Relationship Between Indentation Hardness and Water to Cement Ratio of Hardened Mortar and Concrete

Accurately estimating the water-to-cementitious materials ratio (w/cm) of hardened concrete is one of the most difficult tasks frequently requested of concrete petrographers. Different methods have been developed and implemented with varying degrees of success. To increase the reliability of estimat...

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Bibliographic Details
Published in:Journal of ASTM International 2006, Vol.3 (2), p.1-7
Main Authors: Cong, DX, Reed, MH, Powers, LJ, Shotwell, BL, Brown, BD
Format: Article
Language:English
Online Access:Get full text
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Summary:Accurately estimating the water-to-cementitious materials ratio (w/cm) of hardened concrete is one of the most difficult tasks frequently requested of concrete petrographers. Different methods have been developed and implemented with varying degrees of success. To increase the reliability of estimated w/cm, the indentation hardness of laboratory prepared specimens of neat paste, mortar, and concrete was evaluated using a Buehler semi-automatic testing machine. Preliminary results indicate good correlations between the average indentation hardness measured on the Rockwell HRL scale and the w/cm of the specimens. The data demonstrate a potential for using these correlations to estimate the w/cm of hardened concrete. Testing protocols, sample preparation requirements, and the effects of aggregate and of the composition of concrete mixtures (portland cement and fly ash content) are illustrated. Directions for future work are also discussed.
ISSN:1546-962X
1546-962X
DOI:10.1520/JAI13060