PSI - Issue 23

Małgorzata Lenart et al. / Procedia Structural Integrity 23 (2019) 113 – 118 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Table 2. The composition of tested mortars.

Mortar composition [g/batch]

Mortar

Cement

Water

Sand 1350 1215

Granulate Admixture

C – Control

–

–

450 450 450 450 450 450 450

225 225 225 225 225 225 225

0.45 1.35 3.15 1.35 3.15 4.50

A1 – 10% 1 day granulate A2 – 25% 1 day granulate A3 – 50% 1 day granulate B1 – 10% 14 days granulate B2 – 25% 14 days granulate B3 – 50% 14 days granulate

135

1012.5

337.5

675

675 135

1215

1012.5

337.5

675

675

In the method of automatic shrinkage measurement, the mortar was laid in gutters and after about an hour from its placing the electronic measuring set was started. Whereas, benchmarks were installed in steel molds and then the mortar was laid and compacted in the Graff-Kaufmann method. Three beams were made for each type of mortar. Molds with mortars covered with PE-foil (0.1 mm) were stored for 24 hours in a laboratory at 18 o C and 55% humidity, then they were demolded and the first measurement of the length of individual samples was made. Differences in the storage conditions of samples result from standard testing procedures and have an impact on the obtained values of shrinkage measurements. The changes in mass of the specimens caused by desiccation should be given to support the results and conclusion of performer measurements. Figure 3 shows the view of the automatic gutters measurement stand as well as beams used in Graff-Kaufmann method and stored under the same conditions. Beams and mortars in gutters were stored in a laboratory at 20 o C and 45% humidity.

Fig. 3. Measurement site for automatic shrinkage gutters and the beams used in the Graff-Kaufmann method.

3. Results and analysis of the test results

Figure 4 shows the average measurement results obtained in the Graff-Kaufmann method. This method is characterized by simplicity. Unfortunately its disadvantage is that the first measurement is made after demolding and hardening of the beams. This test procedure means that there is no possibility to measure the early volume changes of the cementitious composite.