Showing papers in "Cement and Concrete Research in 2011"

TL;DR: In this article, a new analysis tool was developed to quantify the experimentally observed changes in morphology of portlandite, allowing the calculation of the relative surface energies of the crystal facets.

TL;DR: The use of silica-rich SCMs influences the amount and kind of hydrates formed and thus the volume, the porosity and finally the durability of these materials.

TL;DR: The current state of knowledge of cement hydration mechanisms is reviewed, including the origin of the period of slow reaction in alite and cement, the nature of the acceleration period, the role of calcium sulfate in modifying the reaction rate of tricalcium aluminate, the interactions of silicates and aluminates, and the kinetics of the deceleration period as mentioned in this paper.

TL;DR: In this paper, four promising alternative binders available as alternatives to Portland cement are discussed, namely calcium aluminate cement, calcium sulfoaluminate cements, alkali-activated binders, and supersulfated cements.

TL;DR: Aluminosilicate-based alkaline cements have been classified into five categories as discussed by the authors, and the key advances made in the understanding of synthetic gels are discussed, which ultimately finds hybrid cements to be technologically viable materials for contemporary construction.

TL;DR: According to the International Energy Agency, the main levers for cement producers are the increase in energy efficiency and the use of alternative materials, be it as fuel or raw materials as mentioned in this paper, and therefore, the cement industry worldwide is facing growing challenges in conserving material and energy resources, as well as reducing its CO 2 emissions.

TL;DR: In this article, the effect of minor additions of limestone powder on the properties of fly ash blended cements was investigated using isothermal calorimetry, thermogravimetry (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) techniques, and pore solution analysis.

TL;DR: In this article, the compatibility relationship between C-A-S-H and N-Aluminum-modified calcium silicate hydrate (C-A,S,H) gels is assessed.

TL;DR: In this article, the microstructure of three AASs with MgO contents between 8 and 13.5% were investigated and the formation of C(−−A)−S−H and a hydrotalcite-like phase was observed in all samples by X-ray diffraction (XRD), thermal analysis (TGA) and scanning electron microscopy (SEM) techniques.

TL;DR: In this article, the hydration of two slags with different Al 2 O 3 contents activated with sodium hydroxide and hydrous sodium metasilicate (commonly named water glass) was studied using a multi-method approach.

TL;DR: In this paper, the decomposition of three clayey structures (kaolinite, illite and montmorillonite) when thermally treated at 600 degrees C and 800 degrees C was investigated and the effect of this treatment on their pozzolanic activity in cementitious materials.

TL;DR: In this article, the authors discuss the underlying principles of hydration and recent evidence for the mechanisms governing this process in both Portland cements and other cementitious materials, and the impact of supplementary materials on hydration considered.

TL;DR: In this paper, the effects on microstructure and composition of cement paste caused by the most common drying techniques, including direct drying (oven, microwave, D-Drying, P-drying, and freeze drying) and solvent exchange methods, are reviewed.

TL;DR: In this paper, the impact on hydration of several classes of chemicals is reviewed with an emphasis on the current understanding of interactions with cement chemistry, including setting retarders, accelerators, and water reducing dispersants.

TL;DR: In this paper, the authors evaluated the mechanical and durability performance of concretes produced using alkali silicate-activated ground granulated blast furnace slag as sole binder.

TL;DR: In this paper, the authors investigated the contribution of each phase to the strength and damage response of concrete, 2D and 3D meso-scale simulations based on a coupled plasticity-damage model are carried out.

TL;DR: In this article, the effect of supplementary cementing materials (SCM) on alkali-silica reaction (ASR) was studied and it was shown that the efficacy of SCM is dependent on the composition of the SCM.

TL;DR: In this paper, a review of recent efforts to model and simulate the highly complex cement hydration process over the past 40 years are reviewed, covering different modeling approaches such as single particle models, mathematical nucleation and growth models, and vector and lattice-based approaches to simulate microstructure development.

TL;DR: In this paper, the influence of replacing natural coarse aggregate with recycled concrete aggregate (RCA) has been investigated on concrete bond strength with reinforcing steel, and two sources of RCA were used along with one natural aggregate source.

TL;DR: In this paper, the authors reviewed the literature related to the properties of fresh and hardened concrete published after the previous (12th) International Congress on the Chemistry of Cement held in Montreal in 2007.

TL;DR: In this article, the effect of Rice husk ash (RHA) and silica fume (SF) on the hydration and microstructure development of UHPC was investigated.

TL;DR: In this article, the authors provide a context for innovative development through a review of what is meant by a hydraulic cementitious binder, identification of key physico-chemical properties of successful binders and how novel systems generally rely on similar factors.

TL;DR: In this article, the effect of the fiber orientation distribution on the tensile behavior of UHPFRCC was investigated in two stages; precracking and post-cracking tensile behaviors.

TL;DR: In this article, the effect of temperature on thermal and mechanical properties of self-consolidating concrete (SCC) and fiber reinforced SCC (FRSCC) was presented. And the results showed that the presence of steel fibers enhances high temperature splitting tensile strength and elastic modulus of SCC.

TL;DR: In this article, a promising external standard method, first described by O'Connor, was used to determine the quantitative phase composition of a hydrating cement paste, and the results indicated that the method used is absolutely to be recommended for the examination of OPC pastes, since it displays many advantages in comparison to internal standard methods and other methods.

TL;DR: In this paper, a vectorized rheograph with boxes for various types of self compacting concrete is proposed, where different applications and types of concrete like slipform, underwater, and high strength are described by workability boxes.

TL;DR: In this paper, a micromechanical explanation for the hydration degree-strength relationship of cement pastes and mortars covering a large range of compositions is presented. But the authors do not consider the microstructural material characteristics which drive this dependence.

TL;DR: In this article, XRD measurements of the hydration of synthetical cement (SyCem) were used to calculate the resulting heat flow from changes in the phase content, and the comparison with data recorded from heat flow calorimetry was in good agreement with the calculated heat flow.

TL;DR: In this article, a simple aqueous-solid solution model of C-S-H (calcium silicate hydrate) is used in studies of cement hydration and waste-cement interactions.

TL;DR: In this paper, the formation of brucite by hydration of a light-burned periclase (MgO) was investigated, and it was shown that the pH of systems rich in MgO tended towards the pH controlled by residual brucites.