Portland cement is composed principally of__________________?
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Answer: A. CaO & SiO2
Explanation
Portland cement is manufactured by heating limestone and clay minerals together in a massive rotary kiln. This high-temperature clinkering reaction combines calcium oxide derived from limestone with silica from clay. Calcium silicates form the primary hydraulic cement compounds responsible for concrete strength development. Raw meal preparation requires precise proportioning of calcareous and argillaceous materials before pyroprocessing. Tri-calcium silicate and di-calcium silicate represent the core mineral phases governing cement hydration behavior. Gypsum is added to ground cement clinker to regulate setting times during concrete mixing operations.
Civil engineering infrastructure relies on Portland cement concrete for constructing bridges, dams, and skyscrapers. Global construction activity drives massive industrial production of cement clinker in energy-intensive rotary kilns. Hydration reactions between cement and water produce a strong interlocking crystalline matrix over time. Silica and alumina are present in clay but lack the essential calcium oxide component needed for cement clinker. Calcium oxide and alumina form calcium aluminate cements, which differ significantly from standard Portland cement. Calcium oxide and iron oxide form ferrite phases, but silica remains the dominant structural component alongside lime.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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