Dry Masonary without Tears Hydraform (South Africa) Makes it Possible
Chitradeep Sengupta

In the present age, we are accustomed to the concept of ‘wet masonry’, or construction using cement mortar to bond two bricks together, which we accept as the easiest, durable form of masonry. This is a very conventional form of construction and have been used for decades now. 

But, dry masonry using stones, or wood, ..etc., has been in use for centuries.  Wood is a scarce material and use of stones is location specific.

With the advent of quick, snap-o-fit plastic elements and systems for a lot of things in our life, it did not take long for people to realise that the same could probably be done with the so-called ‘conventional’ wet masonry using brick and cement.

In the last three to four decades, easy to place, interlocking dry block masonry have been demonstrated by many organisations all over the world. Dry block masonry is not only simpler and faster to use, but also helps in reducing the cost of masonry to a large extent because hardly any mortar is used.

The interesting part is the way these blocks are interlocked. Each of the interlocking blocks has its own merits and demerits. Some, for example, are hollow which not only reduce their weights but also let reinforcement rods be passed through them. Some look very aesthetic in a masonry and some have very intricate and fool proof interlocking system.

However what many of these blocks do not have is the ease of use, water tightness, and flexibility in length. The hydraform block seems to almost(!) - not fully as yet - solve these problems also.

Hydraform (S.A.) have developed a mould and a machine for dry interlocking block masonry using one of the basic construction materials - earth.

The Hydraform building system uses a concept of dry interlocking blocks. These blocks slide one on top of the other to make each course. This concept reduces the use of mortar to the minimum.

The blocks have positive grooves on the top and front and negative grooves at the bottom  and back of the block.  This ensures:

The blocks are easy to use and long walls can be erected at a very fast rate.  The skill level required of the mason is higher than the usual.  Great care has to be taken for achieving vertical and horizontal alignment.

However there is an inherent advantage in these blocks. Even if the wall is not properly aligned, the block layer does not have to (in the worst case) break down the wall and rebuild it. He just has to remove these blocks carefully, without damaging them. After that they can be relaid. A mason normally does not let his wall go off the plumb or the string by more than say a cm or so.  This can be corrected by gentle, careful strokes of a “rubber” hammer.  This rubber hammer has been prescribed as one of the useful tools for masonry using the Hydraform blocks.

It does not take long to train a mason in using these blocks. A week of using these blocks in different conditions will get him trained in the use of these blocks. Field experience will make him a mason with expertise.  Working on an actual project quickly builds up skill.

Unlike most of other interlocking blocks, the Hydrablocks require some ‘shaving’ and/or chipping if two blocks have to be laid perpendicular to each other.

Once the basic principle of using these blocks dry at various joint conditions and angles is understood it is easy to make walls at any given condition.

The grooving of these blocks have a gap of about 1-1.5 mm between the +ve and the -ve groove when placed together. The reason behind this ‘play’ is ease of sliding these blocks one on top of the other, for ease of laying as well as the fact that any defect in the mould might result in uneven sheering of these blocks. This however results in two problems.

(i)  Water seepage through this gap if exposed outside (this is through the edges mainly). Solution is nominal plastering only at the top, edges, corners and joints. A well made hydraform wall will not require to be plastered on its face to protect it laterally from rains (water seepage inside). Thus they go a long way in saving the basic cost of masonry by saving on the use of mortar to the extent of 60-80% depending upon the kind of wall built.

(ii) Uneven shearing of the block if the load applied comes directly on the mid point of the block as this portion is, shall we say, a simply supported portion of the block. Solution is use of slip or very thin layer of mortar or masala.

Other principles of the Earth block masonry hold true for these blocks. Being made of earth they need stabilisation for strength and resistance to forces of nature. 

Like most other interlocking blocks, the Hydra blocks also have a very big advantage over wet block masonry systems. If you want to alter the plan of your house, what would you do? Break down and build it all over again? That would be quite expensive. With these dry interlocking hydraform block walls you just have to take the blocks out and place them according to the new plans. This recycleability is quite an advantage.   q 
 

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