Treated versus Untreated Aggregate Bases for Flexible Pavements: Nationwide Comparative Case Study

Abstract

Aggregates constitute a major part of pavement construction. The strength, durability, and quality of the aggregate affects the overall performance of the pavement structure. Materials sourced near a construction site do not always meet the strength required for pavement construction, however, and haulage of aggregates of the required quality is often costly. For better use of locally available materials, stabilizing agents such as lime, cement, asphalt cement, and fly ash are often used to enhance the strength of the local aggregates. Pavement performance is influenced by both the structure itself and the layer materials present in it. The stiffness of the base layer, for instance, influences the tensile strain in the asphalt layer and compressive strains in the subgrade soil. The tensile strains at the bottom of the asphalt layer and compressive strains in the top zone of the subgrade soils are the main response components affecting fatigue cracking and rutting, respectively. In this study, field performance [rutting, cracking, and roughness measured in relation to the International Roughness Index (IRI)] of pavement sections with treated and untreated base layers were compared to determine the effects of stabilizing agents. In relation to fatigue cracking and pavement surface roughness, the treated sections outperformed the untreated sections. The average values of all three distresses showed better performance for the treated base layer sections with fatigue cracking averaging 2.2 times lower than the untreated sections. The combined rutting and IRI of the treated base layer sections averaged about 0.10 in. and 1.4 times lower than those of the untreated base layer sections, respectively.

Effect of Asphalt Pavement Base Layers on Transverse Shrinkage Cracking Characteristics

“…The durability of asphalt pavement and the driving experience of vehicles are reduced, which is not conducive to the sustainable service performance of asphalt pavement. Relevant studies show that the transverse shrinkage cracking of asphalt pavement is closely related to the performance of the pavement structural layer, especially the material of base layers [4][5][6]. Therefore, it is an important research direction to study the effect of asphalt pavement base layers on transverse shrinkage cracking characteristics, which is helpful to increase the durability of the asphalt pavement structural layer in cold areas.…”

A Resistivity Plate Loading Device for Assessing the Factors Affecting the Stiffness of a Cement-Stabilized Subgrade

“…The hydration reaction between w and C causes the stiffness, w, and ρ d to change with T. As a result, it is essential to clarify the correct C, w, ρ d , and T . This finding ensures an accurate assessment of the stiffness properties to predict the improvement effects of the stabilized subgrade [ 3 , 19 , 20 , 21 ]. Below/above the optimum w and C requirements, the required engineering properties may not reach/exceed the design limit, which may produce different physical and stiffness characteristics of the stabilized subgrade [ 22 ].…”