Ca−OH Bonding in the C−S−H Gel Phase of Tricalcium Silicate and White Portland Cement Pastes Measured by Inelastic Neutron Scattering

Partial replacement of hydrating Portland cement by fly ash produces competing effects: it contributes calcium hydrate silicate (C-S-H) gel through the pozzolanic and alkali-activated reactions but dilutes the contribution of the main Portland cement reaction. To investigate this, two neutron-scattering methods were applied to density-fractionated lignite-type and bituminous-type fly ash/Portland cement pastes (20% by mass replacement). Small-angle neutron scattering (SANS) measured the effect of the fly ash on the fractal C-S-H microstructure, whereas inelastic neutron scattering (INS) measured the pozzolanic reaction in terms of calcium hydroxide (CH) consumption. The CH consumption increased with the effective density fraction, and the fractal microstructure evolved more slowly for all fly ash mixes compared with the pure cement control. However, gel volume measured by SANS showed no correlation with the CH consumption measured by INS. The implications of these results are discussed.

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State of Water in Hydrating Tricalcium Silicate and Portland Cement Pastes as Measured by Quasi-Elastic Neutron Scattering

Journal of the American Ceramic Society ◽

10.1111/j.1151-2916.2001.tb00919.x ◽

2004 ◽

Vol 84 (8) ◽

pp. 1811-1816 ◽

Cited By ~ 73

Author(s):

Jeffrey J. Thomas ◽

Stephen A. FitzGerald ◽

Dan A. Neumann ◽

Richard A. Livingston

Keyword(s):

Portland Cement ◽

Neutron Scattering ◽

Tricalcium Silicate ◽

Cement Pastes ◽

Elastic Neutron ◽

State Of Water ◽

Elastic Neutron Scattering

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Quasielastic and inelastic neutron scattering study of the hydration of monoclinic and triclinic tricalcium silicate

Chemical Physics ◽

10.1016/j.chemphys.2006.02.016 ◽

2006 ◽

Vol 326 (2-3) ◽

pp. 381-389 ◽

Cited By ~ 15

Author(s):

Vanessa K. Peterson ◽

Craig M. Brown ◽

Richard A. Livingston

Keyword(s):

Neutron Scattering ◽

Inelastic Neutron Scattering ◽

Inelastic Neutron ◽

Tricalcium Silicate ◽

Scattering Study ◽

Neutron Scattering Study

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Inelastic neutron scattering study of the hydration of tricalcium silicate

Journal of Materials Research ◽

10.1557/jmr.1999.0154 ◽

1999 ◽

Vol 14 (3) ◽

pp. 1160-1165 ◽

Cited By ~ 24

Author(s):

S. A. FitzGerald ◽

D. A. Neumann ◽

J. J. Rush ◽

R. J. Kirkpatrick ◽

X. Cong ◽

...

Keyword(s):

Neutron Scattering ◽

Calcium Hydroxide ◽

Inelastic Neutron Scattering ◽

Free Water ◽

Inelastic Neutron ◽

Tricalcium Silicate ◽

Curing Temperature ◽

Water Index ◽

Quasielastic Neutron ◽

Neutron Scattering Study

Inelastic neutron scattering is applied for the first time to monitor directly the concentration of calcium hydroxide formed during the hydration of tricalcium silicate. Results taken between 10 and 40 °C show that the onset of calcium hydroxide formation is delayed at lower temperatures but that the final quantity formed appears to be converging to a temperature-independent value. At 20°C, the 28 day value is 1.3 moles per mole of tricalcium silicate. Combining these results with previous measurements of the free water index made using quasielastic neutron scattering reveals that the hydrogen content of the C–S–H gel decreases significantly at increased curing temperature.

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