Effect of grinding additives and hydrophobic additives on the process of the cement hydration : bachelor thesis

Abstract

U radu je istraživan utjecaj aditiva za poboljšanje mljevenja klinkera trgovačkog naziva HEA 213 Grace ili HEA2® kao i aditiva za poboljšanje meljivosti/tečljivosti XS 255 Grace od proizvođača GCP Applied Technologies Inc., na procese hidratacije cementa dobivenog korištenjem poluindustrijskog kugličnog mlina u laboratoriju CEMEX Hrvatska d.d. U fazi priprave cemenata u smjesu klinkera i gipsa dodan je aditiv HEA 213 Grace u iznosima od 0; 0,017; 0,032 i 0,048 mas.% na masu cementa, dok je aditiv XS 255 Grace dodan u iznosu od 1,1 mas.%. U svrhu utvrđivanja utjecaja aditiva za poboljšanje meljave na procese hidratacije provedena su konduktometrijska mjerenja električne provodnosti u sustavima vodenih suspenzija pri temperaturi 20oC uz konstantni omjer voda/cement=4 (V/C). Na odabranom cementu pripravljenom s dodatkom aditiva HEA 213 Grace u iznosu od 0,032 mas.% ispitan je i utjecaj aditiva tipa hidrofoba na procese hidratacije. Provedena ispitivanja ukazuju da aditivi za mljevenje ne utječu na povećanje električne provodnosti, ali s povećanjem udjela aditiva HEA 213 Grace intenzivni period hidratacije se pomiče prema kasnijim vremenima, stoga se može očekivati i veći stupanj hidratacije cementa. Mjerenja koncentracije Ca2+ iona u tekućoj fazi ukazuju na porast sadržaja Ca2+ iona u uzorcima s povećanim sadržajem aditiva HEA 213 Grace. U slučaju korištenja aditiva tipa hidrofoba na uzroku cementa pripravljenog s dodatkom HEA 213 Grace u iznosu od 0,032 mas.% rezultati u sustavima cementnih suspenzija ukazuju na veću provodnost nego u sustavu bez dodatka aditiva, što ukazuje da hidrofob utječe u sustavima suspenzija na povećanje stupnja hidratacije, dok mjerenja na sustavima cementnih pasta ukazuje na kraći period očvršćavanja.In this paper the influence of additives for the improvement of clinker milling properties marked with the trade name HEA 213 Grace or HEA2®, as well as the influence of additives XS 255 Grace for the improvement of clinker milling/flowing properties both products of the GCP Applied Technologies Inc. manufacturer on the processes of cement hydration has been studied. Cement was prepared by using semi- industrial ball mill at the laboratory of the CEMEX Hrvatska d.d., in the preparation process of the cement the HEA 213 Grace additive has been added to the clinker mixture in amounts of 0, 0.017, 0.032 and 0.048 mass% per cement mass until the other type of additive XS 255 Grace has been added in the amount of 1.1 mass% per cement mass. In order to determine influence, the additive milling improvement on the hydration processes the electrical conductivity in aqueous suspension systems was carried out at the temperature of 20C and the constant ratio of water/cement of 4 (W/C). The influence of the hydrophobe type additive on hydration processes has been tested on the chosen cement that was prepared by addition of HEA 213 grace additive in the value of 0.032 mass%. The measured values show that the milling additive HEA 213 Grace, added up to 0.017 mass%, doesn’t increase conductivity into prepared suspension, but with increase addition of the additive it has influence on the prolongation the period when the hydration process is most active, so at the later time of hydration the higher level of the cement hydration can be expected. Measured value of concentrations of Ca 2+ ions in the liquid phase imply that, with the HEA 213 Grace increase, the content of Ca 2+ ions in samples increases. While in the case of the hydrophobe type additive usage on the cement sample that was prepared by the addition of HEA 213 Grace in the value of 0.032 mass%, the results in cement suspension systems imply the grater conductivity while comparing to the system without the added additive. This implies that hydrophobe in suspension systems affects the increase of hydration level, while measurements on the cement paste systems indicate the shorter hardening period