Cement Vs. Plaster of Paris

Cement is a fine powder made from a mix of limestone, clay, shells and silica sand. These are kept in the high heat to form clinker, then grounded into a fine powder. Then, this powder is mixed with water to form a paste that hardens over time. It happens due to a chemical reaction called hydration. Cement is a key item in concrete and mortar. It gives the strength to bond which is needed for construction.

Plaster of Paris is derived from gypsum. It is a soft sulfate mineral that has 70.1% calcium sulfate. When gypsum is heated to almost 120°C, it loses water. Then, it becomes calcium sulfate hemihydrate or Plaster of Paris. After it's mixed with water, POP rehydrates and hardens quickly. It forms a smooth and hard surface. Unlike cement, POP is not used for structural works. But it does wonders in creating detailed molds and decorative items.

Cement is widely used for constructing buildings and home of all kinds. It is generally used to make mortar for bricklaying. Cement is also a popular choice amongst DIY-enthusiasts who use it to make garden paths, patios and decorative items. Its strength and durability make it ideal for both indoor and outdoor work, as it lasts longer.

Plaster of Paris or POP is mainly used for interior decorations. It gives you a smooth finish and sets faster. You can use it for making detailed sculptures, molds and casts. POP is also used for construction work like finishing walls and ceilings. In arts and crafts, it is popular for creating difficult designs like wall moldings, picture frames with ornate designs and architectural accents.

Cement has an initial setting time of 45 minutes and can take as long as 6 hours to set properly. For the cement to fully cure and get to its maximum strength, takes about 28 days. This makes sure of the durability and structural integrity of concrete and mortar works. This allows for gradual and thorough hydration.

Plaster of Paris sets much faster than cement. It starts to set in 10 minutes of mixing. And, fully sets in about 45 minutes. This is best for quick repairs and projects requiring immediate results. But even with its quick initial set, POP takes about 72 hours to fully dry before it can be painted or finished. It helps with small-scale projects and detailed work.

Cement is known for its strength and lasts for long. If you need structural works, this is the best choice. Use it with concrete and mortar, it lasts for a long time. It can hold up a good amount of mechanical stress. These structures are resistant to weathering, water and heavy loads. It takes bare minimum maintenance. Ideal for building foundations, bridges and other infrastructure works.

Plaster of Paris is less durable than cement. It is not the ideal choice for load-bearing or exterior works. It is best used for interior projects where it won't be exposed to moisture or heavy wear. It gives a smooth and pretty finish. But, if you use it in high-traffic areas like hallways, kitchen or entryways or put too much pressure on it, it might crack or chip over time.

Cement has a rougher finish and is well-suited for structural and outdoor works. Plaster of Paris is best known for its smooth and fine finish. It’s best for detailed decorative work. It captures intricate details and provides a pristine surface. This is best for painting or other finishes. You can use it to create sculptures, ornamental moldings and artistic works.