Long-Term Parameters of New Cement Composites

Since the beginning of the 20th century, scientists and cement composite technologists are working on developing various types of new structural multi-component cement composites. Several obstacles prevent more widespread use of these newly developed cement composites in construction. One of the main problems is insufficient information about the long-term properties, which are essential in ensuring the safe and long exploitation of structures. The purpose of this research is to determine the long-term properties of several new cement composites: ultra-high strength cement composite with PVA fiber "cocktail" (2% by volume), with micro silica and nano silica additive; ultra-high strength cement composite with 1% montmorillonite mineral nano-size particles; reference composition. Test specimens were prepared and subjected to constant compressive load in permanent room temperature and level of moisture. There were properties such as compressive strength, modulus of elasticity, shrinkage as well as uniaxial creep deformations investigated in the laboratory. Afterward parameters of long-term properties were determined. The obtained results showed that after approximately 90 days of loading the creep coefficient values of new cement composites were 0,5-3; specific creep values were 30-55 microstrain/MPa; creep modulus was 2-90 GPa. The experimental study proves that new elaborated mixes can be successfully used in the production of concrete, thus potentially decreasing the use of cement, which would lead to the reduction of carbon dioxide released into the atmosphere.