#buildingconservation

Tools of the Trade – Concrete

Concrete

Concrete has been used for thousands of years, assisting man in creating amazing things throughout history, including architecture, infrastructure and more.

It’s made up of 3 basic components:

Water + Aggregate (rock/sand/gravel) + Portland cement = CONCRETE

concrete05
What is concrete made of? Image credit – https://www.pbs.org

Concrete in history:

  • 3000 BC – Egyptian Pyramids:

The Egyptians were using early forms of concrete over 5000 years ago to build pyramids. They mixed mud and straw to form bricks and used gypsum and lime to make mortars.

  • 300 BC – 476 AD-Roman Architecture:

The ancient Romans used a material that is remarkably close to modern cement to build many of their architectural marvels, such as the Colosseum, and the Pantheon. The Romans also used animal products in their cement as an early form of admixtures.

  • 1824 – Portland Cement invented:

The invention of Portland Cement is credited to an Englishman named Joseph Aspdin, a material he produced by firing finely-ground clay and limestone until the limestone was calcined. He called it Portland Cement because the concrete made from it looked like Portland stone, a widely-used building stone in England.

  • 1836 – Strength Testing:

The first test of tensile and compressive strength took place in Germany.

  • 1930 – Air Entraining Agents:

Air en-training agents were used for the first time in cement to resist against damage from freezing and thawing.

  • 1970’s Fibre reinforcement:

Fibre reinforcement was introduced as a way to strengthen concrete.

sika-fibre-reinforced-concrete-tested-712x421
The use of fibre reinforcement changed the game for concrete. Image credit – https://sikaconcrete.co.uk/

With the assistance of concrete, man has been able to push boundaries in the development of construction.

Unfortunately (or fortunately in some cases!) – nothing lasts forever. Just as reassuring as that fact is, it’s also incredibly depressing. You, the people you love, your home, your world – it’ll all be gone one day. Even concrete!

A common pest to us in conservation and the construction industry on a whole is “Concrete Cancer” aka “Alkali-silica reaction” – is caused when the steel reinforcing beams within a concrete slab begins to rust.

Common causes of Concrete Cancer:

  • Poor waterproofing
  • Salt-water chlorides for buildings near the sea
  • Building defects
  • Weather
  • Poor quality concrete and insufficient concrete cover
  • Movement of the earth under the build leading to cracks

Signs include:

  • Crazing and cracking concrete (concrete spalling)
  • Rust stains which seem to leak out from within the concrete
  • Bubbling (also called Plating) of concrete render
  • Leaks which appear in overhead concrete surfaces
screenshot2016-09-20at11.29.09am
Stainless steel reinforcing beams revealed through effects of concrete cancer.

The dangers of:

  • Concrete cancer, especially on the outside of a building, not only looks terrible, but it is potentially dangerous too. Over time, and with increased exposure to the elements, untreated pieces of concrete may fall from your structure. The risk is it falling and damaging property, or even worse, hitting a person walking below.
0155-cancer5
Concrete Cancer: the silent killer. Image credit – https://www.markhamglobal.com

 

Repairing:

While the term hints at how severe this type of damage is, it is possible to fix Concrete Cancer in some cases. Depending on the cause, the engineer may recommend different solutions:

1. Polymer modified repair system solution:

For situations where concrete carbonation and low concrete cover are the issue, the engineer might recommend using a polymer modified repair system. This option removes the concrete around the reinforcing bars and cleans the steel, before applying both the steel primer, and a polymer modified material. They might also apply an anti-carbonation protective coating to the whole concrete surface. Sometimes the experts might recommend using additional reinforcing steel anodes before new concrete is applied, or the steel might be replaced in severe cases.

2. Electrochemical treatment option:

If it’s a case of chloride contamination in a building near the ocean, you might need to have specialist repair work done to treat the concrete cancer. This can include electrochemical treatment, such as cathodic protection.

anode1-2
Electro chemical treatment. Image credit – https://www.concretecorrosion.net/

3. Simple replacement method:

If it’s a case with less severe damage, you might be able to remove the damaged concrete, clean and replace the rusted, exposed steel, and fill in the cracks.

Protection against:

Engineers highly recommend waterproofing the area to stop it from happening. Waterproofing concrete is essential to prevent water from corroding the steel beams. This minimises the risk of future water damage, and prevents harsh chemicals contaminating the concrete from entering through pores. This is an important preventative because poor waterproofing, or worse, no waterproofing, could undo all the repair work on your building.

Waterproof-Concrete.jpg


The services we provide for you at

aura conservation

Roofing

Roof Tiling, Steeplejacks and Lightning Protection, Roof Drainage, Lead Protection, Roof Features.

Masonry

Stone, Brick, Cast Stone, Terracotta, Sculpture, Statuary, Bronze Statuary.

Interiors

Painting & Decorating, Plasterwork, Tiling, Timber Flooring.

Services & Treatment

Protection and Remedial Treatment, Paint Finishes, Mortars & Renders, Pointing, Paint Removal, Masonry Cleaning, Structural Repairs, Epoxy Resin Repairs.

Metal, Wood & Glass

Fine Joinery, Wood Carving, Windows and Doors, Secondary Glazing, Metalwork.


Whats on this month?

January 2019
25 Lime Based Mortars and Traditional Materials for Repair of Civil Engineering Structures
Merryhill Training Centre, Fife
25-26 Project Management and Urban Design
Birmingham City University
28-31 Specifying Conservation Works
West Dean College, West Sussex
29-30 Rubble Wall Building
Merryhill Training Centre, Fife
February 2019
1 Timber Frame Repairs
Cressing Temple Barns, Essex
1-3 Chapel Royal in England: Arechitecture, Music and Worship
Rewley House, Oxford
2 Day Rendering with Lime
Merryhill Training Centre, Fife
4-7 Conservation and Repair of Architectural and Structural Metalwork
West Dean College, West Sussex
5-6 Making and Using Traditional Mortars – C1 Contractor Level 1
Merryhill Training Centre, Fife
5 Housekeeping and Dust
West Dean College, West Sussex
5 Exploring the History, Art and Conservation of Leighton House
Kensington, London
6-7 Understanding Building Conservation
CIOB, London
8-9 Understanding British Buildings
Birmingham City University
9 Sash and Case Window Repairs
Merryhill Training Centre, Fife
12 Historic Cements and Concrete
The Engine Shed, Forthside Way, Stirling
15-16 Disaster Management and Heritage
Birmingham City University
18-22 Intensive Training Assessment and Accreditation in Construction Masonry
Merryhill Training Centre, Fife
18 Conservation of Timberwork
The Engine Shed, Forthside Way, Stirling
19-20 Understanding Building Conservation
Swansea
21 Conserving, Repairing and Maintaining Traditional Windows
Balmoral Castle, Aberdeenshire

Thanks to Building Conservation for proving us with these Key Dates and Events not to be missed in January.


Incorporated in 2006, Aura Conservation have existed for over twelve successful years. We have a sound and experienced management team. We can assist you in any of your conservation needs and have a body of long standing and experienced tradesmen we can call on with specialist knowledge of the conservation world. Along with prudent financial management, we have a sound financial foundation that will see us prosper in the coming years.

You can contact us at:

Dunham House, 181 Wellington Road North, Stockport, Cheshire, SK4 2PB. Tel. 0161 442 9850 Fax. 0161 432 8478

Email  enquiries@auraltd.co.uk
Web    www.auraltd.co.uk

conclusion1

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: