A special attitude regarding the use of natural zeolite (clinoptilolite) of Semnan in the production of green cement

In recent years, huge development projects have been started in the country to increase cement production. It is predicted that Iran will become one of the largest cement producing countries in the next few years. Undoubtedly, this increase in cement production will cause the increasing growth of energy consumption in the country, and subsequently, serious environmental problems will arise, especially in terms of carbon dioxide production. As a result, the use of zeolite materials, especially natural zeolites, as a substitute for part of the cement used, can be a very worthy option to reduce cement consumption. Also, considering the growth of the construction industry in various sectors, especially dam construction and the need to build concrete structures with a longer useful life and better efficiency, especially in environments with unfavorable conditions such as the edge of the Persian Gulf, the importance of using natural zeolites that are available and cheap. This is while effective and common pozzolans in the world such as silica fume, fly ash, metakaolin and fly ash are either produced in Iran in a limited way or are imported from abroad and have a relatively high price. For this purpose, laboratory investigations were carried out in four stages. In the first step, the physical and chemical properties of zeolite were tested. In the second stage, tests of pozzolanic reactivity, normal dough, setting time and autoclave expansion were performed on doughs containing zeolite. According to the results of the pozzolanic activity of zeolite, it was compared with silica fume and natural pozzolan of Jajroud. The results of this test showed that zeolite is not as active as silica fume, it has a suitable reactivity compared to Jajroud pozzolan. In the third step, the effect of zeolite on controlling the expansion caused by the silicate- alkaline reaction of aggregates was investigated by the accelerated mortar method in comparison with fly ash. The results of this section determined that zeolite is effective in controlling the destructive expansion caused by the alkaline siliceous reaction of aggregates such as fly ash. Finally, in the fourth and most important step, zeolite and silica fume were used in concrete with different replacement ratios and the experiments Many mechanics and reliability were done. These tests included slump, air percentage of fresh concrete, compressive strength, tensile strength of splitting in half, water permeability, water absorption, oxygen gas permeability, chlorine ion diffusion and electrical resistance. Based on the obtained results, the performance of concretes containing zeolite with different replacement percentages improved compared to the performance of the control concrete, and in some cases, it was even comparable to the performance of concretes containing silica fume. Therefore, after completing the laboratory and field studies, this company decided to obtain the zeolite Portland cement standard for the first time in Iran from Iran's national standards department, which finally re-investigation and with thecooperation of cement companies, standards department and materials institute The building of Tehran University succeeded in obtaining the ۱۶۴۸۱ national standard of Iran.

کلیدواژه ها:

zeolite ، clinoptilolite ، cement ، concrete ، aggregates