Why Do Grain Silos Crack?
Silo walls are designed and built with long-lasting durability in mind. Even so, constant exposure to the elements and heavy usage inevitably cause the structures to exhibit damage. Vertical and horizontal cracks can appear within silo walls for a number of reasons, including:
Temperature fluctuations
When materials are regularly heated and cooled – and said materials are prohibited from expanding and contracting freely – they are subjected to thermal stress. The Midwest’s continental climate, which is characterized by extreme differences in seasonal temperatures, is especially hostile to the concrete and steel which reinforce silo walls.
Pressure of stored material
A silo can contain a fantastic amount of weight. Even a 20’x50′ structure can safely contain 390 tons of silage. Calculating the exact amount of pressure contained by a silo’s walls requires advanced calculations.
Wind
A relatively gentle wind can exert several tons of force on a silo. The wind’s effects on a silo can be cumulative, and eventually cause a collapse even when strong gusts aren’t present.
Those are only some of the reasons why grain silos can form cracks. Moisture, defective construction and corrosion also contribute to gradual cracking and spalling. Cracks and spalling are a vicious cycle as well. Once they form, they accelerate corrosion of concrete and steel bars. They also allow water to infiltrate the silo walls, where it further weakens the structure by freezing and expanding.
How Are Silo Cracks Repaired?
Property destruction. Loss of valuable silage. Death and physical injury. Repairing cracks in a grain silo’s walls is necessary to prevent all of these disasters. But how exactly do silo restoration contractors reverse damage from cracking?
Post-tensioning
Spalling, cracking and wall separation all commonly result from overstress. In its simplest form, post-tensioning entails installation of long, strong metal bands around the exterior of the silo. This relatively straightforward reinforcement technique can restore a silo’s original load capacity quickly, effectively and economically.
Roofing repair
Repairing a silo’s roof won’t eliminate any cracks that have taken hold in its walls. It does restore the silo’s ability to keep its contents dry. This reduces the amount of weight the silo must contain and also prevents corrosion. Silo roof restoration also reinforces the entirety of the structure, reducing its risk of total collapse.
Rehooping
Stave silos, which are constructed with interlocking concrete blocks, are especially popular for storing construction materials and grains. This type of silo is reinforced with steel hoops that are bound to corrode or fall off altogether over time. Rehooping involves replacing missing hoops, as well as ones that have weakened to a point where they are no longer useful.
Shotcrete
Shotcrete is a type of cement that is applied via air pressure. It bonds readily to silo cracks, prevents them from spreading, and matches the strength of the concrete it is applied to.
Wall replacement
When parts of a silo’s walls are unsalvageable, their complete replacement may be necessary in order to restore structural integrity. Steel silos can have portions of their walls cut out, replaced and relined. Concrete silos can undergo similar treatment. If further fortification is deemed necessary, composite fiber reinforcement can be installed with or without replacing sections of the underlying wall.
Preserving a silo’s structure extends beyond fixing cracks. If you would like to ensure that your silos are ready to withstand environmental challenges and constant usage, then contact NIJAC Roofing & Insulation. Our industry-leading experience in roofing, grain elevator roofing, industrial insulation and grain elevator insulation provide your solution to silo maintenance!