If you are planning to create a concrete pond, then you should be ready to involve in some tiring work. Concrete pond takes weeks to complete and is not a matter of day or two with mixing sand and cement, transporting barrows full of stuff from here and there, all is part of creating a concrete pond. However, this tiring work ensures you that you have a long lasting pond.
Excavate a hole of almost about 15cm (6 inch) deeper and width should wider than the required size. You need to shape the shelves and secure the surface with soil. To prevent the wet cement from sliding to the bottom slope, make sure that the sides are not steeper than 45 degrees.
Remember, if your garden soil is heavy clay, then it has the tendency to shrink in the summer season. This sort of soil is not good for your concrete. It is better to lay 8cm (3inches) of moist builders’ sand layer. For those having sandy soil, no need to lay the layer of moist builders’ sand.
Next step is to apply the base layer. You need to line the hole with a 5cm (2inches) thick base layer of concrete. To get the stronger and durable pond, it is better to adjust the ratios rather than constructing the pond with a single strength of concrete. There are three stages involved in building a strong, durable concrete pond. The first stage involves the base layer. The base layer should be: seven parts of gravel (15mm), one part cement and three parts builders’ sand.
The mixture should be stiff but moist, so that you can easily apply it. Always prepare the mixture near the construction site so that it will not get dry before you apply it. Always wait overnight to dry the first layer before apply the new layer to get the strong joints. Apply the mixture of base layer to the hole. Wait for an hour or so, then take a stiff broom and brush the drying surface to make some rough patches. These rough patches help the second layer to hold the surface firmly. Leave the surface to dry for a night.
On the next day, use 5cm (2inches) of mesh wire netting to cover the base layer to strengthen the concrete. Make sure that you overlap the strips of wire by about 10cm (4inches) and tread it with your feet into the curves of the pond. Now you have to lay another layer of the concrete which should be 10cm (4inches) thick. The ratio of ingredients should be: one part cement along with waterproofing agent, three parts gravel (15mm), and two parts builders’ sand. Use trowel to level the surface and the edges. Also use sacking or horticultural fleece to protect the surface from sunlight. You have to wait for about two weeks before further tasks. In hot conditions, sprinkle the water on the surface.
After two weeks, apply the third and last layer over the entire surface. The layer should be 5cm (2inches) thick with the ratio of: one part cement, waterproofing agent, and four parts builders’ sand. Allow the surface to dry for couple of weeks.
In the end, apply waterproofing primer and sealant. Wash the interior and remove any debris or dirt. Fill the pond with water.