What a proper anchor test report should contain

Five records separate a verified anchor from an assumption. If your test report is missing any of them, you have a certificate, not evidence.

An anchor certificate that says “tested and passed” tells you nothing you can check. What you want is enough raw data to redraw the test yourself.

The five records

• Installation record — hole diameter, drilled and bonded lengths, grout volume and water:cement ratio, dated
• Grout cube results at 7 and 28 days, tied by batch number to the anchor
• Calibration certificate for the jack and gauge used, dated within twelve months
• Load-extension readings at every increment, including the hold periods
• Lock-off load and, for permanent anchors, the corrosion protection detail

“If the jack calibration certificate is older than the site, the test is decoration.”

Read the load-extension curve

The curve is where an anchor tells you the truth. Elastic extension should land inside the theoretical range for the free length — too little and the free length is grouted up; too much and the bond is creeping. A flat tail during the hold period at proof load is what you are paying for.

Creep displacement over the hold period is the single most useful number in the report. It is also the one most often left out.

How to ask for it in a tender

Write the deliverable into the specification rather than the method: “each anchor to be supplied with installation record, batch-linked cube results, in-date jack calibration, full load-extension data including hold-period creep, and lock-off load.” Any competent contractor will price that without blinking. The ones who query it are telling you something.

Written by Priya Nair, Quality & Safety at Wardha Infrastructure. Questions about your own site? Send us the details — an engineer answers.