In the study, raw materials including clinker, gypsum, pozzolan were separately milled on a ball mill (the ball mill size: φ500 mm × L500 mm, productivity: 5 kg / grinding time) to achieve the desired blaine fineness. | Vietnam Journal of Science and Technology 56 (1A) (2018) 159-166 STUDY OF THE EFFECTS OF GYMPSUM, POZZOLANIC ADDITIVE MIXTURES AND THEIR FINENESS ON THE STRENGTH OF PCB50 FICO CEMENT Hoang Canh Nguyen, Nguyen Thi Tuyet Mai*, Tran Thi Xuan Lan, Huynh Dang Chinh, Ta Ngoc Dung School of Chemical Engineering, HUST, 1 Dai Co Viet, Hai Ba Trung District, Ha Noi * Email: maibk73@ Received: 15 August 2017; Accepted for publication: 5 March 2018 ABSTRACT In the study, raw materials including clinker, gypsum, pozzolan were separately milled on a ball mill (the ball mill size: φ500 mm × L500 mm, productivity: 5 kg / grinding time) to achieve the desired blaine fineness. A mixture is mixed at the calculated ratio includes of 90 % fineness clinker, 5 % fineness gypsum and 5 % fineness pozzolan (In it, pozzolanic additive is mixed at different fineness levels). The effects of the mixture of gypsum and fineness pozzolanic additive as well as the fineness of pozzolanic additive to strength of PCB50 Fico cement were investigated. The study shows that, pozzolanic additive have reduced the strength of cement. But, when pozzolanic additive is mixed with gypsum, this additive mixture has increased the strength of the cement at the late time (at the age of 28 days). The fineness of pozzolan has little effected on the early strength of cement. Keywords: gypsum, pozzolan, additive of cement, strength of cement. 1. INTRODUCTION According to statistics of Vicem, total cement production in Vietnam in the years 20152016 is about 75-76 million tons. Forecast production plans in the years 2016-2020 should reach 93-95 million tons to meet the demand for cement in the domestic and export [1, 2]. Therefore, the cement industry is the spearhead of building materials industry. It plays an important role in the national economy. There have been many studies in the world that have studied the effects of additive on improving the properties of cement, as well as improving the strength of .
