Eco Efficiency of Green Eco Cements

According to Cembureau's reports [1], the world's production of cement has increased by about 50% in the past 10 years. The growing demand for cement is the most significant factor affecting technological development and updating of the manufacturing facilities in the cement industry [2-5, 10]. However, the existing technology of portland cement is ecologically harmful because it consumes considerable energy and natural resources, and emits a number of pollutants such as CO2, NOx, and SOx. With annual production of 2.6 billion tons, the cement industry contributes up to 8% to global CO2 emissions [1-5]. Theoretically, the production of 1 ton of portland cement releases 900 kg of CO2; which makes the cement industry an important sector for CO2 emission mitigation strategies.

If the cement industry uses existing technologies to increase the production of bulk cement, products will have the same level of performance at the cost of increasing the consumption of raw materials and energy. The demand from growing markets cannot be met by simply expanding cement industry's current capacity [5], which will substantially degrade the environment, or by factoring the environmental damage from materials as an economic cost. Sustainable development is the future of the cement industry's success; therefore, new products must either perform better or use fewer raw materials and less energy.

Compressive Strength, MPa

FGMA Content:

160 140 120 100 80 60 40 20 0

Supersilica: Economical

v"

FGMA Content:

Compressive Strength, MPa 160 Supersilica: Economical

FGMA Content:

Compressive Strength, MPa 160 Supersilica: Economical

FGMA Content:

Waste Class W Catalyser Alum Waste

Waste Glass W Catalyser Alum Waste

Waste Class W Catalyser Alum Waste

Compressive Strength, MPa 160 Supersilica: Economical

Waste Glass W Catalyser Alum Waste

FGMA Content:

Compressive Strength, MPa 160 Supersilica: Economical

FGMA Content:

Fly Ash

Fig. 15.10 Effect of mineral additives on the compressive strength of HVMA cement

Fly Ash

Fly Ash

Fig. 15.10 Effect of mineral additives on the compressive strength of HVMA cement

Sustainable development can be defined as simultaneously achieving social, economic, and environmental objectives [12-16]. For the construction industry, sustainability can be presented as:

• Social progress that meets the needs of humankind

• Economic growth

• Effective protection of the environment

• Efficient use of resources

The concept of eco-efficiency was formulated at the 1992 United Nations Conference on Environment and Development, or Earth Summit. The World Business Council for Sustainable Development (WBCSD) has proposed the following definition: "Eco-efficiency is reached by the delivery of competitively priced goods and services that satisfy human needs and bring quality of life, while progressively reducing ecological impacts and resource intensity throughout the life cycle, to a level at least in line with the earth's estimated carrying capacity'' [13-15]. WBCSD has identified seven elements of eco-efficiency:

• Reduce the material intensity of products

• Reduce the energy intensity of products

• Reduce toxic emissions

• Increase the engineering performance or ecological benefit

• Enhance material recyclability (recycling ratio)

• Maximize sustainable use of renewable resources

• Extend product durability

• Increase the service life of the products

For the cement industry, these elements of eco-efficiency can be presented in the following guidelines [5]:

• Transfer wet cement technology to dry/semi-dry process and implement technologies for low/reduced-temperature (mineralized/belite) clinker with consequent energy/fuel savings;

• Produce stronger cement and consequently apply stronger concrete in structural members with reduced cross-sections, thereby reducing the amount of concrete raw materials, structural steel, and energy used and reducing bulk consumption of cement and concrete;

• Produce more durable cement-based materials with a significantly increased service life and reduced maintenance costs;

• Apply mineral additives or industrial by-products in blended cement, and reduce energy consumption and the corresponding emissions per unit of the cement produced;

• Implement modern technologies for energy and materials recovery and for reducing heat, dust, and pollutant emissions.

Among the major concerns of the misuse of mineral additives is overdosing which results in reduced early strength, increased water demand of concrete mixtures, and reduced freezing and thawing resistance. The possible adverse effect of blended cements on the properties of concrete must be precisely evaluated in order to meet the specific requirements of a particular construction project.

From a historical perspective, cement made by the Romans around 100 A.D. was highly durable, evidenced by the remains of many ancient structures still standing in Rome today. The earliest reference to the remarkable durability of Roman cement and concrete was made by the architect and engineer Marcus Vitruvius Pollio (25 B.C.). According to Vitruvius, the secret to the durability of Roman cement is based on mixing slaked lime with pozzolana, a volcanic ash from Mount Vesuvius, which resulted in a binder that hardened under water. Modern blended cements also use pozzolana as a mineral additive or cement-replacing material, which is intergrinded or blended with portland cement. At the same time, using volumes of pozzolana that exceed certain limits must be avoided, because it may have a detrimental effect on concrete performance (especially strength, permeability, and durability), despite the evident savings from energy and raw materials.

Blended cements incorporating different mineral admixtures or IBPW, can partly replace the cement clinker, thereby meeting the challenges of increasing bulk production and conserving energy [2-5, 18, 20-24]. In the case of acceptable CO2 emission levels, which are currently ''frozen'' by the EC and US at 2010 levels, the share of conventional portland cement in the market must be drastically reduced by the 2015 [2-5].

Furthermore, updating the existing manufacturing facilities extensively for clinker production (which comprises an essential part of the inferior cements) consumes the bulk of capital investments for many cement manufacturers and yields a very slow return; therefore, the expansion of an existing cement plant requires a proportionally high rate of investment. The major part of this investment is associated with the installation of heavy equipment and construction works; however, in the case of green HVMA cement, new investments are required only to upgrade the grinding unit. This may increase the production capacity by 4050% without additional increase of clinker output.

Since green HVMA cement uses about 30-50% less clinker than inferior cements, it creates less ecological damage, reduces carbon dioxide and other emissions at the source; and uses IBPW materials economically that would otherwise be transported to landfill sites.

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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