Bond Strength between Glass Fiber Fabrics and Low Water-to-Binder Ratio Mortar: Experimental Characterization

Daniel Bohling,Andrzej Cwirzen,Karin Habermehl-Cwirzen

doi:10.1155/2018/8197039

Daniel Bohling, Andrzej Cwirzen + Show 1 more

Open Access

https://doi.org/10.1155/2018/8197039

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Abstract

Full utilization of mechanical properties of glass fiber fabric-reinforced cement composites is very limited due to a low bond strength between fibers and the binder matrix. An experimental setup was developed and evaluated to correlate the mortar penetration depth with several key parameters. The studied parameters included fresh mortar properties, compressive and flexural strengths of mortar, the fabric/mortar bond strength, fabric pullout strength, and a single-lap shear strength. Results showed that an average penetration of mortar did not exceed 100 µm even at a higher water-to-binder ratio. The maximum particle size of the used fillers should be below an average spacing of single glass fibers, which in this case was less than 20 µm to avoid the sieving effect, preventing effective penetration. The pullout strength was strongly affected by the penetration depth, while the single-lap shear strength was also additionally affected by the mechanical properties of the mortar.

Highlights

One of the early attempts to produce ultrahigh strength concrete (UHPC) was made in the beginning of the 1970s
Results showed that an average penetration of mortar did not exceed 100 μm even at a higher water-to-binder ratio. e maximum particle size of the used fillers should be below an average spacing of single glass fibers, which in this case was less than 20 μm to avoid the sieving effect, preventing effective penetration. e pullout strength was strongly affected by the penetration depth, while the single-lap shear strength was affected by the mechanical properties of the mortar
Further increase of the W/B ratio to 0.33 caused a decrease of the exural strength to 12 MPa. ese values must be considered with a caution due to a relatively signi cant standard deviation of the measured values (Figure 8). e observed variations can be directly related to the entrapped air present despite the usage of the vacuum mixer. e negative e ect of random small air voids was certainly enhanced by the small size of the used reference samples, 12 × 12 × 100 mm3

Summary

Introduction

One of the early attempts to produce ultrahigh strength concrete (UHPC) was made in the beginning of the 1970s. Full utilization of mechanical properties of glass fiber fabric-reinforced cement composites is very limited due to a low bond strength between fibers and the binder matrix. Results showed that an average penetration of mortar did not exceed 100 μm even at a higher water-to-binder ratio.

Results

Conclusion