You can refer this procedure to know more in detail about, how to perform crushing value test.
Ref : IS : 2386 (Part IV) Purpose : To determine the crushing value of aggregates. Significance : The aggregate crushing value gives relative measure of the resistance to...
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You need to apply 40 tonnes of load for 20mm aggregates in period of 10 minutes by uniform loading, at the end of 10 minutes, total load will reach to 40 tonnes.
Check your CTM loading unit, in most of the cases it is Kn/sec. do calculation to arrive at rate of loading required to apply load for 10 minutes with uniform loading.