OMC and MDD of soil or soil and other impurity mixtures (Ex. Fly ash, Cement etc.) can be found out by SPT. Which test should one conduct for soil aggregate mix?
Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort
https://www.astm.org/Standards/D698
Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort
https://www.astm.org/Standards/D1557.htm
The most simple and logical way to find out the OMC and MDD value of soil aggregate mix is by using IS:2720 part 8 or ASTM D1557. The mentioned guidelines are for heavy compaction test. Now-a-days for all the soil aggregate mixes such as in Wet Mix Macadam and Granular Subbase, heavy compaction test is preferred. Whereas, for determination of OMC of single soil light compaction can be used.
Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort
https://www.astm.org/Standards/D698
Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort
https://www.astm.org/Standards/D1557.htm
The test to be used is the "Proctor Test". Now the energy of compaction depends on where you are going to use your soil/aggregate mix. If it is to replace bad subgrade or as a fill material for future pavement construction, then standard Proctor energy is good enough (future stresses in the layer are not big). If the mix will be used as a base layer, then stresses induced from truck loading might be high and therefore a Modified Proctor energy is used.
Hi, I have a question related to this, and maybe some of you can help:
How can you calculate the compactive effort that Iou should apply (for instance the n" of blows) to be the same as in the standard proctor, the one you used to draw the density/moisture curve? Is there a formula to correlate for instance, the n# of blows with the mass of material??
I did the British Standard Proctor [*] in my clay/aggregate/ash materials to draw the curve “dry density” vs “moisture content”. Now I want to compact the same materials but in my test cells, which have a different dimension: 100 mm (instead of 105) internal diameter, 100 mm (instead of 115.5) high, 785 (instead of 1000) cm3 volume.
[*] 3 layers of compaction using 27 blows in each layer, with a 50-mm diamerter rammer that drops a weigh of 2.5 kg from an altitude of 300 mm height. The mold is 105 mm internal diameter, 115.5 mm high, thus 1 L volume)
Energy per volume should be the same. Energy is the weight of the hammer (mass time g) time height of drop times number of blows per layer times number of layers. You divide energy per the mold volume, you will get the energy per volume. In your case you have your special mold. Play on the number of blows per lift to get the same energy per volume number
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