REPAIR & STRENGTHENING

Maintenance

Inspection and maintenance carried out on a regular basis can help to reduce the need for major structural repairs. CCL will perform maintenance checks including corrosion inspection and loadchecking, and if necessary, will replace post-tensioned strands.Specialist teams will examine the structure, identify any areas of

concern, and recommend appropriate action.

The CCL Approach

CCL’s approach begins with inspection and evaluation. This fundamental stage allows the Company to correctly identify the problem and to understand the underlying cause. Inspection may take the form of a visual survey and may also involve carrying out destructive or non-destructive testing to ascertain details such as strength or depth of concrete, degree of corrosion or positioning of reinforcement.

CCL will then liaise closely with the client to gain full appreciation of existing conditions and future requirements. Only then can CCL Engineers compile their findings, assess the potential solutions and submit their proposals.

CCL is known and trusted around the world for its technical expertise in concrete design and construction. A specialist in prestressed concrete technology, the Company also provides innovative solutions for the repair and strengthening of concrete and steel structures on building, civil, energy and marine projects. Experience gained from work undertaken across the globe has ensured that the company remains at the forefront of its field.

Repair and Strengthening Solutions

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The Need for Structural Repair and StrengtheningThroughout the service life of a structure surveillance and maintenance will be required in order to ensure the preservation of structural integrity. Most structures will have need of at least minor remedial action, but some will require a greater degree of intervention. Repair and strengthening may be called for because of site defects which occurred during the construction process, change of use, design code changes, the need for additional load capacity, or to accommodate building modifications. General deterioration may be caused by age or environmental attack.

CCL has a long history of providing specialist concrete construction solutions. Its strength lies in correctly identifying the problem and its cause, understanding the needs of the client and interpreting their requirements to develop the most appropriate solution, using the latest methods and technologies.

Surveying concrete to locate reinforcement

Site inspection

CCL will conduct a full inspection before compiling a report containing details of the findings and any recommendations deemed appropriate. The Company can also provide a monitoring service to identify potential problems, allowing prompt remedial action to be taken.

CCL has the capability to deal with strengthening problems using a variety of techniques including the addition of steel reinforcement or steel plates, external post-tensioning and carbon fibre reinforced polymer (CFRP).

Post-tensioning and associated prestressed concrete technology provides an efficient means of effecting structural strengthening. It is used in all sectors of construction including buildings, civil, marine and energy. As well as providing additional strength, external post-tensioning is used to control deflection, stresses and cracking of concrete.

CCL structural solutions also include carbon fibre reinforced polymer (CFRP) applications which provide durable, maintenance-free external reinforcement. CFRP is a versatile material which can offer a long-term, corrosion-free, strengthening solution. Although of a very high strength, CFRP is extremely lightweight and cost-effective. The woven fabric is bonded to the prepared concrete using high performance adhesive and can be used to provide additional reinforcement in situations calling for increased load capacity, structural modification, damage repair or correction of building defects.

As part of its structural repair and strengthening service CCL offers a bearing and expansion joint package which includes inspection, refurbishment and replacement.

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Structural strengthening requires the careful and considered input of qualified engineers. It may be necessary because of changes in load capacity, concrete deterioration, construction faults or the need for additional slab openings. CCL’s teams of structural and civil engineers use their expertise in concrete design and construction and their extensive international experience to determine the most suitable solution for each individual application.

Strengthening

Back span tie down of bridge deck

CFRP applied to underside of slab Remedial to increase punching shear capacity Aramid strengthening around slab opening

External post-tensioning

The reasons for damage to concrete can be many and varied, including impact, exposure to aggressive environmentsand reduced cover.

Concrete Repair

Deterioration may cause spalling and hasten corrosion of the reinforcement, which in turn can reduce flexural strength and may result in failure.

Before remedial work is undertaken the extent of the damage and its underlying cause must be established.

Repair and refurbishment of defective concrete can be carried out successfully using a variety of materials. CCL has provided specialist concrete repair systems for many different applications from grout anchors in concrete slabs to mass filled voids below concrete pipes. The use of grout and resin injection is a proven method of dealing with cracks in concrete structures in order to prevent ingress of water or gases.

The Company has undertaken grout injection repairs to buildings, large civil structures and power plants. Each grouting problem is unique and CCL specialists will assess each application to fully understand the problem before advising on the most appropriate solution.

Resin injection is also part of CCL’s concrete repair solutions package. Epoxy resin injection can produce impressive results, knitting together fragile and fractured structures and providing protection against corrosion. In addition to epoxy resins flexible polyurethane can be used to allow a greater degree of movement in the structure. Although not structural, these resins can be used to bond cracks or joints to prevent water ingress.

If carried out correctly, grout or resin injection can result in the restoration of full structural integrity and can extend the service life of the structure.

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Grout anchor at post-formed opening in slab

Diamond cutting

Resin injection applied to cracked concrete

Void filling to combat delamination

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Cylinder jacks are provided as single acting, double acting, lock-nut design, custom mount, custom stroke and custom bore models. Flat jacks, which are ideal for low height or restricted access situations and require only minimal space for installation, can be used for permanent or temporary applications. When installed on a temporary basis hydraulic oil or water is used for inflation. For permanent location cementitious grout is used.

These highly skilled operations are carried out by CCL specialists or under their direct supervision. A full project review will be conducted to identify the most appropriate method of propping, lifting, lowering, sliding or weighing a structure. CCL has a flexible approach and can tailor a solution to meet the specific requirements of the project, while ensuring that safety remains the highest priority.

Temporary propping to secant pile walls

CCL can offer a range of lifting, jacking and weighing services as either astand-alone option or as part of a structural repair package for buildingsor civil structures.

Jacking and Lifting

Temporary propping to secant pile walls

Preloading of retaining prop using cylinder jack and locking collar

Cylinder jacks with locking collars providing temporary support

Grout filling a flat jack to preload the retaining prop

Preloading of retaining prop using flat jack

The replacement of key components such as bearings and expansion joints is a common aspect of structural repairand strengthening.

Bridge Bearings andExpansion Joints

CCL’s comprehensive bridge bearing and expansion joint package includes inspection, design, supply, refurbishment and replacement.

Bridge bearings are designed to transfer loads, provide restraint and allow rotation, while accommodating displacements caused by shrinkage, creep, live loads, variations in temperature and seismic activity. CCL specialises in the bespoke design of bearings which meet relevant local and international standards and exactly match the requirements of the project.

The role of expansion joints is to allow movements in a structure which may be induced by creep, the effect of shrinkage, thermal changes and the imposition of live loads.

The maintenance or replacement of both bearings and expansion joints should always be entrusted to experienced professionals. CCL recognises that every project is unique and will work to find the optimal solution for each situation.

Following a detailed inspection CCL will provide a comprehensive report recommending appropriate action. Where remedial measures are required the Company will ensure these are carried out safely and efficiently, causing minimal disruption.

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Bridge bearings

Expansion joint from below prior to installation of edge control systemBridge bearing replacement

Installation of expansion joint