Process for producing blended cements with reduced carbon dioxide emissions

Abstract

A process for producing blended cement, where the cement contains Portland Cement mixed thoroughly with a microfiller and possibly a water reducing agent to a dry cement mixture and fine supplementary cementitious materials selected from the materials blast furnace slag, fly ash, quartz, silica, amorphous silicon dioxide, limestone and recycled concrete. The invention is characterized in, that said supplementary materials in a first step are being subjected to a grinding in a dry state to a specific surface of at least 1000 cm2 / g (Blaine), in that in a second step the supplementary grinded materials are being subjected to a grinding together with at least 20 % by weight of the total grinding mass of a highly reactive cement mixture in a dry state to achieve a specific surface of at least 3000 cm2 / g (Blaine), which highly reactive cement mixture contains cement and at least one of the components a SiO2 containing microfiller and a polymer in the form of a powdery water-reducing agent which mixture have been previously been treated in a grinder with vibrating grinding media in which the cement particles are subjected to a large number of impact impulses giving the cement particles an increase in surface energy and chemical reactivity.

Description

technical field [0001] The present invention relates to a process for the production of hydraulic blended cements having a significantly reduced content of silicate clinker minerals and correspondingly increased amounts of auxiliary materials. Background technique [0002] It is known that about one ton of carbon dioxide will be released for every ton of standard Portland cement produced, and about half of it comes from the decarbonization of limestone in the kiln, and the other half comes mainly from the energy consumption in the kiln. [0003] Therefore, the only way the cement industry can achieve a meaningful reduction in CO2 emissions is by reducing the production of silicate clinker and increasing the use of fillers. The cement industry believes that further reductions in energy consumption in the production of standard Portland cement by greater than about 2% to 3% are unlikely. [0004] Traditional methods of producing blended cements consist of intergrinding Portla...

AI Technical Summary

Problems solved by technology

The introduction of the method into the mentioned concrete mix design resulted in a drastic reduction in the strength gain of the concrete and an increase in the setting time, which made it unable to compete with standard Portland cement concrete

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