In brief
- Judge two cement brands with the same checks on the same day, so the comparison is fair and written down.
- Ask each supplier for a mill certificate and a batch date, and record both against the bags you receive.
- A small set test on samples from each brand shows whether both behave the same in your water and your sand.
Contents
Judge two cement brands with the same checks, in the same week, on bags from the same delivery round. Compare the bag marking, the batch date, the storage history, a mill certificate and a simple set test. Write each result against the brand, then choose on those records rather than on the supplier's sales talk.
What should be on the cement bag before you compare anything?
The bag should carry the cement type, the strength class, the net weight, the manufacturer and a batch or production date. If a marking is missing or rubbed off, the bag cannot be compared with another brand because you do not know what it is. Set it aside.
Ask for the mill certificate that matches the batch number on the bags. A supplier may hand over a general product sheet instead, which says nothing about the batch in front of you. Compare the batch number on the certificate with the printed bag number before you accept it. The questions in How do you check a supplier's test certificate in Somaliland? apply to both brands in the same way.
Write the delivery date on each record. Cement strength drops as bags sit in a hot store, and a brand that reached your site months after production starts the comparison at a disadvantage. Ask the supplier how the bags were stored before delivery and write the answer down.
How do you test two brands side by side?
Take a sample from each brand, mix each with the same sand, the same water and the same ratio, and cast small cubes or pats at the same time. Store both the same way and check when each sets and how hard it goes. A laboratory can do this properly and give you a rate on request.
On site, a simple set test tells you whether a brand is badly stale. Weigh a fixed quantity of cement, add a measured amount of water, and note how long the paste takes to stiffen. Do the same for the other brand on the same day. A big gap between the two is a reason to ask the supplier for the production date again.
Use the concrete calculator to keep the batch quantities identical for both trial mixes, so the only thing that changes is the cement. Record the results in the materials acceptance file with the batch numbers and dates.
What changes when a supplier switches source mid job?
When a supplier changes mill or import source, the cement in the next delivery may behave differently. Treat it as a new brand: repeat the bag check, ask for the new mill certificate and run the set test again before the bags go into structural concrete.
The same rule covers two brands bought for one job. Do not mix them in the same pour. Keep bags from each brand in separate stacks with their own delivery record, and use one brand per structural element. The steps in How do you retest materials when a Puntland supplier changes source? show what to log when the source moves.
For any cement, confirm the type and strength class against the project specification and the engineer before you use it in a slab, column or footing. The brand with the better paperwork and the better set test is the one to specify, and the record you keep is what supports that choice.
What to do next
Pick one structural pour on the next job and buy the same quantity from two brands. Run the bag check, the certificate check and the set test on both, and write each result in the acceptance file with the batch number and date. Give the sheets to your engineer before the pour and let the records decide the brand.
Frequently asked questions
Can we mix two cement brands in one concrete pour?
No. Keep one brand per structural pour and keep the bags in separate stacks with their own delivery records, so a later problem can be traced to a batch.
What if a supplier has no batch date on the bag?
Treat the bag as unidentified and do not use it in structural concrete. Ask for a batch with a printed production date and a matching mill certificate.
Sources
Local reporting: this article is written for building work in Puntland. Ground conditions, prices and rules differ between places; confirm the details for your own site.