What is the main ingredient to portland cement and the minor ingredients. What is the base rock that is mined and how high is the heat used to process this rock to a powder for the cement? Before water and aggregate is added what are the other products used. What is the percentage in relation to the base? I hope these questions makes sense.
2006-12-07 07:14:51 · 3 answers · asked by the old dog 7 in Science & Mathematics ➔ Chemistry
The answer above gives you some chemistry, not that I know if its correct.
The type of rocks used depend on the area. Ideally all the raw materials are contained on one site, which can be the case in some places, where the limestone rock can contain the silica and alumina (cement rock). Other places may have the raw materials on the same site but in two forms, limestone for calcium and clay or shale for alumina. The silica and iron may be shipped in but are a small percentage. Chemistry is often difficult to control because it changes within the quarry, and sites that contain both main constituents may be low grades of them.
There are a number of processes still in existence to heat the rock. Wet, semi-wet, semi-dry and dry. With dry split into 3 types, long dry, preheater and precalcina. The materials are ground and heated to around 1500 C (2500F). The materials melt and form the new compound which is then cooled to form clinker.
The clinker is ground to make cement. gypsum is added to the milling as it controls the setting time. Other additives may also be added to make the cement more suitable for whatever application it is going to be used.
The whole process is very carefully controlled using some high tech instrumentation and continuous sampling and lab testing
2006-12-10 01:50:57 · answer #1 · answered by Poor one 6 · 0⤊ 0⤋
Clinker Mass% Cement Mass%
Tricalcium silicate (CaO)3.SiO2, C3S 45-75% Calcium oxide, CaO, C 61-67%
Dicalcium silicate (CaO)2.SiO2, C2S 7-32% Silicon oxide, SiO2, S 19-23%
Tricalcium aluminate (CaO)3.Al2O3, C3A 0-13% Aluminium oxide, Al2O3, A 2.5-6%
Tetracalcium aluminoferrite (CaO)4.Al2O3.Fe2O3, C4AF 0-18% Ferric oxide, Fe2O3, F 0-6%
Gypsum CaSO4 2-10% Sulfate
2006-12-07 15:18:59 · answer #2 · answered by Cesar G 3 · 0⤊ 0⤋
see
http://en.wikipedia.org/wiki/Portland_cement
2006-12-07 15:17:52 · answer #3 · answered by rm 3 · 0⤊ 0⤋