Geopolymer Concrete - Ecofriendly Construction Material

Geopolymer Concrete - Ecofriendly Construction Material

Geopolymer concrete is an innovative and ecofriendly construction material and an alternative to Portland cement concrete. Use of geopolymer reduces the demand of Portland cement which is responsible for high CO2 emission.

What is Geopolymer Concrete:

Geopolymer was the name given by Daidovits in 1978 to materials which are characterized by chains or networks or inorganic molecules. Geopolymer cement concrete is made from utilization of waste materials such as fly ash and ground granulated blast furnace slag(GGBS). Fly ash is the waste product generated from thermal power plant and ground granulate blast furnace slag is generated as waste material in steel plant.

Both fly ash and GGBS are processed by appropriate technology and used for concrete works in the form of geopolymer concrete. The use of this concrete helps to reduce the stock of wastes and also reduces carbon emission by reducing Portland cement demand.

The main constituent of geopolymers source of silicon and aluminium which are provided by thermally activated natural materials (e.g. kaolinite) or industrial byproducts (e.g. fly ash or slab) and an alkaline activating solution which polymerizes these materials into molecular chains and networks to create hardened binder. It is also called as alkali-activated cement or inorganic polymer cement.

Composition of Geopolymer Concrete:

Following materials are required to produce this concrete:

• Fly ash – A byproduct of thermal power plant
• GGBS – A byproduct of steel plant
• Fine aggregates and coarse aggregates as required for normal concrete.
• Alkaline activator solution for GPCC as explained above. Catalytic liquid system is used as alkaline activator solution. It is a combination of solutions of alkali silicates and hydroxides, besides distilled water. The role of alkaline activator solution is to activate the geopolymeric source materials containing Si and Al such as fly ash and GGBS.

Geopolymer Concrete Materials

Mechanical Properties of Geopolymer Concrete:

Compressive strength of geopolymer concrete have been found upto 70 MPa (N/mm2). The concrete gains its compressive strength rapidly and faster than ordinary Portland cement concrete. The concrete strength after 24 hours have been found to be more than 25MPa. Compressive strength after 28 days have been found to be 60 to 70 MPa. -Ref. Paper by – James Aldred And John Day and Test results by SERC Chennai.

Other Properties of Geopolymer Concrete:

• The drying shrinkage of is much less compared to cement concrete. This makes it well suited for thick and heavily restrained concrete structural members.
• It has low heat of hydration in comparison with cement concrete.
• The fire resistance is considerably better than OPC based concrete. -Reference – Paper by – James Aldred And John Day.
• This concrete jas chloride permeability rating of ‘low’ to ‘very low’ as per ASTM 1202C. It offers better protection to reinforcement steel from corrosion as compared to traditional cement concrete.
• This concrete are found to possess very high acid resistance when tested under exposure to 2% and 10% sulphuric acids.

Applications of Geopolymer Concrete:

The applications is same as cement concrete. However, this material has not yet been popularly used for various applications.

This concrete has been used for construction of pavements, retaining walls, water tanks, precast bridge decks.

Geopolymer Concrete Building

Recently world’s first building Structural Building, The University of Queensland’s Global Change Institute (GCI) has been constructed with the use of geopolymer concrete. It is a four storey high building for public use.

Transparent Light Transmitting Concrete - Pure Transparent Concrete Technology

Transparent Light Transmitting Concrete - Pure Transparent Concrete Technology

Transparent concrete also called as translucent concrete or light transmitting concrete is achieved by replacing aggregates with transparent alternate materials. The bonding material in transparent concrete may be able to transmit light by using clear resins the concrete mix. Use of optical fibers and fine concrete also used as transparent concrete.

Transparent concrete was originally developed in 2001 by a Hungarian architect Aronlosonzi by using glass fibers. Transparent concrete is produced by mixing 4% to 5% (by volume) optical fibers in the concrete mixture. This concrete has less weight compared to original concrete.

Materials for Transparent Concrete:

Transparent concrete is manufactured by using combination of fiber optics and fine concrete. These fibers blend into the concrete like any other aggregates. These optical fibers can transmit light from natural and artificial sources into spaces enclosed by the translucent concrete panels. The main reason for using optical fiber in concrete is that it can transmit light even an incident angle greater than 600.

Optical fiber consists of three layers called as core, cladding and buffer coating or jacket. The light is transmitted through the core of the optical fiber.

Cross-Section of Optical Fiber

Cross-Section of Optical Fiber

Transparent concrete is manufactured using fine materials only. It does not contain coarse aggregates. This concrete can have the compressive strength of that of high strength concrete around 70 MPa ( 10,000 psi).

Light Transmitting Concrete

Light Transmitting Concrete

Materials used:

Cement: As the optical fiber is only responsible for transmission of light, there is no special cement required. So, ordinary Portland cement is used for transparent concrete.

Sand: Since the transparent concrete is manufactured only using fine materials, the size of sand should pass through 1.18mm sieve. The sand should be free from any impurities such as vegetation, large stones etc.

Water: Water to be used for transparent concrete should be of drinking water quality, free from any impurities.

Optical fibers: Optical fibers in the range of 4 to 5% by volume is used for transparent concrete. Thickness of the optical fibers can be varied between 2 µm and 2 mm to suit the particular requirements of light transmission.

Transparent Concrete Wall

Transparent Concrete Wall

Advantages of Transparent Concrete:

The main advantage of transparent concrete is that it can transmit light. There, it can be used to make green buildings. Since it can transmit light from natural as well as artificial sources, the building can have fewer lights to meet its demand for lighting. Thus saving huge energy cost.

Transparent concrete uses sunlight as source of light instead of electrical energy and reduces power consumption. This concrete can also be used cold countries to transmit heat with sunlight.