The influence of compaction pores on sorptivity and carbonation of concrete

Concrete itself is a porous composite material consisting of mineral aggregates and the cement matrix that form a durable structure. The transport of aggressive species may follow different mechanisms, depending on the pore structure of the concrete, the exposure conditions and the characteristics of the diffusing substances. According to their origin and characteristics, the pores are classified as compaction pores, air pores and capillary pores (which affect durability) and gel pores. The present study was carried out to investigate the influence of compaction pores on the sorptivity and the carbonation of concrete. To create various levels of compaction porosity (poor, medium and high) different techniques of compaction were used on concrete specimens at casting stage. Compressive strength, porosity, sorptivity coefficient, mass change due to carbonation and carbonation were tested in order to estimate the properties of concrete with various compaction pores. Test results showed that change in the compaction pores may significantly affect the carbonation rate and the sorptivity coefficient.