What is it about?
Ferrocement composites have uniform distribution and high surface area to volume ratio of reinforcement, which identifies them as a good strengthening material for use in structural applications. Because of these properties, they are considered as a substitution for some conventional structural strengthening methods. In this study, ten reinforced concrete (RC) beams of size 1220 mm × 100 mm × 150 mm were strengthened with ferrocement composites using a galvanized square weld, having volume fractions of 1.76% and 2.35%. For this study, ferrocement composites with mortar 1:2, w/c 0.4, and steel slag, with a 30% weight fraction of fine aggregate, are considered. The experimental results showed that the first crack load and the ultimate load are higher for RC beams strengthened with ferrocement having a volume fraction of 2.35% (Vr) and a steel slag replacement of 30%. Theoretical predictions were made based on the elastic moment approach; the ratio between the prediction to experimental moment capacity ranges between 0.99 and 1.04. The outcomes show that ferrocement is an effective strengthening technique for deficient reinforced concrete members
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Why is it important?
The deficient RC members can be strengthened with fibers, such as carbon fibers, steel fibers, etc. [1,2,3], and other materials, including ferrocement composites. Ferrocement composites are the most widely used strengthening materials for deficient RC members because of their toughness, strength, and crack control. Beam column joints strengthened with ferrocement jacketing show enhanced moment capacity and low deflection, and they do not suffer heavy damage [4]. RC beams strengthened with ferrocement composites with extended metal mesh have developed energy absorption capacity when compared to specimens with weld mesh, and the ratio between the experimental and theoretical ultimate was 0.96 to 1.26 [5]. Fire damaged RC beams strengthened with single-layered ferrocement and double-layered ferrocement show an improvement of 46% and 72%, respectively [6]. RC beams strengthened with ferrocement and 6mm diameter shear connectors increase the moment capacity by 26% [7]. RC beams flexurally strengthened with U-jacketing ferrocement containing self-compacting mortar, with weld mesh, exhibits a 110% increase in load carrying capacity when compared to un strengthened beams [8]. Ferrocement composites with a volume fraction of 3.68% and 30% steel slag replacement have a higher load carrying capacity, which makes them a significant strengthening materials for distressed RC members [9]. Reinforced concrete beams strengthened with single- and double-layered weld mesh ferrocement show an increased in load carrying capacity of 31.93% and 59.35%, respectively, when compared to un strengthened beams [10]. Reinforced concrete beams strengthened with ferrocement containing steel mesh increases their load carrying capacity by 36% and their ductility by 23% under symmetrical loading . Ferrocement with chicken mesh increases the load carrying capacity of the rectangular RC elements .The strengthened beams are subjected to the flexural load. Based on the experimental investigation, the first crack load, ultimate load, load deflection behavior, flexural performance of strengthened beams, and crack behavior are studied. Moreover, a theoretical prediction is made for the moment capacity of strengthened RC beams based on the elastic moment approach.
Perspectives
It is found that RC beams strengthened with ferrocement composites with a volume fraction 2.35% and steel slag replacement of 30% by weight of fine aggregate has increased the first crack load, ultimate load, energy absorption, and flexural performance. The inclusion of 30% steel slag and a volume fraction of 2.35% has considerably reduced the deflection and postponed the initial crack load. The failure of the composite beam is characterized by the development of flexural cracks over the tension zone. The space of the cracks is also reduced for the strengthened beams, which ensures better stress distribution. The epoxy mastic ensures the good attachment between the ferrocement laminates and the strengthened RC beams. The equations developed have laid the base to compare the design values of the ultimate moment capacity of the RC beams. The partial replacement of sand by steel slag, which is an industrial waste, is not only cheap, but also provides a potential opportunity for the utilization of these waste products that need not be simply dumped as land fill. the disposal of this waste is one of the crucial problems faced by the steel manufacturing industry. However, it is useful to extend the work for further study into the durability of RC beams strengthened with ferrocement composites containing steel slag.
Prof Gobinath R
S R Engineering College
Read the Original
This page is a summary of: Sustainable Retrofitting and Moment Evaluation of Damaged RC Beams Using Ferrocement Composites for Vulnerable Structures, Sustainability, July 2022, MDPI AG,
DOI: 10.3390/su14159220.
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