A fractured face is defined as being caused either by mechanical means or by nature and should have sharp or slightly blunted edges. A gravel which was previously fractured by hand or by machine and then weathered by water or time is not accepted as fractured.
Natural fractures, to be accepted, must be similar to fractures produced by a crusher. A broken surface constituting an area equal to at least 25% of the projected area of the particle, as viewed perpendicular to (looking directly at) the fractured face, is considered an acceptable fractured face.
1.Mecahnical Splitter 2. Balance 3.Sieve 4.75(No 4)
The sampling is Follows Instructions in Sampling Page, but the sample must be as much as get the desired amount of sample retained on sieve No 4( test samples must just retained on sieve No 4) .Table below is showing the minimum amount of requirement of sample according to the maximum nominal size of aggregate.
|Maximum Nominal Particle Size||Minimum Weight Retained on Sieve No 4|
|19 mm||1000 Grams|
|9.5 mm||700 Grams|
|4.75 mm||500 Grams|
Table No 1 required sample sizes
Note: the (maximum nominal size) expression is to a sample which pass at least 90% of total amount from the same sieve size. for example when we say nominal gradation of a sample is 25 mm ,it mean that at least 90% of total aggregate has passed from sieve 25 mm .
First split the sample to obtain enough amount according the table No 1.Wash the sample and dry it until reaching to a constant mass ,and Weight the sample and called it Test sample weight.
By visual inspection separate the particles first by two category: 1.Crushed 2. Non Crushed ,then separate the Crushed Particles into two category: 1. one surface crushed 2. Two Surface Crushed, that have fractured faces, either one or two fractured faces. separate the particles which have one or two faces individually. then weigh the particles individually and record that .by a simple formula simply found the percentage of Crushed aggregate. Below is a preliminary explanation of Fractured Faces
Picture No ((1))
Picture No ((3))
Percentage of total Fractured faces
W3=Two Faces F
Percentage of One Face Fractured Faces
Report the result to nearest percent (minimum two digit )
For Picture of Procedure Click Here