Here are some formulas for making a re-agglomerated stone brick.

The
Egyptian method uses weathered limestone as a base. If you were to get
spent limestone from a cement plant this should work as the base
material.

Their method was to put into a mixer:
One part sodium carbonate
two parts lime
three parts kaolin.
Mix with water and add 114 parts spent limestone
After
two days add 1/2 part magnesium chloride mix and when the mixture has
evaporated enough water to form a semi-dry paste that will hold its
shape when squeezed then press in CEB press.

Easier method but more caustic.

This
requires a reactive silica-alumina clay that has been calcined from
1200-1500˚F. Metakaolin MK-750 is one such. This is reacted with the
geopolymer solution that is one part lye at 10-14Moles to two and a half
parts sodium silicate at 2.1 molar ratio
or
Potassium silicate at a 1.23 molar ratio with the reactive clay

This
should be between 5-15% of the total mix the rest being your filler. If
you were to use a high silica sand the resulting bricks would look like
quartzite.  However the mixture would have to be increased to 22% of
the mix to make sure there were no pores for frost problems and the
mixing time would have to be 16 minutes to ensure optimal strength.

Fly
ash Type F can be used however you will have to grind to the
appropriate sizes and it cannot be from a fluid bed type furnace. If you
have a source contact me for more information as to how to utilize.

With
all of these geopolymer cements you want to keep your water content to a
minimum as the evaporation will leave some pores and too many will
weaken the structure. Using a press the water content can be lowered to
7%

Another thing is your mortars. Using Portland cement based
mortars is not good in the long run for your buildings. Portland cement
is water proof so it forces the waters (i.e. vapor, wicking action,
condensation, etc.) in the walls to go through the bricks. This can
cause spalding.

 A geopolymer mortar would be:  three parts sand, one part lime, and one part reactive clay.

These
are the mortars found in castles one thousand years old and have a
similar composition to the better quality Roman mortars.