By Gert Schmidt
Hindle Mason Projects (HMP) is a quality corrosion protection solutions provider, including the application of quality corrosion inhibitors.
This knowledge is harnessed throughout concrete structures maintenance programmes to extend their useable life.
In many instances, HMP uses a corrosion inhibitor together with a waterproofing system to prevent rebar exposure to elements.
We are also the approved applicators of systems that specifically prevent chloride-ions from coming into contact with reinforcing steel. This is in addition to corrosion inhibitors that increase the impermeability of concrete mixes.
However, maintaining structures in highly corrosive environments requires specialised approaches. A case in point is the application of corrosion inhibitors directly onto steel reinforcement. This strengthens the passive film around the rebar which safeguards against corrosion. Our methods also increase the electrical resistance of the metallic surface of reinforcing bar. Refer to Corrosion-Resistance Bars – CRSI: Concrete Reinforcing Steel Institute.
HMP partners corrosion protection specialists
HMP partners engineers who are also corrosion protection specialists to help select the most appropriate solution. While we are applicators of broad range of systems, they differ in specifications and formulations. A qualified engineer is also able to evaluate the unique corrosion protection requirements of concrete structures. This informs the concrete repair and corrosion protection design. HMP brings experience working with these systems in various environments. This combined knowledge ensures that the chosen inhibitor serves its purpose, eliminating the risk of premature failure. In this way, we are the bridge between engineer and manufacturer or supplier of corrosion protection solutions. Even the best designed corrosion protection design and quality corrosion protection system will fail if the contactor’s workmanship is poor. An approved applicator can also guarantee the execution of the repair system to the maximum extent possible. This is once the workmanship has been approved by the corrosion protection systems manufacturer or supplier.
HMP usually works with the following chemical additives:
- Amine carboxylate [refer to Specifying corrosion inhibiting admixtures for concrete structures – Page 3 of 5 – Construction Specifier]
- Amine-ester organic emulsion [refer to Multi-functional organic corrosion inhibitor – ScienceDirect]
- Calcium nitrate [Sika® CNI | Corrosion Inhibitors]
- Organic alkenyl dicarboxylic acid salt [Electrochemical characterisation of the ability of dicarboxylic acid salts to the corrosion inhibition of mild steel in aqueous solutions – ScienceDirect]
These are in addition to our systems that can be applied directly to the concrete substrate to protect rebar. These penetrate concrete via its pores to restore the integrity of the passive film on the surface of rebar. In this way, they also waterproof concrete, thereby, serving a dual function.
HMP: corrosion protection and waterproofing
HMP’s first line of corrosion protection is always quality waterproofing.
The most basic function of our waterproofing solutions is to protect concrete against moisture ingress and carbonation [Carbonation of concrete]. This is in addition to other potentially damaging elements. Others offer stain resistance and/or corrosion inhibition. The latter is important in instances where concrete is exposed to sea air with high humidity and chloride levels. Refer to Chlorides and concrete.
HMP selects best corrosion protection
HMP selects the best corrosion protection system for its clients, based on a number of factors. As mentioned earlier, this is done while working with our clients’ engineering teams. It is also good practice to involve the manufacturer or supplier of the system. Their expertise can also be relied upon to provide excellent technical support to ensure that their products are applied correctly.
An important consideration is the correct storage and transportation of liquid or powdered corrosion inhibitors. Both types are usually mixed with concrete or grouting materials to repair damaged structures.
HMP will also consider the extent of damage to the concrete substrate. If there is excessive water penetration, a corrosion inhibitor may need to be sprayed directly onto the replaced rebar. It will then have to set according to the manufacturer’s specification before the repair is completed.
Setting time and weather conditions are also important as these affect corrosion inhibitor efficacy. Therefore, concrete repairs need to be planned very carefully.
HMP will also determine whether it needs to apply a corrosion inhibitor to protect against either carbonation or chlorides. There may be instances where we must use a system that safeguards against both leading causes of concrete corrosion.
HMP’s practical corrosion protection solutions
HMP supplies practical and cost-effective corrosion protection solutions. Therefore, we prefer working with systems that can be easily applied and reapplied. As an expert, we always think about future repair needs and whether corrosion inhibitors will require reapplication. Enterprising clients are well aware of the importance of proactively maintaining their concrete structures. The reapplication of corrosion protection solutions can be coordinated with these operations.
If applied correctly, corrosion inhibitors will reduce concrete spalling. Refer to Spalling concrete: the causes, and control, repair & protection methods | Mapei. Because rebar will remain durable, the concrete cover is not likely to experience damage. This reduces the total lifecycle cost of the structure. Refer to Life-cycle cost analysis of reinforced concrete structures in marine environments – ScienceDirect.
Furthermore, correctly applied corrosion inhibitors can target multiple causes of degradation in one repair. Some concrete structures may be subject to specific types of corrosion-causing materials. However, there are deleterious agents that will always be present, such as carbon. Refer to Carbonation of concrete bridge structures in three South African localities. Moreover, corrosion inhibitor admixtures can provide increased adhesion between substrates increasing the impermeability of concrete. This prevents future corrosion.
For more information about HMP, visit www.hindlemason.co.za
Gert Schmidt is a Director of HMP