Question 1

How long does a pile load test take?

Accepted Answer

After one to two hours of preparation, a dynamic load test takes about 30 to 60 minutes per pile, several piles are possible in one day. A static load test needs one day for setup, one to two days for the load programme, depending on specifications and ground conditions, and about one day for dismantling and clearing.

Question 2

How much lead time does an assignment need?

Accepted Answer

We are very flexible, almost anything is possible at short notice. The limits are the equipment and the time the concrete needs. For integrity tests a few days are usually enough, provided the concrete is about seven days old. Static and dynamic load tests need time for project planning, one to several weeks depending on the effort. Whoever asks early gets the date the construction schedule needs.

Question 3

What must the site provide?

Accepted Answer

All documents on the piles: pile plan, installation records, geotechnical report with soundings and specifications, plus clear access to the work area. For integrity measurements we need freely accessible, uncovered and clean pile heads that consist of sound core concrete across the full surface. For load tests the services provided by the site vary widely and are project specific, for example a crane for setup, a paved access for semi trailer and crane, a level paved working area around the test pile, concreted pile heads or pile extensions, power, space and a container. We specify everything else before the test in a detailed concept.

Question 4

Can the test pile still be used after the test?

Accepted Answer

Yes. Thanks to precise load application, the integrity of the test pile does not change. We prove this with an integrity measurement before and after the test, which is a fixed part of our documentation of evidence. The prerequisites are flawless pile installation and clean pile preparation.

Question 5

Do you also work in winter or at night?

Accepted Answer

Yes. Measurement technology and hydraulics are built for site conditions. We run night and weekend assignments wherever curfews require it, for example in rail and road construction.

Question 6

How much space does a static test setup need?

Accepted Answer

That depends on the pile diameter and the reaction system. Depending on the bill of quantities, EA-Pfähle and DIN, areas from 6 m x 6 m to 16 m x 16 m are needed, plus the standing area of the mobile crane. We give exact figures before the test in a detailed concept.

Question 7

When is the test report available?

Accepted Answer

We give preliminary results directly on site, so the construction schedule does not wait. The report suitable for verification, with evaluation and assessment, follows shortly after the assignment.

Question 8

Dynamic or static, which is right?

Accepted Answer

The static load test is the direct proof, it delivers the load-settlement line under real sustained load and counts as the reference method. The dynamic load test is faster and cheaper and fits when several piles are tested or a result is needed at short notice. A combination is often sensible: calibrate statically, test dynamically across the site.

Question 9

What does CAPWAP do?

Accepted Answer

CAPWAP is the model analysis of the dynamic measurement. A soil model that explains the measured signals is back calculated from the force and velocity curve at the pile head. The result is shaft friction, base resistance and the derived bearing capacity.

Question 10

When is an integrity test enough?

Accepted Answer

When the question is not bearing capacity but construction quality. Low-strain finds cross-section changes, necking, defects and deviating lengths. It does not replace a statement on bearing capacity.

Question 11

What is the difference between cross-hole and low-strain?

Accepted Answer

Low-strain measures from the pile head with a light hammer blow and assesses the pile as a whole. Cross-hole measures between cast-in tubes and also finds defects in the core of large bored piles. Cross-hole must be prepared before concreting.

Question 12

How many piles must be tested?

Accepted Answer

EA-Pfähle gives reference values, depending on the number of piles, ground scatter and structural class. Integrity tests often cover a large share up to all piles, load tests cover individual representative piles. We derive the number from the project, not from a rule of thumb.

Question 13

Can existing foundations also be tested?

Accepted Answer

Yes. In cases of change of use, additional storeys or damage, we test existing piles and deliver the numbers the structural engineer can calculate with.

Question 14

Which standards apply to testing?

Accepted Answer

Static load tests per DIN EN ISO 22477-1, dynamic tests per DIN EN ISO 22477-4, plus the recommendations of the Arbeitskreis Pfähle (EA-Pfähle), DIN 1054 and Eurocode 7. DIN EN ISO 22477-5 or DIN EN 1537 applies for grouted anchors.

Question 15

What is in the test report?

Accepted Answer

Boundary conditions and ground, test setup, measurement technology and calibration, the load programme applied, measured values, load-settlement line or CAPWAP evaluation and the assessment against the required bearing capacity.

Question 16

Is the report accepted by the checking engineer?

Accepted Answer

The reports are designed for proof under Eurocode 7 and are used accordingly by checking engineers and authorities. On request we coordinate the test scope with the checking engineer beforehand, which avoids queries after the assignment.

Question 17

Are you independent?

Accepted Answer

Yes. IPM does not install piles. We measure and assess, without an economic interest in the result.

Question 18

How is the measurement technology calibrated?

Accepted Answer

Force measurement, displacement transducers and hydraulics are calibrated regularly, the certificates belong to the report. Measurement systems and evaluation software come from our own development, so the chain from sensor to diagram is traceable.

Question 19

How high can the test load go?

Accepted Answer

Up to 40,000 kN, that is 4,000 tonnes static. A load frame crown up to 15,000 kN, an HE1000 girder system in S460 up to 40,000 kN and an HE700 system up to 10,000 kN are available for that.

Question 20

Which pile types do you test?

Accepted Answer

Bored piles, driven piles, displacement piles, steel piles, sheet piles, micropiles, ductile piles and grouted anchors. Raking and tension piles can also be tested, the setup is then specified structurally for the specific project.

Question 21

How large may the test load be relative to the service load?

Accepted Answer

A test load clearly above the service load is common, so the load behaviour becomes visible in the governing range. We set the factor together with the structural design, depending on the verification goal and safety factors.

Question 22

Can tests be carried out on confined sites?

Accepted Answer

Yes, with an adapted reaction system. In city centres the beam system is usually the only solution, because dead load needs area that is not available.

Question 23

Do you also work outside Germany?

Accepted Answer

Yes. Assignments in 21 countries so far, among them Austria, Switzerland, Norway, Sweden, Poland, Italy, the Netherlands, Iceland, Slovakia, Croatia, Serbia, Bosnia and Herzegovina, Belgium and Kazakhstan.

Question 24

What does a pile load test cost?

Accepted Answer

The price follows test load, reaction system, number of tests, site location and travel. A dynamic test is clearly below a static one but delivers a different quality of statement. We calculate once ground and test goal are known, not before.

Question 25

Does a load test pay off?

Accepted Answer

Often yes. Without measured values, the foundation is sized with safety margins. A load test replaces the margin with a number, the result is shorter or fewer piles. The saving in pile metres exceeds the test cost on many projects. The test also reveals construction defects early, while they can still be fixed without demolition.

Question 26

How fast can you be on site?

Accepted Answer

For dynamic tests and integrity tests, at short notice, often within a few days. Static setups need lead time. Tell us your preferred date, we are flexible and can usually confirm it.

Question 27

When should IPM be brought in?

Accepted Answer

In the planning phase. After that, the foundation can only be verified, no longer optimised.

Questions on pile testing

Process and organisation

Methods and selection

Standards and proof

Technology and limits

Costs and schedules

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