The effects of Microbial Carbonate Precipitation -MCP- on physical and mechanical properties of Cold Asphalt Emulsion Mixtures -CAEMs- have been investigated. MCP method was performed on CAEMs by two scenarios: -I- Bio-deposition treatment of aggregates and, -II- using a medium culture containing bacteria and urea-CaCl2nutrient solution as a replacement for optimum water content. Additionally, in the second scenario, the effect of different curing durations -7, 14, 28 and 56 days- on the mixtures’ properties has been examined. X-Ray Diffraction, Fourier-Transform Infrared Spectroscopy, Atomic Force Microscopy and FE-SEM technique tests were employed to evaluate the formation of CaCO3 precipitation, micro-roughness of aggregates’ surface and the structure of bio-modified CAEMs. The physical properties, and mechanical properties including ultrasonic pulse velocity, dynamic modulus, indirect tensile strength, fracture energy and resistance to crack propagation -semi-circular bending test- were measured. Results indicated the formation of CaCO3 precipitations and increase of roughness on the surface of treated aggregates. Significant improvements -p-value < 0.05- were observed in the mechanical properties of CAEMs of first and second scenarios, however, these improvements are higher in the CAEMs of first scenario -p-value < 0.05-. Findings revealed that MCP method can significantly improve the mechanical properties of CAEMs. But, it doesn’t significantly affect their physical properties.

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