In brief
- Concrete batching experience gaps show up as mix proportions that change from pour to pour, because the person loading the mixer works by eye and not from a written batch record.
- Ask for the batch record for every pour: cement, sand, aggregate and water weights, plus the aggregate moisture check and the cube test results.
- Close the gap with a written mix design, a working scale, a moisture check on the sand and aggregate, and supervision that signs each batch before the mixer turns.
Contents
Concrete batching experience gaps in Burao matter because batching by eye lets the mix proportions move from one pour to the next. When the person loading the mixer works from a bucket count learned on another job rather than from a written batch record tied to this site, the concrete can end up rich and sticky one day and bony and harsh the next. The cube results may then not match what was placed. That is the gap: not a lack of effort, but a lack of experience in holding proportions steady.
How do batching experience gaps change the concrete?
Batching by eye lets the proportions drift, and the drift changes both strength and workability. If the loader adds half a bag of cement because the mix looks thin, the cement content rises while the water stays the same, so the water-cement ratio falls and the mix turns harsh. Someone then adds water at the drum to restore workability, and that raises the water-cement ratio. If the sand arrives wetter after rain, the same scoop carries more water and less solid, and the batch gets weaker without anyone touching the water can. Where stockpiles dry out, the mix can stiffen and invite the same water addition. General practice is to weigh cement, sand, coarse aggregate and water against a written mix design, and to check the moisture of the sand and aggregate before adjusting the batch water. Confirm the mix design and the tolerances against the project specification or the engineer.
What does a supervisor check on site?
A supervisor checks the batch, not the finished pour, because the batch is where the proportions are set. Ask to see the mix design for this site, then watch one full batch loaded. Does the loader use a scale or a gauge box, or does he count buckets from memory? Is the sand stockpile covered, and is the moisture checked before the water goes in? The batch record should list cement, sand, aggregate and water for each batch, with the time and the pour it went into. Cube results matter, but a cube taken from a batch nobody weighed tells you little about the next batch. If a recent site the same team built can be visited, ask what records, if any, the local authority keeps for it, and ask the team how they set the mix there, who signed the batch record, and whether the cubes met the specified strength. If the answers are vague, the team may lack batching experience on work of this size. Confirm all acceptance limits against the project specification.
How do you close the batching gap before the next pour?
Write the mix design down and put the numbers where the loader stands. Fix a batch sheet to the mixer: one line per material, target weight or gauge box count, and a column for the actual figure. Set up a scale that works and keep it working; a scale that is broken or borrowed is the same as no scale. Check the moisture of the sand and coarse aggregate each morning and after any rain, and adjust the batch water on the sheet, not in the drum. Let the supervisor sign each batch before the mixer turns. Book a laboratory to make and test cubes, and ask the laboratory for its test scope and turnaround time in writing. If the team has not batched this mix before, run a trial batch and adjust the sheet from the result. Ask the engineer to confirm the acceptance criteria before the pour starts.
What to do next
Before the next pour in Burao, ask the contractor to supply the mix design and the batch record from the last pour. Ask the site engineer to confirm the acceptance criteria and the record format before the pour begins. Then watch one full batch loaded and signed, and check the moisture figures against the sheet.
Frequently asked questions
What is a batch record and why does it matter?
It is the written record of each batch: cement, sand, coarse aggregate and water, with the time and the pour. It matters because it links the tested cube to the concrete actually placed. Without it, a passing cube result proves little about the rest of the work. Ask the contractor to keep one sheet per pour and sign it before the mixer turns.
Can a small Burao site batch concrete without a scale?
A gauge box, used consistently and checked against a known volume, can hold proportions steady where a scale is not available. The risk is drift: a worn box, a rounded scoop or a wet stockpile shifts the proportions silently. Weigh the box once against the specified material weight, and recheck it when the mix or the supplier changes. Confirm the method with the project engineer.
How do I check whether a team has batching experience?
Ask for batch records and cube results from a recent job of similar size, then walk that site and look at the stockpiles, the scale and the batch sheet. Ask who set the mix design and who signed the records. A team with batching experience can show those documents and explain why the numbers were chosen. A team without it will describe the mix by eye.
Local reporting: this article is written for building work in Burao and Somaliland. Ground conditions, prices and rules differ between places; confirm the details for your own site.