There are many methods through which high-strength concrete can be produced. Some of the widely known methods and techniques are- re-vibration, the use of admixtures, high-speed slurry mixing, prevention of cracks, Sulphur impregnation or Sulphur filling, use of cementitious aggregates, and seeding.
In this article, we discuss all the methods mentioned above in detail.
Methods for Production of High-Strength Concrete
1. Use of Admixture
The addition of admixture is one of the broad methods for the production of high-strength concrete by reducing water content; the act decreases pores in concrete. Admixtures reduce the water content in concrete and thus increase the strength in comparison to plasticizer and superplasticizer.
Superplasticizer leads to the reduction of water content by up to 30%, and maintain the required workability. Not only does it increase concrete strength to a maximum possible value but also accelerate strength achievement. Water content reduction of up to 15% can be obtained with the use of a plasticizer.
Pozzolanic materials like fly ash and silica fume are mineral admixtures that are usually added to the concrete mix. The pozzolanic materials react with Portland cement hydration product and generate extra C-S-H, extra strength added to concrete. The C-S-H gel is responsible for the strength of concrete.
The mixing water in concrete may bleed, accumulate at certain places, create continuous channels, and cause shrinkage that declines the strength of concrete. In this case, a controlled re-vibration of concrete would decrease the detrimental influences of these factors and consequently increase concrete strength.
3. High-speed Slurry Mixing
High-speed slurry mixing involves the preparation of cement and water mixture in advance, and then the aggregate is added to the mix to produce high-strength concrete.
The achievement of higher compressive strength is associated with the efficiency of cement particles, and water saved in the accurate mixing of cement paste.
4. Inhibition or Prevention of Cracks
Prevention of cracks is another technique by which high-strength concrete is produced. Crack development in concrete is inevitable and may cause concrete failure if it propagates.
The replacement of 2-3% aggregate by polythene or polystyrene pieces of 0.025mm thick results into increased compressive strength.
The polythene pieces stop the progression of cracks without the need for extra water for the workability of fresh concrete. In the laboratory, concrete samples produced by this method gained strength of 105 MPa.
5. Sulfur Filling or Impregnation
The impregnation of Sulphur into low-strength porous concrete is another method of producing high strength concrete.
The impregnation process of concrete in the laboratory involves moist cured fresh concrete for 24hours, dry specimens at 120C for 24hours, the immersion of the specimens in molten Sulphur under vacuum for two hours, and then a release of the vacuum after two hours. The samples are then kept in molten Sulphur for half an hour. Finally, the specimens can be tested.
A concrete compressive strength of 58MPa can be produced in the laboratory using the Sulphur impregnation technique.
6. Use of Cementitious Aggregates
The use of cementitious aggregates, such as fondu, can produce high-strength concrete. The fondu aggregate is a glassy slag clinker cementitious material. It can give strength up to 125 MPa with a water/cement ratio of 0.32.
Seeding is a less practical method of producing high-strength concrete. It includes adding a small percentage of finely ground, fully hydrated Portland cement to the fresh concrete mix. The mechanism of developing high-strength concrete is difficult to explain.
FAQs on Production of High Strength Concrete
What are the various methods used to produce high strength concrete?
There are many methods by which high strength concrete can be produced, for instance, use of admixtures, re-vibration, high-speed slurry mixing, prevention of cracks, Sulphur impregnation, or Sulphur filling, use of cementitious aggregates, and seeding.
How high strength concrete produced?
High strength concrete produced mainly by reducing water to cement ratio below 0.4.
What are the applications of high strength concrete?
It is used in many applications such as high rise buildings and bridges to reduced dead load and decrease the size of structural elements.
What is high strength concrete?
High strength concrete is defined as concrete that has a compressive of 55 MPa or higher.