Concrete Repairs: Silos for Bulk Materials (e.g., Grain)

Concrete repairs : Silos for bulk materials, such as grain silos, are typically large cylindrical reinforced concrete structures, built either as single units or grouped in complexes. Their wall surfaces, especially the external ones, are very difficult to access. Building tall scaffolding is time-consuming, and its use under construction conditions is very expensive. Due to the complex shapes of silos, it often requires the preparation of a specialized scaffolding installation project. Without incurring the aforementioned costs, concrete repairs work on silos can be carried out by specialized companies equipped with alpine climbing gear and possessing the necessary knowledge and experience in performing such tasks.

This means that the selection of concrete repairs technology and materials must allow for the following:

• Completing all work as quickly as possible;
• Minimizing the mass of materials that must be delivered to the repair sites;
• Reducing the time needed to protect freshly applied materials from sunlight, wind, and rain;
• Ensuring the longest possible use of the structure after concrete repairs without the need for further maintenance work.

PCI Repair Solutions

PCI offers a modern concrete repairs system fully compliant with current standards (primarily PN-EN 1504 “Products and systems for the protection and repair of concrete structures – Definitions, requirements, quality control, and conformity assessment”), the PCI Nanocret® system, which optimally meets the above requirements. PCI products are characterized by very low consumption rates, short waiting times before the application of subsequent system layers, rapid resistance to weather conditions, and long-lasting durability.

Concrete repairs such as silo repair can be done by PCI Nanocret® system. Which involves the following actions:

Substrate preparation involves removing all degraded, non-load-bearing, and anti-adhesive elements and layers in relation to repair materials. This includes cracked and chemically degraded concrete cover (e.g., due to carbonation), corrosion layers on reinforcement, and old paint coatings. A highly effective method for comprehensive substrate preparation is abrasive blasting, such as hydro-sandblasting.
Anti-corrosion protection of exposed reinforcement is performed with the cementitious coating PCI Nanocret® AP, containing highly active corrosion inhibitors. Thanks to these inhibitors, reinforcement does not need to be cleaned to the commonly required Sa 2.5 grade (according to PN-EN ISO 8501-1/PN-ISO 12944-4) but only to Sa 2 grade, resulting in significant time and cost savings necessary for proper preparation of reinforcement steel. PCI Nanocret® AP is also a fast-setting mortar. After approximately 1* hour, another layer of the product can be applied, and after an additional 2* hours, concrete reprofiling can begin.
Concrete reprofiling is performed with PCI Nanocret® R4 SM, a cementitious mortar classified as R4 under PN-EN 1504-3. After 28* days, it achieves a compressive strength of >50 MPa, and after just 1* day, it reaches 18 MPa, making it fully resistant to weather conditions. As a cement concrete (CC) material, it requires application conditions similar to conventional cement-based concrete mixtures. It boasts the highest fire reaction class – A1, according to PN-EN 13501-1. The presence of dispersed polymer reinforcement and an optimized aggregate structure ensures a relatively low modulus of elasticity (20 GPa) and minimal shrinkage, eliminating the need for bonding mortars (so-called bonding bridges) even on substrates of significantly lower strength class.
Smoothing with PCI Nanocret® FC cementitious mortar allows for leveling both new and old concrete surfaces before applying paint coatings. This product is classified as R2 under PN-EN 1504-3. Its compressive strength after 28* days is at least 25 MPa, enabling the safe application of all types of concrete protective coatings, including resin-based coatings like epoxy or polyurethane. Despite its extended working time (45 minutes*), diffusion-open paint coatings, such as acrylic, can be applied just 4* hours after its use.
The concrete repairs cycle concludes with the application of the colored acrylic coating PCI Polyflex®. It becomes rain-resistant within 3* hours of application. This elastic coating bridges substrate cracks up to 0.3 mm and is highly permeable to water vapor while effectively protecting against harmful gases and chloride ions. It ensures long-term protection of concrete against fluctuating weather conditions, carbonation, frost damage, and biological aggression from mosses and algae. Additional benefits of PCI Polyflex® include compliance with PN-EN 1504-2 and non-combustibility (class A2-s1,d0 per EN 13501-1).

In the event of the need to adapt the above system to specific requirements of a particular structure (e.g., if additional work such as pressure injection of cracks and fractures is necessary), regional technical and commercial advisors of PCI can assist. They will recommend an appropriate repair technology, provide training for the contractor’s staff, and support the proper application of the products.

            * At +23 ºC and 50% relative air humidity. Higher temperatures and lower relative humidity shorten the specified times, while lower temperatures and higher relative humidity extend them.