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Mineral composition of silicate cement

Release time:2024-04-12 Author:admin

Basic properties of cement

According to the different production processes, cement can be divided into three series, the most common is the silicate cement, or portland cement, others series are aluminum cement and sulfur-aluminate cement.

Mineral composition of silicate cement;

There are 6 main varieties of silicate cement:
①Silicate cement without mixed material is called Type I silicate cement,  name P・I.
In the clinker mixed with not more than 5% of the mass of cement slag (ironmaking blast furnace water quenching slag) or limestone is known as Type II silicate cement, code P・Ⅱ.

② With silicate cement clinker, as well as 6% ~ 15% mixed materials, a small amount of gypsum mixed and ground into the ordinary silicate cement, code P・O.

③ 20% to 70% of the blast furnace slag as the mixing material, known as slag silicate cement, code P・S; 

④mixe 20%~50% of volcanic ash materials, such as coal gangue, volcanic ash rock, etc. and silicate cement clinker and appropriate amount of gypsum mixed and ground into the so-called volcanic ash cement, code name P・P.

⑤ Fly ash silicate cement, in which fly ash accounts for 20%~40% of the cement mass, code P・F.
⑥ Composite silicate cement, which is allowed to be mixed with 2 or several kinds of mixing materials at the same time, and whose total weight accounts for 15% to 50% of the mass of cement, code name P・C.

Minerals in Portland cement clinker have four main forms: 
① C3S, tricalcium silicate 3CaO-SiO2, content 37% ~ 60%; 
② C2S, dicalcium silicate 2CaO-Si02, content 15% ~ 37%; 
③ C3A, tricalcium aluminate 3CaO-Al2O3, content 7% ~ 15%;
④ C4AF, tetra-calcium iron aluminate 4CaO- Al2O3-Fe2O3, content 10% ~ 18%. Al2O3-Fe2O3, content 10%~18%.

The chart shows the mineral content reference for different types of cement:

Mineral content in types of cement (%)
Item ordinary cement low heat cement Early Strength Cement Ultra Early Strength Cement Sulphate Resistant Cement
CS 52 41 65 68 57
CS 24 34 10 5 23
CA 9 6 8 9 2
CAF 9 13 9 8 13
In addition to the above four major minerals, clinker has a small amount of free CaO, a small amount of free MgO and alkalinity.