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Water Reducer
Water reducers are special chemical products added to a concrete mixture before it is poured. They are from the same family of products as retarders. The first class of water reducers was the lignosulfonates which has been used since the 1930s. These inexpensive products were derived from wood and paper industry, but are now advantageously replaced by other synthetic sulfonate and polycarboxylate, also known as superplasticizers. Water reducers offer several advantages in their use, listed below: * reduces the water content by 5-10% * decreases the concrete porosity * increases the concrete strength by up to 25% (as less water is required for the concrete mixture to remain workable) * increases the workability (assuming the amount of free water remains constant) * reduces the water permeability (due to less water being used) * reduces the diffusivity of aggressive agents in the concrete and so improves the durability of concrete * gives a better finish to surfaces (due to al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most widely used building material. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminum combined. Globally, the ready-mix concrete industry, the largest segment of the concrete market, is projected to exceed $600 billion in revenue by 2025. This widespread use results in a number of environmental impacts. Most notably, the production process for cement produces large volumes of greenhouse gas emissions, leading to net 8% of global emissions. Other environmental concerns include widespread illegal sand mining, impacts on the surrounding environment such as increased surface runoff or urban heat island effect, and potential public health implications from toxic ingredients. Significant research and development i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
