Hi,

Generally, the composition for cement is  in the region of 67% CaO, 22% SiO2, 5%

A12O3, 3% Fe2O3 and 3% other components. The limestone is ~90%, and clay ~8%. The actual usage for limestone and clay is based on the mineral composition for the clinker. For the similarity of the composition of clay and laterite, it can be used as clay, I think.

The raw meal composition depends on (i) the purity of limestone and clay (ii) the targets of LSF, SM, AM modules. For pure raw materials - limestone with low content of clay, clay with low content of CaO and an LSF≈96, an average raw mix composition is ~80% limestone and ~20% clay. Laterite that is a material rich in Iron and/or Al2O3 can be used instead of clay, especially if clay has low Fe2O3 and/or  Al2O3 contents, to adjust SM and AM modules. Generally and depending on the clay content in silica, alumina and iron, addiditives like silica sand, bauxite, iron ore or other materials containing the missing element are used as additives.

Thank you so much Drs. Dimitris and Xuerun for your meaningful and useful information.

See this PDF article concerning the chemical study of raw materials: jcsp.org.pk/ArticleUpload/1157-5108-1-RV.pdf.

Another article by FAO: www.fao.org/docrep/s1250e/s1250e07.htm.

Hi Johnson,

Just some more background:

Cement is a binder, that sets and hardens and can bind other materials together. The word "cement" traces to the Romans, who used the term "Opus caementicium" to describe masonry resembling modern concrete made from crushed rock with burnt lime as a binder. Volcanic ash and pulverized brick supplements were added to the burnt lime, to obtain a hydraulic binder, later referred to as "cementum, cimentum, cäment", and finally cement.

Cements used in construction &re characterized as either hydraulic or non-hydraulic. This depends on the ability of the cement to be used in the presence of water.  Non-hydraulic cement will not set in wet conditions or underwater, rather it sets as it dries and reacts with carbon dioxide in the air. It can be attacked by some aggressive chemicals after setting. Hydraulic cement is made by replacing some of the cement in a mix with activated aluminium silicates, pozzolanas, such as fly ash. The chemical reaction results in hydrates that are not very water-soluble and so are quite durable in water and safe from chemical attack. This allows setting in wet condition or underwater and further protects the hardened material from chemical attack (e.g., Portland cement).

The chemical process for hydraulic cement found by ancient Romans used volcanic ash (activated aluminium silicates). Presently cheaper than volcanic ash, fly ash from power stations, recovered as a pollution control measure, or other waste or by products are used as pozzolanas with plain cement to produce hydraulic cement. Pozzolanas can constitute up to 40% of Portland cement. The most important uses of cement are as a component in the production of mortar in masonry, and of concrete, a combination of cement and an aggregate to form a strong building material.

Portland cement is by far the most common type of cement in general use around the world. This cement is made by heating limestone (calcium carbonate) with small quantities of other materials (such as clay) to 1450 °C in a kiln, in a process known as calcination, whereby a molecule of carbon dioxide is liberated from the calcium carbonate to form calcium oxide, or quicklime, which is then blended with the other materials that have been included in the mix. The resulting hard substance, called 'clinker', is then ground with a small amount of gypsum into a powder to make 'Ordinary Portland Cement', the most commonly used type of cement (often referred to as OPC). Portland cement is a basic ingredient of concrete, mortar and most non-specialty grout. The most common use for Portland cement is in the production of concrete. Concrete is a composite material consisting of aggregate (gravel and sand), cement, and water. As a construction material, concrete can be cast in almost any shape desired, and once hardened, can become a structural (load bearing) element. Portland cement may be grey or white.

Portland Cement"; "Class F Fly Ash"; "Class C Fly Ash"; "Slag Cement"; "Silica Fume"

SiO2 content (%) 21; 52; 35; 35; 85–97

Al2O3 content (%) 5; 23; 18; 12 —

Fe2O3 content (%) 3; 11; 6; 1 —

CaO content (%) 62; 5; 21; 40 < 1

Specific surface (m2/kg) 370; 420; 420; 400; 15,000–30,000

Specific gravity 3.15; 2.38; 2.65; 2.94; 2.22

Use in concrete: "Primary binder Cement"; "Replacement Cement"; "Replacement Cement"; "Replacement Property"; "Enhancer"

Hope this helps a bit,

Cheers,

Frank

Mix depends on purity of consituents (limestone and clay). To produce Portland cement composition is generally 80% limestone and 20 % clay . Moreover laterite can be used in cement production as clay.

Thanks you sir Dr,.Franco Medici. Please can I get a referenced material for this?

Manual Tecnológico Del Cemento  – 1 ene 1977

de Walter H. Duda (Autor), Antonio Sarabia Gonzalez (Traductor)

Cement Data Book, Volume One: International Process Engineering in the Cement Industry Hardcover – December, 1985, Walter H. Duda,

Volcanic ash that has significant iron content as laterite is used in pouzzolanic cement. Laterite as iron-rich aluminosilicates can then also being used. It is just necessary to check the nature of iron mineral and work on the production process

Hi, I am looking for 'high iron hydraulic' cements with about 55% Fe2O3, 35% CaO, rest being 5% SiO2 & 5% Al2O3 primarily as impurities from raw materials used. Is there any such composition of cement and is there commercial production of such high Fe2O3 and CaO cements anywhere in the world?