I figure that enough concrete related advancements get posted here that they might as well be combined in one thread.
Cheap cellulose nanocrystals from pulp can increase the strength of concrete by 30 percent
Natural nanocrystals shown to strengthen concrete
WEST LAFAYETTE, Ind. – Cellulose nanocrystals derived from industrial byproducts have been shown to increase the strength of concrete, representing a potential renewable additive to improve the ubiquitous construction material.
The cellulose nanocrystals (CNCs) could be refined from byproducts generated in the paper, bioenergy, agriculture and pulp industries. They are extracted from structures called cellulose microfibrils, which help to give plants and trees their high strength, lightweight and resilience. Now, researchers at Purdue University have demonstrated that the cellulose nanocrystals can increase the tensile strength of concrete by 30 percent.
http://www.purdue.edu/newsroom/relea...concrete-.html
Abstract:
The influence of cellulose nanocrystal additions on the performance of cement paste
Yizheng Cao 1, Pablo Zavatierri 2, Jeff Youngblood 1, Robert Moon 3, Jason Weiss 2,1,*
1 School of Materials Engineering, Purdue University
2 Lyles School of Civil Engineering, Purdue University
3 Forest Products Laboratory, US Forest Service, Madison, WI 53726
* Corresponding author at: Lyles School of Civil Engineering, Purdue University
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.
Linear Mode
