What is the difference between Type 1, 2 & 3 Cements

In the Concrete Precast industry we usually use three types of portland cement (a cement made of limestone and submarine clay), which is specified by ASTM C150. There are a total of 8 types of portland cement: I, Ia, II, IIa, III, IIIa, IV, & V. Below is a very brief synopsis of the three most popular types.

Type I: According to the NPCA this is the most commonly used cement used in most of North America. It is generally assumed unless another type is specified. It is commonly used for general construction especially when making precast and precast-prestressed concrete that is not to be in contact with soils or ground water. The typical compound compositions of this type are:

55% (C₃S), 19% (C₂S), 10% (C₃A), 7% (C₄AF), 2.8% MgO, 2.9% (SO₃), 1.0% ignition loss, and 1.0% free CaO
A limitation on the composition is that the (C₃A) shall not exceed 15%.

Type II: This type offers moderate hydration heat as well as some sulfate resistance. Type II is often used in areas with elevated sulfate levels in the soil. Because of similar price to that of Type I, Type II is much used as a general purpose cement, and the majority of Portland cement sold in North America meets this specification. Typical Composition as follows:

51% (C₃S), 24% (C₂S), 6% (C₃A), 11% (C₄AF), 2.9% MgO, 2.5% (SO₃), 0.8% ignition loss, and 1.0% free CaO

Type III: This Type can reach high strengths quickly, 1740 psi in one day. it is good when you need strength ASAP. Its typical compound composition is: 57% (C₃S), 19% (C₂S), 10% (C₃A), 7% (C₄AF), 3.0% MgO, 3.1% (SO₃), 0.9% Ignition loss, and 1.3% free CaO. Very much like Type I, but ground finer.The only downside is that the six month strength of type III is the same or slightly less than that of types I and II. Therefore the long-term strength is sacrificed a little. It is usually used for precast concrete manufacture, where high 1-day strength allows fast turnover of molds. It may also be used in emergency construction and repairs and construction of machine bases and gate installations.

For more information on Portland Cement check out:

http://en.wikipedia.org/wiki/Portland_cement#Types

https://en.wikipedia.org/wiki/Portland_cement

What happens when cement gets wet?

Why is cement such a good bonding agent for rock and sand?

When a cement particle absorbs water it grows hair (like Velcro) on the surface. This has two effects, the first is that the volume of the cement particle grows, thus filling in the open space between the rock and sand particulates. the other effect is that the "hair" that gow upon the cements hydrated surface attched and bind (like Velcro) to the other materials in the mix.

Above: Image of hydrated cement