Question

If the load carried by a cbr specimen at 2.5 mm penetration is 52.5 kg/cm2, then the cbr value of soil is a 25% b 45% c 60% d 75%

Answer 1

Answer:

45% is the cbr value of soil

Answer 2

Given:

• The standard plunger size we take is 50 mm
• given load 2.5 mm for which penetration is 52.5kg/$cm^{2}$. if penetration was in n/$mm^{2}$ then we dont need to change it but now we have in kg/$cm^{2}$ and we will have to change it in n/$mm^{2}$

To Find: the CBR value of soil ?

as given for 2.5 mm penetration is 52.5kg, after changing it in newton per metre square it is 5.14n/$mm^{2}$

        area = 1964$mm^{2}$

so,

     By using formula      

                                         pressure = load/ area

                                                      p = l/a

                                                      5.14 = p/ 1964

                                                         p = 10094.96N

                                           now changing N into kg

                                                         p = 10094.96/9.81

                                                         p = 1029.04kg

now,

       standard value of cbr for 2.5mm penetration is 1370kg

then,    

                                                    CBR% = $\frac{1029.04}{1370}$×$100$

                                                      CBR% = 75%

hence the CBR value of soil is 75%