Making concrete

·   On Wednesday 3rd April we made concrete in class. First of all we discussed the purpose of concrete buildings, walls, paths, floors, etc. We then discussed the different types of concrete. We learned that you can make concrete using:

ü  Builders sand

ü  Beach sand

ü  Gravel

ü  Mortar mix

·       We then discussed how we would make the concrete. We learned that the ratio for making concrete is 3:1. 3 parts sand to 1 part cement. We also discovered that you need to be very careful when adding water.

·       We then made our way outside and divided into 4 groups. Each group was going to make a different type of concrete:

·     Group 1 made concrete using gravel- we mixed 3 parts builders sand and stones with 1 part cement and we added water sparingly. We made a mistake by adding too much water and had to start again. We mixed the materials in a bucket and poured the mixture into plastic containers. We stuck a lollipop stick in the container to make it easier to remove once it has dried.

·       Group 2 made concrete using beach sand- we mixed 3 parts beach sand with one part cement and added water sparingly. We mixed the materials in a bucket and poured the mixture into plastic containers. We stuck a lollipop stick in the container to make it easier to remove once it has dried.

·       Group 3 made concrete using builders sand- we mixed 3 parts builders sand with one part cement and added water sparingly. We mixed the materials in a bucket and poured the mixture into plastic containers. We stuck a lollipop stick in the container to make it easier to remove once it has dried.

·       Group 4 made plaster using mortar mix- we mixed 1 cup mortar mix, water and 3 cups cement. We mixed the materials in a bucket and poured the mixture into plastic containers. We stuck a lollipop stick in the container to make it easier to remove once it has dried.

·       We labelled all the containers and left them for a week to dry.

·       We then discussed which types of concrete would be the strongest and we carried out a test to investigate. Here are the results:

Types of concrete	We predicted	Result	Used for
Gravel	Very strong	Very strong (4/5)	Paths and floors
Builders sand	Strong	Weak (3/5)	Walls and buildings
Beach sand	Weak	Weak  (3/5)
Mortar	Weak	Very weak (2/5)	Plaster on walls