Advantages And Disadvantages Of Ordinary Portland Cement

Coal is the dirtiest of all fossil fuels. When burned, it produces emissions that contribute to global warming, create acid rain and pollute water. With all of the talk surrounding nuclear energy, hydropower and biofuels, you might be forgiven for thinking that grimy coal is finally on its way out. On the other hand, coal is no sooty remnant of the Industrial Revolution - it generates half of the electricity in the United States and will likely continue to do so as long as it's cheap and plentiful . Clean coal technology seeks to reduce harsh environmental effects by using multiple technologies to clean. Coal is a fossil fuel composed primarily of carbons and hydrocarbons. Its ingredients help make plastics, tar and fertilizers. A coal derivative, a solidified carbon called coke, melts iron ore and reduces it to create steel. But most coal - 92 percent of the U.S. supply - goes into power production .Electric companies and businesses with power plants burn coal to make the steam that turns turbines and generates electricity. When coal burns, it releases carbon dioxide and other emissions in flue gas, the billowing clouds you see pouring out of smoke stacks. Some clean coal technologies purify the coal before it burns. One type of coal preparation, coal washing, removes unwanted minerals by mixing crushed coal with a liquid and allowing the impurities to separate and settle. Other systems control the coal burn to minimize emissions of sulfur dioxide, nitrogen oxides and

For the most commonly used expansive cements, ordinary Portland cement is used as the cementitious ingredient, however the other types of cement may also be employed. There are several widely used materials for expansive ingredient, these materials can be classified into three main categories by the kind of hydrated products formed due to hydration reaction, formation of ettringite (C_6 AS ̅_3 H_32), formation of calcium hydroxide (Ca(OH)_2), and formation of magnesium hydroxide (Mg〖(OH)〗_2).

When reading of the concrete that the ancient Romans used, and learning of their unique mixture of volcanic ash and slaked lime (“pozzolana”) I find it most interesting that this concrete still proves to be standing in some places today! It is said to be less sturdy than what we use here in America (Andrews, 2012) but no doubt it gave modern civilization the ingenuity to create what we use today.

Similar to most coal fired power plants in the United Stated today the Kingston Fossil Plant in Tennessee utilized various ‘scrubbers’, which effectively separated flue-ash, also known as fly ash, a byproduct of the coal combustion process. Through the use of scrubbers fly ash is separated from the flue gases released into the atmosphere. Fly ash is

First, concrete durable. Concrete is something that will outlive other products up to three times over (“What Makes…”). In addition to durability, concrete is efficient. Concrete can be made with byproducts from power plants, and other aspects of manufacturing. Concrete is primarily made up limestone, the most abundant material on Earth. Above all of this concrete can be recycled. Concrete can be crushed and recycled into another structure or product, reducing the need to mine the limestone for production. Concrete also allows water to pass through which reduces the chance of flash flooding, erosion, and water table depletion as compared to other materials. This is a major check in the sustainability of concrete; the conservation of soil, landscape and ecosystems. Concrete is a very green option when it comes to building

But there are also many detrimental factors as well, since the production of coal results in air pollution, sulfur dioxide emission, carbon dioxide emission, acid rain, and hazardous waste [4]. These environmental problems are due to both the mining of coal and coal production plants. Many issues arise with the mining of coal. Firstly, the safety of miners is put at risk as they descend hundreds of feet below the surface of the Earth. After many years in this field of work, many miners develop black lung because of inhaling the coal extensively. Secondly, the extraction of coal is very costly due to the machinery needed along with the transportation of the coal after it has been mined to the various factories that are able to extract the sulfur impurities in coal and burn the coal for energy [5]. New methods have been developed to help with some of the issues relating to coal production. To rid the surrounding environment of toxic pollution, emission-scrubbing

After it is brought out of the ground, the coal is then transported by either a train or a barge to refineries. Upon arriving at the refineries, the coal is either washed by water, or put through a chemical bath to remove some impurities. At the power plant, the coal is then pulverized to a powder just before being burned. The coal powder is then pushed into a furnace where it ignites while still airborne. This fuels the fire which heats up pipes with water running through them. The water begins to boil, and under pressure, the water evaporates and becomes steam, this steam rises and goes through turbines which rotates a generator, and creates electricity. Part or the water is then condensed and put back into the pipes to repeat the process, although much water is lost in the process. During the burning process, the coal powder under goes a chemical reaction that releases its chemical properties into the air. Some of these elements that can be released are sulfur, nitrogen, carbon, arsenic, lead, cadmium, mercury, and some traces of uranium. After the coal has been burned, the emissions are then pumped through filters and scrubbers. Scrubbers use limestone to catch and filter out as much sulfur as possible. After the power has been made in the power plant and the coal has been used, it is then

As the iron oxide is not purely iron, there are other minerals in the ore, which would not melt in the temperatures of the furnace, resulting in a clog. Limestone is added to convert this into slag, which melts and runs to the bottom. The furnace’s temperatures decomposes the limestone to create calcium oxide. (ChemGuide,

The fossil fuel coal is a burnable bituminous black rock that is consisting mainly of carbonized plant matter which is mainly found underground in seams and is also used as a fuel. In time, material that had been plants became coal. The main use for coal today is for generating electricity from one stop to another, cement manufacturing, steel products and as well as a liquid fuel. Coal is formed by plant decay which then turns into peat, the peat will than change to lignite which is a soft brown coal then after that a bituminous coal is formed which is black and brittle but also very polluting, after which an anthracite coal is formed, the anthracite coal contains the highest amount of carbon making it the cleanest and safest to burn. There are two ways coal can be

Firstly, the coal is pulverised into a very fine powder, and then burned in a boiler. It is pulverised to increase surface area so it will burn quicker and hotter. Burning the coal is transforming chemical energy into heat energy. During the process of transforming/transferring energy there will always be energy lost to the environment as heat.

First the coal (1) is ground to a fine powder and blown into the boiler (2), where it is burned, converting its chemical energy into heat energy. Grinding the coal into powder increases its surface area, which helps it to burn faster and hotter, producing as much heat and as little waste as possible.

Fly ash (FA) is a byproduct of the combustion of pulverized coal in electric power generating plants. Upon ignition in the furnace, most of the volatile matter and carbon in the coal are burned off. During combustion, the coal’s mineral impurities (such as clay, feldspar, quartz, and shale) fuse in suspension and are carried away from the combustion chamber by the exhaust gases. In the process, the fused material cools and solidifies into spherical glassy particles called fly ash. The fly ash is then collected from the exhaust gases by electrostatic precipitators or bag filters. Fly ash is a finely divided powder resembling Portland cement.

Coal is a hard, black colored rock-like substance. It is made up of carbon, hydrogen, nitrogen, and varying amount of sulphur. Coal was form as decomposition took place in the absence of oxygen and much of the hydrogen content of the matter was eroded away, leaving a material rich in carbon. The material was compressed over the years by sand and dirt, leaving the form of a carbon known as coal. The different types of coals are Anthracite, bituminous, lignite, peat, coke, and charcoal. Coal is mined out of the ground and used to produce energy. However, they are many deaths, injuries, and sickness involved in mining coal.

Products that last longer are called, high- performance products. Properly proportioned and cured mixtures of super-plasticized concrete, with 0.4 or less w/cm, show a little or no permeability. In fact, super-plasticized concrete mixtures made with blended portland cements containing mineral additives exhibit unusually low permeability ratings in the ASTM C 1202, Rapid Chloride Penetration Test.

Lightweight concrete can also be classified according to the purpose of utilizing as: i) Structural lightweight concrete has cylinder compressive strength at 28 days equal or more than 17 MPa and the approximate density range is about 1400-1800 kg/m3. ii) Masonry concrete (structural / insulating lightweight concrete) has a compressive strength between 7-14 MPa and density range 500-800 kg/m3. iii) Insulating concrete has a compressive strength between 0.7-7 kg/m3 and density lower than 800 kg/m3. (Neville and Brooks, 2010; Slaby, Aziz and Hadeed, 2008)