We are all now under an obligation to ensure that concrete potable water storage tanks and reservoirs comply with the practical guidance of ACOP L8 and subsequently, the stringent WRAS and/or DWI Regulations. Water quality should be confirmed by regular water testing analysis and "maintenance of the cleanliness of the system and the water in it".
Case studies - Recent concrete tank restorations
For detailed documentation of some of the concrete water storage tank repair waterproofing concrete water storage tanks and refurbishment we have completed, please see the case study links below.
Concrete is a mixture of Portland cement, water, fine and course mineral aggregates and various admixtures. On mixing all these ingredients in the correct proportion, a complex chemical reaction is set in motion. If your tank happens to crack, we can use our products to help you seal it and make it functional once again in a short amount of time.
Concrete feels like it is a very strong and hard substance, but unprotected and bare concrete can be subject to deterioration.
It is an inherent quality of concrete to have micro-pores, and if these are interconnected, causing a build up of moisture and pollutants, problems will arise.
Unfortunately, once concrete within the concrete water tank starts the process of erosion, blow holes (more commonly known as "bug holes") and exposed aggregate can become more prominent, providing a potential harbouring ground for bacteria such as micro-aquatic organisms within concrete water tanks.
If the reaction of cement with water generates heat, then it creates the possibility of developing micro-cracks due to shrinkage. Constant water and chemical permeation and abrasion can also wear down the paste and the aggregate.
Water can then penetrate the concrete, freeze and expand when the temperature drops and weaken the concrete from inside. In addition, the reinforcement steel bar can fall apart with oxygen, moisture and chloride ions infiltrating the concrete water retaining structure.
Concrete can be very variable and it is often difficult, if not impossible, to identify the aggregate and ad-mixture source of older tanks or indeed the composition of jointing compounds used at the construction stage; noticeably problems with PCBs (Poly Chlorinated Biphenyls) from jointing compounds historically used. PCBs can damage the immune, reproductive, nervous and endocrine systems. Furthermore, they can also impair children's physical and intellectual development and, according to the Agency for Research on Cancer, PCBs are strongly linked to both animal and human cancer.
Over time, all concrete absorbs water and the early stages of problems can be seen by rust staining from the reinforcing bars, which is clearly going to have an adverse effect on water quality as well as the integrity of the structure. Furthermore, as concrete is a porous substrate, it can harbour waterborne organisms such as bacteria and, subsequently, the substrate will require a relatively high demand for disinfection chemicals.
In summary, concrete is an extremely variable construction material and usually exhibits low surface tensile strength. However, blowholes, micro-pores and air pockets provide an easy access route for water and chloride migration to the steel reinforcing. Under load, concrete will crack, therefore providing further access points for these corrosive forces. When used for transportation and storage of water, even the mildest of chemical solutions can have a rapid deterioration effect on concrete.
A protective coating system for concrete water storage tanks should therefore meet the following requirements:
Acothane DW meets with the above requirements and has successfully been applied to a variety of concrete water storage structures for both dry and total immersion services.
Contact COVAC on 0800 772 3367 to discover more on the work we can conduct on your concrete water tanks.