Proper mixing of concrete material is very essential as it affects the quality of concrete in fresh state as well as in hardened state. A concrete is said to be well mixed if it meets the following requirements.
- Concrete mix should be uniform in color
- Concrete must attain the proper consistency for which it is designed
- Perfect blending of all solid ingredients
- Cement paste should cover the entire surface of the aggregate
Read also: How to batch concrete by volume
Hand mixing is adopted for small works and where the quantity of concrete is less. The following procedure is followed for mixing concrete by hand.
step 1 [Mixing Platform]
A clean and water tight platform should be used for mixing the concrete. Build a platform of bricks or sheets of lean concrete or iron according to the amount of concrete to be mixed. A platform usually made of a sheet of iron with a diameter of 3m. It happens2 Used to shape strips or along curbs.
step 2 [Dry Mixing of Cement & Sand]
Spread the measured amount of sand evenly on the mixing platform. Dump the cement onto the sand and distribute it evenly. Mix sand and cement with shovels, swirling the mixture frequently until it becomes uniform in color.
step 3 [Dry Mixing of C.A. With Cement-Sand Mix]
Once again spread the sand-cement mixture evenly on the mixing platform. spread the measured amount over it CA (coarse aggregate). Do not dump in one place; Otherwise the larger particles will start rolling. mix again at least three times by shoveling towards the center, And then back to the center and again to the side,
step 4 [Addition of Water]
Make a pit in the middle of the mixed heap and slowly pour in half to three-fourths of the total amount of water. While the ingredients are turned toward the center with the shovels, slowly add the remaining water, swirling the mixture frequently until the pile has uniform color and consistency. This will indicate that all the ingredients are well combined. Water should be slowly added to the mixture. This is best done by means of a gardener’s watering to which a rose-head has been planted. Throwing water from the bucket in one go, he will run away and take the cement with him.
- Mixing time should not exceed 3 minutes
- The mixing platform is cleaned at the end of the day’s work so that it is ready for use the next day.
check for compatibility
A rough estimate of the consistency of concrete can be made by performing the following simple and quick field tests.
Take a handful of concrete and squeeze it tightly in your hand. If the concrete is mixed properly, it will hold its shape after releasing the hand pressure. At the same time the surface of the sample shall be moist without water seeping in.