A critical evaluation of shrinkage of saturated cement paste due to thermal cycling, increased ion diffusion through saturated cement paste due to thermal cycling, Powers water permeability data of dried and resaturated cement paste, and dying shrinkage data of Pickett and others reveals an intrinsic instability of Portland cement pastes. The instability is such that even a very mild treatment ...

The objective of this study was to evaluate the sealing ability and antibacterial activity of Ca3SiO5/CaCl2 composite cement. Fifty maxillary anterior teeth were instrumented according to step-back technique and filled with experimental and control materials. To evaluate the sealing ability, a fluid transport model using glucose was employed for quantitative analysis of endodontic microleakage....

Decalcification of cement paste in concrete is associated with several modes of chemical degradation including leaching, carbonation and sulfate attack. The primary aim of the current study was to investigate the effects of decalcification under saturated conditions on the dimensional stability of cement paste. Thin (0.8 mm) specimens of tricalcium silicate (C3S) paste, white portland cement (W...

The properties of graphene oxide (GO)-based cement paste can be significantly affected by the state of GO dispersion. In this study, the effects of uniformly dispersed and re-agglomerated GO on the rheological, mechanical properties and microstructure of cement paste were systematically investigated. Two distinct dispersion states can be achieved by altering the mixing sequence: Polycarboxylate...

A rapid cyclic voltammetric method for studying the influence of cement factors on the corrosion of embedded iron and steel in hardened cement paste is described. The technique employs a “cement electrode” consisting of an iron or steel wire embedded in a miniature cylinder of hardened cement paste. The rapid cyclic voltammetric method is fast, reproducible, and provides information on the corr...

This paper systematically studied the modification of cement-based materials by nano-SiO₂ particles with an average diameter of about 20 nm. In order to obtain the effect of nano-SiO₂ particles on the mechanical properties, hydration, and pore structure of cement-based materials, adding 1%, 3%, and 5% content of nano-SiO₂ in cement paste, respectively. The results showed that the reaction of na...

Exposure conditions significantly affect the resistance of cement to sulfate attack. This article investigates the effect of sulfate on electrical conductivity of ordinary Portland cement (OPC). Cement paste specimens were prepared according to water/cement (W/C) ratio equal 0.25 either free of sodium sulfate or its addition with concentrations of 5000ppm, 10000ppm and 15000ppm by weight. This ...

this study is concerned with the synthesizing of cu-zn nano-ferrite particles in the laboratory applying simple techniques. the morphology of the synthesized nano-particles was analyzed using transmission electron microscopy (tem), and the minerals were identified using x-ray diffraction (xrd). the nano material was used to replace 1- 4 percent by weight of portland cement in cement pastes and ...

BACKGROUND The purpose of this study was to evaluate the effect of dehydration of resin-modified glass ionomer powder/liquid system, resin-modified glass ionomer paste/paste luting cements in three different quantities and to compare them with a conventional glass ionomer luting cement using confocal laser scanning microscope. MATERIALS AND METHODS A conventional glass ionomer (Group I), a re...

a r t i c l e i n f o A powerful and robust numerical homogenization method based on fast Fourier transform (FFT) is formulated to identify the viscoelastic behavior of calcium silicate hydrates (C-S-H) in hardened cement paste from its heterogeneous composition. The identification is contingent upon the linearity of the creep law. To characterize cement paste microstructure, the model develope...