Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Correlating lightweight deflectometer modulus and CBR for compaction control of selected layers
Thesis (MEng)--Stellenbosch University, 2024.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2024
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613937072078848 |
|---|---|
| access_status_str | Open Access |
| author | Kring, Bianca |
| author2 | Jenkins, Kim |
| author_browse | Jenkins, Kim Kring, Bianca |
| author_facet | Jenkins, Kim Kring, Bianca |
| author_sort | Kring, Bianca |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/130649 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:44:04.029Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2024 |
| publishDateRange | 2024 |
| publishDateSort | 2024 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/130649 Correlating lightweight deflectometer modulus and CBR for compaction control of selected layers Kring, Bianca Jenkins, Kim Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. Materials -- Fatigue Granular materials Testing equipment industry Materials -- Dynamic testing Lightweight falling defectometer, California bearing ratio Compacting Thesis (MEng)--Stellenbosch University, 2024. ENGLISH ABSTRACT: This research study focuses on the correlation of Lightweight Falling Deflectometer Modulus and CBR for compaction control of selected layers. The success of an unbound granular material (UGM) in a layer of a flexible pavement structure is due to a combination of the strength and stiffness of the material. Yet, neither of these two parameters is typically tested during construction. Modulus testing equipment, such as the Lightweight Falling Deflectometer, has been around for over a decade, and multiple countries have standards for using the LWD as a quality control tool. The California Bearing Ratio test has been an integral part of material classification and quality assurance, and by correlating the LWD to the CBR, the adoption of the LWD in Southern Africa may be easier. Through field and laboratory testing, this study attempted to find a correlation between the resilient modulus and the CBR. Field testing consisted of LWD testing on a freeway construction site near Windhoek, Namibia, which was correlated with soaked CBR data. Using an LWD with a 300 mm load plate and a 15 kg drop weight, test results of eight lots with different material classes were correlated with the obtained CBR results. A logarithmic correlation with an R2 value of 0.67 was found. This relationship was further refined in a laboratory setting on a G6 material. Material property tests such as the Sieve Analysis, Maximum Dry Density (MDD) and Optimum Moisture Content (OMC) were performed to classify and understand the material. A vibratory hammer and a ModAASHTO hammer were used to determine the MDD and OMC, and the results were compared. To accommodate the standard load plate size of the LWD, a 440 mm Ø * 500 mm high mould was constructed in which the material was compacted. The material was sieved into four different fractions, which were kept constant for all testing. Four different degrees of compactions and different moisture contents were considered for this study. The material in the big mould was compacted with a jackhammer with a tamper plate attached to it. To ensure uniform compaction throughout the total depth of the sample, the material was compacted in nine layers, each 50mm high. LWD tests were done on the compacted sample directly after compaction, as well as up to five days after compaction. This allowed for the observation of the trend in the LWDs resilient modulus (Evd), which is associated with the drying of the uppermost layer of the sample. Four LWD tests were done each day, rotating the plate 90° between each test, which allowed us to assess the repeatability of the LWD. It was found that, on average, the Evd increased 179% between the first day and the fourth day of testing. The LWD tests done on the same day were highly repeatable, with a maximum variance of 10% between consecutive tests. By changing the moisture content and the degree of compaction, the influence of these two parameters on the Evd measurements was also investigated. The LWD measurement was found to be slightly more susceptible to moisture than to the degree of compaction. This and the observation of the increase in the Evd associated with the dry back indicate that a moisture limit should be added to LWD testing and that testing should be done in a specified amount of time after construction. CBR tests were done at the same moisture contents and degree of compactions and correlated with the LWD results. A logarithmic relationship was observed, with an R² value of 0.88. Both parameters are equally affected by higher moisture contents and degree of compaction. The LWD has been shown to be a quick and repeatable test method allowing modulus-based quality control, thus filling the gap between design and construction practices. More testing would be required to formulate a relationship between LWD and CBR, which can be used for the compaction control of selected layers. AFRIKAANSE OPSOMMING: Hierdie navorsingstudie fokus op die korrelasie van Lightweight Falling Deflectometer modulus en CBR vir verdigting beheer van geselekteerde lae. Die sukses van 'n ongebonde korrelmateriaal in 'n lag van 'n buigsame plaveiselstruktuur is te danke aan 'n kombinasie van die sterkte en styfheid van die materiaal. Tog word nie een van hierdie twee parameters tipies tydens konstruksie getoets nie. Modulus-toetstoerusting, soos die Lightweight Falling Deflectometer (LWD), bestaan al meer as 'n dekade, en verskeie lande het standaarde vir die gebruik van die LWD as 'n gehaltebeheerinstrument. Die California Bearing Ratio-toets was 'n integrale deel van materiaalklassifikasie en gehalteversekering, en deur die LWD met die CBR te korreleer, kan die aanvaarding van die LWD in Suider-Afrika makliker wees. Deur middel van veld- en laboratoriumtoetsing het hierdie studie gepoog om 'n korrelasie tussen die veerkragmodulus en die CBR te vind. Veldtoetsing het bestaan uit LWD-toetsing op 'n snelwegkonstruksieterrein naby Windhoek, Namibië, wat gekorreleer is met deurweekte CBR-data. Deur 'n LWD met 'n 300 mm-laaiplaat en 'n 15 kg-valgewig te gebruik, is toetsresultate van agt lotte met verskillende materiaalklasse gekorreleer met die behaalde CBR-resultate. 'n Logaritmiese korrelasie met 'n R2-waarde van 0.67 is gevind. Hierdie verhouding is verder verfyn in 'n laboratorium omgewing op 'n G6 materiaal. Materiaal eienskap toetse soos die Sif Analise, Maksimum Droë Digtheid (MDD) en Optimum Moisture Content (OMC) is uitgevoer om die materiaal te klassifiseer en te verstaan. 'n Vibrerende hamer en 'n ModAASHTO hamer is gebruik om die MDD en OMC te bepaal, en die resultate is vergelyk. Om die standaard lasplaatgrootte van die LWD te akkommodeer, is 'n 440 mm Ø * 500 mm hoë vorm gebou waarin die materiaal gekompakteer is. Die materiaal is in vier verskillende fraksies gesif, wat konstant gehou is vir alle toetsing. Vier verskillende grade van verdigting en verskillende voginhoude is vir hierdie studie oorweeg. Die materiaal in die groot vorm is gekompakteer met 'n jackhammer met 'n peuterplaat daaraan geheg. Om eenvormige verdigting regdeur die totale diepte van die monster te verseker, is die materiaal in nege lae, elk 50mm hoog, gekompakteer. LWD-toetse is op die gekompakteerde monster gedoen direk na verdigting, sowel as tot vyf dae na verdigting. Dit het voorsiening gemaak vir die waarneming van die neiging in die LWDs veerkragmodulus (Evd), wat geassosieer word met die droë agterkant van die boonste laag van die monster. Vier LWD-toetse is elke dag gedoen, wat die plaat 90° gedraai het tussen elke toets, wat ons in staat gestel het om die herhaalbaarheid van die LWD te assesseer. Daar is gevind dat die Evd gemiddeld 179% toegeneem het tussen die eerste dag en die vierde dag van toetsing. Die LWD-toetse wat op dieselfde dag gedoen is, was hoogs herhaalbaar, met 'n maksimum afwyking van 10% tussen opeenvolgende toetse. Deur die voginhoud en die mate van verdigting te verander, is die invloed van hierdie twee parameters op die Evd-metings ook ondersoek. Daar is gevind dat die LWD-meting effens meer vatbaar is vir vog as vir die mate van verdigting. Dit en die waarneming van die toename in die Evd wat met die droë rug geassosieer word, dui daarop dat 'n voglimiet by LWD-toetsing gevoeg moet word en dat toetsing binne 'n bepaalde tyd na konstruksie gedoen moet word. CBR-toetse is gedoen teen dieselfde voginhoud en graad van verdigting en het gekorreleer met die LWD-resultate. 'n Logaritmiese verwantskap is waargeneem, met 'n R²-waarde van 0.88. Beide parameters word ewe beïnvloed deur hoër voginhoude en mate van verdigting. Daar is getoon dat die LWD 'n vinnige en herhaalbare toetsmetode is wat modulus-gebaseerde gehaltebeheer moontlik maak en sodoende die gaping tussen ontwerp- en konstruksiepraktyke vul. Meer toetsing sal nodig wees om 'n verwantskap tussen LWD en CBR te formuleer, wat gebruik kan word vir die verdigtingsbeheer van geselekteerde lae. Masters 2024-02-16T08:22:42Z 2024-04-27T01:17:54Z 2024-02-16T08:22:42Z 2024-04-27T01:17:54Z 2024-02 Thesis https://scholar.sun.ac.za/handle/10019.1/130649 en_ZA en_ZA Stellenbosch University xiv, 129 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Materials -- Fatigue Granular materials Testing equipment industry Materials -- Dynamic testing Lightweight falling defectometer, California bearing ratio Compacting Kring, Bianca Correlating lightweight deflectometer modulus and CBR for compaction control of selected layers |
| title | Correlating lightweight deflectometer modulus and CBR for compaction control of selected layers |
| title_full | Correlating lightweight deflectometer modulus and CBR for compaction control of selected layers |
| title_fullStr | Correlating lightweight deflectometer modulus and CBR for compaction control of selected layers |
| title_full_unstemmed | Correlating lightweight deflectometer modulus and CBR for compaction control of selected layers |
| title_short | Correlating lightweight deflectometer modulus and CBR for compaction control of selected layers |
| title_sort | correlating lightweight deflectometer modulus and cbr for compaction control of selected layers |
| topic | Materials -- Fatigue Granular materials Testing equipment industry Materials -- Dynamic testing Lightweight falling defectometer, California bearing ratio Compacting |
| url | https://scholar.sun.ac.za/handle/10019.1/130649 |
| work_keys_str_mv | AT kringbianca correlatinglightweightdeflectometermodulusandcbrforcompactioncontrolofselectedlayers |