Construction sector has been registered with a growth rate of 7.05 percent. The seven plus growth in this sub-sector is due to rapid execution of work on various projects, increased investment in small scale construction and rapid implementation of development schemes and other projects of federal and provincial governments.
Housing and construction is one of the major drivers of growth in more than 70-100 other small industries are part of the construction industry. In addition, for the building of roads, flyovers, bypasses and dams, there is a mass and consistent need of pre-fabricated blocks across the country.
The proposed project envisages the setup of a Pre-fabricated Construction Blocks manufacturing unit. Construction blocks industry is an important industrial sector and has registered with a growth rate of 7.05 percent. The seven plus growth in this sub-sector is due to rapid execution of work on various projects, increased investment in small scale construction and rapid implementation of development schemes and other projects of federal and provincial governments.
Proposed location for setting up a pre-fabricated construction blocks manufacturing unit largely depends on the availability of raw material and its transportation to the factory at low cost. Moreover, construction and allied industries produce environmental pollution which may cause bronchial diseases to the people and hence are preferred to be setup at a distance, in dedicated industrial zones in major cities of Pakistan.
Proposed Product Mix include: Solid Blocks, Hollow Blocks, Pavers and Kerbstones.
Installed capacity is 11.5 million blocks per anum and initial capacity utilization is 50% with 5% increase in subsequent years up to the maximum capacity utilization of 70%. Total Cost Estimates is Rs.68 million with fixed investment Rs.61.6 million and working capital Rs.6.4 million. Given the cost assumptions IRR and payback are 54% and 2.57 years respectively
The critical considerations or factors for success of the project are:
- Contacts with builders / constructors / Civil work consultants
- Contracts with raw material suppliers
- Active participation in Government tenders & prequalification bids
- Targeted marketing strategies for builders and developers
The proposed project envisages the setup of a pre-fabricated construction blocks manufacturing unit. Construction blocks industry is an important industrial sector, producing blocks used as prefabricated material for various construction activities i.e. construction of road side pave ways, garage parking floorings, walls making, block paved driveways, and floor coverings of commercial buildings, etc.
It is easy to make a concrete block. The successful block yard must however make blocks of uniform quality and sell them at a price high enough to cover costs and make a reasonable profit. Before to start a block yard, it is essential therefore to investigate the economic feasibility of the venture. Determination of level of demand for blocks in the area (how many per month) and degree of competition from other block yards are important factors having a significant bearing on the feasibility of the venture. Then comes the cost estimation based on various methods of production and output. Factors which influence unit cost include:
- Purchase price of site
- Cost of site improvements: fencing, paved areas for production and stockpiles, pathways, roadways and buildings
- Cost of equipment: concrete mixer, block making machine and miscellaneous equipment
- Cost of services: water and electricity
- Material costs
- Maintenance costs of site and equipment
- Output: number of blocks per day – dimensions of block, solid or hollow.
- Labor costs etc.
Market Entry Time for Concrete Block Business in Pakistan
Blocks making business depends on activity and movement in construction industry. Housing and construction plus government initiated development projects demand mass availability of blocks all over the year. Therefore, a block manufacturing unit could be established at any time of the year.
The legal status of business tends to play an important role in any setup; the proposed business is assumed to operate on Sole Proprietorship basis.
Production capacity of the plant for the proposed pre-fabricated construction blocks manufacturing unit would be 35,000 blocks of different shapes and categories per day. It is estimated that Karachi alone has a daily demand of 0.5 million prefabricated construction blocks. However, as there are variety of concrete based pre-fabricated construction blocks, cost will largely depend on the selection of block types, which are as follows:
- Solid Blocks
- Hollow Blocks
Raw Material Sourcing
Raw material to be used for the production of concrete based block is available in the local market at reasonable price. Main production material components include: cement and sand/crushed stone. A number of suppliers are available for Sand and Crush in each region and area of Pakistan and could easily be contacted, whereas, cement could be procured from any well-known cement company. Cement suppliers could also be one of the sources for sand and crush supply reference. Low quality Chinese cement is also available in the local market which has been declared substandard for consumption by PSQCA.
Volatility in cement prices is the biggest threat while working in construction industry. This risk can be minimized by making long term supply contracts with the cement manufacturers which is a common practice of large scale industrial consumers of cement.
Investment Required to Start Construction Block Business in Pakistan
Proposed location for setting up a pre-fabricated construction blocks making unit largely depends on the availability of raw material and its transportation to the factory at low cost; however, factors like availability of manpower, utilities and easy access to the target markets should also be carefully examined. For this feasibility, we propose a location in industrial sectors in major cities of Pakistan where all aforementioned resources are available at reasonable price. Moreover, construction and allied industries produce environmental pollution which may cause bronchial diseases to the people and hence are preferred to be setup at a distance, in dedicated industrial zones.
The pre-fabricated construction blocks making units are being operated countrywide. The reason is the demand which is spread all over the country, though is concentrated around developed cities and towns i.e. Karachi, Lahore, Multan, Faisalabad, Peshawar, Quetta, Hyderabad, Sialkot etc.
Key Success Factors
Pre-fabricated construction blocks business is dependent on the pricing and margins given to builders, suppliers and retail customers. It also depends on efficient supply of blocks to the customer and transportation facilities provided to the prospective clients, retailers and order booking agents.
Conventional Order Booking Arrangements – Distribution As we have discussed earlier, pre-fabricated construction blocks is one of the allied sectors of construction industry. Therefore, all raw material suppliers to the construction industry are considered to be the part of the distribution network for the pre-fabricated construction blocks. A block maker when setting up a block yard, institutes contacts with the construction material suppliers, retailers and signup a contract in order to appoint them as order booking agents. Generally, construction and building material supplier is the part of the whole chain, and brings together the customers and suppliers.
Ordering and Delivery Procedure: Block maker appoints order booking agents (building material suppliers) with in the city who entertain the customer. Customers usually send someone or personally go to the booking office and place the order which includes details indicating quantity, quality, size and time of delivery etc. Booking agent gets the payment in cash (mostly) and issues an order / delivery slip to the customer, showing order details.
Buyer hires a truck or loading vehicle and goes to the block yard, where he produces the order slip (in local term called perchi) to the person responsible for the physical delivery of the blocks. That person renders the order as given on the slip. After loading the vehicle he hands it over it to the order booker and here ends the role of the block maker.
Pre-fabricated construction blocks producers also book direct orders at site office for the construction contractors, retail customers and builders on phone and supply directly to the identified delivery points; however, these types of facilities are provided only for bulk orders. Bulk deliveries typically account for around 30% of the total annual sales. In the Pre-fabricated construction blocks industry, the role of the middle man is played by building material suppliers at a nominal margin of 1% to 2% of the order booked.
In the manufacturing industry, marketing is considered to be of significant importance. In the Pre-fabricated construction blocks industry, marketing parameters are very limited and largely associated with the construction sector’s performance. Some of the marketing promotion activities which should duly be rendered are given below:
- Developing contacts with the building material suppliers, well known builders and contractors.
- Keep up to date information on civil and construction works initiated by local, provincial and central government.
- Draw linkages with material suppliers to the housing industry at town level.
- Emphasis on image development and building acquaintances across individual contractors serving private sector.
- Establish contacts with local civil engineering firms, individuals and professionals.
Concrete can be molded in numerous shapes and sizes. The range of product which can be made is limited only by our imagination. For the purpose of calculation only three products which are mostly sold in Pakistan are taken.
Advantages of Concrete Hollow Blocks:
- Economy in design of sub-structure due to reduction of loads.
- Saving in mortar for lying of blocks as compared to ordinary brick and blocks.
- Saving in mortar for plaster work.
- Uniform Plaster thickness of 12 mm can be maintained due to precision of the size of block as compared to ordinary brick/ block work where plaster thickness of average 20 mm is required to produce uniform and even plastered surface due to variations in the sizes.
- Insulation of walls is achieved due to cavity, which provides energy saving for all times.
- Similarly hollowness results in sound insulation.
- Paint on finished walls can be applied due to cavity, which provides energy saving for all times.
- No problem of the appearance of salts, hence great saving in the maintenance of final finishes to the walls.
- Laying of blocks is much quicker because of the uniformity of end product.
Pavers are made of Stone chips, crush Gravels, Stone Dust, Sand and Cement at different proportions. Paving Blocks are used for the pathways neighborhood, pedestrian, walkways in the garden and house carport yard. The usage now is not limited to the above mentioned areas. Due to the enhancement in making pavers for high traffic areas, the usage of concrete Pavers for roads and parking areas, even heavy load areas like Docks, Truck stands, Container yards etc is now preferred. The pavers have advantages over asphalt.
Advantages of Pavers:
- The many colors and textures available in pavers allow for more versatility in looks and styles than premix asphalt. Patterns, lines and images may be built into the paving.
- The interlocking action of pavers facilitates far better load distribution than the premix asphalt.
- In the event of changes or renovations being made in the paved area, any reclaimed blocks are not wasted, but may be used elsewhere.
- If services are required beneath the paving can be lifted without becoming damaged and can be re-laid without leaving any unsightly scars and at no further material cost.
- Add-ons are easily made in any size to match existing paving.
- Paving is more resistant to chemical attacks than premix asphalt, particularly in the case of petro-chemicals.
- The maintenance costs of paving are fraction of those of premix asphalt. Paving is more resistant to wear than premix asphalt.
- Drainage channels may be built into the design with paving.
- Finishing off around trees, etc., may be made with a header course, which is both attractive and practical.
Safety features which are particular to paving include:
- High skid resistance
- High luminance
- Rapid shedding or rainwater
- Low traffic noise levels
For these reasons, paving is usually the preferred material where the following conditions apply:
- Heavy industrial loading is applied to the surface.
- Stop/start traffic
- Turning and slewing wheels
- Petro-chemical or other contaminants in contact with the pavement surface.
- Cushion or solid tired wheels
Furthermore, it is known that asphalt surfaces need to be overlaid after some years of use. Some survey indicates that the period of time before an overlay is required may vary between 7 and 15 years. As the premix asphalt surface layer makes up approx. 27% to 37% of the total pavement cost. This is the amount that needs to be added at present costs if an asphalt overlay is required over the life of the asphalt pavement.
Kerbstones are made of Stone chips, crush Gravels, Stone Dust, Sand and Cement at different proportions depending on application. Kerbstones are used for the sides or as the name implies the curb of Streets, roads, walkways in the garden and house backyard. These are used in different ways on Highways also. The usage is not limited to the above mentioned areas. These are increasingly been used because of their strength and innumerable different shape, sizes and colors.
Following are few advantages of Kerbstone:
- The many colors and textures available in curbstones allow for more versatility in looks and styles than any other means. Patterns, lines and images may be built into the paving.
- Kerbstones are more resistant to chemical attacks, particularly in the case of petrochemicals.
- The maintenance costs of Kerbstones are low.
- Kerbstones are more resistant to wear.
- Due to there even look have better aesthetic value.
Construction sector is one of the largest economic sectors of Pakistan in terms of employment. It directly and indirectly affects more than 40 allied industries which also includes prefabricated construction material industry. Block making has a significant position in the construction process particularly in the housing sector where prefabricated blocks are used extensively with more than 40% of the total structure of the building.
Traditional construction has been relying on hand made bricks rather than concrete block which have been a high cost option while selecting material for the house construction both in urban and rural areas of the country. Concrete based construction is comparatively new phenomena and historically has been employed in the urban areas where technology and machinery was introduced due to mass demand of building material and comparatively high average income.
Pre-fabricated construction block have different categories from smallest size of a brick to a huge sized pre-cast concrete bridges. However, for the purpose of this pre-feasibility, we have focused on the manufacturing setups where various types of blocks are manufactured with the help of automatic or semi-automatic plant and machinery. This sector is largely unorganized and no statistics are available in terms of how many block manufacturing units are working and their scale of operations. The pre-fabricated construction blocks manufacturing sector can be divided into three categories:
Organized Sector – Machine Blocks
Organized sector constitutes few major players in Karachi: Envicrete Private Limited, Hubcrete, Izhar Paver Blocks and Crete N Crete Private Limited. All companies use imported plants and machinery due to their large scale of operations. Standard blocks are generally available in the sizes of 8”x8”x16”, 6”x8”x16” and 4”x8”x16”. Product quality is defined in PSI (per square inch pressure) which a block can survive. Generally it depends on the use of block which varies from product to product. Housing construction purpose block has a normal PSI of 400 and pavers are manufactured with 5000 PSI strength.
Unorganized Sector – Machine Blocks
This sector mainly includes block yards where hand operated mechanical machines are used to make concrete blocks which lay six and above blocks at a time. Therefore, their operations are limited and usually work on the basis of area to area demand. Hundreds of such setups could be seen in each area of the country where these setups are fulfilling the local housing construction demand of blocks of three different sizes and strengths depending upon the individual requirements of the customer. Standard blocks are generally available in the sizes of 6”x8”x12”, 5”x8”x12” and 4”x8”x12”. As far as PSI is concerned, no defined standard could be found; however, 400 PSI is normal in this sector.
Unorganized Sector – Hand Made Blocks
This sector is gradually shrinking and now operating on a very small scale in the low income areas where concrete based structure is scarce. Single mold is used which lays only one block at a time. Such blocks are easily breakable; therefore they are generally not preferred even by the customers who have very limited capital to invest in house construction. The current scenario of this sector shows that most of such block yard operators are switching to machine made blocks option due to customer preference and production limitations of the hand made blocks making process.
Environmental Aspects of Pre-Fabricated Concrete Blocks
Block making results in persistent exposure to the asbestos (due to dust emission), which is a natural fiber found in the dust particles of cement and blocks. To avoid its harmful effect on human health, it is suggested to follow guidelines provided by the provincial agency of environment protection. These procedures do not particularly apply on the block manufacturing industry, rather, a standard material, product and process handling guidelines applicable to construction and allied industries are available on the website: www.environment.gov.pk
Market Potential in Pakistan
Pre-fabricated construction blocks making units across the country are working mostly as unorganized sector (about 80%) and no reliable data is available, precisely, for the installed capacity and the number of units working etc. However, since it is an allied industry of the construction sector, growth in construction sector may be considered as a close proxy for the growth in pre-fabricated construction blocks sector which is 7.05%. The Housing and Construction sector has also been declared as Industry.
Import & Export of Construction Blocks in Pakistan
Pre-fabricated construction blocks or other products are heavy; hence there are limited opportunities for export due to high cost of transportation. The market scope for prefabricated construction blocks is found to be encouraging in local market with the increased demand from construction industry. There is also a sufficient demand from Govt. Contractors for lying of roads and construction of industries.
Manufacturing Process of Concrete Blocks in Pakistan
The production of concrete blocks consists of four basic processes: mixing, molding, curing, and cubing. Some manufacturing plants produce only concrete blocks, while others may produce a wide variety of pre-fabricated concrete products including blocks, flat paver stones, and decorative landscaping pieces such as lawn edging, etc.
The following steps are commonly used to manufacture concrete blocks:
- The sand and gravel are stored outside in piles and are transferred into storage bins in the plant by a conveyor belt as they are needed. The Portland cement is stored outside in large vertical silos to protect it from moisture.
- As a production run starts, the required amounts of sand, gravel, and cement are transferred by gravity or by mechanical means to a weigh batcher, which measures the proper amounts of each material.
- The dry materials then flow into a stationary mixer where they are blended together for several minutes. There are two types of mixers commonly used. One type, called a planetary or pan mixer, resembles a shallow pan with a lid. Mixing blades are attached to a vertical rotating shaft inside the mixer. The other type is called a horizontal drum mixer. It resembles a coffee can turned on its side and has mixing blades attached to a horizontal rotating shaft inside the mixer.
- After the dry materials are blended, a small amount of water is added to the mixer. If the plant is located in a climate subject to temperature extremes, the water may first pass through a heater or chiller to regulate its temperature. Admixture chemicals and coloring pigments may also be added at this time. The concrete is then mixed for six to eight minutes.
- Once the load of concrete is thoroughly mixed, it is dumped into an inclined bucket conveyor and transported to an elevated hopper. The mixing cycle begins again for the next load.
- From the hopper, the concrete is conveyed to another hopper on top of the block machine at a measured flow rate. In the block machine, the concrete is forced downward into molds. The molds consist of an outer mold box containing several mold liners. The liners determine the outer shape of the block and the inner shape of the block cavities. As many as 15 blocks may be molded at one time.
- When the molds are full, the concrete is compacted by the weight of the upper mold head coming down on the mold cavities. This compaction may be supplemented by air or hydraulic pressure cylinders acting on the mold head. Most block machines also use a short burst of mechanical vibration to further aid compaction.
- The compacted blocks are pushed down and out of the molds onto a flat steel pallet. The pallet and blocks are pushed out of the machine and onto a chain conveyor. In some operations, the blocks then pass under a rotating brush which removes loose material from the top of the blocks.
- The pallets of blocks are conveyed to an automated stacker or loader which places them in a curing rack. Each rack holds several hundred blocks. When a rack is full, it is rolled onto a set of rails and moved into a curing kiln.
- The kiln is an enclosed room with the capacity to hold several racks of blocks at a time. There are two basic types of curing kilns. The most common type is a low-pressure steam kiln. In this type, the blocks are held in the kiln for one to three hours at room temperature to allow them to harden slightly. Steam is then gradually introduced to raise the temperature at a controlled rate of not more than 60°F per hour (16°C per hour). Standard weight blocks are usually cured at a temperature of 150-165°F (66- 74°C), while lightweight blocks are cured at 170-185°F (77-85°C). When the curing temperature has been reached, the steam is shut off, and the blocks are allowed to soak in the hot, moist air for 12-18 hours. After soaking, the blocks are dried by exhausting the moist air and further raising the temperature in the kiln. The whole curing cycle takes about 24 hours.
- Another type of kiln is the high-pressure steam kiln, sometimes called an autoclave. In this type, the temperature is raised to 300-375°F (149-191°C), and the pressure is raised to 80-185 psi (5.5-12.8 bar). The blocks are allowed to soak for five to 10 hours. The pressure is then rapidly vented, which causes the blocks to quickly release their trapped moisture. The autoclave curing process requires more energy and a more expensive kiln, but it can produce blocks in less time.
- The racks of cured blocks are rolled out of the kiln, and the pallets of blocks are unstacked and placed on a chain conveyor. The blocks are pushed off the steel pallets, and the empty pallets are fed back into the block machine to receive a new set of molded blocks.
- If the blocks are to be made into split-face blocks, they are first molded as two blocks joined together. Once these double blocks are cured, they pass through a splitter, which strikes them with a heavy blade along the section between the two halves. This causes the double block to fracture and form a rough, stone-like texture on one face of each piece.
- The blocks pass through a cuber which aligns each block and then stacks them into a cube three blocks across by six blocks deep by three or four blocks high. These cubes are carried outside with a forklift and placed in storage.
Three aspects should be monitored to ensure quality masonry units: strength, dimensions and shrinkage.
Strength: Quality of blocks should be controlled so that strengths are adequate (to avoid breakages or rejection by customers) and mixes are as economical as possible. Ideally, blocks should be regularly tested for strength and mixes and production processes modified if necessary. If testing is impracticable or unaffordable, block strength should be continually assessed by noting whether corners and edges, or even whole blocks, tend to break in handling. Strength can also be assessed by knocking two mature bricks together.
Dimensions: The length and width of the units are determined by the mould and will not vary greatly. However, the height can vary and should be monitored using a simple gauge. Units of inconsistent height will lead to difficulties in the construction of masonry and possible rain penetration.
Shrinkage: Concrete masonry units shrink slightly after manufacture. In order to avoid this happening in the wall, blocks should be allowed to dry out for at least seven days before being used for construction
Raw Material Requirement for Concrete Block
Cement is the standard binder used with aggregates to make concrete products. The quality of cement, particularly with regard to the rate of strength gain and sensitivity to curing, or lack of curing in many cases, should be considered in choosing cement. Cement may be stored in paper bags but protected from any deterioration or in silos. Cement should preferably be batched by mass, either using a full 50 kg bag or weighing each batch of cement either from a silo or opened bags. Volume batching must allow for the bulking of the cement, normally around 20%.
Aggregates form the bulk of concrete. They significantly affect the cost and quality of the final product and the ease with which the products are manufactured and finished. Aggregates used are mostly derived from solid rock, which is crushed or has been broken down by weathering. All sources of these aggregates preferably be checked to see they are of adequate quality. This might be done by testing the aggregates in a laboratory or by reference to the successful service performance of the aggregates in concrete.
In general, aggregates should consists of clean, hard, strong, dimensionally stable and durable particles free from clay coatings or foreign materials (especially organic matter) that may interfere with the normal strength development of the cement. Aggregates that do not have a reliable service performance record should be tested in a laboratory.
The aggregate is known in Pakistan as crush gravel, stone chips and stone dust as well.
Pigments may be used to coloring concrete products. The production of color-stable concrete requires care both in choice of colors and in the composition of the concrete mix. Specialist advice should be sought on best pigments to use to obtain the required color and their dosage.
The final choice of pigment and appropriate dosage will be made on the visual examination of dry concrete in which the pigment has been used. Usually in the preliminary stages, concrete is made with a range of dosages of cement pigment to determine the optimum dosage to give the required color. Dosages should not exceed 7% of the mass of cement.
Water in concrete makes the fresh concrete workable and reacts with the cement to give strength to the concrete; its quality is important. Water fit to drink is normally suitable. Evaluation of suspect water such as industrial wastewater, observing if the setting and strength gain of the concrete is affected may carry out water from underground mining activities and raw effluent.
Water is batched by volume. An experienced operator can judge the amount of water required in the particular concrete. If stored in tanks, the water should be protected from low temperatures, as this affects the setting time of the concrete and its rate of gain of strength.
In hot weather, water flowing in black pipes subject to direct sunlight can become excessively hot and cause rapid loss of workability of the concrete. Pipes should either be protected or insulated, or water should be stored when cool for subsequent use.
Although small mixing and molding units are available in the local market, yet, complete mechanized plants are not available and organized setups are using imported plant and machinery for concrete block making. European and American plants are available which give good quality output; however, these are very expensive and not generally preferred even by the leading players due to high capital requirement. Therefore, we have selected Indonesian machinery for the proposed project which gives good quality output and is relatively more economical.
Machinery for the project which will cost around Rs. 29.2 million.
Installation Components Required for Concrete Block Production Machinery
- Multiblock machine
- Pallet transfer unit
- Chain conveyor
- Belt Conveyor CB 8 M
- Dry concrete Mixer
- Batching plant
- Gantry crane with hoist
Vehicles for Transportation
The proposed setup would require three to four vehicles (new machinery has been considered for the proposed project) to carryout transportation of raw material and finished products. Besides, dumping and loading vehicles for the transportation of finished product to the stacking points would be a pre-requisite.
During the discussions with the market experts and entrepreneurs, it was observed that, though the above machinery/vehicle could also be hired on rent, yet, the incremental cost difference between rented and purchased machinery would be very close over a long period of time. Therefore it would be preferred to acquire own machinery rather than obtaining these services on rent.
Machinery is expected to be serviced on an annual basis. During the projected period, maintenance expenses are estimated to be around 5% of the total cost of machine.
Land & Building Requirement in Pakistan
Selecting a site
In selecting a site, consider location, access, ground slope and size. Each of these is discussed below.
This should be considered in relation to:
- Supply of raw materials
- Market for blocks
- Location of the labor force
- Security of the area
- Availability of services, i.e. roads, water, sewerage, electricity, etc.
The site must be accessible to trucks delivering aggregates and cement and collecting finished blocks.
Ideally, the site should be level or nearly so. Steep slopes make handling and production difficult. Terracing a steep slope is expensive.
The site should be big enough for aggregate stockpiles, cement storage, production (slab or stationary machine) block stacking, staff facilities, an office and on-site access. With all provisions for the business, one acre would be sufficient for the project.
Establishing the Site
The site should have provision for stockpiling aggregates and storing cement, a production area, a stacking area, staff facilities, an office, and access between different areas and facilities. Each of these is discussed below.
Aggregates must be stockpiled in such a way that: they do not become contaminated by soil, leaves, etc; different aggregates are kept separate; and rainwater can drain away. Ideally therefore, aggregates should be stockpiled on a concrete slab. If this is not done, the layer of aggregates in contact with the soil should not be used for production. Aggregates must not be stockpiled under trees. Partitions should be erected between different types of aggregate. Stockpiles should be on a slight slope so that rainwater does not collect in the aggregates.
The best way to store cement is in a silo. For small scale block yards, however, cement will be delivered in bags. Cement in bags should preferably be stored in a weather-proof room. Bags should be stacked on a plastic tarpaulin or on closely spaced wooden strips so that they do not absorb damp from the floor. The storeroom should be big enough to hold at least a week’s supply of cement. If it is not possible to provide a storeroom, cement in bags should be stored in stacks raised above the ground and completely covered with tarpaulins.
The size of this area depends on the method of producing blocks. A stationary machine, which forms blocks on pallets, needs a relatively small area with space around it for operators. A mobile “egg-laying” machine needs a fairly large slab on which blocks are made. Details of such a slab are discussed below.
Construction of a Production Slab
A flat concrete slab, big enough for at least one day’s production, is required. To minimize breakages in cold weather, it is recommended to increase the cement content of the mix or the curing period before moving the blocks.
Normally block production is carried out in the open, and the concrete slab should have a minimum slope of 1 in 100 to ensure proper drainage.
Large production machines require a minimum slab thickness of 150 mm.
To prevent uncontrolled cracking of the slab, it should be divided into panels which should be square or as close to square as possible. The half round keyway prevents differential settlement of adjacent slabs. The maximum joint spacing depends on the thickness of the slab and should not exceed 6 m for slab thicknesses of 150 and 200 mm.
An area big enough to stack two weeks’ production is needed for curing and drying blocks. It is normally not necessary to pave this area. To avoid muddy conditions, a layer of concrete stone, about 100 mm thick, should be enough.
Office and Staff Facilities:
These include toilets, ablutions, and possibly change rooms. An office should be provided for all but the smallest of yards.
The factory would be located at any industrial areas in major cities of Pakistan. The reason for the selection is that utilities, water, electricity and skilled manpower are conveniently available, whereas, comparatively low cost of land, proximity to the target market, good transport and communication facilities, also account for its selection.