Ask any architectural historian about the single-stone pillar and he/she will endorse its impressive image and instant attraction.
The way antique markets get flooded by pillars from demolished buildings and regularly get sold proves their time-tested popularity.
Of course, stone pillars cannot be set in every building and are not affordable by all. Also, such pillars today are exclusive, expensive and require advanced procurement. For those who cannot afford them, but would still love to have them, pillars made of individual stones, called size stones, are a blessing. Unlike the single-stone pillars that demand time and money in making them, size-stone pillars are very easy to build and comparatively inexpensive. Any experienced stone mason can build them at site, along with the person who would dress them to size.
Merges or contrasts
Stone pillars are ideal for short spans that do not require RCC, and where the walls are already being built with natural materials such as stone, mud or brick. As a material, stone either merges or contrasts with the other natural materials, as such compliments any building. Depending upon the region of India, stones come in varied colours, textures and chemical compositions, wherein some varieties are best suited for pillars. The specific details of stone pillars may vary accordingly, but the basic approach is the same everywhere.
Dressing & bonding
All the visible surfaces of stone need to be dressed, by chipping off the unevenness. The degree of dressing, i.e. how smooth or rustic the surface should be, could be a decision left to the discretion of the owners. Comparatively richer mortar mixes, like in the range of 1:2 to 1:4, are required to ensure good bonding.
The size of stones varies between regions and quarries, where the pillar stones can be 6”x6”x6” cubes or 6” x 4”x 8” rectangular blocks. In the former, there would be four stones in each course, measuring up to a pillar 12”x12” size. The latter size will also have four pieces per course in a 12”x12” sized pillar, leaving a small void in the centre. This void could be filled with concrete and a reinforcement rod to take higher and non-axial loads.
Mason's role
In case electrical conduits are to be encased within the pillar, it's very easy, running the pipe in the centre. However, these smaller-sized stones are normally used for a 9”x9” pillar with only two stones per course. Not all masons are comfortable with smaller pillars, even if they are minimal load contexts, hence should be employed with due care.
The mason has to take extra precaution in building the pillar, ensuring the corner stones are mutually aligned creating the proper vertical corners and horizontal joints. For the stability of pillar, load from top is mandatory.
As such, until the roof is placed, it is common that the freshly built pillar appears weak. As such it is better not to check its strength by trying to push it!
(The writer is an architect working for eco-friendly designs and can be contacted at varanashi@gmail.com)
