Belzona Versus Concrete
One important technical benefit of Belzona over concrete is related to its vibration resistance and its adhesion to existing concrete and metallic substrates. Concrete is by nature a very rigid material; it performs well under compression but poorly under tension and dynamic loads.
Belzona 4111, being a polymer, has a better plastic behavior than concrete, being more resilient and absorbing vibrations better. On top of that, by adhering well and creating a solid interface between different substrates, the whole system of the equipment being repaired operates and transfers loads better, without accumulating stresses in one specific area. Concrete on the other hand doesn’t adhere well to existing concrete.
Problem Facing the Pulp Mill
This case study presents a Pulp Mill that is one of the largest in Brazil, with the capacity to produce 1.5 million tons of pulp a year. The mill’s crane was responsible for moving and transporting wood logs from the piling area to the processing equipment.
Due to great cyclical stresses transferred into the crane foundations, some of the existing anchor bolts sheared off, loosening the equipment, and causing excessive and unwanted vibrations.
According to the Pulp Mill, the conventional solution of laying down a new concrete foundation would result in a shutdown of about 45 days, including time for moving the equipment, demolishing the damaged foundation, laying down new concrete, and waiting for its long curing time.
On top of this logistical setback, repairing with concrete again would just delay the same reoccurring issue, if it happened once, it would probably happen again. The ideal situation for the customer is to find a solution that would reduce the shutdown of the equipment, be less labor-intensive, use material that would perform well under dynamic loads, and would adhere well to both concrete and metal.
Based on those needs, HITA Comércio e Serviços offered a Belzona 4111 system that would meet all the application criteria established by the customer. The proposed Belzona 4111 solution would be able to achieve about 90 MPa of compressive strength in 16 hours, which would allow the equipment shutdown to be reduced from 45 days to only 72 hours when counting time of preparation, application, and curing.
|Conventional Solution Demolition and New Concrete Base||Alternative Solution Belzona 4111 & Belzona 4151|
|High cost||52% reduction in cost|
|Shutdown time: 45 days||Shutdown time: 3 days|
|High probability of the same issue occurring again||Material designed to work under high mechanical stress|
HITA Comércio e Serviços are the exclusive Belzona distributorship in Brazil since 1995. To be able to service a country of continental size like Brazil, with many different industries, customers, and markets, HITA’s team consists of over 140 people.
This was a new customer for HITA Comércio e Serviços, they had to convince the Pulp Mill of all the benefits the proposed solution would bring their plant and their operations. Being a new customer, establishing confidence is hard since you do not have a track history with the same plant, that is why day-to-day support through the consultant was important.
HITA’s know-how doing similar concrete repairs in other parts of the country helped and once the Mill saw that other big companies were effectively using Belzona 4111, they felt safer that this solution would work for them. After this first repair, two other cranes were re-anchored with Belzona 4111.
How Belzona Repaired the Concrete Surface
HITA and the customer assessed that removing the existing template of anchor bolts would be a time-consuming and unnecessary job, so a new template of 48 anchor points was designed outside the existing one that failed.
Surface preparation on the metal surface under the equipment skid was grit blasted in accordance with NACE 2 (Sa 2 ½). The concrete was pressure washed and cleaned with compressed air, including the concrete floor and the anchor bolt holes.
Once a new skid was properly placed on the concrete foundation, a slurry of Belzona 4111 and Belzona 4151 was poured into the anchor bolt holes with the excess being used to fill the space between concrete and bottom of the skid. That way, Belzona was able to do two applications in one pour, anchoring the bolt and grouting the base of the equipment.
By adhering to both concrete, skid, and anchor bolts, Belzona allows the entire system to perform as one monolithic body, better transferring the loads between components and reducing the overall vibration of the equipment.
Benefits Of Utilizing Belzona For Concrete Repair
The repair, from beginning to end was done in less than 72 hours, fitting the maintenance agenda established by the customer. The equipment is still running now with no further issues, and the success of that first application led to two others with the same customer.
The major benefit and what brings the most potential for this application is not necessarily technical, but logistical. Any repair of equipment foundations with concrete would involve a large operational shutdown, to account for disassembly of equipment, demolition of the existing foundation, and extra 28 days for the new concrete to cure.
A lot of other cement-based grouts in the market can reduce this curing time to 5-7 days, but they will still show some of the disadvantages of a concrete repair since they are still cement-based, like poor adhesion to existing substrates and shrinkage.
Belzona can achieve all the properties of 90 MPa of compressive strength, excellent adhesion to concrete and metal, and its plastic behavior for dynamic loads and vibration in about 16 hours. So, any customer would love to hear that Belzona can help them reduce the operational shutdown and the maintenance schedule of a plant from 30 days to about 16 hours. Especially when one accounts for all the labor hours that can be saved and the profit loss that a piece of equipment not running can cause to their production.
Interested in purchasing Belzona’s repair composites and protective coatings?