# Aggregate Type and Concrete Age Effects on Anchor Breakout Performance: Large Database and Insights
## 3 Results
### Material Characterization
#### 3.1.2 Concrete Mechanical Properties  
Standard concrete compressive strength tests [30] were carried out in order to identify the mechanical properties of each investigated concrete. Compressive strength (\(f_{c,150}\)) values were obtained on cubes with a side length of 150 mm (5.91 in.) in parallel with the anchor tests. The cubes and concrete slabs used for anchor tests underwent the same curing and storage conditions, satisfying anchor approval guidelines [9], until tested. Figure 3 summarizes all experimentally obtained concrete compressive strengths (\(f_{c}\)) plotted against  
Figure 2: Los Angeles (L.A.) coefficients for the chosen coarse aggregates.  
the corresponding L.A. coefficient. Each color represents a research group and marker style concrete-strength class: blue circles for CDL, red circles for CSTB normal-strength concrete, and red diamond markers for CSTB high-strength concrete. Additionally, empty markers represent 28-day test results, while filled markers represent results for the second age (70 days for CDL tests and 180 days for CSTB tests).  
As shown in Figure 3, the covered concrete compressive strengths (\(f_{c}\)) are widely spread among concretes, with a minimum of 27.2 MPa (3.9 ksi) at 28 days and a maximum of 80 MPa (11.6 ksi) at the 184-day age. It is shown that the L.A. coefficient is not or barely correlated with the compressive strength since for substantially different L.A. coefficients, almost the same compressive strength can be found (e.g., empty and/or filled circles). Compressive strength characterization tests show that CDL and CSTB low-strength concretes (blue and red empty circles) finally belong to the same concrete class with mean compressive strength of \(\sim\)31 MPa (\(\sim\)4.5 ksi) at 28 days. As expected, the high-strength concretes (empty diamonds) show a significantly higher compressive strength with a mean value of \(\sim\)67 MPa (\(\sim\)9.7 ksi). The mean compressive strength values and respective coefficients of variation for all concretes and ages are listed in Table 5, together with the experimentally obtained indirect tensile strength (\(f_{t}\)) values from Brazilian splitting tests. Each mean value is based on five tests for CDL and three tests for CSTB.  
For both anchor failure mechanisms considered in this investigation--concrete cone failure and edge breakout--the concrete compressive strength (\(f_{c}\)) is the only material parameter involved in anchor load capacity predictions according to ACI [28; 31] and fib [18]. Thus, the discussion is limited to this material property. More insights into correlations between concrete cone capacity and other concrete properties as well as aggregate properties and concrete properties are given in [PERSON] et al. [32] for the CDL concretes in which other concrete mechanical properties, including cylinder compressive strength, compressive loading modulus, and total fracture energy, are reported.  
Figure 3: Concrete cube compressive strength (\(f_{c,150}\)) for all tested concretes and ages (note: 1 MPa = 0.15 ksi).