I've started making some small decorative concrete objects. Like trays, potters, table legs, etc.
But recently my pours all go straight to the garbage bin.
The problem (or the symptom) is that the poured concrete breaks by looking at it, it breaks like a cookie, that soft.
The concrete that I used is bought, about, 8 months ago. It's translated called extra strong concrete mix. It has a water/mix ratio of 1,8/2 Liters per 20 Kg Mix. But since I use small amounts I've scaled it down to 0,09/0,1L per 1Kg.
Here are some of my thoughts and more detail:
- In most molds I use black pigments. Could I over do it with the ratio and make it brittle?
- I've got 60Kg of ~8 months concrete mix. Could it be old? I do have to crush big chunks from the bag.
- Since I don't use the entire bag, and I work my way down the bag, could it be the cement is in top and sand in the bottom? Resulting in not getting a good mix scooping it out of the bag?
- I've tried bigger and smaller water ratios. (the ration mentioned on the bag was way too little. It made it a bit wetter than damp sand.
Any tips are more than welcome 🙂
Best Answer
It’s too old.
An obvious clue is you stating you have to break up large chunks.
You may find it better to buy the separate components and mix your own mix.
This would mean you can get the cement fresh per batch. The other components won’t « age » so much or at all - thinking of gravel sand etc but any moisture content needs accounting for.