Abstract
NDT methods such as Portable Falling Weight Deflectometer (PFWD) provide measurements based on the engineering properties of materials (stiffness) instead of physical properties like field density and moisture content. However, PFWD testing method is not yet proven to be reliable enough for construction quality control. In this research, a laboratory testing unit box was prepared in which unbound materials were compacted at different compaction levels. The stiffness modulus of the compacted layers were then determined under PFWD Testing. The tests were repeated several days after construction when the materials moisture content was decreased to lower values. The results indicated that acceptable correlations exist between the stiffness modulus and both compaction percentage and moisture percentage. In addition, field testing was carried out on different unbound layers in several highway construction sites in Tehran and laboratory results were used in order to control in-situ conditions. With Comparing field and laboratory testing results, it was concluded that PFWD is an appropriate testing device for quality control and compaction monitoring of pavement layers during construction phases. Santrauka NDT metodai, kaip krintančio svorio deflektometrai (PFWD), leidžia matuoti technologines ir fizikines medzcaron;iagu savybes (standumą, tankį ir įmirki). Tačiau PFWD bandymu metodas ir dabar dar nera patvirtintas kaip patikimas konstrukcijų kokybei kontroliuoti. Šiame darbe atlikti laboratoriniai ir natūriniai bandymai, kuriuose buvo tirtos skirtingais lygiais sutankintų tarpusavyje nesujungtų sluoksnių konstrukcijos. Tiriamų medžiagų sluoksnių standumo moduliai buvo nustatyti PFWD metodu. Bandymas buvo pakartotas išlaikius konstrukciją keletą dienų, kai drėgmės kiekis medžiagose sumažejo. Rezultatai parodė, kad yra reikšmine koreliacija tarp standumo modulio ir abiejų sluoksnių sutankinimo lygio bei drėgmės kiekio. Vėliau Teherano vietovese buvo atlikti natūriniai konstrukcijų su skirtingais nesujungtais sluoksniais bandymai. Išanalizavus natūriniu ir laboratoriniu bandymų tyrimų rezultatus, buvo nustatyta, kad PFWD yra tinkamas bandymo metodas konstrukcijų kokybei kontroliuoti ir tinkamam dangos sluoksnių tankinimui parinkti.
Highlights
Current criteria of embankment compaction specifications utilize moisture content and maximum dry density measurements to ensure that in-situ materials have obtained required compaction
Research works have been performed to develop dynamic stiffness measuring devices such as Portable Falling Weight Deflectometer (PFWD) that can quickly measure the in-situ stiffness of unbound pavement layers (Peterson et al 2006)
This paper presents the results of laboratory and field tests conducted to assess PFWD stiffness modulus as a construction quality control criterion of unbound layers
Summary
Current criteria of embankment compaction specifications utilize moisture content and maximum dry density measurements to ensure that in-situ materials have obtained required compaction. While a proper density may result in pavements to resist against settlement and deformation, this does not mean that proper bearing capacity has been achieved. The measurement of unbound layers stiffness in terms of resilient modulus, allows a soil layer to be characterized by engineering properties. If the embankments and pavement unbound layers have sufficient stiffness, the strains induced in the pavement structure during service loading can be minimized. Research works have been performed to develop dynamic stiffness measuring devices such as Portable Falling Weight Deflectometer (PFWD) that can quickly measure the in-situ stiffness of unbound pavement layers (Peterson et al 2006).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
