Types of concrete with applications for different structural components like beams, columns, slabs, foundations are explained here. Special concrete with uses.
Light weight concrete
One of the main advantages of conventional concrete is the self weight of concrete. Density of normal concrete is of the order of 2200 to 2600. This self weight will make it to some extend an uneconomical structural material. Self weight of light weight concrete varies from 300 to 1850 kg/m3. It helps reduce the dead load, increase the progress of building and lowers the hauling and handling cost. The weight of building on foundation is an important factor in the design , particularly in case of weak soil and tall structures. In framed structure , the beam and column have to carry load of wall and floor. If these wall and floor are made of light weight concrete it will result in considerable economy. Light weight concrete have low thermal conductivity.( In extreme climatic condition where air condition is to installed the use of light weight concrete with low thermal conductivity is advantageous from the point of thermal comfort and low power consumption.
Only method for making concrete light by inclusion of air. This is achieved by
a) replacing original mineral aggregate by light weight aggregate,
b) By introducing gas or air bubble in mortar
c) By omitting sand fraction from concrete. This is called no – fine concrete.
Light weight aggregate include pumice, saw dust rice husk, thermocole beads, formed slag. Etc Light weight concrete aggregate exhibit high fire resistance.
Structural lightweight aggregate‘s cellular structure provides internal curing through water entrainment which is especially beneficial for high-performance concrete.
Lightweight aggregate has better thermal properties, better fire ratings, reduced shrinkage, excellent freezing and thawing durability, improved contact between aggregate and cement matrix, less micro- cracking as a result of better elastic compatibility, more blast resistant, and has better shock and sound absorption, High-Performance lightweight aggregate concrete also has less cracking, improved skid resistance and is readily placed by the concrete pumping method
Aerated Concrete
Aerated concrete is made by introducing air or gas into a slurry composed of Portland cement.
No fine concrete is made up of only coarse aggregate , cement and water.These type of concrete is used for load bearing cast in situ external walls for building. They are also used for temporary structures because of low initial cost and can be reused as aggregate.
High density concrete
The density of high density concrete varies from 3360 kg/m3 to 3840 kg/m3.They can however be produced with density upto 5820 kg/m3 using iron as both fine and coarse aggregate.
Heavyweight concrete uses heavy natural aggregates such as barites or magnetite or manufactured aggregates such as iron or lead shot. The density achieved will depend on the type of aggregate used. Typically using barites the density will be in the region of 3,500kg/m3, which is 45% greater than that of normal concrete, while with magnetite the density will be 3,900kg/m3, or 60% greater than normal concrete. Very heavy concretes can be achieved with iron or lead shot as aggregate, is 5,900kg/m3 and 8,900kg/m3 respectively.
They are mainly used in the construction of radiation shields (medical or nuclear). Offshore, heavyweight concrete is used for ballasting for pipelines and similar structures.
The ideal property of normal and high density concrete are high modulus of elasticity , low thermal expansion , and creep deformation Because of high density of concrete there will be tendency for segregation. To avoid this pre placed aggregate method of concreting is adopted.
High Modulus of Elasticity, Low thermal Expansion ,Low elasticity and creep deformation are ideal properties.
The high density. Concrete is used in construction of radiation shields. They are effective and economic construction material for permanent shielding purpose.
Most of the aggregate specific gravity is more than 3.5
Mass concrete
Mass concrete is defined in ACI as, any volume of concrete with dimensions large enough to require that measures be taken to cope with generation of heat from hydration of the cement and attendant volume change to minimize cracking.‖ The design of mass concrete structures is generally based on durability, economy, and thermal action, with strength often being a secondary, rather than a primary, concern. The one characteristic that distinguishes mass concrete from other concrete work is thermal behavior. Because the cement-water reaction is exothermic by nature, the temperature rise within a large concrete mass, where the heat is not quickly dissipated, can be quite high. Significant tensile stresses and strains may result from the restrained volume change associated with a decline in temperature as heat of hydration is dissipated. Measures should be taken where cracking due to thermal behavior may cause a loss of structural integrity and monolithic action, excessive seepage and shortening of the service life of the structure, or be aesthetically objectionable. Many of the principles in mass concrete practice can also be applied to general concrete work, whereby economic and other benefits may be realized. Mass concreting practices were developed largely from concrete dam construction, where temperature-related cracking was first identified. Temperature-related cracking has also been experienced in other thick-section concrete structures, including mat foundations, pile caps, bridge piers, thick walls, and tunnel linings
Ready-mix Concrete
Ready-mix concrete has cement, aggregates, water and other ingredients, which are weigh-batched at a centrally located plant. This is then delivered to the construction site in truck mounted transit mixers and can be used straight away without any further treatment. This results in a precise mixture, allowing specialty concrete mixtures to be developed and implemented on construction sites. Ready-mix concrete is sometimes preferred over on-site concrete mixing because of the precision of the mixture and reduced worksite confusion. However, using a pre-determined concrete mixture reduces flexibility, both in the supply chain and in the actual components of the concrete. Ready Mixed Concrete, or RMC as it is popularly called, refers to concrete that is specifically manufactured for delivery to the customer‘s construction site in a freshly mixed and plastic or unhardened state. Concrete itself is a mixture of Portland cement, water and aggregates comprising sand and gravel or crushed stone. In traditional work sites, each of these materials is procured separately and mixed in specified proportions at site to make concrete. Ready Mixed Concrete is bought and sold by volume – usually expressed in cubic meters. Ready Mixed Concrete is manufactured under computer-controlled operations and transported and placed at site using sophisticated equipment and methods. RMC assures its customers numerous benefits.
Advantages of Ready mix Concrete over Site mix Concrete
A centralised concrete batching plant can serve a wide area.
The plants are located in areas zoned for industrial use, and yet the delivery trucks can service residential districts or inner cities.
Better quality concrete is produced.
Elimination of storage space for basic materials at site. Elimination of procurement / hiring of plant and machinery Wastage of basic materials is avoided.
Labor associated with production of concrete is eliminated. Time required is greatly reduced.
Noise and dust pollution at site is reduced.
Disadvantages of Ready-Mix Concrete
The materials are batched at a central plant, and the mixing begins at that plant, so the traveling time from the plant to the site is critical over longer distances. Some sites are just too far away, though this is usually a commercial rather than technical issue.
Access roads and site access have to be able to carry the weight of the truck and load. Concrete is approx. 2.5 tonne per m². This problem can be overcome by utilizing so-called 'minimix‘ companies, using smaller 4m³ capacity mixers able to access more restricted sites.
Concrete‘s limited time span between mixing and going-off means that ready-mix should be placed within 2 hours of batching at the plant. Concrete is still usable after this point but may not conform to relevant specifications.
Polymer concrete
Concrete is porous. The porosity is due to air voids , water voids or due to inherent property of gel structures. On account of porosity strength of concrete is reduced , reduction of porosity result in increase in strength of concrete. The impregnation of monomer and subsequent polymerization is the latest technique adopted to reduce inherent porosity of concrete and increase strength and other properties of concrete
There are mainly 4 types of polymer concrete
It is a precast conventional concrete cured and dried in oven or by dielectric heating from which the air in the open cell is removed by vacuum. Then a low viscosity monomer is diffused through the open cell and polymerized by using radiation, application of heat or by chemical initiation.
Mainly the following type of monomers are used Methyl methacrlylate(MMA)
Polyster- styrene
Polymer concrete
Polymer concrete is an aggregate bound with a polymer binder instead of Portland cement as in conventional concrete. The main technique in producing PC is to minimize void volume in the aggregate mass so as to reduce the quantity of polymer needed for binding the aggregate. This is achieved by properly grading and mixing the aggregate to attain maximum density and minimum voids
Shotcrete
It is defined as a mortar conveyed through a hose and pneumatically projected at high velocity on to a surface. There are mainly two different methods namely wet mix and dry mix process. In wet mix process the material is conveyed after mixing with water.
Pre packed concrete
In constructions where the reinforcement is very complicated or where certain arrangements like pipe, opening or other arrangements are incorporated this type of concreting is adopted. One of the methods is concrete process in which mortar is made in a high speed double drum and grouting is done by pouring on prepacked aggregate. This is mainly adopted for pavement slabs
Vacuum concrete
Concrete poured into a framework that is fitted with a vacuum mat to remove water not required for setting of the cement; in this framework, concrete attains its 28-day strength in 10 days and has a 25% higher crushing strength. The elastic and shrinkage deformations are considerably greater than for normal-weight concrete.
Pumped concrete
Pumped concrete must be designed to that it can be easily conveyed by pressure through a rigid pipe of flexible hose for discharge directly into the desired area. Pozzocrete use can greatly improve concrete flow characteristics making it much easier to pump, while enhancing the quality of the concrete and controlling costs.
Light weight concrete
One of the main advantages of conventional concrete is the self weight of concrete. Density of normal concrete is of the order of 2200 to 2600. This self weight will make it to some extend an uneconomical structural material. Self weight of light weight concrete varies from 300 to 1850 kg/m3. It helps reduce the dead load, increase the progress of building and lowers the hauling and handling cost. The weight of building on foundation is an important factor in the design , particularly in case of weak soil and tall structures. In framed structure , the beam and column have to carry load of wall and floor. If these wall and floor are made of light weight concrete it will result in considerable economy. Light weight concrete have low thermal conductivity.( In extreme climatic condition where air condition is to installed the use of light weight concrete with low thermal conductivity is advantageous from the point of thermal comfort and low power consumption.
Only method for making concrete light by inclusion of air. This is achieved by
a) replacing original mineral aggregate by light weight aggregate,
b) By introducing gas or air bubble in mortar
c) By omitting sand fraction from concrete. This is called no – fine concrete.
Light weight aggregate include pumice, saw dust rice husk, thermocole beads, formed slag. Etc Light weight concrete aggregate exhibit high fire resistance.
Structural lightweight aggregate‘s cellular structure provides internal curing through water entrainment which is especially beneficial for high-performance concrete.
Lightweight aggregate has better thermal properties, better fire ratings, reduced shrinkage, excellent freezing and thawing durability, improved contact between aggregate and cement matrix, less micro- cracking as a result of better elastic compatibility, more blast resistant, and has better shock and sound absorption, High-Performance lightweight aggregate concrete also has less cracking, improved skid resistance and is readily placed by the concrete pumping method
Aerated Concrete
Aerated concrete is made by introducing air or gas into a slurry composed of Portland cement.
No fine concrete is made up of only coarse aggregate , cement and water.These type of concrete is used for load bearing cast in situ external walls for building. They are also used for temporary structures because of low initial cost and can be reused as aggregate.
High density concrete
The density of high density concrete varies from 3360 kg/m3 to 3840 kg/m3.They can however be produced with density upto 5820 kg/m3 using iron as both fine and coarse aggregate.
Heavyweight concrete uses heavy natural aggregates such as barites or magnetite or manufactured aggregates such as iron or lead shot. The density achieved will depend on the type of aggregate used. Typically using barites the density will be in the region of 3,500kg/m3, which is 45% greater than that of normal concrete, while with magnetite the density will be 3,900kg/m3, or 60% greater than normal concrete. Very heavy concretes can be achieved with iron or lead shot as aggregate, is 5,900kg/m3 and 8,900kg/m3 respectively.
They are mainly used in the construction of radiation shields (medical or nuclear). Offshore, heavyweight concrete is used for ballasting for pipelines and similar structures.
The ideal property of normal and high density concrete are high modulus of elasticity , low thermal expansion , and creep deformation Because of high density of concrete there will be tendency for segregation. To avoid this pre placed aggregate method of concreting is adopted.
High Modulus of Elasticity, Low thermal Expansion ,Low elasticity and creep deformation are ideal properties.
The high density. Concrete is used in construction of radiation shields. They are effective and economic construction material for permanent shielding purpose.
Most of the aggregate specific gravity is more than 3.5
Mass concrete
Mass concrete is defined in ACI as, any volume of concrete with dimensions large enough to require that measures be taken to cope with generation of heat from hydration of the cement and attendant volume change to minimize cracking.‖ The design of mass concrete structures is generally based on durability, economy, and thermal action, with strength often being a secondary, rather than a primary, concern. The one characteristic that distinguishes mass concrete from other concrete work is thermal behavior. Because the cement-water reaction is exothermic by nature, the temperature rise within a large concrete mass, where the heat is not quickly dissipated, can be quite high. Significant tensile stresses and strains may result from the restrained volume change associated with a decline in temperature as heat of hydration is dissipated. Measures should be taken where cracking due to thermal behavior may cause a loss of structural integrity and monolithic action, excessive seepage and shortening of the service life of the structure, or be aesthetically objectionable. Many of the principles in mass concrete practice can also be applied to general concrete work, whereby economic and other benefits may be realized. Mass concreting practices were developed largely from concrete dam construction, where temperature-related cracking was first identified. Temperature-related cracking has also been experienced in other thick-section concrete structures, including mat foundations, pile caps, bridge piers, thick walls, and tunnel linings
Ready-mix Concrete
Ready-mix concrete has cement, aggregates, water and other ingredients, which are weigh-batched at a centrally located plant. This is then delivered to the construction site in truck mounted transit mixers and can be used straight away without any further treatment. This results in a precise mixture, allowing specialty concrete mixtures to be developed and implemented on construction sites. Ready-mix concrete is sometimes preferred over on-site concrete mixing because of the precision of the mixture and reduced worksite confusion. However, using a pre-determined concrete mixture reduces flexibility, both in the supply chain and in the actual components of the concrete. Ready Mixed Concrete, or RMC as it is popularly called, refers to concrete that is specifically manufactured for delivery to the customer‘s construction site in a freshly mixed and plastic or unhardened state. Concrete itself is a mixture of Portland cement, water and aggregates comprising sand and gravel or crushed stone. In traditional work sites, each of these materials is procured separately and mixed in specified proportions at site to make concrete. Ready Mixed Concrete is bought and sold by volume – usually expressed in cubic meters. Ready Mixed Concrete is manufactured under computer-controlled operations and transported and placed at site using sophisticated equipment and methods. RMC assures its customers numerous benefits.
Advantages of Ready mix Concrete over Site mix Concrete
A centralised concrete batching plant can serve a wide area.
The plants are located in areas zoned for industrial use, and yet the delivery trucks can service residential districts or inner cities.
Better quality concrete is produced.
Elimination of storage space for basic materials at site. Elimination of procurement / hiring of plant and machinery Wastage of basic materials is avoided.
Labor associated with production of concrete is eliminated. Time required is greatly reduced.
Noise and dust pollution at site is reduced.
Disadvantages of Ready-Mix Concrete
The materials are batched at a central plant, and the mixing begins at that plant, so the traveling time from the plant to the site is critical over longer distances. Some sites are just too far away, though this is usually a commercial rather than technical issue.
Access roads and site access have to be able to carry the weight of the truck and load. Concrete is approx. 2.5 tonne per m². This problem can be overcome by utilizing so-called 'minimix‘ companies, using smaller 4m³ capacity mixers able to access more restricted sites.
Concrete‘s limited time span between mixing and going-off means that ready-mix should be placed within 2 hours of batching at the plant. Concrete is still usable after this point but may not conform to relevant specifications.
Polymer concrete
Concrete is porous. The porosity is due to air voids , water voids or due to inherent property of gel structures. On account of porosity strength of concrete is reduced , reduction of porosity result in increase in strength of concrete. The impregnation of monomer and subsequent polymerization is the latest technique adopted to reduce inherent porosity of concrete and increase strength and other properties of concrete
There are mainly 4 types of polymer concrete
- Polymer impregnated concrete
- Polymer cement concrete
- Polymer concrete
- Partially impregnated and surface coated polymer concrete.
It is a precast conventional concrete cured and dried in oven or by dielectric heating from which the air in the open cell is removed by vacuum. Then a low viscosity monomer is diffused through the open cell and polymerized by using radiation, application of heat or by chemical initiation.
Mainly the following type of monomers are used Methyl methacrlylate(MMA)
- Acrylonitrile
- t- butyl styrene
- Other thermoplastic monomer
- The amount of monomer that can be loaded into a concrete specimen is limited by the amount of water and air that has occupied the total void space.
- PIC require cast in situ structures Polymer cement concrete
Polyster- styrene
- Epoxy-styrene
- Furans
- Vinyldene chloride
Polymer concrete
Polymer concrete is an aggregate bound with a polymer binder instead of Portland cement as in conventional concrete. The main technique in producing PC is to minimize void volume in the aggregate mass so as to reduce the quantity of polymer needed for binding the aggregate. This is achieved by properly grading and mixing the aggregate to attain maximum density and minimum voids
Shotcrete
It is defined as a mortar conveyed through a hose and pneumatically projected at high velocity on to a surface. There are mainly two different methods namely wet mix and dry mix process. In wet mix process the material is conveyed after mixing with water.
Pre packed concrete
In constructions where the reinforcement is very complicated or where certain arrangements like pipe, opening or other arrangements are incorporated this type of concreting is adopted. One of the methods is concrete process in which mortar is made in a high speed double drum and grouting is done by pouring on prepacked aggregate. This is mainly adopted for pavement slabs
Vacuum concrete
Concrete poured into a framework that is fitted with a vacuum mat to remove water not required for setting of the cement; in this framework, concrete attains its 28-day strength in 10 days and has a 25% higher crushing strength. The elastic and shrinkage deformations are considerably greater than for normal-weight concrete.
Pumped concrete
Pumped concrete must be designed to that it can be easily conveyed by pressure through a rigid pipe of flexible hose for discharge directly into the desired area. Pozzocrete use can greatly improve concrete flow characteristics making it much easier to pump, while enhancing the quality of the concrete and controlling costs.
