Performance Comparison between Densified and Undensified Silica Fume in Ultra-High Performance Fiber-Reinforced Concrete

Abstract

Silica fume (SF) is a key ingredient in the production of ultra-high performance fiber-reinforced concrete (UHPFRC). The use of undensified SF may have an advantage in the dispersion efficiency inside cement-based materials, but it also carries a practical burden such as high material costs and fine dust generation in the workplace. This study reports that a high strength of 200 MPa can be achieved by using densified SF in UHPFRC with Portland limestone cement. Additionally, it was experimentally confirmed that there was no difference between densified and undensified SFs in terms of workability, compressive and flexural tensile strengths, and hydration reaction of the concrete, regardless of heat treatment, because of a unique mix proportion as well as mixing method for dispersing agglomerated SF particles. It was experimentally validated that the densified SF can be used for both precast and field casting UHPFRCs with economic and practical benefits and without negative effects on the material performance of the UHPFRC.

Early hydration of C4AF with silica fume and its role on katoite composition

“…Mostly amorphous SF contains low content of quartz and cristobalite. The chemical composition of silica fume 19 and C 4 AF determined by XRF is given in Table 1. C 4 AF was crushed and ground in a laboratory ball mill for 12 min.…”

A study on HyFRCC consisting of PE and carbon fiber: Investigation of electrical and fracture properties based on orthogonal design

“…The carbon fibers could be dispersed as much as possible due to the lubrication action of cement and silica fume with small particle size and spheroidal shape. 26 Then, the mixture was stirred with water at a high-speed rotation for 5 min to obtain a fresh mortar containing carbon fiber. Next, the PE fibers were dispersed into the fresh carbon fiberreinforced mortar.…”

“…The binder, fine sand, superplasticizer powder, and carbon fibers were mixed in the mixer with low‐speed stirring for 5 min. The carbon fibers could be dispersed as much as possible due to the lubrication action of cement and silica fume with small particle size and spheroidal shape 26 . Then, the mixture was stirred with water at a high‐speed rotation for 5 min to obtain a fresh mortar containing carbon fiber.…”

Modification of Iron-Tailings Concrete with Biochar and Basalt Fiber for Sustainability

“…Meanwhile, the peaks of Ca(OH)2 in samples PFB21 and PFB22 are high than that in samples PFB11 and PFB12. The high content of Ca(OH)2 means that the effect of secondary hydration reaction is poor, leading to the reduction of C-S-H generation; this shows that when the content of basalt fiber is 0.1 wt.%, the mixing property of samples can be improved; this also promotes the contact between cement particles and water, improves hydration reaction [32], and generates more C-S-H. Thereby improving the mechanical properties of The hydration products which are beneficial to mechanical properties are C 3 S, C 2 S, and Ca(OH) 2 ; it can be seen from Figure 5 that the peak values of CS (C 3 S and C 2 S) in samples PFB21 and PFB22 are significantly higher than those in other samples.…”