When we traveled to Kananga Elder Billings showed us the block making building they had built and are using to make all the block for two new LDS meeting houses.
This is the building they have built on church property. Eventually it will be used for storage, but now, prior to the church being built, is being used to house the concrete block making operation. They have to make about 70,000 concrete blocks (35,000 for each new building).
Inside the building the workers take a lunch break from working on the blocks.
This is the block-making mold. Concrete is put into the mold, tamped down, then as the concrete is pushed out of the mold it creates one block. It takes about 30 seconds to fill, tamp, and push out one block.
As one person forms the blocks, another two or three work to make the correct mix of concrete, sand, lime, water, etc., to the right consistency.
A close-up of the block mold.
The blocks are kept inside and out of the rain for one or two days, then are moved outside to dry.
The blocks are not stacked at first, letting them dry and harden for a day or two, then they can be stacked for further drying. It takes about 30 days for the block to dry or ‘cure’ and for the concrete to become hard.