How do you check prop removal on a Berbera build?

Props come down when the concrete has reached the strength the engineer specified for that element, not when the props are next needed. Supervision gaps around prop removal in Berbera leave no record of the pour date, the cure period or the strength result that justified striking. The check is paperwork plus a walk of the soffit.

What does weak supervision look like during prop removal?

It looks like props struck on a calendar date rather than a strength result. On a supervised job, someone records the pour, keeps the cubes or cylinders with their test dates, and sets the strike sequence before work starts. Under weak supervision, those records may be incomplete or written after the fact.

Watch for props removed from a slab while the floor above is being loaded with block, sand or tiles. Watch for back-propping missing under a recently struck span. Watch for formwork removed from a cantilever or a long span before a test result exists. Any of these can load concrete that is still gaining strength.

Concrete strength gain depends on mix, water content, temperature and cure. Hot, dry or windy conditions can dry a slab surface quickly, so ask what was done to keep it moist and for how long, and ask the engineer what cure duration the specification requires. General practice is that striking times and cure periods come from the project specification, not from habit, and they must be confirmed with the engineer. Record keeping is easy to skip when nobody asks for it, so ask for the records and check them against the specification.

How do you detect premature loading on site?

You look at the soffit, read the dates and ask for the strength records. A slab loaded too early often shows hairline cracks at mid-span, corners or around columns, or a visible sag when you sight along the underside.

Walk these checks:

• Sight along each recent soffit and note where cracks start and how wide they are.
• Compare the pour date on the concrete delivery records with the date the props were struck.
• Ask for cube or cylinder test results for that pour, with the laboratory named and the dates printed.
• Ask which loads sat on the slab between the pour and the strike, and who approved them.
• Look for props still in place under the floor above, and check they bear on solid ground or a properly braced support, not on loose fill.

A single crack is not proof. A crack plus a short gap between pour and strike plus no test record is a pattern worth stopping work over. Ask the engineer to review the element before you cover it up.

How do you close the gap before the next pour?

You fix it in the method statement, not in a conversation after the fact. Before the next suspended slab, agree who records pour dates, who holds the test results and who signs off each strike.

Put it in writing:

• List every element to be propped, with its span and the strike criterion from the specification.
• Name the person who approves each strike and the person who physically removes the props.
• Keep a strike register on site: element, pour date, test date, result, approval, strike date.
• Store the cube or cylinder results with the register, not in a folder at another office.
• When a test result is missing or late, leave the props in place and ask the engineer.

Ask the municipal engineer's office whether it holds records for similar buildings in the area, and ask a laboratory for its sampling and testing procedure before you rely on its results.

What to do next

Pick one suspended slab on your current job and pull its file: pour date, cure record, test result, strike date and the name of the person who approved it. If any of those is missing, ask the engineer to review the element before further loads go on, and set up a strike register before the next pour. Then walk a recent slab and look at the soffit.