Because of the tendency of many Kansas limestones to cause D-cracking, the stand

Question

Because of the tendency of many Kansas limestones to cause D-cracking, the standard Kansas paving mix contains a blend of 70% fine aggregate and 30% coarse aggregate to help minimize the amount of problem coarse aggregate in the concrete. Even with this blend, there have (historically) been problems with D-cracking. It is possible to make a paving mix containing 100% sand with adequate properties in terms of placeability, freeze-thaw resistance, and strength. In terms of cost, sand is less expensive that limestone. Why was a 100% sand mix not adopted?

Explanation / Answer

Coarse aggregates provide economy and strength to the mix. A very high amount of sand will make your mix very brittle and weak against all kinds of forces.

100 % sand means the surface area will be very large due to the fineness of sand. Larger the surface area, larger will be the heat of hydration produced. Consequently, there will be a problem of water deficiency due to more absorption of water by sand as well as the cracks will be formed due to the high heat of hydration.

So a 100% sand mix was not adopted.

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