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An assessment of how penetration curve adjustment affects the California bearing ratio (CBR) Cover

An assessment of how penetration curve adjustment affects the California bearing ratio (CBR)

Studia Geotechnica et Mechanica
Volume 43 (2021): Issue 4 (December 2021)
By: Łukasz Bednarek  
Open Access
|Oct 2021

Figures & Tables

Figure 1

Cross section of pavement structure (Judycki et al., 2012).
Cross section of pavement structure (Judycki et al., 2012).

Figure 2

Nomograph for determining the thickness of base and subbase layers (Çelik et al., 2017)
Nomograph for determining the thickness of base and subbase layers (Çelik et al., 2017)

Figure 3

CBR test.
CBR test.

Figure 4

Adjusted penetration curve.
Adjusted penetration curve.

Figure 5

Map of the places where samples were taken for testing (http://redstone-exploration.com/country-profiles/poland/, 2021).
Map of the places where samples were taken for testing (http://redstone-exploration.com/country-profiles/poland/, 2021).

Figure 6

The curves of grain composition of the mixtures of 0–31.5 mm.
The curves of grain composition of the mixtures of 0–31.5 mm.

Figure 7

The curves of grain composition of the mixtures of 0–63 mm.
The curves of grain composition of the mixtures of 0–63 mm.

Figure 8

Sample no. 1 of 0–31.5 mm mixture (directly after compaction).
Sample no. 1 of 0–31.5 mm mixture (directly after compaction).

Figure 9

Sample no. 2 of 0–31.5 mm mixture (directly after compaction).
Sample no. 2 of 0–31.5 mm mixture (directly after compaction).

Figure 10

Sample no. 1 of 0–31.5 mm mixture (after four days of soaking in water).
Sample no. 1 of 0–31.5 mm mixture (after four days of soaking in water).

Figure 11

Sample no. 2 of 0–31.5 mm mixture (after four days of soaking in water).
Sample no. 2 of 0–31.5 mm mixture (after four days of soaking in water).

Figure 12

Penetration curves with adjustments for 0–31.5 mm granite aggregate (sample no.1 directly after compaction).
Penetration curves with adjustments for 0–31.5 mm granite aggregate (sample no.1 directly after compaction).

Figure 13

Penetration curves with adjustments for 0–-31.5 mm granite aggregate (sample no.1 after four days of soaking in water).
Penetration curves with adjustments for 0–-31.5 mm granite aggregate (sample no.1 after four days of soaking in water).

Figure 14

Penetration curves with adjustments for 0–31.5 mm granite aggregate (sample no.2 directly after compaction).
Penetration curves with adjustments for 0–31.5 mm granite aggregate (sample no.2 directly after compaction).

Figure 15

Penetration curves with adjustments for 0–31.5 mm granite aggregate (sample no.2 after four days of soaking in water).
Penetration curves with adjustments for 0–31.5 mm granite aggregate (sample no.2 after four days of soaking in water).

Figure 16

Sample no. 1 of 0–63 mm mixture (directly after compaction).
Sample no. 1 of 0–63 mm mixture (directly after compaction).

Figure 17

Sample no. 2 of 0–63 mm mixture (directly after compaction).
Sample no. 2 of 0–63 mm mixture (directly after compaction).

Figure 18

Sample no. 1 of 0–63 mm mixture (after four days of soaking in water).
Sample no. 1 of 0–63 mm mixture (after four days of soaking in water).

Figure 19

Sample no. 2 of 0–63 mm mixture (after four days of soaking in water).
Sample no. 2 of 0–63 mm mixture (after four days of soaking in water).

Figure 20

Penetration curves with adjustments for 0–63 mm dolomite (1) aggregate (sample no.1 directly after compaction).
Penetration curves with adjustments for 0–63 mm dolomite (1) aggregate (sample no.1 directly after compaction).

Figure 21

Penetration curves with adjustments for 0–63 mm dolomite (1) aggregate (sample no.1 after four days of soaking in water).
Penetration curves with adjustments for 0–63 mm dolomite (1) aggregate (sample no.1 after four days of soaking in water).

Figure 22

Penetration curves with adjustments for 0–63 mm dolomite (1) aggregate (sample no.2 directly after compaction).
Penetration curves with adjustments for 0–63 mm dolomite (1) aggregate (sample no.2 directly after compaction).

Figure 23

Penetration curves with adjustments for 0–63 mm dolomite (1) aggregate (sample no.2 after four days of soaking in water).
Penetration curves with adjustments for 0–63 mm dolomite (1) aggregate (sample no.2 after four days of soaking in water).

Figure 24

Regression analysis results.
Regression analysis results.

Figure 25

Residuals from analysis results.
Residuals from analysis results.

Properties of the tested mixtures_

MineRock typeMixturesMass fraction of passing 0.0063 mm, f [%]Flatness index, Fl [%]Shape indicator, Sl [%]Sand equivalent, SE [%]Optimum moisture content [%]Maximum dry density [g/cm3]Uniformity coefficient, Cu [−]Coefficient of gradation, Cc [−]
DubieDolomite (1)0–31.5 mm4.3-19.748.75.82.2137.52.4
0–63 mm3.3-14.847.06.22.16442.1
GrochówMagnesite0–31.5 mm5.714.814.517.56.92.0236.74.4
0–63 mm6.113.012.618.27.31.9856.05.5
Winna GóraBasalt0–31.5 mm4.149.363.750.56.52.2316.51.4
0–63 mm2.435.153.750.73.92.2217.91.4
RogoźnicaGranite0–31.5 mm3.615.320.535.63.12.0852.57.6
0–63 mm2.712.914.533.72.12.0542.47.4
ŻelatowaDolomite (2)0–31.5 mm10.9-31.018.06.32.07193.312.6
0–63 mm8.6-29.016.05.62.04178.611.0
OsielecSandstone (2)0–31.5 mm8.735.544.212.04.32.05253.32.0
0–63 mm4.627.230.012.04.72.02280.01.4
BarciceSandstone (1)0–63 mm12.722.524.413.04.52.10269.81.6

Minimum CBR values for specific materials by layer and traffic class (Judycki et al_, 2012)_

StuffLayers
RoadbaseSubbaseCapping layerImproved subgrade
KR1-KR2KR3-KR4KR5-KR7KR1-KR2KR3-KR7KR1-KR2KR3-KR7KR1-KR7
Unbound mixtures6080The layer does not exist for these traffic categories60253520
Non-expansive soilDoes not applyDoes not apply253520

Regression statistics_

CoefficientsStandard errort Statp-valueLower 95%Upper 95%R square
Intersection−1.079640.9721−1.110630.269592−3.010040.8507570.9471
CBR1.016230.02978534.11882.22E-540.9570831.075377
SE0.1302870.0258225.0456152.23E-060.079010.181564
DOI: https://doi.org/10.2478/sgem-2021-0017 | Journal eISSN: 2083-831X | Journal ISSN: 0137-6365
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Language: English
Page range: 323 - 336
Submitted on: Feb 9, 2021
|
Accepted on: May 18, 2021
|
Published on: Oct 9, 2021
Published by: Wroclaw University of Science and Technology
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year
Keywords:
CBR,
pavement structure,
subbase,
roadbase
Related subjects:
Geosciences,
Geosciences, other,
Materials sciences,
Composites,
Porous materials,
Physics,
Mechanics and fluid dynamics

© 2021 Łukasz Bednarek, published by Wroclaw University of Science and Technology
This work is licensed under the Creative Commons Attribution 4.0 License.

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