Krishna Prapoorna Biligiri

Crumb Rubber and Silica Fume Inclusions in Pervious Concrete Pavement Systems: Evaluation of Hydrological, Functional, and Structural Properties

The main objective of this research study was to comprehensively investigate the hydrological, functional, and structural characteristics of 21 pervious concrete (PC) mixtures encompassing four dosages of crumb rubber (CR), four proportions of silica fume (SF) contents, and three distinct aggregate gradations. A total of 126 PC cylindrical specimens were available to measure density, porosity, permeability, abrasion resistance, and compressive strength properties. The inclusions of CR and SF in the PC enhanced the compressive strength and abrasion resistance compared to the control unmodified PC specimens. However, CR-modified PC showed reduced permeability because of a decrease in the porosity of those mixes. Nonetheless, the study results did not reach any optimum values of CR or SF replacement and indicated that there is more scope to replace the coarse aggregate with CR and cement with SF so as to identify the optimum dosages of these two modifiers in future. The use of CR in PC as a partial replacement of aggregate can become a potential way of conserving the natural aggregates that are becoming scarce. Furthermore, SF can be used as a partial replacement for cement that will eventually reduce carbon dioxide emissions from cement production, thus being able to achieve the significant use of renewable resources in producing green pavement systems.

Novel procedural pragmatics of dynamic Semi-Circular Bending test for fatigue evaluation of asphalt mixtures

This paper proposed novel load-level selection pragmatics of Semi-Circular Bending (SCB) test that could practically be utilised to characterise fatigue performance of asphalt mixtures. A strain-controlled technique was devised and illustrated to determine the load input as a prerequisite to run dynamic SCB test. Three initial strains were selected as target criteria to determine the loads. The key features of the proposed approach were discussed with test results on 216 specimens. It was concluded that the formulated system rationally determined the load levels of dynamic SCB test to obtain response parameters, and is envisioned to replace the current conventional trial-and-error method.

Effect of pore structure on fatigue of pervious concrete

Pervious concrete (PC) is a class of porous pavement whose properties are largely influenced by pore parameters. Under repeated vehicular loads, PC undergoes reduction in stiffness leading to failure. The purpose of this study was to understand the influence of porosity and pore sizes on fatigue of 13 PC mixtures encompassing 104 beams, and establish stiffness reduction model / damage evolution in respect of repeated loads for PC based on the existing model used for conventional concrete. Fatigue life and stiffness depend on porosity at the fractured face of specimens as investigated using image analyses, which was more influential than the volumetric porosity determined through ASTM C1754. The reduction in stiffness followed S-curve depicting three distinct stages of damage evolution. The damage model fitted the experimental data with very high accuracy (R2u2009>u20090.95) and precision. The specimens shifted from secondary to tertiary stage when the reduction in initial stiffness was 65–85%, which occurred at 90–98% of the total life. This study is envisioned to assist in the development of fatigue test protocols as well as recommend PC pavements as part of the maintenance and rehabilitation programmes.