Portland cement

History and Development of Portland Cement
– Portland cement developed from natural cements made in Britain in the 18th century
– Named after Portland stone, a building stone quarried in Dorset, England
– John Smeaton experimented with different limestones and additives for construction
– Roman cement was popular but replaced by portland cement in the 1850s
– James Frost and Edgar Dobbs made advancements in cement production

Composition and Manufacturing of Portland Cement
– Portland cement is a hydraulic cement that hardens and forms a water-resistant product
– Consists of hydraulic calcium silicates, calcium sulfate, and other compounds
– Clinkers make up over 90% of the cement, along with minor constituents
– High temperatures cause chemical reactions to form key components of portland cement
– Calcium oxide and belite combine to form alite
– Portland cement clinker is made by heating a mixture of raw materials in a cement kiln
– Fusion temperature of about 1,450°C is required to sinter the materials into clinker
– Alite, belite, tricalcium aluminate, and tetracalcium alumino ferrite are the main components of clinker
– Aluminium, iron, and magnesium oxides act as a flux and contribute little to strength
– Limestone and clay are the primary raw materials used in clinker-making

Types and Uses of Portland Cement
– Ordinary portland cement (OPC) is the most common type of portland cement
– White portland cement is also available
– OPC is grey and named after its resemblance to portland stone
– Different types of portland cement have specific characteristics and uses
– Various standards regulate the composition and properties of portland cement
– Portland cement is a basic ingredient in concrete, mortar, stucco, and grout
– It is widely used in construction due to its low cost and availability
– Concrete, made with portland cement, is a composite material consisting of aggregate, cement, and water
– It provides strength, durability, and versatility to various construction projects
– Portland cement is essential for the development of modern infrastructure.

Cement Grinding, Setting, and Hardening
– A 10 MW cement mill produces cement at 270 tonnes per hour
– Calcium sulfate (usually gypsum or anhydrite) is added to the clinker to achieve desired setting qualities
– The grinding process in a cement mill produces a powder with a broad particle size range
– The specific surface area is used to measure the fineness of the cement
– Cement is stored in silos for one to 20 weeks of production
– Cement sets through a complex series of chemical reactions
– The interlocking of crystals gives cement its strength
– Carbon dioxide is absorbed to convert portlandite into calcium carbonate
– Warm water immersion speeds up the setting process
– Gypsum is added to prevent quick setting

Environmental Impact and Innovation in Cement Manufacturing
– Wet cement is caustic and can cause skin burns
– Cement dust can cause severe eye or respiratory irritation
– Chromium(VI) levels are regulated in some countries
– Cement production has environmental impacts like dust emissions and CO2 release
– Research is ongoing for suitable replacements for Portland cement
– Decarbonation of limestone and kiln fuel combustion are major sources of CO2 emissions in cement manufacturing
– Cement kilns can be used for waste disposal or processing
– Concrete emits less CO2 compared to other modern building systems
– Innovation focuses on reducing CO2 emissions and adopting more efficient processes
– Worker exposure to dust and particulates is a concern in cement manufacturing
– Cement kilns efficiently destroy hazardous organic compounds in waste streams
– The use of supplementary cementitious materials can contribute to a more sustainable cement industry.https://en.wikipedia.org/wiki/Portland_cement