Moisture flow in porous media is the driving force behind early age drying shrinkage. Fracture in the interfacial transition zone (ITZ), between cement paste and aggregateinclusion, is related to restraint caused by, among others, aggregates that obstruct free deformation of the paste. Environmental Scanning Electron Microscope (ESEM) test results are used as a base for the developed method for...

Attack of Portland cement by ambient sulfates presents a considerable risk to structures in some environments. In this study, x-ray microtomography, a high resolution variant of medical “CT”, noninvasively mapped the progression of damage in Portland cement resulting from exposure to an aqueous solution of Na2SO4 (sodium ion concentration of 10,000 ppm). Cement paste samples from water-to-cemen...

Small-angle neutron scattering was used to measure the effect of water-to-cement ratio (w/c) and cement batch variation on the surface area of ordinary Portland cement (OPC) paste after hydration for 28 days at room temperature, and to measure the development of surface area over the first three days of hydration at 30 ̊C. The 28 day surface area was found to increase with w/c ratio in proportio...

Synopsis The hydration behavior of Portland cement and C 3 S with and without stress applied were studied at water to solid (w/s) ratios of 0.35 and 0.50. A greater degree of hydration and denser microstructure were obtained with hydration under stress at an early stage of the hydration process, normally within 48 hours. This observation was confirmed by the determination and comparison of CH c...

INTRODUCTION The setting times of commercial mineral trioxide aggregate (MTA) and Portland cements vary. It was hypothesized that much of this variation was caused by differences in particle size distribution. METHODS Two gram samples from 11 MTA-type cements were analyzed by laser diffraction to determine their particle size distributions characterized by their percentile equivalent diameter...

Rheological study constructs a non-equilibrium thermodynamic model of cement paste.