it was proved that autogenous shrinkage of high-strength concrete could be almost the same as drying shrinkage, even in water, for cement paste with low water-cement ratio.

TL;DR: In this paper, the effect of various chemical activators on strength of lime fly-ash pastes manufactured with two types of fly ash (LFA) and a high calcium subbituminous ash (HFA) was evaluated.

TL;DR: In this article, the compressive strengths of silica fume cement paste and mortar were evaluated at various water-cementitious ratios and it was shown that the increase in compressive strength of mortar containing silica-fume, as a partial replacement for cement, greatly contributes to strengthening the bond between the cement mixture and aggregate.

TL;DR: In this article, the elastic behavior of mortar and concrete as a composite material and the influence of the transition zone on the elastic modulus is studied, and the theoretical bounds of Hashin-Shtrikman for the modulus of elasticity of two-phase composite material are used as a criteria in the analysis.

TL;DR: In this paper, the authors extended the one-dimensional finite element model for the analysis of the carbonation mechanism to two-dimensional problems, where the governing equations for the propagation of aggressive agents through concrete are rewritten for two-dimensions.

TL;DR: In this article, the authors describe a very rapid test that measures the permeability of concrete to chloride ions, which involves saturating a concrete sample with a 5 M NaCl solution, before measuring the conductivity of the sample.