How do you prevent sulfate attacks on concrete?
HOW TO PROTECT CONCRETE FROM SULPHATE ATTACK?
- Use of Sulphate Resisting Cement. The most efficient method of resisting the sulphate attack is to use cement with the low C3A content.
- Quality Concrete.
- Use of Air-entrained Admixture.
- Use of Pozzolana.
- High Pressure Steam Curing.
- Use of High Alumina Cement.
What is sulphate attack concrete floors?
Sulphate attack on ground floor slabs is a very serious problem which can cause structural damage to the main walls of a building. The problem occurs when the fill material (hardcore) beneath the slab contains sulphates and these migrate into the concrete. The sulphates react with the concrete causing it to expand.
What is sulphate attack in concrete How is it controlled?
Sulphate attack on concrete is a chemical breakdown mechanism where sulphate ions attack components of the cement paste….Control of Sulphate Attack on Concrete.
| Exposure | Concentration of water-soluble sulphates in soil percent | Concentration of water-soluble sulphates in water ppm |
|---|---|---|
| Very severe | >2 | >10000 |
How does sulphate enter concrete?
Sulfate attack is a common form of concrete deterioration. It occurs when concrete comes in contact with water containing sulfates (SO 4). Expansion due to ettringite formation causes tensile stresses to develop in the concrete.
What type of cement is sulfate resistant?
| Type of cement | Description |
|---|---|
| MS | Moderate sulfate resistance cement. This type of cement is generally used in New England, USA. ProBase cement is a MS type cement used in soil stabilization techniques. |
| MH MHb-10F | Moderate heat of hydration cement. Enercem™ MH cement type used for mass concrete construction. |
What is sulphate resisting cement?
Sulphate Resisting Cement is a type of Portland Cement in which the amount of tricalcium aluminate (C3A) is restricted to lower than 5% and (2C 3A +C4AF) lower than 25%, which reduces the formation of sulphate salts. The reduction of sulphate salts lowers the possibility of sulphate attack on the concrete.
What is a sulphate attack on a property?
A sulphate attack occurs when hardcore that contains sulphates was used for a the base of concrete floor slabs in a building. Sulphates react with concrete which causes it to expand. This causes the cracks and damage that is commonly seen across Northern Ireland property.
How do you check for sulphate attacks?
These include:
- heaving and cracking of the floor.
- lumpiness or doming of floors.
- traces of white salts on the floor surface.
- expansion of flooring at the damp-proof course level, pushing the outer brick walls sideways.
- lateral movement of brickwork.
- stepped diagonal cracks in external walls.
How does sulphate damage concrete?
Once the sulphates and concrete are in contact, react with each other. This reaction produces crystals, which force the concrete slab the expand. The reason sulphate attack can be so serious is that the expansion of the concrete puts pressure on the external walls, pushing them outwards and destabilising them.
Which compound is mainly responsible for sulphate attack?
The compounds responsible for sulfate attack on concrete are water-soluble sulfate-containing salts, such as alkali-earth (calcium, magnesium) and alkali (sodium, potassium) sulfates that are capable of chemically reacting with components of concrete.
What makes cement resistant to sulphate?
What is sulphate cement used for?
Sulfate-resisting Portland Cement (SRPC) is a special purpose cement used where sulfates are present in concentrations that would damage concrete made using CEM I or CEM II cements. Sulfate resistance is achieved by adjustments to chemical composition to limit the level of C3A in the SRPC.
What is sulfate attack?
Sulphate attack is the reaction between concrete constituents and sulphate ions in the pore solution of concrete that results in the production of new product with a fairly large molar volume.
What is sulfate resistant cement?
Sulfate-Resisting Cement. Sulfate-resisting cement is more resistant than ordinary portland cement to the action of mineralized water containing sulfates; it also has lower heat of hydration, slower hardening, and higher frost resistance. Sulfate-resisting cement is produced by the fine pulverization of clinker of standard mineral content.
What is sulfate resistance?
Sulfate-resisting Portland Cement (SRPC) is a special purpose cement used where sulfates are present in concentrations that would damage concrete made using CEM I or CEM II cements. Sulfate resistance is achieved by adjustments to chemical composition to limit the level of C3A in the SRPC.