Abstract
In this paper, the reliability of vertical vibration test method (VVTM) was evaluated by comparing the changes in moisture content and gradation before and after forming the test piece by VVTM and static pressure method and the mechanical strength correlation between the laboratory compaction sample and the core sample in the field. The effects of cement content, curing period, gradation, and compaction degree on the unconfined compressive strength, splitting strength, and compressive rebound modulus of VVTM‐compacted cement‐stabilized crushed gravel (CSCG) were studied, and a mechanical strength prediction equation for VVTM‐compacted CSCG was formulated. The results show that the correlation between the strength of the VVTM specimen and the field core sample can reach 92%; the mechanical strength of CSCG will increase with increase in the cement content, and when the cement content reaches approximately 4%, the increase in its mechanical strength will slow down; the mechanical strength of VVTM‐compacted CSCG with different cement dosages and gradation types increased fast at 14 days of curing period and began to level off after 90 days. Compared with XM gradation, using GM gradation can improve the mechanical strength. Under different gradations and curing periods, the mechanical strength linearly increases with increase in the degree of compaction. The mechanical strength prediction equation has a high reliability; therefore, it can accurately predict the strength growth rules. Moreover, the degree of compaction increases by 1%, and the mechanical strength increases by approximately 10%.
Highlights
Macadam is characterized by irregular shapes and very sharp corners
cement-stabilized crushed gravel (CSCG) can only be tested in a laboratory under simulated conditions. erefore, the correlation between the mechanical properties of mechanically crushed gravel samples produced in the laboratory and the field core samples is a key indicator for evaluating the quality of laboratory compaction methods [29]
vertical vibration test method (VVTM) mainly simulates the vibration and oscillation of heavy rollers by vertical vibration testing equipment (VVTE), forcing solid materials to “resonate,” and small particle aggregates fill the gaps, thereby simulating the compaction effect of the roller and improving the performance of CSCG. e correlation of core samples in the field is higher [32, 33]. erefore, the VVTM-treated cement-stabilized macadam mixture shows better performance than static pressure method (SPM), and the water content and dry density obtained by VVTM are more reasonable in terms of construction quality control
Summary
Macadam is characterized by irregular shapes and very sharp corners. It is evenly distributed in strength and basically controllable in quality. Erefore, the correlation between the mechanical properties of mechanically crushed gravel samples produced in the laboratory and the field core samples is a key indicator for evaluating the quality of laboratory compaction methods [29]. Erefore, the VVTM-treated cement-stabilized macadam mixture shows better performance than SPM, and the water content and dry density obtained by VVTM are more reasonable in terms of construction quality control. Using 7 d unconfined compressive strength to analyze the mechanical properties, under the same cement dosage, the performance of VVTM is higher than that of SPM, which is more reasonable and effective for construction site control [18]. Erefore, the reliability of VVTM was evaluated by comparing the moisture content, gradation changes of VVTM and SPM before and after molding, and the mechanical strength correlation between the sample and the core sample in the field. The above research has explored the road performance of CSCG, most of these studies are based on SPMforming test specimens, which are no longer compatible with the more advanced paver machinery, roller compaction machinery, and construction technology introduced in China’s domestic construction, and there are limitations in the correlation between material composition and performance, leading to insufficient theoretical basis for optimizing material composition. erefore, the reliability of VVTM was evaluated by comparing the moisture content, gradation changes of VVTM and SPM before and after molding, and the mechanical strength correlation between the sample and the core sample in the field. e influence of gradation, cement content, curing period, and compaction on the mechanical strength of CSCG was studied using VVTM. e research results can provide a reference for engineering practice
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