توسعه پایدار و ابتکارات تغییر آب و هوا

In the present paper we argue that the cement and concrete industry is contributing positively to the Climate Change Initiative by: ⁎ Continuously reducing the CO2 emission from cement production by increased use of bio-fuels and alternative raw materials as well as introducing modified low-energy clinker types and cements with reduced clinker content. ⁎ Developing concrete compositions with the lowest possible environmental impact by selecting the cement type, the type and dosage of supplementary cementitious materials and the concrete quality to best suit the use in question. ⁎ Exploiting the potential of concrete recycling to increase the rate of CO2 uptake. ⁎ Exploiting the thermal mass of concrete to create energy-optimized solutions for heating and cooling residential and office buildings.

Sustainable development has been defined by the World Business Council for Sustainable Development (WBCSD) as: “Forms of progress that meet the needs of the present without compromising the ability of future generations to meet their needs” [1]. The WBCSD continues: “Given the scale of world poverty today, the challenge of meeting present needs is urgent. But we must look ahead and do our utmost to ensure that what we do today for our ever-growing population does not compromise the environmental, social and human needs of our descendants”. Concretes made with hydraulic binders (almost all based on Portland cement) are by far the most widely employed construction materials worldwide in terms of volume, and as such have a huge impact on the environment and also on sustainable development. Produced using readily available raw materials, being easy to use and possessing good strength and durability, concrete is indispensable for meeting modern society's needs for infrastructure, industry and housing. The fast growth in developing economies such as China or India can only be sustained if an inexpensive construction material with low environmental impact is available. Concrete fulfils these requirements. In the present paper we argue that the cement and concrete industry is contributing positively to the Climate Change Initiative by: • Continuously reducing the CO2 emission from cement production by increased use of bio-fuels and alternative raw materials as well as introducing modified low-energy clinker types and cements with reduced clinker content. • Developing concrete compositions with the lowest possible environmental impact by selecting the cement type, the type and dosage of supplementary cementitious materials and the concrete quality to best suit the use in question. • Exploiting the potential of concrete recycling to increase the rate of CO2 uptake. • Exploiting the thermal mass of concrete to create energy-optimized solutions for heating and cooling residential and office buildings. Much scientific evidence links climate change to greenhouse gas (GHG) emissions of which carbon dioxide (CO2) ranks amongst the most important, accounting for 82% of the total. It is estimated that the cement industry produces approximately 5% of global manmade CO2 emissions, but it emits almost no other GHGs. When all GHG emissions generated by human activities are considered, the cement manufacturing industry is found to be responsible for only about 3% of total anthropogenic GHG emissions. Apart from emissions linked with the energy used for clinker burning, grinding and other operations, there is a natural release of CO2 associated with the de-carbonation of limestone to give the calcium silicates and aluminates in clinker. This “Raw Materials CO2 Emission” is roughly equal to 0.53kg per kg of clinker. The total CO2 emitted in cement manufacture includes, in addition, the “Fuel-Derived CO2” and also takes into account the dilution of clinker by other cement ingredients. Humphreys and Mahasenan [2] report that the cement industry emitted in 2000, on average, 0.87kg of CO2 for every kg of cement produced (worldwide cement production in 2000: 1.57billion tonnes, in 2004: over 2billion tonnes). >An analysis carried out by Battelle [2] shows that cement sector CO2 emissions are set to rise dramatically in the coming decades. Demand for cement in industrial nations is increasing slowly, but in developing countries it rose by 55% in the 1990s. It is expected that, by 2020, global demand will have increased by 115–180% from 1990 levels, with a four-fold increase likely by 2050. It is critical that the CO2 emissions associated with such growth in cement production be reconciled with international efforts to reduce GHG effects. The cement industry is fully aware of the sustainable development stakes and, over the past decades, has been actively involved in seeking ways to consume less energy and natural resources, and emit less CO2 per unit of cement produced. Recent innovations such as self-compacting concrete, high-performance concrete and surface-active materials further contribute to sustainable development by reducing the costs of construction and maintenance, improving health and safety as well as the outdoor and indoor environment.

The current examples of self-compacting concrete, ultra-high performance cement-based materials and surface-active materials show how well-directed R&D can bring innovation into the traditionally conservative concrete construction technology. However, further important R&D efforts are necessary to develop concretes with a wider range of attractive properties, such being as self-cleaning, self-repairing, with better insulating properties, and even more resistant to environmental degradation and to extremes of temperature. The scientific approach to concrete is rather recent. Concrete is a product which even today is still poorly understood. Cement and concrete science is largely interdisciplinary, often involving nano- and micro-scale phenomena. Until the introduction of modern investigation techniques, little fundamental progress had been made in elucidating relevant chemistry and physics required to control material properties and performance. In 2004, 12 industrial partners3 and 19 academic institutions4 in Europe, convinced of the necessity to improve the fundamental understanding of cement-based materials, created a Research Consortium named NANOCEM. The network, involving 120 permanent academic researchers from 9 countries, has now been in existence for 3years and is exclusively funded by the industrial partners. They believe that the newly-generated pre-competitive knowledge will lead to new technological breakthroughs that will provide value to the whole cement-based construction industry. Industrial application of this knowledge will impact the overall performance and sustainability of cement-based materials and, given the huge quantities used worldwide, will have a significant influence on environmental, social and economic progress — the three pillars of sustainable development.