REINFORCED CONCRETE WWTP’S
One of the most widely discussed environmental issues in recent years has been the treatment of both domestic and industrial effluents.
The so-called WWTP’S – Wastewater Treatment Plants – are usually works which, due to their specificity, both in terms of project and execution, prove to be costly, in addition to the costs involved in maintenance and operation that occur throughout their useful life.
Considering that we are talking about works executed in reinforced concrete, and in order to guarantee its watertightness as a way to avoid the contamination of the surrounding soils, as well as preventing the proper functioning of reinforced concrete – contact with aggressive environments from the chemical point of view – we are in presence of design projects where normally the thicknesses of the concrete elements and the concentrations of reinforcement increase considerably when compared with other types of reinforced concrete projects.
It should be noted that reinforced concrete does not in itself guarantee watertightness. On the other side and when in contact with chemically aggressive environments, the concrete tends to deteriorate rapidly as well as the reinforcement, whose functioning will certainly be affected.
Also micro and macro cracking of the structures will be a factor in accelerating the deterioration process mentioned above.
As a result of the above, it is necessary to provide waterproofing systems for this type of structure with the double objective of providing the necessary watertightness to the structure and at the same time protecting it from chemical attacks by effluents.
On the other side and at the level of the project of this type of structures, the requirements of thickness and reinforcement concentration may be less severe, resulting in considerable economic gains, to which can be added considerable gains in the useful life of these works, thus contributing to a greater and more effective durability of the concrete work.

Technical options and their advantages
Within the materials used in this type of work, modified bitumen membranes present advantages for this type of application.
The waterproofing system consists of an APP polymer bitumen membrane, with a mass of 4 kg/m2, doubly reinforced – 150 g/m2 polyester reinforcement and 50 g/m2 glass fibre reinforcement and covered on both sides with a polyethylene film.
This membrane is available in rolls of 1×10 m and its commercial name is POLYSTER R40 .
The APP (Atactic Polypropylene) modified bitumen compound guarantees better waterproofing and a longer duration compared to other materials.
The main advantages of this type of material are:
– Absence of physical and mechanical degradation due to atmospheric agents;
– Resistance to temperature variations and ultraviolet rays, which allows it to operate without any type of protection;
– The fact that the bituminous membrane is doubly reinforced – 150 g/m2 polyester reinforcement and 50 g/m2 fibreglass reinforcement – gives this type of material excellent mechanical resistance.
– Easy to apply as we are talking about materials that, on concrete supports, are completely adhered by torch flame action;
– Any damage can be easily repaired by simply applying a piece of the same material to the area to be repaired using a torch flame.
– Good chemical resistance to different organic and inorganic compounds at different concentration levels and temperatures as demonstrated in laboratory studies.
In addition to the advantages already mentioned, these are materials tested by LNEC – Laboratório Nacional de Engenharia Civil – for which this body has issued an approval document, within the scope of approvals of new materials and construction processes.

Manufacturing Quality Control
The quality control factor in the manufacture of this type of material is decisive for its performance in terms of waterproofing system.
Imperalum, as a certified company (NP EN 9001 and 14001), guarantees, through the control of raw materials, manufacturing and the finished product, the consistent quality of the materials produced at its manufacturing facilities, thus enabling the appropriate effectiveness and longevity of the bituminous membranes that make up the waterproofing systems.

Conclusion
The aim of this short approach is to provide some elements that will enable both planners and contractors of wastewater treatment plants to design waterproofing systems, using APP modified bitumen bitumen membranes, resulting in economic gains that we believe can be significant.