Silo Chimney & Cooling tower

RCC Silo in Rourkela

Problem:

• After putting to use, the silo reported major cracks due to construction error

Solution:

• Steel supports were provided for supporting the hopper internally.
• Cracked sections were rebuilt using thixotropic mortar.
• Minor cracks were grouted with epoxy based chemical.
• Silo was externally wrapped with alternate layers of vertical and Horizontal Light weight GFRP and CFRP wraps.

RCC Silo in Dala, Varanasi

Problem:

• Poor workmanship during construction of 70.0 m high RCC Silo by slip form method
• Bulging of Silo at few locations and out of plumb construction at certain location
• Poor quality of Concrete
• Bulging and eccentric construction causing excessive localized stress leading to minor cracks

Solution:

• Finite element analysis was carried out to know nature and intensity of stress at critical locations
• FE Model from level of 19m to 68m. Eccentricity was modeled based on the input data
• It was found that several FRP overlays are required for retrofitting
• Instead of conventional wrap system, factory made composite profiles were used and fixed at site by chemical adhesive and mechanical anchors
• Exhaustive grouting with polymeric cement slurry and low viscosity monomer was carried out
• Project was completed in 180 working days

RCC Chimney in Karnataka

Problem:

• The 60m tall and 2.9m diameter RCC chimney at Goa minerals, Dharwad showed sway of 273mm due to construction error.
• This resulted in excessive moments at different levels of chimney.

Solution:

• Complete design build solution to take care of this additional moments of chimney.
• A hybrid system of carbon laminates and wraps at bottom and helical GFRP wraps at top was designed and executed by Sanrachana Team
• Cracked sections were rebuild using thixotropic mortar
• Minor cracks were grouted with epoxy and silo was externally wrapped with alternate vertical and Horizontal GFRP and CFRP wraps.
• Protective UV resistant Coating was applied on FRP System.

Chimney for Nirlon Ltd

Problem:

• The 40m tall RCC chimney at Nirlon LTD, Goregaon old factory premises converted to an IT park, was damaged due to corrosion and concrete spalling was visible.
• Tough non-functional chimney was to be retained to preserve the history of the area.

Solution:

• Cracked concrete was removed and RCC structure was grouted with epoxy to improve microstructure.
• Anti-corrosion treatment was given to rebars and additional reinforcement was added wherever required and coated with corrosion inhibitors.
• Lost concrete section was rebuilt using Micro Concrete and Thixotropic repair mortar.
• From durability aspect the whole structure was treated using vertical and horizontal CFRP wraps
• Use of CFRP kept the dead weight low and helped to maintain the original cross section size
• Protective UV resistant PU coating was applied on the chimney.

NTPC Cooling Tower, Faridabad

NTPC Bhilai

Problem:

• The cooling mechanism was enclosed in an aged building that required retrofitting
• Corrosion effects such as spalling was visible in several locations.

Solution:

• Anti-corrosion treatment was performed on all exposed steel bars
• Polymer modified mortar was used to plaster over the treated portions
• Fiber wrapping for confinement and additional strength
• 0.3 mm thick moisture protection coating for durability of the structure..

Masonry Chimney

Problem:

• 46m tall 6m diameter 60-year-old masonry chimney of industrial plant, had major vertical cracks which were over 12mm wide
• Tension bolts of Hoop ring have been found to have failed
• Chimney was designed only for gravity and wind loads. Adjoining structure constructed later, was imposing lateral thrust on it, for which it was not designed.

Solution:

• Creating a separation between the chimney and adjoining structure.
• Micro-fine cement grouts for filling cracks
• Stitching of cracks using SRM-C wrap (carbon fiber wrap)
• Additional confinement provided using glass fiber wrap (SRM-G Wrap)
• Design-build solution offered by Sanrachana