The microstructure of a cement composite based on a secondary raw materials

Abstract

Waste management and its use as a secondary raw material is a matter that is being given increasing attention. Such raw materials also include waste products from the energy industry or municipal waste disposed of from the recycling process. This study explores the use of secondary raw materials in specific cement–based cement composite as a partial binder substitute. Selected secondary raw materials were pre–treated by grinding to a specific surface of 300 and 500 mkg. As a reference material, a commercially available mixture was selected to produce cement composites intended for the environment with high physical–mechanical demands. Cement was substituted by secondary raw materials at a rate of 20 and 40% in the reference recipe. Basic physical–mechanical characteristics such as compressive strength and tensile strength at bending were determined on standard 160×40×40 mm prisms. Strengths were determined after 3 and 28 days of ageing. In addition, the influence of binder substitute by the admixtures on the microstructure of cement stone was monitored by sample scanning using an RTG tomography. The positive effect of a part of the binder substitution by selected secondary raw materials on microstructure was proved in all tested samples. From the measured data, it is evident that the higher specific surface of the pre–treated admixtures did not have a significant positive effect either on strengths or the microstructure.Waste management and its use as a secondary raw material is a matter that is being given increasing attention. Such raw materials also include waste products from the energy industry or municipal waste disposed of from the recycling process. This study explores the use of secondary raw materials in specific cement–based cement composite as a partial binder substitute. Selected secondary raw materials were pre–treated by grinding to a specific surface of 300 and 500 mkg. As a reference material, a commercially available mixture was selected to produce cement composites intended for the environment with high physical–mechanical demands. Cement was substituted by secondary raw materials at a rate of 20 and 40% in the reference recipe. Basic physical–mechanical characteristics such as compressive strength and tensile strength at bending were determined on standard 160×40×40 mm prisms. Strengths were determined after 3 and 28 days of ageing. In addition, the influence of binder substitute by the admixtures on the microstructure of cement stone was monitored by sample scanning using an RTG tomography. The positive effect of a part of the binder substitution by selected secondary raw materials on microstructure was proved in all tested samples. From the measured data, it is evident that the higher specific surface of the pre–treated admixtures did not have a significant positive effect either on strengths or the microstructure.