Somerset Wall Cracking and Spalling
Market: Coal Facility Material Stored: Washed Coal Silo Size: Jumpform, concrete silo 86′ x 176′ Issue: Significant wall cracking and spalling, requiring a liner installation. Project Background Project Background When a coal facility needed a new 80' diameter, 176' tall concrete silo for washed coal storage, Marietta Silos was presented with a new design and construction challenge. The original silo was a Slipform reinforced concrete construction. Its unloader portion spanned the first 24', with a 5' reinforced floor containing seven stainless steel cones to discharge coal onto a conveyor system for customer loadout. View of 80' Jumpform rig from inside the silo during construction. The project involved the design and construction of the first Jumpform cast-in-place reinforced concrete silo liner at this scale. Until now, Jumpform systems were limited to silos no larger than 65' in diameter. Expanding beyond that size required rethinking the entire rig engineering. While complex, the effort carried significant benefits to the customer as Jumpform silo construction is one of the most durable and cost-effective silo construction methods. Silo Details Over the course of two months, Marietta Silos' expert engineers redesigned and modified the proprietary Jumpform system to accommodate the expanded size. The result was a new platform, the largest Jumpform system in the industry, capable of supporting the construction and repair of silos up to 80' in diameter. The finished Jumpform silo construction operations. To keep the project on schedule and aligned with stringent quality standards, Marietta Silos partnered with local steel and stainless-steel fabricators. These partners produced all structural steel components and the seven stainless steel replacement cones. Local collaboration also extended to the concrete supplier, who assisted with mix design adjustments to ensure lasting strength and durability, quick set times, and consistent quality. Marietta Silos' project engineers determined that an exterior liner would require the demolition of adjacent structures and additional measures to address harsh winter conditions typical at the site. A reinforced interior liner was therefore selected for the project. The new liner design covered 132' of the 147' storage area, the portion exposed to the greatest stressors of loading and unloading. Conclusion Despite the complexity of redesigning the Jumpform system, the demanding schedule, and adverse weather, Marietta Silos successfully delivered the project. With the work completed, the redesigned silo is expected to deliver another 20 years of service. "Marietta was a great group to work with, very knowledgeable, and we look forward to working with them again." Customer & Site Project Manager.
Post Tension Solution for Silo Damage Caused by Asymmetrical Flow – Arizona
Market: Manufacturing Material Stored: Coal Silo Size: Slip form, concrete silo 40′ x 107′ Issue: Cracking in the silo wall due to asymmetrical flow. Project Background A Marietta Silos silo repair crew is shown placing support strands around the exterior wall of a silo that has cracked due to interior pressure loads and an imbalance of load management. Once in place, these strands will be tensioned to meet professional engineering specifications for wall reinforcement. This project was initiated following an inspection that determined horizontal forces from an asymmetrical material flow caused the silo walls to crack. Once the strands are properly tensioned through a hydraulic process, steel lock couplers are positioned and tightened. Tension is a critical component in the silo repair, and is determined by a qualified engineer using such factors as silo size, stored material weight and how the silo is used. Once completed, the tensioning assures that the silo can be safety used. Shown: Concrete encasements are poured around the lock couplers for protection from the elements. Tensioned strands that surround the silo are encased in an ultraviolet resistant sleeve to prevent sunlight deterioration.
Grout Finish on Two Clarifying Units – KY
Market: Power Material Stored: Bottom Ash in Water Silo Size: 72′ Issue: Needed smooth, top layer of grout on the bottom of two clarifier units. Project Background The bottom of the clarifying tank. Bottom ash is a by-product of a coal-burning power generation facility. After the coal has been consumed, bottom ash remains and must be removed from the bottom of the boilers which typically consists of various metals, slate, and rock. As you can see in the above image, the clarifying tank bottom is sloped to assist in the flow of the bottom ash solution. The tank bottom is made to specification, but with a 2” below grade so the grout can be added. The grout allows for a smoother finish for increased flow of the bottom ash. The finished product: a 4,000-pound PSI grout with a smooth finish. The large agitator arms coming off the center pole are part of the clarifier unit. Agitator arms are used to trowel the grout to the correct height and the correct slope of the clarifier. Once in use, the agitator moves around the bottom of the clarifier, keeping the bottom ash moving and preventing collection of solids on the bottom.
Slip Form, Concrete Silos Inspection
Market: Manufacturing Material Stored: Raw materials in granular and powder form Silo Size: (4) 17′ x 75′; (4) 20′ x 75′ Issue: Exterior wall, spalling concrete exposing reinforcing steel. Project Background Silo engineer uses hammer during particular inspection technique, referred to as concrete sounding, to check for delamination of the exterior silo wall. Pictured above is an experienced silo engineer performing an exterior inspection of slip formed, concrete silos. Due to heavy usage, original design and potential construction issues the silos under inspection have significant spalling on the exterior walls exposing reinforcing steel in numerous locations. An in-process interior concrete silo inspection conducted by an experienced silo engineer. Safety is paramount, particularly during confined space entry. All silo entrants are trained on applicable OSHA & MSHA standards prior to arriving on-site. As shown above, the entrant can fit through an entry point on the silo as small as 18” square or 18” diameter. By removing an air duct, a professional can gain entrance to the silo interior and diagnose existing conditions. The silo engineer descending into the silo during interior inspection. Once inside, the engineer can ascertain many things about the silo. Using various industry specific methods for the inspection, a detailed report is completed with all the inspection findings. After the report is completed, all issues discovered are then prioritized and the customer is provided a proposal to repair the operational or safety deficiencies discovered. To maintain operational safety and silo efficiency, it is imperative to establish a routine silo inspection schedule.
New Construction of 2 Fly Ash Concrete Silos – West Virginia
Market: Power Material Stored: Fly Ash Silo Size: 40′ diameter by 113′ tall (Quantity 2) Issue: Required two new fly ash silos for bulk storage. Project Background Two structurally complete silos. Pictured above are two structurally complete silos. The silos have a shared stair tower between them for secondary access to the roof and equipment floor in the silos. The brown colored steel head house is used to enclose the equipment on the roof. While this equipment storage is very nice, it is also very expensive and creates significant additional weight to the top of the silo structure that must be considered during the silo design. There are other adequate and more economical ways to enclose the rooftop equipment. Initial design is critical in construction of a new silo for bulk material storage. From the foundation, up, it is imperative that a silo specific engineering group is involved to take into account all the factors associated with implementing a structurally sound, efficient bulk storage system into the process.
Construction of Two New Fly Ash Concrete Silos – Tennessee
Market: Power Material Stored: Fly Ash Silo Size: 45′ diameter by 141′ tall (Quantity 2) Issue: Two new fly ash silos needed for bulk storage. Project Background Construction of two fly ash storage silos in process. The picture above shows two fly ash storage silos during the construction process with the shoring to pour the bin floor through the large truck door penetration and the temporary stair tower for employee access to the work deck. The silo to the right has the walls completed while walls are still being poured for the silo to the left; the block-outs are still in place and the concrete forms are three high at the top of this silo. A closer look at the concrete forms. Individually the concrete forms are 4'x4' and connected together to form three rows around the silo for a total form height of 12’. Once the top form is poured and reinforcing steel is placed, the bottom 4’ form is detached and jumped to the top of the forms. This is known as ‘jumping a concrete silo.’ Also pictured is the continuous work deck inside the silo walls where employees tie vertical / horizontal reinforcing steel, place block-outs and penetrations and set the forms when jumping to the next level. This work deck is completely self-supported by nine masts that go down to the foundation, so none of the load is suspended. It moves vertically by hydraulics and utilizes a dual pin locking system in each pole to ensure safe operation and stability. Because this is a continuous work deck surrounded by the top form, it is exempt for the OSHA standard for fall protection. Completed fly ash silos. Pictured above are the structurally complete silos. The silo to the right has a permanent stair tower that provides roof access to the left silo via walkway. Equipment has not been placed on these silos yet, but they are ready to be put into operation. Initial design is critical in construction of a new silo for bulk material storage. From the foundation, up, it is imperative that a silo specific engineering group is involved to take into account all the factors associated with implementing a structurally sound, efficient structure.
Cleaned and Coated 3 Limestone Silos – Texas
Market: Chemical Manufacturing Material Stored: Lime Silo Size: 26′ diameter by 50′ tall (Quantity 3) Issue: Cleaned and coated silos Project Background A concrete stave silo being coated with a specifically designed coating. Pictured above is a concrete stave silo. The Marietta Silos crew is using a specifically designed, cementitious coating with a bonding agent that will protect the steel galvanized hoops and prevent leakage. The employees are working off of a suspended work platform while wearing body harnesses as part of the fall protection, safety program. As time and the weather elements affect concrete stave silos, this coating seals and protects the concrete staves from moisture. Stave silo construction utilizes the steel galvanized hoops for the structural integrity of the bulk storage system. Not protecting them in the correct manner will negatively affect the hoops longevity. The three silos after being coated. In order to effectively repair or recoat a silo, the exterior must be thoroughly cleaned. It is very important to choose a company and engineering firm with experience in selecting a cementitious silo coating that will protect the steel galvanized hoops and prevent leakage. It is recommended that all silos are inspected periodically to insure their structural integrity, operability and safety.
New Fly Ash Concrete Silo Construction – West Virginia
Market: Power Material Stored: Fly Ash Silo Size: 46′ diameter by 110′ tall (Quantity 2) Issue: Desired two new fly ash silos for bulk storage. Project Background Two fly ash storage silos during the construction process. Pictured above are two fly ash storage silos during the construction process. The silos are structurally completed: walls, large truck door openings, equipment floor openings, roof with handrail around the perimeter and access ladders with platforms to the roof. To the left of the silos is the crane that is still onsite. Marietta Silos uses the crane during the construction process to lift structural steel, embeds and penetrations up onto the work deck where it can be easily accessed by the construction crew. The crane is also utilized for lifting a concrete bucket during wall construction. The concrete is poured into the forms in a circular pattern until the 4' forms are filled for that particular jump.
Bulging and Cracked Stave Silo Walls with Broken Frame – Pennsylvania
Market: Manufacturing Material Stored: Clay Silo Size: 28′ diameter by 58′ tall Issue: Bulging and cracked wall with a broken frame. Project Background A concrete stave silo cracking from continued stress on its walls. Stave silos were originally designed and used in agricultural markets for silage storage and are typically less than 30’ in diameter. Stave silos were adapted for use in industry. The introduction of side discharge chutes, vacuum or pressure loading and unloading, heavier materials and the need for faster throughput requirements have led to misuse and resulting complications. As demonstrated by the silo above, stave silos were not engineered for industrial applications. With the continued stress put on the structure the wall began to push or bow out from its normal form, cracking the concrete staves around this frame. A closer view of the cracking silo. Pictured above is a closer view that shows the broken frame which is almost completely pushed out of the silo wall. The steel galvanized hoops are attached to this frame. As it is pushed out of the wall, this entire cross section of the silo’s structural integrity is compromised. This is the initial stage of a silo wall failure and, if not addressed, can lead to a catastrophic failure of the silo wall. It is far more cost effective to make repairs of this nature, rather than build a new silo for changing applications and markets. Stave silos, however, must be inspected regularly to ensure they remain safe and efficient. As application needs change over time and new factors are integrated with an older structure, a professional silo engineer must be consulted to ensure continued safety.
Cracking and Broken Stave Silo Repair – Pennsylvania
Market: Manufacturing Material Stored: Aggregates Silo Size: 28′ diameter by 66′ tall Issue: Cracking and broken staves Project Background A concrete stave silo that uses galvanized steel hoops around the silo for structural support. Pictured above is a concrete stave silo with galvanized steel hoops around the silo for structural support. The hoops were not in good condition and were subsequently replaced. This silo is constructed with a suspended cone that is welded to a steel ring girder that protrudes through the wall. Below is a closer look at the inside of the suspended cone. It shows evidence of obvious water leakage around the steel ring girder and the suspended cone. Anchoring cones into silos this way is not an accepted method. New silos are constructed with vertically supported cones instead of horizontally suspended. This silo cone could have been repaired by pouring pilasters from the foundation up to the cone and attaching it, creating a suspended cone. However, the customer deemed it non-economical and took this silo out of service. It is imperative to have silos inspected regularly. It is imperative to have silos inspected regularly by an experienced, professional silo company. Preventive maintenance and inspections should be incorporated for all material handling equipment to ensure its safe and efficient operation for all industry.