Experimental investigations on tensile strength behavior and microstructure of ultra-high-performance fiber-reinforced concrete

Abstract

This study experimentally investigates the aged tensile strength behavior and microstructure of the ultra-high-performance fiber-reinforced concrete (UHPFRC) fabricated with an optimal ratio between the concrete and steel fibers. In the mixing process, a superplasticizer is added to enhance the tensile strength with the increasing age of the material. The appropriate addition of the superplasticizer is extremely crucial because it significantly affects the workability, durability, and tensile strength of the UHPFRC. In this work, the volumetric fraction of the steel fibers is determined to achieve the target splitting tensile strength of 25 N/mm 2 at elevated temperatures in which several properties of the concrete are degraded. It is shown that the proposed UHPFRC can achieve the target tensile strength in 28 days. To better understand this tensile strength behavior, a microstructure analysis is also conducted using scanning electron microscope images. From this analysis, it is determined that micro-silica is involved in imparting high density to the microstructure and increases the packing density of the compounds. This phenomenon directly influences the increment in the tensile strength of the proposed UHPFRC.

Theoretical and experimental analysis of precast slabs composed of pre-stressed joists

“…As shown in Table 4, average measured values of fct,m for all joists are above the 3.0 MPa theoretical value which, in theory, should result in a higher fissuring bending moment on the systems. As noted by Surdashan and Rao [31], cementitious matrix tensile strength was related to the size of pores, connectivity between pores and zone interface between aggregates and cement paste. Consequently, variations in the mix ratio could lead to considerable changes in tensile strength as it was highly susceptible to it.…”

Effect of water to cement (W/C) ratio and age on mechanical behavior of tire‐recycled steel fiber reinforced concrete

“…Combining the effects of low W/C ratio and high fiber percentage (well seen in L4 mixture), results in mixtures with very high amounts of air voids. In these mixtures, due to low cement‐aggregates or cement‐fiber bondage and weak matrix, a decrease in mechanical strength and durability is expectable; other researchers also saw this pattern in their studies 46–49 …”

“…In these mixtures, due to low cement-aggregates or cement-fiber bondage and weak matrix, a decrease in mechanical strength and durability is expectable; other researchers also saw this pattern in their studies. [46][47][48][49] The failure mode observed in most flexural specimens is a single vertically crack placed in the middle one-third span (mainly in the mid-section). The crack path was generally straight for all the tested specimens without a significant curve.…”