PSI - Issue 17

Ana Isabel Marques et al. / Procedia Structural Integrity 17 (2019) 1002–1009 Author name / Structural Integrity Procedia 00 (2019) 000–000

1008

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partial ratios obtained with both dynamic methods, there are some sporadic differences, but the majority of the ratio values are acceptably similar (differences under 15%).

Table 4. Ratios between static and dynamic E values for each mortar composition and test parameters sets.

- -

Age [days]

Overall Age Ratios (S. Deviation)

Overall Binder Ratio (S. Deviation)

Mortar Composition

14 21 28 90 14 21 28 90 14 21 28 90 14 21 28 90

1.16 1.12 1.08 1.13 1.05 1.28 1.16 1.18 1.13 1.06 1.32 1.40 1.25 1.24 1.17 1.38 1.30 1.47 1.42 1.36

1.09 1.10 1.17 1.17 1.04 1.27 1.21 1.20 1.13 1.08 1.33 1.40 1.30 1.21 1.11 1.49 1.40 1.60 1.47 1.44

1.12 (0.03)

Ci_1:2

1.11 (0.06)

365

1.23 (0.06)

Ci_1:3

1.13 (0.06)

365

1.25 (0.14)

1.36 (0.04)

Ci_1:4R

1.21 (0.07)

365

1.39 (0.08)

Ci_1:4A

1.46 (0.08)

365

The partial ratios are more reliable than the overall ratios, because apparently different specimen ages or mortar composition influence the ratios and, as a result, cannot be fully discarded. However, specimen age appears to have a distinct impact on ratio values, depending if the specimen is uncured (age below 28 days) or fully cured, probably related to humidity content. This means that a usable overall age based ratio can only be achieved, with acceptable reliability levels, with fully cured mortar ages. While having lower reliability, the overall binder based ratios values can still be useful when access to high quality static E values are impossible to obtain, or for comparison purposes among mortars with some common parameters, or even to estimate static E values for an unknown coating mortar composition by applying the corresponding overall ratio value on available dynamic E values. Another alternative is to consider a ratio range, instead of a single ratio value, to describe cement wall coating mortar as a whole. By only using data from ages corresponding to fully cured cement coating mortars, since those ages are more representative of civil engineering applications, the obtained ratio range is 1.1 to 1.5. Deciding which type of ratio to use is mainly dependent on the actual application at hand, and the data accuracy it requires. Further work is still required on this subject, but the obtained data indicates that proper ratios between static and dynamic E values can be determined for cement coating mortars, and eventually for other types of wall coating mortars.