Description

Crown Portland Composite Cement is CEM-II/A-M which is a cement consisting of Clinker, Gypsum, Pulverized Fuel Ash (PFA), Blast Furnace Slag and Limestone designated by the recommendation of BDS EN 197-1: 2010; CEM -II/A-M (V-S-L), 42.5 N. PCC is the most suitable cement for constructions in Bangladesh. CEM – II /A-M contains 80-94% Clinker, which is substantially higher than CEM – II/B-M containing 65 – 79% which provides us extra advantage in strength development and better of concrete performance.

Both slag & fly ash (PFA) are used in PCC. Percentage of SiO2 in PFA is higher than slag which is advantageous to gain more long-term strength and ensure production of durable concrete. This type of cement is used for most of constructions all over the world and it has been used during the last few decades.

The hydration process of normal cement produces Calcium Silicate Hydrate CHS & Calcium Hydroxide Ca(OH)2. Calcium Hydroxide Ca(OH)2 does not contribute to gain strength and it is the weak part of reaction which is not suitable for concrete. Since PFA contains higher portion of reactive silica and slag contains alumina, it helps to convert Ca(OH)2 into CSH to gain further Compressive strength.

Other Features of this cement are:

• Improved workability
• Improved fresh concrete properties
• Lower heat of hydration
• Higher long-term strength
• Low permeability, dense structure
• Optimum early strength
• Low effective alkali content
• High chemical resistance (Sea water, chloride diffusion, sulphate attack) Compact ability