STUDENT SPOTLIGHT: Each month, or every other month, a student will provide a 1-page illustrated abstract of the research they are currently conducting. This is a wonderful opportunity for the student, for our International Society for Concrete Pavements (ISCP) Members, and for the transferring and sharing technology/research through our concrete paving industry.
The ISCP “STUDENT RESEARCH SPOTLIGHT” for October 2026 is Md Nasir Uddin, a PhD candidate at Texas State University (San Marcos, USA).
BIO:
Md Nasir Uddin is a Ph.D. candidate in the Materials Science, Engineering, and Commercialization (MSEC) Program at the Ingram School of Engineering, Texas State University, under the supervision of Dr. Xijun Shi. He is expected to graduate in May 2027. He received his B.S. from China University of Mining and Technology (CUMT) and his M.Eng. from Tongji University, where his thesis received the Excellent Thesis Award; he also served as a visiting researcher at The Hong Kong Polytechnic University. His doctoral research focuses on developing sustainable precast concrete sewer pipes that incorporate reclaimed asphalt pavement (RAP) and recycled steel fibers (RSF) recovered from end-of-life tires. The work is supported by the NSF Partnerships for Innovation – Technology Translation (PFI-TT) award “Eco-Friendly Concrete for Cheaper and Safer Concrete Pipes” (#2314080), with industry partner Circle Concrete Tech.
TITLE: Integrating recycled steel fibers and reclaimed asphalt pavements in sustainable and cost-effective infrastructure systems
Precast concrete pipes carry much of the nation’s stormwater and wastewater, and conventional reinforced pipes depend on steel cages that add cost, labor, and embodied carbon. At the same time, pavement rehabilitation produces large volumes of reclaimed asphalt pavement (RAP), and scrap tires contain recycled steel fiber (RSF) that is usually downcycled. Uddin’s research combines these two waste streams to produce fiber-reinforced pipe concrete: RAP partially replaces virgin aggregate, and RSF provides crack-bridging reinforcement that can reduce or replace conventional steel cages.
The first phase established the material. RAP/RSF pipe mixtures were characterized for fresh properties tests (mini slump, green test, and shape retention test), compressive and splitting tensile strength, elastic modulus, and post-cracking flexural toughness (ASTM C39, C496, and C1609), along with durability indicators relevant to buried service such as chloride permeability, sorptivity, absorption, and shrinkage.
In the fresh-properties testing, the green strength test was used to evaluate the stability of the dry-cast concrete mixtures. The results indicated that the mixture containing 1.25% RSF exhibited greater stability than the mixture containing 1.0% RSF. Subsequently, RSF-based dry-cast concrete was used to produce pipes, and the process is illustrated in Figure 2. The compressive strength and cracking patterns for different fiber dosages are presented in Figure 3. The results show how RSF mitigated the stiffness and strength losses associated with RAP and achieved the required residual flexural strength for the pipes.
Figure 1: Green strength test to see the stability of the dry cast mixtures (RSF-1% and 1.25%)
The second phase scaled up to full-size pipes. Prototype RAP/RSF pipes will be produced and tested under the three-edge bearing (TEB) test, the standard acceptance test for precast pipe. In parallel, Uddin will develop finite element models of the pipes in ABAQUS using the Concrete Damaged Plasticity model, with tension-softening input derived from beam tests. The models will be validated against the prototype TEB results. He will extend the framework to a probabilistic, two-scale approach that accounts for measured RSF orientation and dosage in the pipe wall, so fiber distribution from manufacturing can be linked directly to pipe capacity.
Figure 2: Prototype making process (RSF-1.0%)
Figure 3: Compressive strength test using different dosages of RSF.
ISCP would like to feature a “STUDENT RESEARCH SPOTLIGHT” each month, or every other month. If you would like to nominate a student, or if you are a student and would like to nominate yourself or a colleague, please send ISCP an email to: newsletter@concretepavements.org