The small-scale manufacture of concrete bricks and blocks for masonry is well suited to small businesses. Production can be carried out in the open, the process is simple and equipment does not require high capital investment. The aim of this publication is to provide the information needed to set up and run a blockyard to manufacture concrete bricks and blocks on a small scale. The publication is intended mainly for development agencies, local authorities, builders’ associations, housing consultants, trainers, etc, but could be of use to entrepreneurs and blockyard managers. Aspects dealt with include the feasibility study, selecting and establishing a site, selection of equipment, materials for blockmaking, trial mixes and production. This publication focuses on technical information. Topics outside the scope of this leaflet are:
concrete bricks & blocks
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Cost of equipment: concrete mixer, blockmaking machine, miscellaneous equipment, eg wheelbarrows and trolleys, and tools. Cost of services: water and electricity Material costs (See section 7.2 for mix ratios. As a first estimate, assume that 1-m3 of loose aggregate will yield 0,7-m3 of concrete volume.) Wastage Maintenance costs of site and equipment Output: number of blocks per day – dimensions of block, solid or hollow. Labour costs Cost of finance
A list of possible sources of information and assistance is available from the C&CI.
3. Selecting a site
In selecting a site, consider location, access, ground slope and size. Each of these is discussed below.
Detailed cost analysis Manufacture of paving blocks
Bricks and blocks are masonry units and are referred to as such in SABS standards. Units may be solid or hollow. The difference between bricks and blocks is one of size. In this pamphlet “block” is used throughout, but the same principles apply to brick.
This should be considered in relation to:
2. Feasibility study
It is easy to make a concrete block. The successful blockyard must however make blocks of uniform quality and sell them at a price high enough to cover costs and make a reasonable profit. Before you start a blockyard, it is essential therefore to investigate the economic feasibility of the venture. Determine first what demand there is for blocks in your area (how many per month) and find out if there would be competition from other blockyards. Then estimate costs based on various methods of production and output. Factors which influence unit cost include:
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Supply of raw materials Market for blocks Location of the labour 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.
3.3 Ground slope
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.
Purchase price or rental of site Cost of site improvements: fencing, paved areas for production and stockpiles, pathways, roadways and buildings
4. 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.
considered. Large production machines may require a minimum slab thickness of 150-mm. Concrete If you mix the concrete yourself, the proportions shown in Table 1 should be used.
Size of stone mm 19,0 or 26,5 13,2 1 bag 75 l 55 l Proportions by volume* Cement 1 1 bag 1 Quantities per cubic metre of concrete Stone m3 0,7
4.1 Aggregate stockpiles