FAQ

Cement is a finely ground powder of minerals produced by firing a mixture of limestone, clay and iron ore at a temperature of 1450°C. The outcome of this process is clinker, the main ingredient of cement. Clinker is ground together with gypsum and other additives to make cement. Upon being mixed with water, cement acts as a binder that holds together the sand and the aggregates in the concrete. Cement hardens both in the atmosphere and under water. Its properties are standardized to ensure the required stability, reliability and ease of use. The various applications require different types of cement, each with its own specific composition. The characteristics of cement can also be modified with the use of additives.

Hydraulic properties: the reaction between cement and water (hydration) is unique. The material sets and then hardens. Interestingly, the hydraulic nature of the reaction enables hydrated cement to harden even under water.

Aesthetic priorities: before it sets and hardens, watered cement's plasticity means that it can be poured into formworks of various shapes and forms and moulded into aesthetically interesting architectural structures which are hard to obtain with other construction materials.

Durability: suitably employed (e.g. following good concrete mix design practices), cement can be used for construction projects of a long functional lifespan, which will be resistant to extreme changes in weather conditions even in chemically aggressive environments.

Thermal mass: this is the property of construction materials such as concrete to absorb, store and then diffuse significant amounts of thermal energy. Buildings made of concrete are capable of achieving reduced energy consumption for heating/cooling due to the high thermal mass of concrete.

Acoustic properties: cement-based materials, suitably designed, can provide excellent sound insulation.

Fire protection: concrete is the ideal construction material for a structure’s highest resistance and best response in the event of a fire. Concrete has the best fire resistance performance (class AI) according to EN 13501-1:2007- A1:2009.

Cement is the main ingredient of concrete. Concrete is a mixture of aggregate solid materials and a liquid paste consisting of water and cement. Cement constitutes 10-15% of the volume of concrete. Once the cement is hydrated, the mixture of aggregates and paste hardens and develops high strength. The setting process continues for years, and the strength of concrete increases with age.

The ELOT ΕΝ 197-1 standard of 2011 includes 27 different types of common cement. It is acknowledged that different cements have different properties and performance. The currently available performance tests (i.e. setting time, strength and volume stability) are included in ΕΝ 197-1:2011.

The ELOT ΕΝ 197-1 standard sets out the specifications for the 27 distinct types of common cements and their ingredients. The definition for each cement type includes the proportions at which the ingredients must be combined to produce these distinct products across a range of six strength grades. The definition also includes the requirements the ingredients must meet in terms of the mechanical, physical and chemical properties of the 27 products and strength grades. ELOT ΕΝ 197-1 also describes the criteria of compliance with the relevant regulations and sets out the necessary durability requirements.

The designations of common cements must include at a minimum the name of the cement type as listed in Table 1 of ELOT ΕΝ 197-1:2011 and the figures 32,5, 42,5 or 52,5 that signify the strength grade. The designation N or R is added to signify the early strength grade.

Early setting time is the interval from the moment that cement is mixed with water and until the mix loses its binding and plastic properties.

Cement is ground at the factory into very fine particles to enhance its reaction with water and the rheological behavior of the water-cement mix for as long as it remains fluid. Increased fineness helps the cement's performance up to a point (easier mixing within the concrete and enhanced strength); too fine a concrete, however, sets earlier and its application is impeded.