Irrigation Channels
Irrigation Channels Waterproofing
We will divide this subject into three distinct areas of application:
a) Channels built on compacted soil
b) Channels built in concrete
c) Rehabilitation of degraded concrete channels.
Due to their characteristics and dimensions, hydraulic works to collect and distribute water for irrigation must be carried out at low construction and maintenance costs.
This type of project, usually on a large scale, requires careful technical and economic studies in order to meet the water needs of agricultural communities and simultaneously allocate economic resources that are normally scarce given the scale of this type of work.
In order to make a technical and economic contribution to the above, we will now list three types of situation where the application of bituminous materials may prove to be very advantageous.
The introduction of an anti-root additive in the manufacturing process will allow roots to be simply repelled during operation, thus avoiding degradation of the membrane, the concrete support and its joints, as well as the deposition of plants on the drainage surface of the channel.
This membrane has a mass of 5Kg/ m2, is available in rolls of 1 x 8 m and its commercial name is POLYSTER 5O T Garden.
We are dealing with materials tested by LNEC – Civil Engineering Laboratory – for which this organization has issued the Application Document – DA 68.
The main advantages of these materials are listed below:
– Resistance to the effect of roots and other vegetation.
– Absence of physical and mechanical degradation due to atmospheric agents – Resistance to temperature variations and to ultra violet rays.
– The mass of 5Kg/m2 allows for application on irregular substrates and even on the soil, with good mechanical resistance to the stresses and strains to which it will be submitted.
– It is easy to repair any damage by simply applying a piece of the same material using a torch flame.
– Easy application as the membrane is applied directly over the existing back and bottom of the channel.
– This type of material can be placed directly on the soil without the need for concrete structures.
a) Irrigation channels built on compacted soils
The most important issue to consider will be to analyse the soil characteristics in order to guarantee optimum compaction levels.
It is also recommended to remove existing stones from the soil in order to avoid puncturing effects on the bituminous membranes when submitted to hydraulic load.
In order to avoid losses, we recommend cutting the membrane to a length equal to the width of the channel.
15cm overlap distance should be considered in relation to the weld joint between membranes.
At the upper edges the membrane will be fixed by trenches (0.50×0.50 m) duly filled and compacted.
b) Irrigation channels built in concrete
As a preventive measure to increase the service life of channels made of concrete, waterproofing during the construction phase of this type of work could prove to be very advantageous
– Protection of the concrete structure.
– Effective fight against the action of roots, particularly at the joints.
– No deposition of plants and vegetation on the concrete surface thus increasing the flow capacity of the channels.
In this way, although there is an initial cost related to the application of bituminous membranes, it is possible to guarantee greater operating efficiency and to a certain extent delay future maintenance work.
c) Rehabilitation of degraded irrigation channels
The main factors responsible for the degradation of irrigation channels are:
– Poor soil compaction and subsequent submitting of the concrete structure to movements and settlements.
– Action of roots and other vegetation.
– Poor or non-existent drainage system.
The rehabilitation of degraded channels using bituminous membranes is a relatively low-cost solution in terms of execution and maintenance.
The most important characteristics of this type of solution are as follows:
– Waterproofing in order to avoid water loss.
– Long-lasting in order to avoid the need for new waterproofing in the short or medium term.
– Low cost, falling below the prices of other existing solutions.
– Over-complying with Application Document DA 68.
– Easy to apply, as the membrane is placed directly on the existing surface and bottom, and does not require any type of protection due to its resistance to ultraviolet rays.
– With technical characteristics that have been duly tested and proved in the laboratory and on job site, particularly in terms of resistance to traction and tearing, as well as to static and dynamic puncturing, and also resistance to ageing and abrasion.
– Anti-root repellent action which, by acting as a repellent, is particularly important in joints, preventing their degradation, and also improving the flow rate by preventing the fixation of plants on the surface of the channels.
