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EXAMPLES OF CALCULATIONS (see page 35 for details of methods, formulae and notes.)
EARTH-CEMENT MIX
Given: rc: 1250
(kg/m³); rE 1300 (kg/m³)
C required: 6 %; containers: 60 l capacity wheelbarrows and 12 l capacity
buckets.
Method 1
The weight of the cement is obtained, the volume of earth and the rate of stabilization having been decided: Vol.E = 2 wheelbarrow loads = 0.12 m³.
(formula 3)
The weight of the cement is rounded up to 10 kg (1/5 of a sack) to make it easier to measure out.
(formula 5)
Method 2
The volume of earth is obtained, the weight of the cement - 10 kg (1/5 of a sack) - having been decided.
(formula 4)
The volume is rounded down to 2 wheelbarrow loads of earth = 0.12 m³, which gives the same results as method 1 above using formula 5. The actual proportion used is therefore 6.4 %.
EARTH + SAND (OR GRAVEL) + CEMENT MIX
Given: rc: 1250
(kg/m³); rE: 1350
(kg/m³)
rS: 1450
(kg/m³); rE = 80 %, S = 20 %
C required: 5 %; containers = 60 l capacity wheelbarrows and 12 l capacity
buckets. 1 wheelbarrow load = 5 bucket loads.
Method 1
The weight of the cement is obtained, the volumes of earth and sand and the rate of stabilization having been decided.
Vol.E = 1 wheelbarrow load + 3 bucket loads = 96 l
capacity = 0.096 m³
Vol.S = 2 bucket loads = 24 l capacity =
0.024 m³
the total is Vol.E + Vol.S = 2 wheelbarrow loads = 0.12 m³.
(formula 6)
The weight of the cement is rounded up to 8.33 kg (1/6 of a sack).
(formula 9)
The percentages of earth and sand are rechecked.
(formula 10)
(formula 11)
Method 2
The volumes of earth and sand are obtained, the weight and the percentages of the cement, the earth, and the sand (or gravel) having been decided.
WC = 10 kg (1/5 of a sack), C = 5 %, E » 80 %, S = 20 %
(formula 7)
(formula 8)
Vol. E = 0.12 m³ (2 wheelbarrow loads); Vol. S = 0.024 m³ 2 buckets loads
(formula 9)
The percentages of earth and sand are rechecked.
(formula 10)
(formula 11)
CALCULATION OF QUANTITIES USING WET MATERIALS
Cement must be kept dry or it will not work. The other materials
(earth, sand, etc.) on the other hand are rarely dry, whether in the quarry or
when stocked at the brickworks.
For this reason we give below formulae which
can be used to calculate quantities using wet materials. Their moisture content
must, however, be known (fpr how to measure moisture content) and it must be
remembered that dry and wet materials will vary greatly in looseness, which
means that the volume of a dry material can be very different from its volume
when wet and this must be observed.
The methods of calculation are the same
as those explained on p. 35 and the formulae have been give the same numbers,
followed by bis.
KEY
|
rWE: |
density of wet earth (kg/m³) |
|
rWS: |
density of wet sand (kg/m³) |
|
Vol. WE: |
volume of wet earth (m³) |
|
Vol. WS: |
volume of wet sand (m³) |
|
WE: |
moisture content of wet earth (%) |
|
WS: |
moisture content of wet sand (%) |
FORMULAE
|
Formula 3 bis |
|
|
Formula 4 bis |
|
|
Formula 5 bis |
|
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Formula 6 bis |
|
|
Formula 9 bis |
|
For how to use this apparatus and
calculate strength see above.
This kind of block-breaking
apparatus enables one to test for high strengths, as the pressure applied to the
block is equal to five times the load. It should preferably be made out of
metal, so that it is sufficiently robust but less bulky.
FIGURE
Overall height = 1 × 3 m. (including stand)
usable
surface area of screen = 1.5 m²
grid size = 1.00 × 1.75 m
mesh
size = variable depending on use = 5, 10, 15 or 20 mm.
Note: the stand is not
nailed to the screen so that it can be tilted at different angles
FIGURE
EQUIPMENT LIST
- 2 or 3 small containers
- folding or retracting measuring tape
- 5 or 6 transparent cylindrical jars of » 11 capacity
- 1 to 2 mm mesh sieve
- a source of heat (gas, electricity, kiln) + pan or dish
- watch or stop-watch
- graduated container (bucket, test-tube etc.)
- scales (approx. 10 kg capacity and accurate to + 10 to 100g)
- mason's set-square
- pocket penetrometer
- site block-breaking apparatus
- bradawl or styles
- metal brush
- trough min. I × w × h=50 × 35 × 15 cm
USE
- soil (touch test, cigar test, etc.)
- cigar test or checking blocks
- quick sedimentation test (for soil, sand, gravel)
- checking cement or soil preparation, cigar test
- measuring moisture content or salinity
- mixing and retention time
- checking capacities of measuring out containers
- moisture content, blocks, capacities, dry density
- parallelism of blocks
- compaction of blocks
- rupture test
- piercing blocks
- brushing blocks
- immersion and capillary absorption of blocks
Note: all the equipment listed for site tests is also needed. Only additional equipment is listed here.
EQUIPMENT
- 5 × 20 mm f sieves with 2, 1, 0.4, 0.2, and 0.1 mm meshes
- 1 rubber pestle and mortar
- 1 Casagrande apparatus
- 1 roll of pH indicator paper
- 1 hand-press for strength tests (optional)
- 2 metal troughs 30 × 30 × 8 cm
- 2 fine brushes for sieving
- 200 ml pipette
- 1 kiln or oven
- 1 pair of scales or dynamometer (1 to 2 kg capacity, accuracy ± 1g)
- 1 pair of 20 kg capacity scales, accuracy ± 10 to 50 g
- 20 to 30 small sample containers (aluminium or plastic)
- 1 stop-watch or accurate watch
- 1 small spade
- 1 flexible, 150 mm spatula
- 1 knife
- 1 × 140 mm o funnel
- 1 × 25 ml graduated tube
- 1 × 51 carboy
- 1 hydrometer, 1 thermometer
- 3 to 6 × 1 l test-tubes
- 1 × 30 × 30 cm sheet of glass
USE
- Particle size analysis
- Sedimentation analysis
- Atterberg limits
- Acidity
- Bending and compressive strengths
The following pages show the record sheets which form the "memory'' of the production unit, and thus make it easier to manage, both in terms of quantity and quality. They were designed for use in a particular context and are not necessarily suitable for all production units. They are given here as examples and are shown in order of importance. Control sheets should be completed weekly or twice weekly. Record sheets and quality control sheets should be completed monthly and enable all the data collected in the follow-up and control sheets to be summarized.
The daily check sheet (see below) summarizes the daily activity of the production unit and enables all the critical data to be recorded (amounts used, personnel, equipment, production, disbursements).
The manufacturing control record sheet (see below) is used to check the quality of the ingredients and of the manufacturing procedures for each processing operation.
The product block control record sheet (see below) is used for a final check of the products obtained after processing, i.e. the compressed earth blocks.
The production and quantities consumed record sheets (see below) record inputs and outputs, as well as stocks in hand, and highlight any shortfalls (due to theft or loss).
The output record sheet (see below) enable one to measure the efficiency and regularity of the production unit and to observe rapidly any malfunctionning in the means of production or in its organization.
The quality control sheet (see below) summarizes internal checks (recorded on control sheets) as well as any external laboratory checks carried out.
The summary of outgoings sheet (see below) provides a monthly audit of all expenses linked to production (ingredients, running costs, etc.) and thus a quick check of the variable production cost.
The summary of receipts sheet (see below) provides a monthly audit of income and a quick check of the production unit's profits, by comparing outgoings and income.
The presenting the CEB production unit sheet (see below) provides an overall description of the unit (its statutes, infrastructure, means of production, targets, etc.); it records the history of the unit and tends to be aimed at an external audience (financial backers, clients, etc.).
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