Corrosion Protection Methods for Underwater Piles

Protective Coatings for Underwater Piles

Protective coating for underwater piles is necessary as it causes corrosion of piles. The Corrosion protection of underwater pile methods provides a great solution to corrosion of underwater piles.

The surface of pile comes in contact with water, corrosion in piles forms. To protect the piles from coming in contact with water, the pile is cover with non-porous material which is anti-corrosive. There is some non-corrosive chemical materials use in corrosion of underwater piles. Several chemical coating uses for corrosion protection.

The different types of coatings employes for underwater piles are mention below:

• High build Epoxy coatings
• Zinc Rich epoxy primer
• FRP composites
• Inorganic zinc silicate primers

1. High Build Epoxy Coatings

These epoxy coatings are abrasion and chemical resistant. These epoxy coatings provide a high level of service and more tolerant ambient weather conditions. And most effective in maintaining the damage area and breakdown of a coating system.

2. Zinc Rich Epoxy Primers

Zinc Rich epoxy primer is a mixture of  Inorganic Zinc Silicates Primer and High Build Epoxy Coating. It provides a high level of service and more tolerant ambient weather conditions. And most effective in maintaining the damage area and breakdown of a coating system.

3. Application of FRP Composites for Corrosion Protection of Underwater Piles

FRP a mix of wet concrete is economic to repair on substructure parts. Repair of this parts requires the enlargement to accommodate new ties. Completely corroded part of the elements should remove by using FRP.

spreading of corrosion to other piles are protect by FRP. The aesthetics of FRP repair is one of its unheralded benefits.

4. Inorganic Zinc Silicates Primers

The structure below the splash zone always immerse in water are commonly not coat with cathodic protective layers. There are numerous types of anti-corrosive pigment primers in which inorganic zinc silicate is the best. It arrests rust creep or undercutting of the coating surrounding.

Repairing concrete columns are two category

• Surface or cosmetic  –  covers local deterioration
• structural repair –   strengthens the affected columns.

Repairing Concrete Methods for cracks and damages

1. Unloading Columns

unloading the column is necessary. Entire cross-section of the repair column is capable of carrying the reintroduce design load. Without unloading, new repair does not carry any load. Drying shrinkage of new material reduces the share of the load.

2. Redistribution of the Load

In corrosion of reinforcement and concrete deterioration, Redistribute a load of column concrete with alternative supports for repair.

 3. Supplemental Reinforcing Steel

The supplemental vertical bar to fix outside the original cage with extra ties. Provide adequate cover and Place Apartment’s bars outside the tie bars to increase column dimensions. Use Hairpin ties, of stainless steel laterally to support the supplemental bars. Column ties cannot disturb at the repair of the longitudinal bars as it causes buckling.

4. Concrete Removal

Remove concrete within a column cage and unload the column. If not, the longitudinal bars are buckle and compression failure of column take place.

5. Corroded Reinforcing Steel

It’s not necessary to remove the corrode reinforcing bar with the reduce cross-sectional area if the loss is supplement with additional reinforcing bars. The partially corrode reinforcing bars are thoroughly clean by sandblasting to obtain the bare metal. The bars with excessive corrosion is replacing with fresh reinforcement having full laps on both sides.

6. Corroded Ties

Replace the corrode ties by adding stainless steel hairpin ties that are anchor into the concrete. It is often necessary to deposit extra material around columns to provide an adequate cover over the supplemental ties.

7. Low-strength Concrete

Where the concrete strength is low, resulting in insufficient load-carrying capacity, several alternatives are available:

• Shore the column and remove and replace the in-place concrete.
• Shore column and increase the size of the column to reduce bending stresses, and increase confinement on placed weak concrete.
• Wrap the column with carbon- or glass-reinforced plastic.
• Install a supplemental column.

Reasons of Roof Repairing

1. Damages

Roofs of Asbestos Sheet and Polycarbonate materials leak if joints get loose by the wind. Connecting screws loosen up making up holes bigger creating leakages.

Damage roof are not take care, water seeps into roofs and accumulates underneath roof seeps into beams, through ceilings, into the home. Damage is by the broke, loose, missing, or water-logged surface.

If water penetrates to roof for a long period of time, a home’s structure gets damage. To avoid unnecessary water damage, the roof to maintain regularly. And the damage must replace quickly.

2. Leakages

The main reason for a leak is joint on the roof. In the sloping roof, the leakages are at the joints and junctions.

The reasons for roof leakages are wear and tear. Along with wear and tear, harsh weather cause leakages. In the flat roof, leakage is by poor workmanship, cold joints in the concrete.

Deciding on Roof Repair vs. Roof Replacement

The repairing of the roof is a better option. This option is better because of lesser cost application. Sometimes even after repairing, there is a need for replacement of roof which costs more. It is a better option for roof replacement if there is heavy damage. Another consideration to take of is the age of the roof. If it is more than 20 to 25 years old than better to select the option of roof replacement rather than repair.

Methods of Flat Roof Repairs

Residential Flat Roof Repair

1. Rubber Roofing Repair

Rubbing roofing includes products like EPDM, modified bitumen and other roofing products available as thin, rubber-like material. For minor leaks and holes, the roofer is typically using a primer and adhesive patch to seal the damaged area.

Alternatively, the roofer may use a specially-designed glue to repair small holes or cracks. Larger repairs often require replacing an entire section of rubber roofing and resealing the seams.

2. Built-up Roofing Repair

Apply a metal mesh patch along with additional layers of asphalt material to solve most leaks and cracking problems.

Apply a water and UV-resistant coating to protect the roof from future damage.

Flat roof repairs are temporary in nature. It extends the life of the roof for more years. completely replace if the flat roof has started to fail.

3. Tile Roof Repair

To avoid replacing an entire roof, quickly repair tile. As a tile has warped, cracked, fallen, or become chipped, repair it.

The tile falls or becomes warped, repair tiles without replacing the entire roof. Water begins to seep underneath any damage roof tiles and result in replacing the entire roof.

If there are any signs of water damage inside the home, tile roof is beyond repair. Water penetrates to home’s structure, it is too late to simply repair the damaged tiles.

Cost of a Residential Flat Roof Repair

The cost of repairing the roof is affordable and depends upon the extent of damage, location of the project. If compromise with small repair its good way to save money, and not beneficial in a long way. The cost of repairing is more than replacing in the major residential flat.

Precautions

Precautions to roof damage are to clean the roof of loose leaves, tree limb, standing water on a regular basis. And repair leak soon as possible. This avoids further damage to the roof.

Properties and composition of the screed

A screed is a construction element constructs in a range of thickness. Its purpose is to bring the surface of the flooring to the design height. And to provide a suitable surface for installing the specific flooring.

The screed is a flat board or an aluminum tool. It uses to smoothen the concrete after it places over a surface.

A screed makes from pre-blended mortar mixes with binders. They set as guides for straight edges. And helps in bringing the surface of floor concrete to the required level.

The screed is hard in nature. This resists the stresses and the distortion causing on the spreading and leveling of the floor topping.

Specifications of an effective screed

1. Acts as a substrate, important for fixing the specified flooring
2. It is laying on schedule
3. shows durability under various service conditions

The service conditions specify it is external or internal for civil, commercial and industrial flooring purpose.

Composition of Screed

The major components of screed show good performance

• Admixtures for mixing it with water, liquid and powdered superplasticizers, cement, and aggregates.
• Special binders to mix with water and aggregates.
• Mixes of aggregates in a granulometric curve to make the screeds.
• Special pre-blended mortars to mix with water.

Advantages

• Improve the quality of concrete
• Reduce repairs
• Lower costs
• Improvement of health and safety
• Elimination of vibrators
• Reduce of noise around the site
• Thinner concrete
• Good durability and
• Quality of concrete
• Ease of placing
• Reduce equipment and
• Labors

There are many causes of corrosion. It relates to the quality of concrete and quality of construction. The first step in corrosion of steel is to provide good quality of concrete. The quality of concrete materials, mixing and compaction and workmanship help to control the steel corrosion.

Quality in construction reduces corrosion. There are various methods, they are

Steel corrosion control methods

• Cement-Polymer Composite Coated Rebars (CPCC)
• Fusion Bonded Epoxy Coated Rebars (FBEC)
• Corrosion Resistant Steel Deformed Rebars (CRSD)

1. CPCC

It set in concrete surrounds by an alkaline medium. A cement base coating is more useful for steel corrosion control. Apply two coats of cement polymer on rebar.

Products in CPCC are:

• De-rusting Solution
• Alkaline Powder
• Phosphating Jelly
• Inhibitor Solution
• Sealing Solution

2. FBEC

It produces from 100% solid finely ground fuse powder particles. At heating, it melts to form an adherent film. There is no primer film provide in FBEC rebars. It makes a medium of weakness in the path of a bond between rebar and concrete.

Epoxy coats the rebar by

• Melts
• Flows
• Gels
• Cures
• Cools
• Stick to coat

3. CRSD

Corrosion begins with the formation of an initial layer of rust. On common rust on normal rebars, the CRSD rust is self-renewing. The protective oxide is fine texture, tightly stick and a barrier to moisture, oxygen, carbon dioxide, Sulphur dioxide. And chloride prevents corrosion.

Use corrosion resistance bars to prevent corrosion of concrete structures, damage, and failure of structures. This increases the strength and lifespan of structures.

• Thermal movement
• The permeability of concrete.
• Corrosion of Reinforcement
• Creep
• Moisture Movement
• Structural design and specifications
• Poor Construction practices.
• Improper maintenance

1.Thermal movement

All materials expand on heating and contract on cooling. The thermal movement depends on temperature variations, dimensions, a coefficient of thermal expansion and physical properties of materials. The external exposed to direct solar radiation and the roof subject to thermal variation is liable to cracking.

Remedial Measures:

Thermal joints avoid by expansion joints, control joints and slip joints.

2.The Permeability of concrete

Concrete permeability controls by factors like water-cement ratio, water hydration, curing, air voids, micro-cracks and continues exposure to thermal variations.

3.Corrosion of Reinforcement

Concrete provides protection to reinforcing steel. Steel will not corrode as concrete around it is impervious. And does not allow moisture or chlorides to penetrate within the coverage area. A properly designed and constructed concrete is initially water-tight. The reinforcement steel protects by a physical barrier of the concrete cover having low permeability and high density.

Remedial Measures:

Increase the concrete cover with proper materials like plastic, concrete, readymade cover blocks, etc., instead of using stones and wood pieces. Increased concrete cover over the reinforcing bar reduces corrosion.

use concrete with low permeability.

4.Creep

Concrete subjected to loading exhibits a slow time-dependent deformation known as creep. Creep increases with increase in water and cement content, water-cement ratio and temperature. It decreases with increase in humidity of surrounding atmosphere and age of material at the time of loading. Use of admixtures and pozzolanas in concrete increases creep. Amount of creep in steel increases with rising in temperature.

5.Moisture Movement

Shrinkage occurs in all building materials that are cement/lime based. Heavy aggregate concrete shows less shrinkage than lightweight aggregate concrete.

Materials with pores in the structure in the form of intermolecular space expand on absorbing moisture and shrink on drying. These movements are cyclic in nature and causes by increase or decrease in inter pore pressure with moisture changes.

Remedial Measures:

Shrinkage cracks in masonry minimize by avoiding the use of rich cement mortar in masonry.

Plastering of masonry after proper curing.

6.Structural design and specifications

Cracks in concrete forms due to poor structural design and specifications. At the starting of design first, consider the environmental conditions existing around the building site. It is important to determine the type of foundations, the type of concrete materials use in concrete. And the grade of concrete depending on chemicals present in groundwater and sub­soil. Closely spaced of reinforcement steel bars due to inadequate detailing causes segregation.

precautions while designing

specification for concrete materials and concrete.

Proper quality and thickness of concrete cover around the reinforcement steel.

proper reinforcement layout and detailing

7.Poor Construction practices

Construction should design and supervise only by civil engineers or persons having proper knowledge and experience in construction practices. People without construction knowledge are engaging nowadays to supervise construction works and to carry out construction works.

Lack of good construction practices due to ignorance, carelessness, greed or negligence.

For a healthy building, it is necessary to ensure good quality materials selection and good construction practices.

Some of the main causes for poor construction practices

• Using poor quality materials
• improper selection of materials
• cheap and nonstandard materials
• improper concrete mix
• Inadequate control on various steps of concrete products such as batching, mixing, transporting, placing, finishing and curing
• Inadequate quality control and supervision causing large voids(honeycomb)
• Improper construction joints between
• Addition of excess water in concrete and mortar mixes.
• Poor quality of plumbing and sanitation materials and practices.

8.improper Maintenance

Buildings should maintain at regular interval of time properly to avoid damages. Attend Leakages as earliest as possible before corrosion of steel inside concrete starts. The external painting of the building helps in protecting the building against moisture and other chemical attacks. Necessary water-proofing and protective coating on reinforcement steel or concrete.

The pile designs considering the punching shea around the heads of the piles and column base. It also designs for bending moment due to the transmission of loads from columns to the individual piles.

Pile cap Necessity

Pile is necessary when the bearing capacity of soil below the structure is insufficient for a spread footing. It transfers the load to deeper, firmer strata. Piles used where the soil particularly affects by seasonal changes, to transfer the load below the level of such influence.

The load support exceeds the bearing capacity of a single pile, a group of piles uses.

The group capped by a spread footing or a cap to distribute load to all piles in the group. Where there are a large number of closely space piles, provide individual caps. It is more economical to provide just one large cap, forming a piled raft.

SHAPES

The shape and plan dimensions of the pile cap depend on two factors.

1. Number of piles in the group and
2. The spacing between each pile.

The most common shapes are

1. Number of piles in the group

A group of piles accommodates in a pile cap.

Two pile

In two pile cap, two piles are embeds in one pile cap. The picture shows a two and one pile cap PCC arrangments for pile cap.

Three pile

The picture shows a typical three pile arrangement PCC for pile cap.

Three pile cap

The image shows a three pile cap concreting.

The shapes of the pile caps minimize the plan area for symmetrical pile arrangement about the load.

It is overhand the outer piles by at least 150mm and not excessive. And not more than the diameter of the pile diameter.

There are different shapes of pile caps according to the number of piles.

DEPTH

The overall depth provides sufficient bond length for the pile reinforcement and the column reinforcement.

The depth decides by the following criteria.

1. Punching shear.
2. Pile anchorage.
3. Shrinkage and swelling of the soil.
4. Frost attack.
5. Groundwater table.

The most important thing is a shear capacity of the pile which affects the selection of the pile depth.

SECONDARY REINFORCEMENT:

The secondary reinforcement provides to prevent the piles from splaying outwards from the pile cap.

1. This reinforcement provided at the bottom of the pile cap running around the longitudinal reinforcement. Projecting from the piles into the pile cap.
2. The direction of the secondary reinforcement is changing at the head of each pile.

The amount of secondary reinforcement changing its direction at the head of each pile. And is not less than 20% of the main tensile reinforcement and well bond.

The process and schedule will also be affected by the size and style of the house; the lot; the construction techniques used; the amount of customization required; the number of municipal inspections; whether the home is located in a large development; availability of labour, and many other factors. Ask your builder to explain the process for your home.

Phase One: Pre-construction

Before any construction begins, plans for your home are developed, finalized and submitted to the municipal building permit office for review. Permits may be required for all or some of the following work: building, electrical, plumbing, septic system and sewer connection.

Prior to this, a number of site tests may be conducted to examine the water table, the soil and the bearing capacity of the ground and to conduct environmental tests. With this information, final engineering adjustments can be made to the plans.

Phase Two: Foundation

Your house is staked out and the land is prepared. Often, the topsoil is removed and piled elsewhere for later use. Excavation is done, and the footings (concrete slabs to support the foundation walls) are formed and poured. Water, electricity, telephone and cable services may be brought in at this time.

The foundation walls are erected (may use poured concrete in temporary wooden forms or permanent insulated blocks, concrete blocks or preserved wood, for instance). The foundation may be insulated and damp-proofed. Drainage is installed to keep ground moisture away from the house. A municipal inspection of the foundation may be conducted before the outside perimeter is backfilled.

At this time, the builder may ask you to begin making your selections—deciding on flooring, tiles, cabinets and so on. While it will be weeks before these items are installed, they must be ordered early to prevent delays later.

Phase Three: Framing

Exterior walls, interior partitions, and the roof are assembled. This usually means erecting a framing skeleton and applying an exterior sheeting, or another framing technique may be used.

Once the house is fully framed, windows and doors are installed. The builder’s aim is to get to “lock-up” where it is closed as quickly as possible to protect the structure from the elements.

The basement floor is installed. Electrical and plumbing services are roughed in, and ducting for heating, cooling and ventilation is put in place.

At this time, your municipality will probably require a structural inspection to ensure that the home meets all building code requirements. Electrical and plumbing inspections will likely be conducted as well.

Phase Four: Interior and exterior work

For the next several weeks, a great deal of work will happen inside and out, much of it at the same time.

The exterior walls and the roof are insulated, and a vapour barrier is applied. Another municipal inspection may take place to ensure this work has been done properly, before the drywall is installed. Heating and cooling systems are installed, including fireplaces.

Walls and ceilings are painted, flooring is laid, and kitchen and bathroom cabinets are installed. Plumbing and electrical fixtures are put in, trim is applied, and interior doors are hung.

Siding is applied on the outside, along with eavestroughing, and porches and decks are installed. Final lot grading is done, and the driveway and walkways are put in.

Several additional municipal inspections may occur—for instance, after completion of the interior to check stairs, handrails and other health and safety-related items, and/or after final grading outside. Plumbing and electrical work will probably require the final inspection.

During this period, your builder will stay in regular contact with you, to update you on progress and to meet deadlines for selecting finishes and other decisions you may need to make.

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Phase Five: From near-completion to hand-over

At this point, your builder and crew are busy completing the final touches and cleaning up. You will be asked to do a walk-through of your home with the builder. Any last-minute touch-ups will be done. On the date of possession, you will be handed the keys–the home is now yours!

For our cabin, we decided to build a fairly large deck so that we’d have plenty of room to enjoy the view of the lake.  In total, we had about 1000 sq ft of deck to construct.  The front deck was built 12 ft wide and the covered side deck was 10 ft wide.   We decided to go with Trex for the durability and long-term maintenance.  The first step however was installing the deck footings.

We hired a backhoe to come dig our deck footings.  Top of footings needed to be 24″ below the final grade for frost protection.  Make sure you’re careful around those utility lines..especially the electrical conduit because it’s not very deep.  You’ll notice we had already constructed the floor of the deck and temporarily supported it with 2x4s.  The neighbors were worried this was permanent and quickly came over to see if we were really going to support our deck like that.  The floor of the deck was framed with hangers and 2x8s.  We used some Glu-Lams for the front part of the deck where we had to span further across the garage areas.

Whoops….forgot about that damn foundation drain pipe!

The next step to installing the deck footings is the concrete forms. We formed the footings out of 2x8s and sonotubes.  Rebar was installed at the base of the footing and a couple lengths were inserted in the cylindrical portion when we poured the concrete in.

Footings for the side deck.

We poured all the sonotubes full and had some extra concrete to dump in the base of a few of them.

Once the concrete started to set up, we smoothed the footings off and inserted a bolt that would hold the future posts on the footing. The link below takes you to the installation of our Trex deck.  That concludes the installation of our deck footings.