Intelligent Soil Compaction Technology

Abstract

Intelligent compaction (IC) is a new technique in the U.S. construction market that uses an instrumented compactor to control soil or asphalt compaction in real time. This technology provides one of the first opportunities to apply process control to civil construction. IC is based on the measurement of the mechanical characteristics of the compacted soil, commonly soil stiffness, but other properties are used also. Initiatives in both the United States and Europe started more than 10 years ago and have demonstrated the technical viability of measuring in situ soil stiffness. The measured soil stiffness is used to estimate or compute in situ soil modulus on the basis of assumptions about soil behavior and the interaction between the compaction machine and the soils. IC offers immense potential benefits in embankment, buried structure, and dam and pavement construction. These benefits–-including improved quality, reduced compaction cost, reduced life-cycle cost, and integration of design with construction and pavement performance–-arise from surface-covering documentation and process control of the compaction operation.

Cooee bitumen: Chemical aging

“…The number of molecules of each type was implemented in each mixture and the corresponding weight fractions were calculated knowing the molar mass of each molecule. The weight fractions of asphaltene molecules in mixtures I and IV are close to the weight fractions of asphaltene molecules in an unaged AAD-1 bitumen and in the same bitumen aged through the TFAAT (Thin Film Accelerated Aging Test) method at 113 • C for 72 hours, respectively [1,4]. The natural abundance in asphaltene molecules in AAD-1 bitumen is around 20% and it reaches 36%…”

“…To go from one composition to another the reaction "2 resins → 1 asphaltene" is applied. This reaction is chosen because some experimental results suggest that as bitumen ages, the asphaltene content increases and the resin content undergoes the greatest mass loss [4]. However, the experimental literature proposes also other scenarios for chemical aging: the aromatic content could decrease while the resin and asphaltene contents increase [3] or the resin and aromatic contents increase due to a decrease in the saturates content while the asphaltene content is mainly constant but composed of molecules with increasing molecular mass [17].…”

“…after aging through TFAAT. The TFAAT method is known to reproduce chemical aging of bitumen for a period between 5 to 10 years [1,4]. This value is our best estimate of the aging period our reaction models.…”

“…Road deterioration is partly due to the aging of bitumen, of which viscosity [1][2][3][4] and brittleness [5,6] increase over years. Bitumen chemical species can be categorized into the SARA classification [7], for which S stands for saturates, the first A for aromatics, R for resins, and the second A for asphaltenes.…”

“…Asphaltene molecules represent the crude oil fraction not soluble in alkane, usually heptane [7][8][9] and are the largest molecules found in crude oil. Chemical aging is characterized by an increase of the asphaltene content in bitumen [1][2][3][4]. Experimental work has shown that an increase of the asphaltene content leads to an increase in viscosity [10][11][12].…”