PSI - Issue 63

Stanisław Majer et al. / Procedia Structural Integrity 63 (2024) 51–57

56

3. Results Mixes No. 1 and No. 2 were chosen for field testing based on the results of the preliminary laboratory tests (Table 4). The trial construction sites were located at the planned tanks location. They were removed after the test. The compaction equipment used in the test was the same as in the future construction. The slabs were cast in 3 three lifts and 150/300 mm cylinders were cored after 7 days of curing (see construction site in Fig. 5).

Table 4. Gives the results obtained on the tested mixes after seven days of curing. Mix No. E s 7 days [MPa]   f c 7 days [MPa]

f c 28 days [MPa]

1 2 3

7,594 2,882 2,123

23.2 17.1 18.1

2.54 0.85 0.77

3.86 1.76 1.52

Fig. 5. Trial construction site and coring of cylinders for E-modulus test.

Finally, the construction supervision team and lead designers approved the Contractor’s proposal to use Mix 2 as a material for construction of the designed foundation slabs for the tanks in question. The research results clearly indicate that each of the three prepared mixtures exhibits a significantly higher modulus of elasticity than required by the designers in the analysed case. The average results obtained ranged from 2100 MPa to 7500 MPa (Table 2), suggesting that it is not possible to design a mixture with such a low modulus as required. The addition of cement and the binding of the layer, achieving very low strength at the level of 0.77 MPa (after 7 days), allows achieving a modulus of at least 2000 MPa. 4. Conclusions The modulus of elasticity of cement bonded granular materials (CBGM) is a key parameter used in the design of road infrastructure and other construction projects. This paper presents the results of our research on cement-bonded materials. Three mixtures varying in grain size composition and cement content were tested. Therefore, a research method suitable for concrete was adapted for this purpose. Mix 2 was selected as the most suitable, despite the fact