Cast Stone Arch

Chuck of Oswald Masonry placed an order for jack arches, sills, and radial arches made of cast stone for a 5 unit townhouse. Cast stone or precast is a concrete product that essentially is man made limestone. We fabricate cast stone in our shop using raw materials in a mix of approximately 70% sand, 20% portland cement, 10% water, and less than 1% admixture of superplasticizer and water reducer. Here are pictures of the stone starting at the CAD design.

full scale paper template

template made into a wooden mold


We use the dry tamp method to make our cast stone at Archway System. Dry tamp uses zero slump concrete (the consistency of pancake mix if you only used half the milk the recipe called for). We make a custom mold of what the finished stone is going to look like and add the mix into the mold. We then use a vibrating rammer to tamp the mix into the mold face down. Epoxy coated rebar is inserted in the middle of the stone for reinforcement and then more mix is added and tamped until the desired thickness is achieved. The mold is then flipped onto a table and the mold is removed.

stone flipped out of mold



The stone is then "pointed up" by hand to fix any imperfections that happened when removing the mold. Then the mold is put back together and the process repeated all day long.

5 cast stone arches


Cast stone cures in warm temperature and high humidity on these tables and is about 95% cured after 7 days. The arches are rock solid after a few days and the brick layer installs the cast stone above the windows.

Maple Lawn in Howard County Maryland/Oswald Masonry