How Pressing Works?

The hydraulic pressing process consist of filling a mould with a wet mix concrete with an aggregate/cement ration between 5:1 & 7:1. Then the pressure is applied of 100 psi (6.9 MN/m²) and this remove excess water and the expelled and compaction is complete.

The aggregates and cement are measured accurately and dispensed into mixer. Then the water is added to form a slurry having the approximately ratio of 1:1. Unlike the conventional precasting the quantity of the water is not critical as extra water forced out in pressing. Select the aggregate appropriate so the maximum quality can achieve and get the maximum production. The aggregate must be pre-washed and does not have any contamination.

There is dust or ‘fines’ are used to get a close-texture and smooth surface of the finished product. For preventing the escape of ‘fines’ the water is drawn off by pressure. For this a sheet of porous paper of filter cloth is placed or fixed at the bottom of the mould former.

Then the measured amount of wet mix is poured into the mould. The mix easily runs and fills the mould without any need of vibration and second paper or filter cloth is attached to the die head.

The press is actuated and hydraulic ram presses down into the mould and squeeze the excess water. The drainage of excess water is an important part of the process as the mix presses with 400 tons of pressure. For this there is vacuum top drainage system. The duration of the pressing ranges from 10 to 30 seconds depend on the aggregates quality/grading and characteristics.

After pressing the product is strong enough to be handled and removed from the press. After that it stacked near the machine within a dry atmosphere of the building overnight for curing. In some of hot places the kerbs are watered to ensure that curing does not happen to quickly. Then the products are stacked out into stacking area for normal curing. The process of curing can be accelerated by using the steam curing.

The majority of the products produced on the press are paving and kerbstones. There products are sectional garage panels and counterbalance weight are also produced. The factory should be near to the aggregate supply and it is big enough to handle the production and store the ready product.