The influence of cellulose nanocrystal additions on the performance of cement paste. (February 2015)

• Record Type: Journal Article
• Authors: Cao, Yizheng; Zavaterri, Pablo; Youngblood, Jeff; Moon, Robert; Weiss, Jason
• Is Part Of: Cement & concrete composites. Volume 56(2015)
• Page Start: 73
• Page End: 83
• Publication Date: 2015-02
• Subjects: Cellulose nanocrystal -- CNC -- Degree of hydration -- Ball-on-three-ball flexural test -- Steric stabilization -- Short-circuit diffusion; Composite-reinforced concrete -- Periodicals; Concrete -- Periodicals; Composite materials -- Periodicals; Composites de ciment -- Périodiques; Béton -- Périodiques; Composites -- Périodiques; Béton léger -- Périodiques; Cement composites; Composite materials; Composite-reinforced concrete; Concrete; Lightweight concrete; Periodicals; Electronic journals; 620.135
• DOI: 10.1016/j.cemconcomp.2014.11.008
• Languages: English
• ISSNs: 0958-9465

Abstract

Abstract: The influence of cellulose nanocrystals (CNCs) addition on the performance of cement paste was investigated. Our mechanical tests show an increase in the flexural strength of approximately 30% with only 0.2% volume of CNCs with respect to cement. Isothermal calorimetry (IC) and thermogravimetric analysis (TGA) show that the degree of hydration (DOH) of the cement paste is increased when CNCs are used. The first mechanism that may explain the increased hydration is the steric stabilization, which is the same mechanism by which many water reducing agents (WRAs) disperse the cement particles. Rheological, heat flow rate measurements, and microscopic imaging support this mechanism. A second mechanism also appears to support the increased hydration. The second mechanism that is proposed is referred to as short circuit diffusion. Short circuit diffusion appears to increase cement hydration by increasing the transport of water from outside the hydration product shell (i.e., through the high density CSH) on a cement grain to the unhydrated cement cores. The DOH and flexural strength were measured for cement paste with WRA and CNC to evaluate this hypothesis. Our results indicate that short circuit diffusion is more dominant than steric stabilization.