Enhancing the Hardened Properties of Recycled Concrete (RC) through Synergistic Incorporation of Fiber Reinforcement and Silica Fume

Abstract

Portland cement concrete is fragile in tension and it has numerous negative impacts on the environment. To deal with these issues, both fiber reinforcement and recycled materials can be utilized to manufacture sustainable and ductile concrete. In this study, the synergistic effects of high-performance mineral admixture silica fume and glass fiber reinforcement were investigated on the hardened properties of RC. For this purpose, two concrete mix families, namely, NC and RC were prepared. To understand the benefits of synergistic utilization of glass fiber and silica fume, in both NC and RC, 0.5% glass fiber was incorporated with three different levels of silica fume. i.e., 0%, 5%, and 10%. Both strength and permeability-related durability properties were investigated. Results revealed that combined incorporation of 0.5% fiber and 10% silica fume can help in the production of RC having better mechanical and durability performance compared to reference “NC”. Simultaneous incorporation of silica fume and glass fiber produces a combined effect greater than their individual effects on both mechanical and permeability properties of concrete. Silica fume plays a very dominant and positive role in the development of CS, WA, and CIPR of RC, whereas glass fiber plays a vital role in upgrading STS and FS of RC and whereas, with the addition of 0.5% glass fiber, RC can yield 8–9 times higher flexural toughness than that of the plain NC.

Effect of Varying Steel Fiber Content on Strength and Permeability Characteristics of High Strength Concrete with Micro Silica

“…Micro-silica (also known as silica fume obtained from Jaza Minerals, Karachi, Pakistan) containing 90–94% silica was used as a partial cement substitute. Properties of cement and micro-silica can be assessed from the study of Ali et al [ 2 ]. Siliceous sand from the Lawrancepur quarry (Attock, Pakistan) was used as fine aggregate.…”

“…To test for water absorption (WA) capacity, 100 φ mm × 50 mm concrete disc specimen of each mix was tested following ASTM C642 [ 32 ]. To determine chloride ion penetration (CIP) resistance of each mix, an immersion technique was adopted as explained by the authors [ 2 ]. For the CIP test, a 100 mm × 100 mm cylindrical specimen was first cured in normal water for 28 days.…”

“…After conditioning in chloride solution, the specimen was split, and the failed surface of the specimen was sprayed with 0.1 N AgNO 3 solution to observe the depth of CIP. The further detailed procedure for CIP testing can be assessed from studies [ 2 , 33 ]. All the results presented in this research are the mean values of the three results of each concrete mixture.…”

“…Its splitting tensile strength (STS) is very low compared to its compressive strength (CS). According to Ali and Qureshi [ 1 , 2 ] and Koushkbaghi et al [ 3 ] PCC has a STS/CS ratio of about 7–9.5%. Zain et al [ 4 ] showed that the STS/CS ratio decreases as the strength class of concrete is upgraded, therefore, high strength PCCs are more vulnerable to brittle failure than normal strength PCCs.…”

“…Moreover, poor bond strength between fiber and binder matrix reduces the utilization of full potential of SF. It is essential to investigate the influence of such materials (i.e., MS) on SFRC that help in strengthening binder matrix and improve the dispersion of fibers [ 2 , 10 ]. This study is designed to evaluate the effects of varying SF dosage on the properties of a high strength concrete.…”