Who checks block strength in Hargeisa?

Who actually checks block strength in Hargeisa?

Block strength checks in Hargeisa often stop at a visual pass. A supervisor looks at a stack of concrete blocks, checks edges and colour, and moves on. The block's compressive strength is what the design assumes for loadbearing walls, and no visual pass measures it. The block strength checks skills gap sits between the person who is responsible for the check and the person who has the method and the tools. A homeowner, a finishing supervisor or a clerk of works may be standing on site, but none of them may have run a crushing test or read a mix record.

How does the skills gap arise on a Hargeisa site?

It usually comes from a missing link between the specification and the person on site. The engineer writes a strength class into the drawings. The contractor buys blocks from a yard. The supervisor accepts the delivery. No one is asked to convert the class into a number, and a batch certificate may never be requested on some sites. The equipment and training needed to test blocks, a calibrated machine and someone who can interpret the result, are not part of a normal site setup. Ask the municipal engineer's office which records are expected on a permit file, and ask what documentation applies to a loadbearing wall. Ask the block supplier which batch a delivery came from, and write it down.

What skills does a block strength check require?

A person who can run the check needs three things: a method, a specimen, and a way to read the number against the design. Under general practice, compressive strength is tested on whole blocks or half blocks, cured to the age the specification names, and crushed in a laboratory press. The project specification or the engineer sets the number of units per sample, and the reader should confirm that count with the engineer or the laboratory. The method and the acceptance rule come from the specification, not from the yard. The person supervising should be able to say which batch was sampled, how the units were cured before testing, and which laboratory produced the certificate. Request test records from a recent site, and ask the laboratory for its own rate for a block compression test. Do not accept a verbal result.

What can a supervisor check before the blocks are laid?

Start with the delivery record. Ask for the batch date, the mix design or the cement content, and where the units were cured. Block strength can fall if units are cured in the open under the sun or moved wet, but confirm the curing requirements against the project specification and the engineer's direction. Walk the wall line and look for cracks, hollow faces and broken corners. Ask two suppliers for written quotes on the same block class, and ask the block maker for a sample for testing. Confirm with the laboratory how many units it needs and how it conditions them before the press. If a sample fails the specification, ask the engineer what the next step is and keep the failed units on site until that is answered. The specification is the reference, not a rule of thumb.

What to do next

Pick one loadbearing wall on the current build and trace the blocks back to their batch. Ask the block supplier for the batch record, ask the engineer which strength class the wall needs, and ask the laboratory what it charges for a compression test on that class. Put the answers in the site file before the next delivery arrives. If the contract allows, confirm who pays for failed tests before the sample is sent.