Search results
Results from the WOW.Com Content Network
Environmental impact of concrete. The environmental impact of concrete, its manufacture, and its applications, are complex, driven in part by direct impacts of construction and infrastructure, as well as by CO 2 emissions; between 4-8% of total global CO 2 emissions come from concrete. [ 1 ] Many depend on circumstances.
Environmental concerns are the high energy consumption required to mine, manufacture, and transport the cement, and the related air pollution, including the release of the greenhouse gas carbon dioxide, dioxin, [citation needed] NO x, SO 2, and particulates. Production of portland cement contributes about 10% of world carbon dioxide emissions. [26]
The chemistry of these reactions is not completely clear and is still the object of research. [7] First, the limestone (calcium carbonate) is burned to remove its carbon, producing lime (calcium oxide) in what is known as a calcination reaction. This single chemical reaction is a major emitter of global carbon dioxide emissions. [8]
Concrete is a composite material composed of aggregate bonded together with a fluid cement that cures to a solid over time. Concrete is the second-most-used substance in the world after water, [ 1 ] and is the most widely used building material. [ 2 ] Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminium combined.
An emission intensity (also carbon intensity or C.I.) is the emission rate of a given pollutant relative to the intensity of a specific activity, or an industrial production process; for example grams of carbon dioxide released per megajoule of energy produced, or the ratio of greenhouse gas emissions produced to gross domestic product (GDP).
EMCs are produced using only a "fraction" of the energy used in Portland cement production (claimed ~100 KWh/tonne, <8% of Portland cement). No CO 2 is released by the process. It is "zero emissions". The purpose of an EMC is to replace the Portland cement requirement in the mortar or concrete being used. More than 70% replacement is claimed.
The main components of LC3 cements are clinker, calcined clay, limestone, and gypsum. [24] [25] [26] The fresh concrete production involves synergetic hydration.[10] [27] Adding large amounts of calcined clay and ground limestone to the dry cement powder, [28] [29] when adding water to the mix for making concrete, cement and additives start to hydrate and the soluble aluminates released in ...
and for the reverse conversion: where: ppmv. = air pollutant concentration, in parts per million by volume. mg/m 3. = milligrams of pollutant per cubic meter of air. T {\displaystyle T} = atmospheric temperature in kelvins = 273.15 + °C. 0.08205.