Experimental Investigation on Flexural Behaviour of Sustainable Reinforced Concrete Beam with a Smart Mortar Layer

Abstract

This paper deals with an experimental study of the flexural behavior of sustainable reinforced cement concrete (RCC) beams with a smart mortar layer attached to the concrete mixture. In total, nine RCC beams were cast and tested. Two types of reinforced concrete beams were cast, and three different beams of sizes 1000 × 150 × 200 mm and six different beams of sizes 1500 × 100 × 250 mm were considered. The flexural behavior of these RCC beams was studied in detail. The electrical resistivity of these beams was also calculated, which was derived from the smart mortar layer. Research on the application of smart mortars within structural members is limited. The experimental results showed that the smart mortar layer could sense the damage in the RCC beams and infer the damage through the electrical measurement values, making the beam more sustainable. It was also observed that the relationship between the load and the fractional change in electrical resistance was linear. The fractional change in electrical resistivity was found to steadily increase with the increase in initial loading. A significant decrease in the fractional change in electrical resistivity was seen as the load approached failure. When a layer of mortar with brass fiber was added to the mortar paste, the ultimate load at failure was observed and compared with the reference beam specimen using Araldite paste. Compared to the hybrid brass-carbon fiber-added mortar layer, the brass fiber-added mortar layer increased the fractional change in the electrical resistivity values by 14–18%. Similarly, the ultimate load at failure was increased by 3–8% in the brass fiber-added mortar layer when compared to the hybrid brass-carbon fiber-added mortar layer. Failure of the beam was indicated by a sudden drop in the fractional change in electrical resistivity values.

Strain Monitoring of Concrete Using Carbon Black-Based Smart Coatings

“…Kim et al [104] reported a maximum sensing response of 2% for 10 mm thick MWCNT-based coatings within a stress range of 30% of flexural strength. Durairaj et al [103] obtained FCR values of between 10% and 15% for a strain range similar to the one investigated in this study by employing a 6 mm deep mortar layer with various combinations of brass and carbon fibre. Wen and Chung [101] obtained a maximum FCR amplitude of 0.15% on the tension side for a 5 mm thick coating with 0.5 wt% added carbon fibre for a beam deflection of about 0.09 mm.…”

“…It was conjectured that greater strain transmission occurred in thinner coatings, thus leading to a greater gauge factor. Likewise, Durairaj et al [103] applied carbon fibre and brass fibre mortar coatings to concrete beams under flexural bending for damage detection while employing different coating attachment methods; although a dependency between the electrical properties and the applied load was evident, the strain-sensing sensitivity was not calculated. Moreover, Kim et al [104] investigated the sensing behaviour of multi-walled carbon nanotube (MWCNT)-cement repairs under bending, and while a change in electrical properties under a load was observed, the sensing coefficient of the repairs was not determined.…”

Study on the calculation method of the maximum number of bonded steel plates at the bottom of reinforced concrete beams

“…It was found that the mechanical properties and durability of granite pulver self-curing selfcompacting concrete mixture can be improved through the optimal replacement of cement by granite pulver. Durairaj et al (2023) conducted an experimental study of the flexural behavior of sustainable reinforced cement concrete beams with a smart mortar layer attached to the concrete mixture. It was found that structural members can be coated with either carbon or brass fibers in thin mortar layers to detect damage to the member.…”

Advancing sand concrete sustainability: transforming quarry waste into high-quality crushed sand for superior properties

“…The mechanical properties of concrete, such as tensile strength, compressive strength, exural strength, and modulus of elasticity, are essential metrics for evaluating its behaviour under various loads and environmental conditions [41], [42], [43], [44]. Tensile strength determines the concrete's capacity to resist tensile (stretching or pulling) forces, whereas compressive strength measures its ability to withstand compression.…”