CBR on cement-treated soils

[jharm]

We have made a recommendation for 3-5% cement treating of the uppermost 12-inches of soil to underly pavement on a newly constructed road. Local Agencies require we verify a CBR of 7 for the material. Hence, we'll be determining the m-d curves using ASTM D558. However, as I undertand it, it is nearly impossible to run a CBR on cement-treated material? Can it even be done for CT Soils in accordance with D1883, since curing is an issue? Is there another way to determine the CBR by making pills and breaking them using a compressive strength machine? TIA!

 

[civilperson]

Build a granular subbase of CBR value required and put a 2" HMA pavement over the sand/gravel. Put same 2" HMA over cement treated base and compare deflections with equal truck loadings. This will sell the relative CBR value.

 

[geohec]

I tested soil fly ash samples back in 2002. That soil man is so hard after 7 days curing. We used nomal concrete curing days such as: 7, 14, 28 days for the samples.

The best way is to collect the data electronically when performing a CBR under ASTM 1883. It is not an impossible thing to do.
Good luck!

 

[sunny7uc]

I have done CBR on cement+fly ash+soil mix samples, it can be done.

 

[escrowe]

You'll max out the typical 10k CBR load cell long before you reach 0.5in penetration, so be careful.
I always built a correlation between UCC and CBR for soil-cement projects,
using samples with varying admixture percentages.
That way, UCC samples could be field-molded for subsequent lab testing.
And we did have to sell that package to a number of public agencies, but the effort paid off big time.
Of course, we did encounter resistance from counties
with significant aggregate production facilities.

 

[Mickney]

I have done several alternate test techniques for CBR testing of lime or cement treated soils. I have performed in-field CBR tests and Unconfined Compression Tests on cored samples of the treated soil. Keep in mind that the "traditional" CBR test simulates worse-case parameters since the samples are inundated in water. Adjust the field CBR values and UC correlations accordingly.