Hamlin M. Jennings

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Although Portland cement concrete is the world's most widely used manufactured material, basic questions persist regarding its internal structure and water content, and their effect on concrete behaviour. Here, for the first time without recourse to drying methods, we measure the composition and solid density of the principal binding reaction product of(More)
The nanometer-scale structure of cement paste, which is dominated by the colloidal-scale porosity within the C-S-H gel phase, has a controlling effect on concrete properties but is difficult to study due to its delicate structure and lack of long-range order. Here we present results from three experimental techniques that are particularly suited to(More)
The concentrations of Ca, S, Al, Si, Na, and K in the pore solutions of ordinary Portland cement and white Portland cement pastes were measured during the first 28 d of curing at temperatures ranging from 5–50 jC. Saturation indices with respect to solid phases known to form in cement paste were calculated from a thermodynamic analysis of the elemental(More)
Inelastic neutron spectroscopy (INS) was used to determine the content of Ca-OH bonds in a series of mature tricalcium silicate (3CaO‚SiO2) and white portland cement (WPC) pastes that were decalcified to calcium/silicon molar ratios (Ca/Si) as low as 1. These measurements indicate that the band in the INS data at 41 meV, which originates from lattice modes(More)
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(More)
The properties, structure, and behavior of cement paste, including surface area, drying shrinkage, creep, and permeability are discussed with the assumption that the C-S-H gel is an aggregation of precipitated, colloidal-sized particles that undergoes chemical aging. A basic thesis of this paper is that C-S-H particles bond together over time, increasing(More)
Hydrated cement paste has a high specific surface area due almost entirely to the calcium-silicate-hydrate reaction product. The surface area of cement paste is closely related to many crucial properties, including strength and permeability, and is therefore a useful predictive measurement. It is also a useful parameter for studying the nature of the(More)
The Journal of Physical Chemistry C is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Article Influence of Nucleation Seeding on the Hydration Mechanisms of Tricalcium Silicate and Cement Jeffrey J. Thomas, Hamlin M. Jennings, and Jeffrey J. Chen J. Phys. Chem. C, 2009, 113 (11), 4327-4334• DOI:(More)
Cement-based materials have complex multi-component, multiscale structures that first form through chemical reaction and then continue to change with time. As with most classes of materials, the porosity of cement paste strongly influences its properties, including strength, shrinkage, creep, permeability and diffusion. Pores in cement paste range in size(More)