**GENERAL AGGREGATE BLENDING PROBLEMS**

1.  Given two aggregates A & B, what combination of the two would you
    use in a blend to meet specification C?

  ---------------- ------------------ ------------------ ------------------
  Sieve            Percent Finer Than                    

                   A                  B                  Spec

  12.5 mm          100                100                100

  9.5 mm           92                 100                95-100

  4.75 mm          70                 98                 75-90

  2.36 mm          43                 89                 60-80

  600 m            14                 53                 20-40

  150 m            2                  27                 10-20

  75 m             1                  9                  4-8
  ---------------- ------------------ ------------------ ------------------

> Percentage of A is \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
>
> Percentage of B is \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

2.  The following are the results of gradation tests on three
    aggregates. Combine them to the gradation required. What is the
    combined specific gravity?

  ----------- -------------- -------------- -------------- --------------
  Sieve       Percent                                      
              Passing                                      

              Aggregate A    Aggregate B    Aggregate C    Required

  25 mm       100            100            100            100

  19 mm       92             100            100            95

  9.5 mm      41             100            100            62

  4.75 mm     19             77             96             45

  2.36 mm     7              60             79             32

  600 m       4              42             40             

  300 m       2              36             16             13

  75 m        1              28             3              5

  Specific    2.750          2.600          2.700          
  Gravity                                                  
  ----------- -------------- -------------- -------------- --------------

> Percent of A is \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
>
> Percent of B is \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
>
> Percent of C is \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
>
> Combined Specific Gravity is \_\_\_\_\_\_\_\_\_\_\_\_\_

3.  Given the following data develop a mix design. You are to develop a
    12.5 mm nominal maximum size mix. Determine the desired blend.

  -------------- -------------- -------------- -------------- --------------
  Sieve          3/8 Crushed    No. 67         Limestone      Concrete Sand
                 Gravel         Limestone      Screenings     

  25 mm          100            100            100            100

  19 mm          100            98             100            100

  12.5 mm        100            65             100            100

  9.5 mm         88             34             100            100

  4.75 mm        57             6              72             96

  2.36 mm        36             5              42             91

  1.18 mm        23             5              24             78

  0.600          15             4              18             51

  0.300          10             3              13             16

  0.150          6              3              10             3

  0.075          3              2              8              1

  Percent                                                     

  Coarse         87/78          100/100                       
  Aggregate                                                   
  Angularity                                                  

  Fine Aggregate                               45.0           45.4
  Angularity                                                  

  Los Angeles    39             24                            
  Abrasion                                                    

  Absorption     0.5 %          0.4 %          1.6            0.3

  Bulk Specific  2.620          2.722          2.721          2.639
  Gravity                                                     

  Sand                                         57             98
  Equivalent                                                  

  Percent of     51             26             15             8
  each sieve                                                  
  -------------- -------------- -------------- -------------- --------------

.