**2. Materials and Methods**

Printed beam shape specimens were prepared for tensile stress impact on printed specimens to relate creep and shrinkage property determination. Each printed specimen had four layers. They were modeled to be 40 × 40 × 1000 mm, but due to the cement composite mix flowability, the width of the specimens at the base was 83 mm, and 67 mm at the top. The used cement composite composition was similar to cement mortar. Due to the fact that the composition of the used cement composite is a trade secret, specific amounts and types of materials cannot be disclosed in this article. The mass partition of the used cement composite is shown in Table 1. The specimen printing process is shown in Figure 1.

**Table 1.** Used cement composite composition partitions.


**Figure 1.** Test specimen printing process.

When specimens were printed, they were left overnight to set. At the same time, cast specimens were prepared. They were poured into a steel prismatic cast of 40 × 40 × 160 mm. A day later, cast specimens were unmolded, and printed specimens were cut to the same shape (40 × 40 × 160 mm) as the cast specimens. They all were placed in an aqueous environment for 25 days. After 25 days, all specimens were prepared for the creep and drying shrinkage tests.

The compressive strength was determined for four specimens (prismatic specimens 40 × 40 × 160 mm) out of each specimen type. The load was applied to the specimens for creep tests according to the determined compressive strength values. Compressive strength and creep and drying shrinkage (further in the text referred to as shrinkage) tests were conducted using the identical shape specimens so that creep specimens would not have shape factor impact (if the compressive strength specimens were larger or smaller than creep specimens) in the load that they were subjected on the test stands. All of the specimens intended for creep testing were loaded with 20% of the ultimate compressive strength value. Specimen placement into the creep test stand and shrinkage stand is shown in Figure 2.

(**a**) (**b**) **Figure 2.** The 3D-printed and cast cement composite shrinkage (**a**) and creep (**b**) test setup.

Creep and shrinkage tests were carried out for 28 days. Creep and shrinkage testing procedure, except testing time, was performed according to RILEM TC 107 recommendations [10]. The laboratory conditions for the creep and shrinkage tests were 24 ± 1 ◦C and 30 ± 3% relative humidity.

After creep and shrinkage tests to determine the reasons for inequal creep and shrinkage strains to the specimen sides, as well as to see the 3D-printed layer adhesion, quantitative image analysis was performed to the specimen's polished sections that were prepared and made according to the [11] used process.
