2.2.2. Autogenous Shrinkage

The autogenous shrinkage was assessed according to the methodology developed by [36], which is a modified method of [37] using the [38] apparatus, shown in Figure 3. The test consists of the measurement of the deformation of mortars, cast in a prismatic mold with nominal dimensions of 7.5 × 7.5 × 28.5 cm. Each mold was previously prepared, with polystyrene layers inside to decrease friction, allowing the concrete to move freely. Additionally, two threaded metal pins were placed in the extremities of the mold aligned with the specimen's longitudinal axis. Strain gauges are couples in these pins and connected to a computer to collect and store the data. The distance between these pins is called G, and the measurement of this distance determines the shrinkage.

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(**b**)

**Figure 3.** Autogenous shrinkage test: (**a**) test setup scheme and (**b**) on going test.

After casting, to prevent the loss of water to evaporation, the mold with the mortar was wrapped with multiple layers of polystyrene and adhesive tape. The weight of the mold with mortar was measured, and they were stored in a chamber with 50 ± 2% of humidity and 21 ± 2 ◦C for 28 days, where the straingauges continuously recorded the G distance.
