Micro- and nano-structural evolutions in white Portland cement/pulverized fuel ash cement pastes due to deionized-water leaching

Journal Article · Mon Jan 15 04:00:00 EST 2018 · Cement and Concrete Research

DOI:https://doi.org/10.1016/J.CEMCONRES.2017.10.014· OSTI ID:22806452

Jia, Shanshan

Thin slices of white Portland cement-low calcium pulverized fuel ash (pfa) blended cement pastes containing 30 or 50% pfa were leached progressively in de-ionized water. The paste with 50% pfa was aged 13 years prior to leaching and those with 30% pfa were aged 1 and 13 years. Pastes were leached for up to 75 days and were characterized using thermal analysis, X-ray diffraction, analytical scanning and transmission electron microscopy, and solid-state nuclear magnetic resonance spectroscopy. Leaching affected the pastes in the following sequence: (i) crystals of Ca(OH){sub 2} large enough to be resolved by backscattered electron imaging were removed completely prior to any effect on C-A-S-H; (ii) the Ca/Si ratio of C-A-S-H reduced from ≈ 1.4 to ≈ 1.0 whilst the aluminosilicate structure was unaffected; (iii) further reduction in the Ca/Si ratio of C-A-S-H was accompanied by lengthening of the aluminosilicate chains; (iv) the Ca/Si ratio of C-A-S-H reduced ultimately to ≈ 0.6.

• OSTI ID: 22806452
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Vol. 103; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CALCIUM
CALCIUM HYDROXIDES
CALCIUM SILICATES
CRYSTALS
FLY ASH
LEACHING
NUCLEAR MAGNETIC RESONANCE
PORTLAND CEMENT
PULVERIZED FUELS
RADIOACTIVE WASTES
SPECTROSCOPY
THERMAL ANALYSIS
TRANSMISSION ELECTRON MICROSCOPY
WATER
X-RAY DIFFRACTION