Unified approach to characterize the strength of cement stabilized macadam subjected to different loading modes

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Department of Civil, Environmental, and Geospatial Engineering


Cement stabilized macadam base is the primary stress diffusion and bearing layer of semi-rigid asphalt pavement, therefore its mechanical behavior directly affects pavement performance. The indirect tensile strength, unconfined compressive strength, and bending strength are the essential parameters for evaluating the bearing capacity of cement stabilized macadam. In the design of a pavement structure, the conventional mixing strength values of a test sample are analyzed and calculated at a fixed loading rate. By using this procedure, the influence of the mixing method and the different loading rates on the strength values are ignored. Besides, the strength obtained by using the fixed loading rate with different loading modes has significant differences. As a result, the artificial randomness of the strength parameter in the design of a semi-rigid asphalt pavement structure increases. In an attempt, to improve the effectiveness and completeness of the strength parameters of cement stabilized macadam under different loading modes, mechanical tests were conducted on samples prepared with both vibration mixing and conventional mixing methods. This procedure included, indirect tensile strength test, unconfined compressive strength test, and four-point bending strength test under different loading rates. The results of these strength tests each group of samples (vibration and conventional mixing method) were compared. Besides, all samples were subjected to 6 different loading rates when conducting each loading mode. These experimental values were analyzed. The loading rate and the strength value have a power function relationship and the correlation of strength rates was revealed. The results demonstrated that the vibration mixing method increases the indirect tensile strength, unconfined compressive strength, and four-point bending strength by 13%, 14%, and 10%, respectively. A unified strength model (S/S0 = 0.9841 + 0.16856ln (0.01019 + v/v0) under two mixing methods and various loading modes were established by using the variation between loading rate ratio and strength ratio. In the unified model, the strength under vibration mixing and conventional mixing methods, and the strength among different loading rates can be converted, which improved the test efficiency. The established unified model solves the problem of uncertainty and uniqueness of strength parameters under different loading modes. The accuracy of the semi-rigid asphalt pavement structure resistance design was effectively improved, thereby providing theoretical guidance for the construction of semi-rigid base asphalt pavement engineering.

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© 2020 Elsevier Ltd. Publisher’s version of record: https://doi.org/10.1016/j.conbuildmat.2020.120143

Publication Title

Construction and Building Materials