Brick Arches

The following four types of brick arches are in use:

1. Gaughed arches
2. Axed or rough cut arches
3. Rough brick arches
4. Brick flat arches

The above classification is based on the type of bricks used in the arch construction. The different types of bricks which can be used for arches are as follows:

1. Ordinary standard bricks.
2. Ordinary bricks cut to a wedge shape.
3. Special bricks of different sizes and shapes called as purpose-made bricks.
4. Soft bricks which are made of diatomaceous earth. They can be sawn and rubbed to the required shapes.

In gaughed arches, bricks are cut to the required wedge shapes so as to suit the various voussoir sizes. True radii joints are made with thin joints. The required centring is erected and each voussoir is fitted in its position with mortar. After all the voussoirs are in position, the key stone is fitted and hammered slightly. Figure 19.5 shows gauged flat arch and semi-circular arch.

Figure 19.5 Gauged brick arches

For axed arches, bricks are cut with a bricklaying axe to make wedge-shaped bricks. They show rough joints. Construction procedure is same as that of gauged arches.

Rough brick arches are constructed using ordinary bricks. Here, the length of extrados is greater than that of the intrados. Thus the joints near the extrados are wider. These arches do not give pleasing appearance.

Flat brick arches are constructed using cut bricks made to wedge shape and arranged such that to have a flat under surface (Fig. 19.5(a)). All the joints are made to radiate from one point. One brick or half brick may be used. In case of large loads, segmental or semi-circular arches can be built above the flat arches in order to reduce the load on the latter (Fig. 19.6).

Figure 19.6 Relieving arch over flat arch