Concrete stave silos are reinforced with exterior, galvanized steel hoops, which help compress the walls and provide necessary tension for structural integrity. The concrete staves act to distribute the load of the material over the hoops.
The hoops are the primary structural stabilizer of the silo and for this reason; it’s essential to inspect the condition of the exterior hoops, as they are vital to the health and safety of the silo. The exterior hoops shouldn’t be bent, broken, falling off, or lying on the ground. It’s also important to make sure the hoops aren’t heavily corroded. Hoops are bolted together with a lug, which can lead to issues if it begins to corrode. The hoops are tensioned to a specific rating and pressure, so it’s essential that the hoop has not been welded to and stands independently.
Since stave silo construction utilizes steel galvanized hoops for structural integrity of the bulk storage system, failure to protect these hoops properly will shorten the designed stability of the entire system. A cementitious silo coating is ideal on concrete stave silos, protecting the steel galvanized hoops and preventing leakage. These bonding and waterproofing agents seal the joints between the staves and add a level of corrosion protection to the exterior steel hoops, ensuring long lasting defense against corrosive elements and deterioration.
One recent case study examines a concrete stave silo with rusted and broken hoops, showing further evidence that failing to inspect your silo regularly will put your silo’s structural integrity, operability, and safety in jeopardy and require costly repairs in the future.
The quality of your stored cement can be compromised by the conditions on top of and inside your cement silo. In fact, no matter the design or the materials stored, silos are susceptible to material flow issues. Material flow that is unimpeded by moisture or other issues is essential for smooth operations and the continued functionality of your silo.
To prevent stored cement from setting inside the silo due to moisture and humidity levels, the structure must be completely watertight. Even the smallest leaks in silo roofs and walls can damage your stored cement and result in material flow issues. Ambient humidity levels can also cause some materials to set. If you do aerate stored materials, it is essential to use an air dryer system to help lower the ambient humidity level in your silo. You should also avoid over aerating stored materials as excess aeration can pump unneeded moist air into the silo, which may lead to hydration of the cement. Hydrating occurs when moisture mixes with stored material and causes it to solidify within the silo (cement is highly susceptible to hydrating). When this happens, the cement can expand and cause added wall pressure, increasing the likelihood of structural failure.
Silo Maintenance Schedules
Verify during inspections that regular preventive maintenance measures are being followed. Essential maintenance includes exterior waterproof coatings and keeping your air pad and air stones in good operational condition. Silo maintenance should also include a routine professional cleaning and regular, complete silo emptying.
Of these measures, one of the most important is regular emptying. Silos that are regularly emptied and refilled are less likely to experience buildup issues that can be seen in silos that are kept topped off. Regularly emptied silos need professional cleaning less frequently and are less likely to experience problems, such as material compacting and hydrating.
The importance of inspecting your silo on a regular basis and making sure your structure is protected from the elements, especially the roof, is the focus of one of our recent case studies, which specifically examines a leaking concrete silo roof, with cement stored inside.
Prevention is the most effective method to ensure the integrity of concrete structures, surfaces and silos. A proactive maintenance and inspection program is crucial to increase the life of your concrete and ensure the safety of those working around your structures. A proactive safety program should always include annual or semi-annual inspections to check for concealed damage and to assess visible problems that could lead to structural failure.
Though concrete is a superior material for the construction of storage silos, normal loading and unloading operations can lead to structural issues over time. Cracks in silo walls, linings and foundations are an indication of stress.
Concrete walls that show horizontal, vertical or diagonal cracking may be an indication of delamination, or separation of the concrete into layers. Delamination of the concrete is caused by the lack of bonding to the interior structural steel reinforcement, thus weakening the silo’s structural capacity. Issues of this nature will require repair sooner rather than later. Delamination of silo walls can lead to wall failure or collapse and should be addressed by a professional silo repair company immediately. Corrosion of metal silo components, exposed rebar or other deterioration like spalling should also be noted during a visual inspection.
Horizontal and vertical cracks are typically caused by temperature variations, moisture and internal pressure from the stored material. Cracks can cause concrete and steel rebar corrosion which can decrease wall stiffness, allow deflection, degrade durability and strength due to carbonation, and permit water penetration into the concrete wall.
To repair cracks in a poured in place silo, an epoxy injection is used to fill in the cracks. After epoxy injection, it is recommended to add post-tensioned strands completely around the silo area of delamination to provide additional structural integrity. These strands can replace all of the original steel reinforcing and, assuming the concrete is still sound, the silo can be returned to its original load capacity in an economical manner.
Much of this damage is preventable through routine inspection and maintenance. Third-party inspections, maintenance and repair services are the best way to manage safety on any scale. Many structural issues can be easily and economically addressed if caught early. One of our recent case studies inspects a slipform concrete silo with a horizontal crack.
To learn more, be sure to check out our full library of silo inspection videos on silo maintenance, inspection and repair on