Influence of mineral nano-fibers on the physical properties of road cement concrete material

Abstract

In this paper, brucite nano-fiber is processed and used as reinforcement to improve the toughness of road cement concrete material. The brucite nano-fiber is obtained by soaking the natural low-coat brucite short fibers in the superplasticizer solution and then agitating in a forced mixer to refine it to the nano meter level. The mechanical properties as elastic modulus, dry shrinkage, anti-frost, thermal expansion, and flexural fatigue performance of the nano-fiber concrete are investigated. The nano-fiber reinforced cement concrete was also put into practice in highway. Results show that nano-fiber concrete has better toughness. Its flexural strength is 7.4% and 17.7% higher than that of the ordinary fiber concrete and the plain concrete, respectively. Its ratio of compression to flexural strengths is 6.4% and 16.1% lower than that of the rest two. Nano-fiber concrete has lower static modulus and higher dynamic modulus. Compared with ordinary fiber concrete and plain concrete, nano-fiber concrete is 41.0% and 61.3% lower in flexural elastic modulus, and is 1.12 and 1.24 times higher in dynamic modulus of elasticity. Nano-fiber concrete has stronger capability to resist dry shrinkage, freeze-thaw damage, thermal expansion and bending fatigue stresses. Compared with ordinary fiber concrete and plain concrete, nano-fiber concrete is 35.7% and 55.9% lower in dry linear shrinkage; 3.2% and 7.9% less loss rate in compression strength, and 1.9% and 4.5% less loss rate in flexural strength after 50 cycles freezing-thawing; 13.9% and 28.7% lower in coefficient of thermal expansion; and 15% and 50% more longer in bending fatigue service life. Nano-fiber concrete is comprehensively superior to ordinary fiber concrete and plain concrete in cost performance. After more than 8 years traffic practice, the nano-fiber concrete test road is still in good condition.