White Portland Cement Pastes Research Articles

Surface-to-Volume Ratio of Porous Materials Obtained by a Combined Use of NMR and MIP

Porous materials are characterized by a finite and discrete number of pore radii by deconvoluting the respective mercury intrusion porosimetry (MIP) curves. Introducing a perturbed cylindrical pore model enables these MIP radii to be correlated to the NMR spin−lattice relaxation time T1 of the pore-confined water to give the surface-to-volume ratio (S/V) of the pores. The technique is exemplified using four different well-hydrated white Portland cement pastes covering a wide distribution of pore sizes. However, the technique should be of general use when characterizing high surface-to-volume ratio materials.

The influence of ethanolamines on the surface properties of Portland cement pastes

The effect of ethanolamines-monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA) -on the pore-size distribution of the white Portland cement pastes (white PC) has been investigated. The cement pastes with and without admixtures were cured at various hydration times ranging from 1 day to 90 days. Cumulative pore areas and total pore volumes of the samples obtained from nitrogen desorption isotherms were presented along with pore-size distributions calculated using the method of Dollimore and Heal.

The influence of ethanolamines on the hydration and mechanical properties of portland cement

The effect of ethanolamines—monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA)—on the hydration, mechanical and surface properties of the white Portland cement pastes (white PC) has been investigated. The cement pastes with and without admixtures were cured at various hydration times ranging from 1 day to 90 days. Hydration development of cement pastes were followed by setting times, flexural and compressive strengths, specific surface area measurements and thermal analysis techniques. The measurements showed that all these admixtures retard the hydration of white Portland cement in order TEA>DEA>MEA.

The thixotropic behavior of white Portland cement pastes

In the present work the approach suggested by Cheng and Evans has been taken into account in order to derive a constitutive equation capable for characterizing completely the flow behavior of white Portland cement pastes. To this end, pastes were produced with a w/c ratio ranging from 0.36 to 0.42. The rheological tests were accomplished with the rotating coaxial cylinder viscometer Rotovisko-Haake 3. The material to be tested was subjected immediately after mixing to a constant shear rate. The rheological parameters derived from the constitutive equation were correlated with some compositive parameters of the pastes.