A Roman arch is a weight bearing arch built of brick, first used in antiquity, now used in construction everywhere throughout the world. Although the Romans did not invent the technique, they were the first to use it widely, and most famously in the aqueduct system. The Romans used an even number of rectangular bricks, and an odd number of trapezoidal bricks to build their arches, using a sand mixture for mortar. This project uses plain sugar cubes and a sweet mortar in place of trapezoids.
Tear off a piece of aluminium foil a little larger than your finished project will be. The arch will need to harden overnight, so put it on a portable tray if you don't have counter space to devote. We will construct the arch horizontally, and stand it up once it is dry.
Lay out your sugar cubes in an arch shape. The side columns should both have the same number of cubes. Remember to leave about 1/4 inch between for mortar. The arch itself should have a centre "keystone" and two or three cubes in a curved layout on each side leading down to the columns, depending on the final size. Don't worry about the space between, we will fill it up with frosting mortar.
Add mortar to one side of the a bottom cube with a table knife, and press gently so it adheres to the next one. Do the other side the same way. Continue to add layers of mortar and bricks until your column is as tall as you want it.
Place the drinking glass or cup inside the arch bricks to hold them in place. Start cementing arch bricks together using the same method as above. When placed, there will be a small gap at the outside edge, which can be filled with frosting mortar after it is positioned. When you add enough mortar, the arch bricks will take on a trapezoid shape.
Allow to dry overnight. Once dry, you can spray with acrylic sealer to make it last a little longer. Stand arch up carefully once dry.
Be sure to transport arch flat, and packed gently with tissue paper or paper towel.
If sprayed with acrylic sealer, your arch is no longer edible. Be sure to add a sign that warns against eating your project.
Tips and warnings
- Be sure to transport arch flat, and packed gently with tissue paper or paper towel.
- If sprayed with acrylic sealer, your arch is no longer edible. Be sure to add a sign that warns against eating your project.