Yeswanth Paluri

With the growing need for sustainable building materials, the use of recycled materials in concrete production is encouraged. Reclaimed asphalt pavement (RAP) is a by‐product of road rehabilitation operations and is one possible substitute for natural aggregates (NAs) in concrete. In the case of RAP aggregates, however, the asphalt that has aged on the surface weakens the bond between the cement matrix and aggregates, resulting in lower mechanical performance. The aim of this study is to investigate the effect of RAP aggregates and steel fiber reinforcement on the strength, durability, and microstructural properties of concrete used for rigid pavement construction. Eight mixes of concrete were produced using different RAP content levels (0%, 10%, 20%, 25%, and 30%) and a steel fiber content of 0% and 1%. Mechanical properties, durability parameters, and microstructural properties were assessed in terms of compressive strength, split tensile strength, flexural strength, ultrasound pulse velocity, sorptivity, acid resistance test, and scanning electron microscopy (SEM). The test results show there is a reduction in compressive strength as RAP content increases; mixes with 20% RAP meet the pavement quality concrete (PQC) requirements. The addition of steel fibers markedly enhanced the split tensile strength by about 45% and flexural strength and toughness/durability performance were also improved. The results of microstructural analysis showed that there were weak interfacial zones between RAP aggregates and cement paste and that the steel fibers had better crack‐bridging properties. The study proves the steel fiber‐reinforced RAP concrete (SFRRAPC) can be used as a sustainable material for rigid pavement construction.

Concrete being one of the most extensively used material worldwide, the ecological influence of the manufacture of the raw materials for concrete is substantial. The scale of the problem makes it essential to examine other sources of raw materials to minimize the consumption of available natural resources. Since more than 70% of the bulk of conventional concrete consists of aggregates, maximizing the use of alternate/waste materials brings remarkable benefits such as a decrease in the demand for natural aggregates and saving energy costs related to natural aggregate production and conveyance. India, the second-largest consumer of crushed aggregates in the world, is making great strides in using waste/recycled materials as aggregates in pavement construction. Every year, millions of tons of reclaimed asphalt pavement (RAP) are being produced from the repair and reconstruction of existing roads. If this waste material can be reused without much processing in the construction of new pavements, it could be a great alternative to natural aggregates. This paper is intended to examine the flexural fatigue behavior of RAP-based concrete with and without steel fibers. The study considers varied proportions of RAP content (0% to 30%), fiber content (0% and 1%), and stress levels (0.9, 0.8, and 0.7). A total of 96 prismatic samples were examined under static and flexure fatigue load. The frequency for the fatigue loading was kept at 2 Hz, maintaining a stress ratio at 0.1. The results indicate a decrease in flexural fatigue life with an increase in the RAP content at all the stress levels. However, there is a substantial enhancement in fatigue life when steel fibers are added to RAP-based concrete. The results show that two-parameter Weibull distribution is the best fit for modeling fatigue life variation. The fatigue strength (at a survival probability of 0.9, corresponding to two million load repetitions) decreased by 9%, 18%, and 23% for RAP contents of 10%, 20%, and 30%, respectively. The addition of fibers enhanced the fatigue strength of RAP-based concrete by 50%–65%.