Portland Limestone Cement

CEMEX Cemstone is a factory produced Portland-limestone cement with a lower carbon footprint that complements our range of Portland (CEMI) cements. 

Cemstone provides benefits in a wide range of concrete, mortar, render, screed and grout applications. Cemstone is manufactured by burning a precisely specified mixture of raw materials containing lime, silica, alumina and small quantities of other materials to form a clinker. The clinker, high purity limestone and calcium sulfate (to control setting), are interground to produce a very consistent cement with special characteristics. 

CEMEX Cemstone is suitable for use as an alternative to Portland cement in most types of concrete except where aggressive ground conditions demand the use of sulfate resisting cement, when CEMEX Extra should be specified. 

To produce a durable concrete using CEMEX Cemstone, the cement content of the mix must be maintained at an acceptable level. BS 8500; Concrete, Complementary British Standard to BS EN 206-1), gives guidance for using a CEMII/A-L cement in concrete, under various exposure conditions.

Once in place, concrete requires moisture to develop its full strength and premature drying out must be avoided. In normal conditions and at temperatures in excess of 10ºC, concrete should be cured under damp conditions for 1 to 3 days, (cover with curing membrane, plastic sheeting or wet hessian); at temperatures below 10ºC, this curing time should be doubled. Protection against freezing is required until the concrete reaches a compressive strength of 5 MPa.

All normal concrete admixtures (eg plasticisers, air-entrainers, retarders) may be used with CEMEX Cemstone. Trials should, however, be carried out to establish required dosage rates.

A range of admixtures complying with BS EN 934 are also available from CEMEX.

Mixes to resist chemical attack

• Please refer to the latest version of the Building Research Establishment (BRE) Special Digest 1 or BS8500 Concrete
• CEMEX Cemstone can be used in the same ground conditions as CEMI (CEMEX Portland), up to Design Chemical Class 2 Sulfate Conditions.
• In some marine environments an alternative cement to Cemstone may be necessary depending on the exposure conditions.