Wedge shaped stone at apex of arch is ______
🏛️ Deconstructing the Arch: Identifying the Key Components
To identify the correct term, it's essential to understand the specific roles of different stones in and around an arch.
(A) Key stone: The Apex Stone
The Key stone (or keystone) is the correct answer. It is the distinct, wedge-shaped stone placed at the very apex (the highest central point) of an arch. Its function is critical: it is the last stone to be placed, and its shape locks all the other stones (voussoirs) into place, activating the compressive forces that make the arch self-supporting. The keystone's task is to provide balance and distribute the weight from above down through the side support blocks.
(B) Springer: The First Stone
A Springer is the lowest voussoir, or wedge-shaped stone, on each side of the arch. It is the first stone that "springs" from the vertical support (the abutment or pier). Its upper surface is curved to match the arch, while its lower surface rests on the angled top of the support (the skewback).
(C) Quoin stone: The Corner Stone
A Quoin stone is not part of the arch itself. Quoins are the cornerstones of masonry walls, used for reinforcement or for decorative effect. They are the large, dressed stones at the corners of a building, and they are not necessarily wedge-shaped.
(D) Closer stone: The Bond Maintainer
A Closer stone (or more commonly, a closer brick) is also not part of an arch. It is a piece of a brick or stone cut lengthwise, used to complete the bond pattern at the end of a course of brickwork. Its purpose is to prevent vertical joints from aligning in adjacent courses.
🖼️ Visual Diagram of Arch Components
This diagram helps to visualize where the keystone and other key components are located on a typical arch structure.
📖 Additional Arch Terminology
- Voussoirs: The general term for any of the wedge-shaped stones used to construct the arch. The keystone is the most important voussoir.
- Haunch: The part of the arch roughly midway between the springer and the keystone, where the outward thrust is greatest.
- Spandrel: The triangular area between the arch's outer curve and the rectangular frame that encloses it.