In brief
- A bag that is torn, damp or carrying hard lumps has already lost strength, and mixing it into the batch hides the loss.
- One person should own delivery checks in writing, with the truck number, supplier, date and rejected bags recorded on a signed sheet.
- Cement that arrives hot or has sat in a hot store can set faster than the mix design assumes, so ask the supplier for dispatch dates and batch information.
Contents
Cement handling risks in Berbera begin at the gate, not at the mixer. A bag that arrives torn, damp or carrying hard lumps has already lost some of its strength, and once it is tipped into the batch there is no way to see that. The delivery check is the cheapest quality control on the site, and it is the one most often skipped when the lorry is waiting.
What does a damaged cement bag look like on arrival?
Look at the bag before it comes off the lorry, not after it is stacked in the store. A sound bag is flexible, holds its shape and has no hard pieces inside. Squeeze it near one end: if you feel lumps that do not break under hand pressure, that portion has taken on moisture and begun to hydrate.
Work through the load in daylight and set aside anything with a tear on a seam, a damp stain, a crusted patch or a set lump. Torn bags spill fines, and the fines carry much of the cement's reactive content, so a full-looking bag can be short of what the mix design assumes. Check whether the load was stored uncovered or in an exposed yard before it reached you, and confirm the storage expectations for the project against the specification or with the engineer.
Ask the supplier how the load was stored before dispatch and what the dispatch date was. General practice is to use cement in the order it arrives, and to keep any bag for more than a few weeks in a raised, dry, sealed store. Confirm the storage and use-by expectations in the project specification or with the engineer.
How do you record and reject a bad delivery?
Decide who checks and who signs before the first lorry arrives, then put both names on the delivery note. The checker walks the load, counts bags, marks the rejects and photographs the torn or damp ones while they are still on the lorry. The storekeeper signs for what was accepted only.
Keep a delivery sheet at the gate with the date, supplier, lorry number, number of bags offered, number accepted, number rejected and the reason. Mark rejected bags with paint or a tag so they cannot drift back into the store, and keep them away from the accepted stack until the supplier collects them or credits them. Write down what the supplier agrees to replace.
Check what the contract and purchase order allow for rejected material and credits before you argue about a load. If the same fault keeps arriving, ask the supplier for batch information and dispatch records, and ask the engineer whether the affected concrete needs testing before it is placed.
What does bad handling do to the concrete?
Cement that has partly hydrated loses strength, and the loss shows up in the finished element, not in the bag. Weak or variable cement makes the mix water demand rise, which pushes up shrinkage and cracking risk. In a hot, dry, windy site the same cement also loses workability faster, so the crew adds water at the mixer to keep placing. That extra water lowers strength and raises the chance of a dusty, weak surface.
Hot cement straight off a lorry can set faster than the mix design assumes, which shortens the time available to place and finish a pour. A batch made from mixed fresh and older bags will not behave the same from one mix to the next, so testing one cube tells you little about the next lorry.
You can check the local picture without a laboratory of your own. Walk a recent site nearby and look at the underside of slabs and the surface of columns for dusting, map cracking or soft patches, then ask the supervisor how the cement for those pours was received and stored. Ask the municipal engineer's office whether it holds any records of failed cube tests on nearby work, and ask a testing laboratory what it charges to test cement or a cube sample from your own pour.
What to do next
Write a one-page delivery check for your site today. Name the checker and the storekeeper, list the bag faults to reject, and print a delivery sheet with columns for lorry number, bags offered, bags accepted and reason for rejection. Take it to the gate before the next lorry arrives, and tell the supplier in writing that damaged bags will be recorded and returned.
Frequently asked questions
Can I use a bag of cement that has a few lumps in it?
No. Break a lump open: if it is hard through, that cement has already hydrated and will not react as the mix design expects. Reject the bag and record it.
How long can I store cement in Berbera?
That depends on your store and the specification. General practice is to use cement in arrival order and keep the store raised, dry and sealed. Ask the engineer or the specification what storage period is acceptable on your project.
Who should sign the delivery note?
The person who actually checked the bags, not whoever is nearest the lorry. The signature should cover only the bags counted and accepted, with rejects and reasons written on the same sheet.
Local reporting: this article is written for building work in Berbera and Somaliland. Ground conditions, prices and rules differ between places; confirm the details for your own site.