EFFECT OF HYDROTHERMAL CURING ON MECHANICAL AND MICROSTRUCTURAL PROPERTIES OF CEMENT-BASED MATERIALS

The Aim, the Signaficance, and the Expected Outcomes of the Project:
     There is an urgent need for the systematic control of the quality of concrete and other construction materials in our country especially after the recent devistating earthquake in Marmara region. The most important worlwide quality standard of cement which is the mos important component of concrete is the 28 day compression strength test. The sale of cement currently in industry is complete after 6 days of production which means that it is not fully tested before possible use. The development of a faster standard method which can facilitate hydration reactions and make the achievement of the 28 day compressive strength in a shorter period would be very useful for the quality control of cement before its sale and use.

     The development of a new technique for the assesment of the 28 day compression strength of concrete samples in 48 hours is going to be investigated in this work. Strength development in concrete is a result of of a series of complicated hydration reactions and the formation of a gel structure. This gel network and its chemical/physical bonds with the nearby phases/aggregates is responsible from the strength of concrete.

     The effect of high pressure (5-15 bars) and temperature (180-210^oC) on the progress of these hydration reactions in 48 hours will be investigated by using an autoclave in this work.The comparison of the compressive strengths of the autoclaved and 28 day standard samples will be used in the development of a new test. The effects of cement composition, cement particle size distribution, SO₃ content and surface area on the compressive strength will also be investigated. The effect of hydrothermal curing on the microstructure and phase composition of the concrete samples will be investigated by optic microscopy, SEM, and XRD.