California bearing ratio - wikipedia California bearing ratio The California bearing ratio ( CBR ) is a penetration test for evaluation of the mechanical strength of natural ground, subgrades and base courses beneath new carriageway construction. It was developed by the California Department of Transportation before World War II. The basic site test is performed by measuring the pressure required to penetrate soil or aggregate with a plunger of standard area. The measured pressure is then divided by the pressure required to achieve an equal penetration on a standard crushed rock material. The CBR test is described in ASTM Standards D1883 - 05 ( for laboratory - prepared samples ) and D4429 ( for soils in place in field ), and AASHTO T193. The CBR test is fully described in BS 1377 : Soils for civil engineering purposes : Part 4, Compaction related tests, and in Part 9 : In - situ tests. The CBR rating was developed for measuring the load - bearing capacity of soils used for building roads. The CBR can also be used for measuring the load - bearing capacity of unimproved airstrips or for soils under paved airstrips. The harder the surface, the higher the CBR rating. A CBR of 3 equates to tilled farmland, a CBR of 4.75 equates to turf or moist clay, while moist sand may have a CBR of 10. High quality crushed rock has a CBR over 80. The standard material for this test is crushed California limestone which has a value of 100, meaning that it is not unusual to see CBR values of over 100 in well - compacted areas. C B R = p p s ⋅ 100 ( displaystyle CBR = ( \frac ( p ) ( p_ ( s ) ) ) cdot 100 quad ) C B R ( displaystyle CBR quad ) = CBR ( % ) p ( displaystyle p quad ) = measured pressure for site soils ( N / mm2 ) p s ( displaystyle p_ ( s ) quad ) = pressure to achieve equal penetration on standard soil ( N / mm2 ) References Jump up ^ http://www.civilengineerbuddy.com/cbr-test-procedure-california-bearing-ratio-test-procedure/ Geotechnical engineering Exploration Investigation Testing On - site Cone penetration test Standard penetration test Monitoring well piezometer Borehole Crosshole sonic logging Nuclear densometer test Static load testing Laboratory Atterberg limits California bearing ratio Direct shear test Hydrometer Proctor compaction test R - value Sieve analysis Triaxial shear test Hydraulic conductivity tests Water content tests Soil Materials Clay Silt Sand Gravel Peat Permafrost Loam Loess Properties Soil classification Hydraulic conductivity Water content Void ratio Bulk density Thixotropy Reynolds ' dilatancy Angle of repose Cohesion Porosity Permeability Specific storage Mechanics Effective stress Pore water pressure Shear strength Overburden pressure Consolidation Compaction Shear wave Lateral earth pressure Foundations Shallow Deep Bearing capacity Dynamic load testing Pile integrity test Wave equation analysis Statnamic load test Retaining walls Gabion Ground freezing Mechanically stabilized earth Pressure grouting Slurry wall Soil nailing Tieback Stability Slope analysis mass wasting landslide Deformation monitoring automated Earthquakes Soil liquefaction Response spectrum Seismic hazard Ground -- structure interaction Geosynthetics Geotextile Geomembrane Geosynthetic clay liner Cellular confinement Numerical analysis SEEP2D STABL SVFlux SVSlope UTEXAS Retrieved from `` https://en.wikipedia.org/w/index.php?title=California_bearing_ratio&oldid=841687558 '' Categories : Road transport Pavements Soil tests Transportation engineering Talk About Wikipedia Deutsch Español Euskara Français Italiano Latviešu 日本 語 Polski 中文 3 more Edit links This page was last edited on 17 May 2018, at 11 : 49. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: what is the meaning of cbr in soil test
Answer: a penetration test for evaluation of the mechanical strength of natural ground, subgrades and base courses beneath new carriageway construction