Papers by Author: Sheng Jin Tu

Abstract: This paper presents the results of laboratory and outdoor exposure site studies on belite-rich cement concrete with phosphorous slag powder and fly ash. The parameters studied included strength, hydration heat, ultimate elongation, Young’s modulus, and adiabatic in temperature. The experimental results showed that belite-rich cement resulted in a higher rate of strength development of mortar and concrete at later ages when compared with that of moderate-heat Portland cement. And the hydration heat of belite-rich cement is lower than that of reference. This is due to the different phase composition of the two cements. Belite-rich cement contains less C₃S but more C₂S than moderate-heat Portland cement. In addition, belite-rich cement concrete with phosphorous slag powder and fly ash exhibited better performances than those of moderate-heat Portland cement concrete.

Abstract: The present study aims to investigate the opportunity to largely substitute low heat Portland cement of mass concrete with supplementary cementitious materials. The pozzolanic reaction of two types of supplementary cementitious materials, phosphorous slag powder and fly ash , were determined by X-ray diffraction, differential thermal analysis–thermogravimetry and scanning electron microscopy from 28 to 90 days. The properties of mortar and mass concrete containing 30% of supplementary cementitious materials were also investigated. Results showed that supplementary cementitious materials could decrease the amount of calcium hydroxide, fill the capillary pores, thus making the mortar and mass concrete more compact and durable. Long-term strength of mass concrete containing 30% of supplementary cementitious materials were comparable (or even better) than the control concrete (without supplementary cementitious materials) at constant workability, while the Young’s modulus was lower than the control concrete.

Abstract: An experimental program has been conducted to investigate the influence of limestone powder (LP) on fluidity, strength, and hydration of cement mortar. Four laboratory grinds were prepared using a ball mill. The relationship between roundness of the LP and water requirement of paste, fluidity and strength of mortar was studied. The influence of LP on hydration of cement was investigated. Hydration products were determined by X-ray diffraction (XRD) analysis. Test results show that the roundness of LP significantly affected the water requirement of paste, fluidity and strength of mortar. In addition, the sites for the nucleation and growth of hydration products, provided by LP, accelerate the hydration of cement at early ages. While the enhancement of cement hydration at later ages mainly due to the formation of calcium aluminate monocarbonate.