Cement, Energy and Environment

additives in HVMA cement. The maximum quantity of mineral additives in HVMA cement depends on the type of mineral admixtures and its desired strength/ durability level. The optimization of the composition of HVMA cement allows the production of cement with maximal strength and at minimal cost. The feasibility analysis demonstrated the opportunity of a profitable production of HVMA cements in industrial scale. In the past 25 years, there has been considerable interest in developing new construction materials incorporating industrial by-products and waste (IBPW). Accompanying industrialization the volume of IBPW has significantly increased and will dramatically expand in the future creating a number economical and ecological problems. Consequently, there is a demand for the development and application of new technologies to reduce IBPW and transform it into useful products. The process named 'high performance cement technology' was found to be very effective for the utilization of IBPW in high volumes. A newly developed technique using a special admixture during the cement grinding process helps to significantly improve the properties of ordinary cement. This approach resulted in the formulation of a new high-tech product. High Performance (HP) Cement. The main idea of HP Cement is the addition of a new reactive silica– based complex admixture (Supersilica) during the grinding of the portland cement. Thus, in the case of HP Cement, the clinker is ground in a ball mill together with mineral additives, gypsum and Supersilica. The resulting cement is then available for producing a wide range of concrete including high-performance concrete. As a result, HP Cement can be made to order from super strong cements with rugged durability to low cost cements with up to 70% mineral additives. To use a high volume of inexpensive mineral additives (sand, limestone or various industrial by-products) has an important economic and ecological impact. Courtesy: Cement and Concrete World, TCMB Jan. Feb.2002, Pp. 54-61. Email: info@tcma.org.tr Web: www.tcma.org.tr MULTI-COMPARTMENT MIXING SILO FOR SPECIAL CLIENT-ORIENTED CEMENTS H. W Billhardt, Erwitte, M. Rammele, Hamburg/ Germany Over the last six years cements with several main constituents have increased their market share in Germany from less than 10 to over 23%. Portland slag cement and Portland limestone cement together make about 92%. of all composite cements. These types of cement are also regarded as an important part of the product range of special cement in Erwitte. A multi-compartmentmixing silowas built so that in future clients would be provided with a better service for special mix formulations. There was an inauguration ceremony for the plant in August 2001 on the company's 75 1 " anniversary. The largely automated cement despatch and quality-assured cement production systems are regarded as an indication of the way ahead. This was essentially a matter of being able to produce special cement mix formulations to meet clients' requirements. Such demands exist, for example, for the production of sprayed cements and tunnel ce~ents. These cements contain a slag content adapted to suit the weather to ensure a uniform heat of hydration and an equal setting time in summer and in winter. The company is capable of producing a large number of mix formulations by mixing separately ground constituents. The mixing silo was designed for