Question
Download Solution PDFWhen conducting CBR test, it is observed that the load dial reading at 2.5 mm penetration is 33 divisions, if the one division represents 190 kg load in the calibration chart, what is the CBR at 2.5 mm penetration?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept:
CBR Test
It is a strength test conducted on the soil by introducing a surcharge load at the compaction rate of 1.25 mm per minute on a completely soaked soil sample passing through 20 mm sieve size.
\({\rm{CB}}{{\rm{R}}_{\rm{\delta }}} = \frac{{{{\rm{P}}_{\rm{\delta }}}{\rm{\;of\;soil}}}}{{{{\rm{P}}_{\rm{\delta }}}{\rm{\;of\;standard\;crushed\;aggregate}}}} \)
δ = displacement in mm
Pδ = Load corresponding to ‘δ’ settlement
Ps = Load for standard crushed aggregate:
At 5 mm penetration Standard load Ps = 2055 kg
At 2.5 mm penetration standard load Ps = 1370 kg
Calculation:
Given data,
The load dial reading at 2.5 mm penetration = 33 divisions
one division = 190 kg load
Sustained load at 2.5 mm penetration = 33 × 190 = 6270 kg
At 2.5 mm penetration,
\(CBR = \;\frac{{{\rm{Load\;carried\;by\;specimen}}}}{{{\rm{load\;carried\;by\;standard\;specimen}}}}\)
\(CBR = \;\frac{{6270}}{{1370}}\) = 4.576
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