driveway blocks

[j77drs]

i have purchased some new driveway blocks ( 3 pallets ) and noticed that a large percentage and white on the top and washing them does nothing

these are brand new,

Any ides and how i can sort it before i lay the bricks ?

 

[cjard]

white as in efflorescence:
http://www.bing.com/images/search?q=efflorescence+&FORM=AWIR

?

 

[xdave]

If a large number have efflorescence present on the pallet then they may have been stored incorrectly so they have been saturated with water. I'd be returning them to the supplier and getting replacements. Cheaper blocks tend not to be cured for very long by the manufacturer and can suffer more from efflorescence, but ultimately most concrete blocks will experience some of it. Tumbled/aged blocks tend to hide it better than smooth/uniform blocks due to the texture.