Research On The Vibratory Compaction Effect Of Cement Stabilized Aggregate

Base is the main bearing layer in the pavement structure and cement stabilized crushedstone is the typical material for base in China. The compaction quality has signiifcent impacton overall performance of pavement. Two main aspects of quality control of compaction arethe determination of laboratory compaction ctrition and ifeld test of compaction degree.Laboratory vibratory compactor is capabale of simulating the ifeld states of compaction, butits working parameters are complicated and further study on how to choose the mechanicalparameters properly is still needed. Real time monitoring on compaction degree can be usedto improve the quality control of pavement construction and speed up the construction. So itis important to study compaction methods with laboratory compactor and the real timemonitoring of compaction degree.The theory about vibratory, compaction and the testing and processing methodologies ofsignal were reviewed ifrst. The vibration in vibratory compaction is periodical vibration, andis ift for analysis with Fourier methods; the effective vibratory signals were obtained by usingpreprocess measures such as wave ifltering. Based on test results from laboratory compactionon cement stabilized crushed stone, the relation between mechanical parameters andcompaction effects was studied and inetrpreted from the point of energy. The relationbetween acceleration of compactor and compaction degree was studied and the factorsaffecting this relation were examined.According to the features of Fourier analysis on vibratory compaction, a new abstractingmethod for signals was developed; the compaction procedure of cement stabilized crushedstone was devided into four stages based on Fourier analysis on acceleration.During the laboratory etsts, the mechanical parameter should match with each other,when adjust mechanical parameters. The reasonable centrifugal force range is5000-8000N，frequency range is26-30Hz，eccentric angle range is30-90°. The frequency and counterweight should be same increase/decrease direction and the eccentric angle should be theopposite direction.More detailed on the law of vibratory compaction research was conducted through thelaboratory test. Based on the analysis of vibratory signal, compaction index was studied. Acceleration fundamental value can relfect the materials compaction degree well; thedependence of Acceleration fundamental value to the mechanical parameters material wasstudied, which enhance the applicability of this compaction index applicability underdifferent conditions. Vibratory frequency and the angle of the eccentric block is the mostsigniifcant impact factors, the acceleration of fundamental value increase signiifcantly withthe increase of frequency, and decreased signiifcantly with the increase of eccentric blockAngle，but when the frequency is less than24Hz the eccentric block angle is30-90°，theacceleration of the fundamental value is not sensitive to the two factors; When the Angle ofthe eccentric block is greater than120°or vibratory frequency is less than24Hz,acceleration fundamental value is small and there is no harmonic values or subwave wavevalue. Acceleration fundamental value has little correlation with vibratory compactionenergy; while acceleration fundamental value has certain correlation with exciting force. Theacceleration fundamental value increase with the increase of exciting force increased, but therelationship is complicated. This research provides conference for the ifeld real-timecompaction degree detection.Outdoor small vibratory roller test and ifeld test show that compaction index can be usedto relfect cement stabilized aggregate compaction degree.