Hur påverkar kalksten betongens egenskaper? : Kalkstens påverkan på betongens egenskaper

Sammanfattning

Today, the concrete industry stands for a very large amount of the world’s total carbondioxide emissions. In order to accomplish the goal in the Paris agreement, to limit the global temperature increase to 2°C, the search for environment friendly concrete mixes has begun. One of the solutions, that has proven to reduce the carbon dioxide emissions of concrete, is the replacement of parts of the cement with limestone powder. The purpose of the thesis is to contribute to the research regarding how the substitution of cement with limestone powder affects its properties. In this thesis, a total of 8 different concrete types have been mixed, 4 containing superplasticizer and 4 without. Furthermore, in each mix, a gradual 5 % substitution of concrete with the limestone powder Limus 40 has been made. The different mixes’ slump losses, strength, air content and evaporation have been tested. The results showed that the use of limestone powder lowered the concrete’s strength and air content. However, the limestone powder did not show any significant effect on the slump loss, the pH value nor the evaporation. The extent of the results however seemed to depend on other factors as well, such as whether the mixes contained superplasticizer or not. The conclusion of the thesis was that the limestone powder affected some of the concretes’ properties, but that the extent of the effects could be mitigated by other properties such as the w/c ratio, as well as the use of superplasticizer.