Abstract
The state of water in cement compositions containing polypropylene glycol (PPG) and hexanol in the course of their hardening for a time up to 28 days was studied by the NMR relaxation technique. A model of the porous structure formed in the process of cement hardening, which takes into account the distribution of water in pores of cement stone in the presence of additives, is proposed. It is shown that, in the absence of additives, the number of large pores in cement stone (being the largest defects, these pores determine the strength of cement stone) noticeably decreases with increasing the hardening time from 7 to 28 days. PPG and hexanol have different effects on the structure of cement stone in the process of its hardening. According to NMR data, the presence of PPG results in the formation of large-size pores (19 - 35 μm), whose number increases with increasing hardening time and the additive concentration. In the presence of hexanol (1%), the content of macropores in cement stone is close to their content in the reference sample; however, in the presence of hexanol, this level of macropore content is attained in shorter hardening times (about 7 days).