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 May 2022 is Andréia Posser Cargnin, a Ph.D candidate at the Polytechnic School of the University of São Paulo (São Paulo, Brazil).
BIO:
Andréia Posser Cargnin, Ph.D Candidate-Polytechnic School, University of São Paulo (São Paulo, Brazil), under the supervision of Prof. José Tadeu Balbo and Prof. Liédi L. Bariani Bernucci. Andréia obtained her Bachelor’s degree in Civil Engineering from the Federal University of Santa Maria, Rio Grande do Sul, Brazil and master’s degree in Transportation Engineering at Polytechnic School of USP, working with continuously reinforced concrete pavements (CRCP). Cargnin’s research along the last years deals with investigating cementitious materials properties for pavement purposes as well as sustainable pavements. Her Ph.D research is focused on cement-treated crushed stones for pavements under heavy traffic.
TITLE:
HIGH-PERFORMANCE CEMENTED BASES FOR PAVEMENTS UNDER HEAVY TRAFFIC
The chemical stabilization of granular materials is a technique commonly used to build high stiffness bases for both hot mix asphalt (HMA) and Portland cement concrete pavements (PCCP). The stabilization of graded crushed stones with small consumption of hydraulic binder results in the so-called cement-treated crushed stone (CTCS) which is like a roller compacted concrete (RCC) with continuous gradation, differing only on its cement content: while RCC for pavements cement consumption up to 150 kg/m³ (representing 6% to 7% of the total volume of concrete), the CTCS is produced for cement consumptions lower than 120 kg/m³ (5% of total volume of material). Therefore, the CTCS mechanical strength is an outcome of the combined effects of granular skeleton and cementitious matrix; the first one is responsible for the material mechanical stability through aggregate interlocking after compaction (see Figure 1), whereas the second one is accountable for strength development through the bonding promoted by the cement hydration products (mainly C-S-H).
Click to enlarge
Because of its peculiar characteristics, especially regarding the low cement consumptions, former studies on CTCS have pointed out low static and fatigue strength as well as small fracture toughness. Concomitantly several problems related to premature fatigue cracking and their reflection to the surface HMA were recorded at important Brazilian roads.
As the relation modulus/strength for pavement design and analysis is an important indicative of performance under loads, since the little this ratio is better for durability in terms of fatigue, one of the purposes of this research is to develop an improved material using additives capable to modify the adhesion between the aggregates and the cement paste, improving their mechanical strength without impacting the modulus of elasticity significantly. The laboratory study involves evaluation of shrinkage, mechanical characteristics like (static and fatigue strength, modulus of elasticity and fracture toughness) to understand the material macro and microstructural behavior.
Then the field step comprehends the construction of an experimental track which will be monitored regarding its shrinkage cracking and stiffness through backcalculation of elastic modulus by means of FWD search. Additionally, the temperature profile in the cementitious base will be measured, allowing to upgrade the design procedure for CTCS in Brazil and local with similar climatic characteristics, taking into account the combined effects of traffic and thermal stresses occurring in the cemented base underneath asphalt or concrete pavements surface course.
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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
ALL SPOTLIGHTS:
DECEMBER 2021—Inaugural: Katelyn Kosar, Phd Student-Department of Civil and Environmental Engineering, University of Pittsburgh (Pitt): www.concretepavements.org/2021/12/14/new-at-iscp-student-research-spotlight/
JANUARY 2022: Aniruddha Baral, Ph.D. Candidate-Department of Civil and Environmental Engineering, University of Illinois-Urbana-Champaign: www.concretepavements.org/2022/01/15/student-research-spotlight-jan-2022/
FEBRUARY 2022: Jordan Ouellet, Tech, BEng, MASc, PhD Candidate, Teaching and Research Assistant, University of Illinois at Urbana-Champaign: www.concretepavements.org/2022/02/26/student-research-spotlight-february-2022/
MARCH 2022: Sampath Kumar Pasupunuri, Ph.D. candidate, Pavement Engineering-School of Civil Engineering, University of Nottingham, UK: https://www.concretepavements.org/2022/03/31/student-research-spotlight-march-2022/
APRIL 2022: Anupam B R, Pursuing his doctorate-Indian Institute of Technology Bhubaneswar, India: https://www.concretepavements.org/2022/04/15/student-research-spotlight-april-2022/