Control of Tensile Behavior of Ultra-High Performance Concrete Through Artificial Flaws and Fiber Hybridization

The purpose of the paper is to determine the influence of two widely used steel fibers and polypropylene fibers on the sulphate crystallization resistance, freeze-thaw resistance and surface wettability of ultra-high performance concrete (UHPC). Tests were carried out on cubes and cylinders of plain UHPC and fiber reinforced UHPC with varying contents ranging from 0.25 to 1% steel fibers and/or polypropylene fibers. Extensive data from the salt resistance test, frost resistance test, dynamic modulus of elasticity test before and after freezing-thawing, as well as the contact angle test were recorded and analyzed. Fiber hybridization relatively increased the resistance to salt crystallization and freeze-thaw resistance of UHPC in comparison with a single type of fiber in UHPC at the same fiber volume fraction. The experimental results indicate that hybrid fibers can significantly improve the adhesion properties and reduce the wettability of the UHPC surface.

Section: Introductionmentioning

confidence: 99%

Effect of Fiber Hybridization on Durability Related Properties of Ultra-High Performance Concrete

Smarzewski

Barnat-Hunek

2017

“…Research concerned with incorporating various types of steel fibres in UHPC has raised significantly interests due to its ability to achieve ductile behaviour under tension (Lim and Hong 2016;Abdallah et al 2016;Kang et al 2016;Wille et al 2014;Lee et al 2010). Yet, for the same ingredients of UHPC a significant difference in compressive strength can be found due to different W/B ratio (Torregrosa 2014).…”

Section: Introductionmentioning

confidence: 99%

Pull-Out Behaviour of Hooked End Steel Fibres Embedded in Ultra-high Performance Mortar with Various W/B Ratios

Abdallah

Fan

Zhou

2017

This paper presents the fibre-matrix interfacial properties of hooked end steel fibres embedded in ultra-high performance mortars with various water/binder (W/B) ratios. The principle objective was to improve bond behaviour in terms of bond strength by reducing the (W/B) ratio to a minimum. Results show that a decrease in W/B ratio has a significant effect on the bondslip behaviour of both types of 3D fibres, especially when the W/B ratio was reduced from 0.25 to 0.15. Furthermore, the optimization in maximizing pullout load and total pullout work is found to be more prominent for the 3D fibres with a larger diameter than for fibres with a smaller diameter. On the contrary, increasing the embedded length of the 3D fibres did not result in an improvement on the maximum pullout load, but increase in the total pullout work.Keywords: pullout behaviour, bond mechanisms, water/binder ratio, hook geometry, embedment length and fibre-matrix interface.

“…Drying shrinkage is the mechanical deformation of the matrix caused by a driving force, the capillary tension ( Fig. 2) (Han et al 2006;Kang et al 2016). The capillary tension may be shown as the coefficient of radius curvature and the surface tension, and when water evaporates due to drying, the radius curvature decreases and the capillary tension increases, so that shrinkage occurs.…”

Section: Principle Of Shrinkage Reducing Agentmentioning

confidence: 99%

Durability of Latex Modified Concrete Mixed with a Shrinkage Reducing Agent for Bridge Deck Pavement

Lee¹,

Kim

2018

Latex modified concrete (LMC) is used for a bridge deck pavement method that was introduced in Korea in the 2000s, and it is currently the concrete pavement method being used for most highway bridges. It has been recommended that mixing with latex approximately 15% in terms of polymer-cement ratio (P/C ratio) by weight showed no occurrence of cracks with sufficient tensile strength and bond strength of LMC. However, many cracks occur in the actual field mostly due to drying shrinkage of concrete, requiring frequent repair. Therefore, this study examined the feasibility of applying a shrinkage reducing agent(SRA) that could reduce plastic shrinkage cracks at early age as well as drying shrinkage cracks of LMC. Based on the test results, it was confirmed that adding a shrinkage reducing agent could secure the durability without affecting the fresh and hardened properties of LMC. The compression strength test results presented a 1.7-5.7% improvement in strength to the SRA mixture compared to the plain mixture. Length change test results indicated that SRA mix conditions presented more outstanding performance compared to mix conditions with the expansive admixture. The amount of shrinkage reducing agent suitable for achieving performance requirements in length change, crack resistance, chloride ions penetration resistance and scaling resistance, was evaluated as 3% by weight ratio of binding material under the limited condition of the present study.