Comparison of Known and Determined Water-Cement Ratios Using Petrography


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Title: Comparison of Known and Determined Water-Cement Ratios Using Petrography

Author(s): J. J. Liu and M. S. Khan

Publication: Special Publication

Volume: 191


Appears on pages(s): 11-26

Keywords: alkali-silica reaction; concretes; deterioration; freezing and thawing; microscopy; petrography; porosity; water-cement ratio

Date: 12/1/1999

At present, there are no standardized test methods for the determination of water-cement ratio (w/c) of a specimen of hardened concrete. Various methods that have been used include absorption of a water drop on a concrete surface, resistance of cement paste to scratching, polarized-light microscopy, and optical fluorescence microscopy. In these determinations, usually experience and judgment are heavily relied upon. In the absence of a reliable standardized technique, it is prudent to estimate the w/c by using specimens with known w/c and a combination of several techniques, rather than relying on a single technique. The objective of this paper is to demonstrate the successes achieved by following this approach. Concrete specimens with w/c of 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70 were prepared and analyzed by visual examination, resistance to needle scratching, water absorption, and blue-dyed thin section techniques. This combined technique approach was then used to analyze concrete specimens from the field.