Er. Jagvir Goyal*
Construction equipment sector has undergone an eye-opening transformation at international level. In India however, the construction industry still remains labor-intensive. While the specialized structure segment is now fast adopting equipment technology, building construction work still remains alien to available equipment. It is time for a change, if we really want to build faster and better.
Whenever a building is to be constructed, the mason has the last word. Same tools—the spade and the basket, the trowel and the pan, the chisel and the hammer remain in use. Only the concreting work has seen the change from hand mixed concrete to machine mixed one and from manual compaction to vibrator compaction. No effort has been made to induct more of available equipment, which if used can lead to faster, easier and better work. Here, have a look at some of available equipment:
CHASE CUTTING EQUIPMENT
Chase cutting: In most of the buildings, the walls are first erected in bricks or concrete and work of laying water supply lines begins thereafter. To do this work, chisel and hammer are used to cut chase in the walls. Generally, this results in uneven cutting of walls. Sometimes, a harder stroke drives a brick out and a permanent source of inviting dampness gets created in the wall. All efforts to plug the hole thus created in a foolproof manner go waste. In addition, the vertical lines of the chase cut in the walls are totally uneven. After the laying of pipes, when the repair is applied, it can always be noted later on, even after providing a number of paint coats. Resultantly, the wall looks ugly and spoils the beauty of the room.
One can reconcile if the problem is limited to one room. Today, the design of the houses is such that the water supply lines and conduits are running all over the house. We wish to provide wash bowls in the lobby and dining room, we attach bathroom or toilet to each bedroom and we want the kitchen to be big and well equipped. We also look for water supply points in the balconies and on the terrace. A terrace swimming pool or terrace garden is becoming a common feature. Needless to say that availability of water is required in all corners of the house. Under such circumstances, lines are to be laid all over the plan, to be hidden well in the walls and are desired to function properly.
Chase Cutting Machines: Chase cutting machines eliminate the problems linked to manual chasing work. These do exceptionally neat and clean and fast work. Electrically run, these machines can work on the brick walls, concrete as well as cement blocks. Whereas a worker may take two hours to cut chase in a wall of 10 feet height, these machines can cut chase in 10 feet height in just 2 minutes! The size of the chase cut in the wall is exactly as per requirement and perfectly in rectangular shape. The machine weighs around 8 kg and can be handled easily. It has the ability to accommodate different cutters to do chase cutting of different sizes. To cut out a big size chase, two small chase cuttings can be done close to each other and then central material can be struck off.
Cutter sizes: Water supply pipes laid inside the houses are of 15 mm to 25 mm diameter. To accommodate these pipes, grooves of 25 mm X 25 mm, 30 mm X 30 mm and 35 mm X 35 mm are sufficient. Milling cutters to provide these sizes of cuts can be used on the same machine. The manufacturer sometimes, also make modifications in cutters as per requirements of the user.
Main features: Chase cutting machines use single phase electric motors of about 2.5 horsepower. Mostly made of cast aluminium, these are sturdy, weigh around 8 kg and have a good life. Cutters run at about 1000 rpm and the power consumption is about 2 units per hour. As the cutting speed of the machines is fast, overall power consumption is negligible. Another main advantage of the machines is that these take out the bricks and concrete in small fragments thus avoiding production of too much dust all around.
Cutter life: To make best use of cutters, these need to be sharpened after every 30 hours of use. One milling cutter can cut chase over 15000 to 20000 metres length before its replacement. This is a fairly good output for a single cutter. However, to achieve this, the cutters need to be used after their full sharpening. A cutter costs around Rs. 2500 to Rs. 3500, depending upon its size for the chase to be cut. Thus the cost of cutter per metre of chase cutting works out to be in fraction of a rupee!
Uses: Chase Cutting machines can cut chase for embedding water supply lines, electrical conduits, cables or any other similar pipes or conduits in the walls. The speed of working is highest in a hollow block wall followed by brick walls, solid cement block walls and concrete walls. Dust produced by the chase cutting machines is much lesser than that produced by diamond disc cutters. In comparison to conventional methods, there is a saving of 70% labor. Unlike manual chase cutting, no physical fatigue is caused. The machine can be run vertically, horizontally, along a circle or in any direction. While running, it can be left on the vertical wall itself and it will not fall down. Only during its running, the operator needs to push it along the direction of the chase.
Availability: Chase cutting machines are being imported to India from Spain. Priced at around Rs. 40000.00 only, these are fast coming under use by the builders and real estate developers.
MORTAR SPRAYERS
Mortar sprayers: Application of cement mortar on the inner and outer faces of walls in buildings is an essential item to provide smooth and proper base to the painting and finishing work. In brick or cement block walls, plastering is essential. Plastering work can be avoided in concrete walls as good formwork can itself result in smooth surfaces of walls. However, in practice, joints of forms allow the concrete mortar to seep through and surface looks to be treated with plaster, may be of lesser thickness. For one brick thick walls having 9 inch thickness, only one face of brickwork can be kept smooth and the other face requires thicker plaster to be done in two coats. Most common practice is to use 12 mm thick plaster on smooth surface and 20 mm thick plaster on rough face. Plaster with thickness more than 12 mm is always recommended to be done in two coats otherwise it comes off after some time. First coat is of 12 mm and applied by throwing mortar from a distance and keeping its surface rough to allow key for the next coat. Second coat is of 6 to 8 mm thickness and finished with a trowel. All this work requires a lot of skill, labor and time. An equipment invented to do plastering work is Mortar Sprayer. It helps in avoiding manual work, achieving faster progress of work and in major labor saving.
Features of mortar sprayers: Mortar sprayers spray the mortar on the surfaces to be plastered under pressure through spray guns attached to the pumps operated by diesel or electrically operated engines. In all cases, the sprayers are attached to air compressors which help in delivery of mortar. Air pressure has to be adjusted at site as per requirement, depending upon the diameter and length of the hose pipe. From the back of the spray guns, an air line goes to the compressor.
Mixer for mortar sprayer: Mortar sprayers can be fed by site mixers or can have inbuilt mixers also. Their guns can deliver mortar up to a height of 60 metres which is quite a significant height. Built and supported over pneumatic wheels, the equipment can be stationed at suitable locations. An automatic safety device auto cuts the sprayer when over pressure gets created. Rubber hoses and air hoses of required length, spray guns and nozzles form part of the equipment. Single or three phase motors can be added to the sprayers and the piston can pump out mortar at a rate of 1400 litres per hour. These sprayers are likely to see an increased use once the cost of equipment comes down.
REBAR BENDING MACHINES
Bar bending machines: Mostly, cutting and bending of reinforcement bars has been a manual affair at all construction sites. A temporary arrangement is made at site by the blacksmiths by fixing wooden sleepers over vertical posts and fixing the anchors over them. Bar are cut and cranked to shape and the job is quite tedious and time consuming. Development of bar cutting and bending machines has resulted in making this job much easier. Different models of these machines have been developed by the manufacturers for different ranges of diameters of steel bars. Cutting machines are normally capable of cutting plain bars up to 42 mm diameter and TMT bars up to 36 mm diameter. Bar bending machines are designed for diameters up to 16 mm, 36 mm and 42 mm in case of plain bars and 12 mm, 32 mm and 36 mm in case of TMT bars. Spartan, Sana, Walia, Jayem, Bellstone and Cosmos are some of Indian companies manufacturing and selling these simple but useful machines. Icaro machines from Italy can cut and bend steel bars up to 70 mm diameter and are being marketed in India by Ispat Sales, Mumbai. ICARO is also producing a combined machine that can do the cutting as well as bending of steel bars. Equipped with 3 to 5 HP three phase motors, these machines are hydraulically operated with easily replaceable blades in cutting machines and multiple dies in bending machines. ICARO machines can be fitted with computerized automatic angle selector which can select 5 bending programs and bend the bars accordingly.
STIRRUP BENDING MACHINES
Stirrup bending machines: More difficult than cutting and bending of re-bars is the bending of steel stirrups. Spartan has devised a machine for the bending of steel stirrups also. The machine can bend to shape steel bars up to 12 mm diameter. Normally, stirrups of 8 mm, 10 mm or 12 mm diameter only are used. Higher diameter stirrups are required only in very heavy beams or structures. Stirrup bending machine can produce 900 stirrups in 10 hours if a single steel coil is used and 1800 stirrups if double coil is used. Weight wise, 6 to 8 tonne of steel can be converted to stirrups in a 10 hour shift. These electrically operated machines make the reinforcement work in buildings quite easier and fatigue free. ICARO stirrup bending machines can produce multiple shapes of stirrups including square, rectangular, trapezoidal, L-shaped or polygonal ones. Minimum size of stirrup has to be 80 mm. Maximum side size can be as large as 1500 mm. These machines also allow simultaneous bending of many coils if diameter of bar is small. 2 bars of 12 mm dia can be bent together and the number of bars goes up to 7 if diameter of bar is 6 mm.
Make use of above building equipment for faster, easier and accurate construction. Happy Building!
* Author, Technical & General books; Columnist, leading journals and newspapers; Recipient of many awards and honours.
