Which is better for use in slabs : PPC/PSC or OPC ?

When deciding between Ordinary Portland Cement (OPC), Portland Pozzolana Cement (PPC), and Portland Slag Cement (PSC) for slab construction, several factors need to be considered, including strength requirements, durability, setting time, and environmental conditions.

Portland Pozzolana Cement (PPC)

• PPC is often recommended for slab construction, especially in residential and educational settings, due to its several advantages:
  • It has a slower rate of heat of hydration, which reduces the risk of thermal cracks and shrinkage245.
  • PPC offers better resistance to sulfate attacks, making it suitable for areas where the soil or water contains sulfates234.
  • It provides enhanced waterproofing, is suitable for tiling, brickwork, and plastering, and has better workability and finishing due to the spherical shape and finer size of fly ash particles245.
  • PPC is generally cheaper than OPC and offers long-term durability and strength, although it takes longer to achieve the same initial strength as OPC245.

Portland Slag Cement (PSC)

• PSC is another viable option for slab construction, particularly in scenarios where specific properties are required:
  • It has a lower heat of hydration, which is beneficial for large concrete pours and reduces the risk of thermal cracking35.
  • PSC offers excellent resistance to chemical attacks, including sulfates and chlorides, making it suitable for coastal or industrial environments35.
  • It has a slower early strength gain compared to OPC but provides robust and long-lasting strength5.

Ordinary Portland Cement (OPC)

• OPC is known for its high compressive strength and fast setting time, making it suitable for projects that require rapid construction and high early strength:
  • However, OPC generates more heat during hydration, which can lead to thermal cracking in large concrete pours15.
  • It has limited chemical resistance compared to PPC and PSC, which can be a limitation in certain environments5.

Conclusion

For slab construction, especially in residential and educational settings:

• PPC is generally the better choice due to its resistance to sulfate attacks, lower heat of hydration, and better workability and finishing. It is also more economical and environmentally friendly245.
• PSC can be considered for projects requiring low heat of hydration and high resistance to chemical attacks, particularly in aggressive environments35.

In summary, PPC is usually the preferred option for slab construction due to its balanced properties and advantages, while PSC is a good alternative in specific scenarios requiring its unique benefits. OPC, while useful for rapid construction and high early strength, may not be the best choice due to its higher heat of hydration and limited chemical resistance.