Key Results from Test Data
The following are the key learning points from the numerous tests undertaken on correctly installed Resin Bonded Anchors (ECO/PECO anchor). The majority of the tests were supervised by an industrial expert who provided the calibrated test equipment.
All tests are “axial” – direct pull.
1. The ECO/PECO anchor begins to be extracted from the substrate at around 40Kn
LEARNING POINT: The anchor does not fail catastrophically, that is, the anchor does not simply fall out of the substrate, it requires a further load of around 40Kn to continue the extraction.
2. At around 19Kn, the “P” of the anchor is deformed (NB: extraction does not occur to around 40Kn).
LEARNING POINT: This is considered a safety feature, as any anchor that has an elongated “P” has clearly been subjected to at least 19Kn, and should be replaced.
3. 12 tests were recorded to calculate the “Proof Test Load” which is 17Kn
4. The “Safe Working Load” is calculated to be 11.46Kn exceeding both BSEN 795 and EN 959:2007
5. Aerated concrete (breeze block) block test: An anchor was installed in an aerated concrete block and subjected to a load of 10Kn for 15 seconds. This test was repeated 122 times (until the operator had a sense of humour failure). The purpose of this test was to demonstrate the strength of the resin bond in a substrate weaker than limestone.
LEARNING POINT: The BCA puller can only test to 10Kn and even though the Safe Working Load and Proof Load are greater than 10Kn, we wanted to demonstrate that repeated testing up to 10Kn had no detrimental impact in the integrity of the resin bond.
6. Radial testing: BCA has, as yet, been unable to locate a test rig that can be configured to test to egress in Radial mode (although we are still working on it).
7. Drop testing: Using lanyards manufactured specifically for the test programme, a number of FF1 drop test were undertaken using a 100kg weight. In each test, the “P” of the anchor was deformed, but the anchor remained secure in its placement. (Most of the lanyards failed on the second test – which was quite exciting!)
LEARNING POINT: In the majority of caving situations the ECO/PECO is loaded at 90 degrees to its fixing (Radial mode), which means an even greater strength to the anchor.