MASIMBA CONSTRUCTION ZIMBABWE
THE PROJECT FOR IRRIGATION DEVELOPMENT FOR NYAKOMBA
IRRIGATION SCHEME
Execution Scheme of Placing Concrete at Pump Station A
MBA
ation A
Contents
1. Organization Chart and Working hours
2. Schedule of Placing Concrete
3. Equipment and Labour
4. Drawing
5. Flow chart of Placing Concrete
6. Quality Control
7. Safety Control
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1. Organization
NYAKOMBA IRRIGATION PROJECT
PROJECT MANAGER: Stephen Chatambudza
SITE ENGINEER: Innocent Chitemere
SECTION AND PLANNING ENGINEER:
Tendai Mafoti
QUALITY CONTROL ENGINEER -
Timothy Wamedza
FOREMAN - Emmanuel
Mawune
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FOREMAN - Emmanuel
Mawune
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Working Hours During Placement of Concrete on Base Only
Day 1 (Base) 4:50 - 5:00 : Physical exercise and safety meeting
5:00 - 15:00 : Placing concrete
15:00 - : Finishing & Cleaning
Day 2 (Base) 4:50 - 5:00 : Physical exercise and safety meeting
5:00 - 14:00 : Joint Preparation and Placing concrete
14:00 - : Finishing & Cleaning
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2. Schedule of Placing Concrete
Key
Plan
Actual
Aug-17
Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 39 30 31
Rebar (Reinstallation)
Inspection
Form work
BASE
Water Stop
100m3 84m3
Concrete Placement
Finishing & Curing
Scaffolding
Rebar
WALL - LIFT 1 (1.9m depth)
Formwork
53m
Water Stop
. 106
Concrete Placement
Curing & Stripping
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3. Equipment and Labour
Item SPEC Unit Qnty Remarks
Mixing
2 x Concrete Mixers Total = 10m3/hr Combined output from 2 mixers
500R Mixer # 1 5m3/hr 1 On Duty
500R Mixer # 2 5m3/hr 1 On Duty
500R Mixer # 3 5m3/hr 1 On Stand by
Labourers 16
Mixer Operators 2
Sand & Stone Handling
Back Hoe Loader (JCB) Bell / JCB nos 1 Transport Material
Back Hoe Loader Operator 1
Water Supply
Steel Tanks - - 2
Water Pump Petrol 1 Pumping water from Gairezi River to storage tanks
Water Pump Operator 1
Placing / Vibration of Concrete + Joint
Preparation
Diesel Powered Concrete Pump nos 1 Conveying fresh concrete
Vibrators Petrol 45 mm nos 4 Concreting vibrating during casting
Nap Sack Sprayer - - nos 2 Application of retarding agent on first lift
Pressurised water cleaner Petrol - nos 1 Removing laitance
Power Floating Machines (Helicopter) Petrol nos 2 Steel float finish
Air compressor 8.6 bar Ingersoll nos 1 cleaning
Powerfloat Operators 2
Vibrator Operators 4
Carpenters 1
Steel Fixers 1
Pump Operator 1
General Workers 1 Handling and directing pump outlet
General Workers 2 Placing with shovels
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Flow chart of Placing Concrete
Preparation for Placing Concrete
Concrete Mixing
Concrete Testing (Slump Test and Cube Sampling)
Conveying and Placing Concrete
Concrete Finishes
Curing Concrete
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Preparation for Placing Concrete
Preparation and checking of all equipment including scafolding, and lighting equipment
Inspection Forms for Survey, Reinforcement, Formwork and construction joints
Formwork and old concrete shall be cleanedpressurised water and air compressor.
Old concrete shall be well soaked with water before casting. (No free water shall be present on the woodwork when concreting.)
Concrete Mixing
Concrete class is "class A"
Concrete Mixing by 2 mixers with a combined output of 10m3/hr
Cement required for Base = 1410 bags , stock is available.
Aggregate and Sand shall be stored in a separate bins or compatment having a floor.
Aggregate and Sand at batch plant shall be stored under shed as protection against direct sunlight during hot months
Water is from Gairezi river
A retatarder will be applied on joint surfaces and shall be cleaned off using pressurised water to expose aggregates
Concrete mixing time is minimum 1.5 minute.
Concrete mixing volume using 500R mixer will be 3 bag mix ==> 0.39m3/batch.
Base Only:-
Day 1 = 100m3 = 50m3 per mixer = 7.6*50/3 = 127 batches per mixer (3 bag mix will be used per mixer)
Day 1 = 84m3 = 42m3 per mixer = 7.6*42/3 = 104 batches per mixer (3 bag mix will be used per mixer)
Sampling and Testing
Testing is slump (cm), temperature (), Chloride content (%).
Samples will be taken for a series of 6 cubes at one time for each day,
or each 50m3 of concrete.
Base, Slabs and Beams ==> 3 cubes to be tested at 7 days and 3 cubes at 28 days.
Walls and Columns ==> 3 cubes to be tested at 2 days , 3 cubes to be tested at 7 days and 3 cubes at 28 days.
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Conveying and Placing Concrete
Conveying and Placing shall be carried out using Concrete Pump
Concrete shall not be dropped from a height exceeding 1.50m.
Concrete shall be compacted by vibrators.
Concrete shall be carefully placed and vibrated to provide a complete bond
between the concrete and all embedded areas of the water stop.
Concrete should be placed in layers not exceeding 50 cm in thickness.
The reinforcement of the previously poured section should be cleaned of adhering concrete
with a wire brush and properly spliced to the new reinforcement.
Concrete Finishes
Exposed Surfaces
Smooth finish using plywood or metal forms for vertical planes and using a steel trowel
on the horizontal surface of unset concrete.
Unexposed Surfaces
Smooth finish using plywood or metal forms for watertight concrete.
Rough finish for other concrete.
Surfaces to Receive Applied Finishes
Rough finish to receive cement mortar.
Smooth finish for coating with paint, waterproof coating or similar coating without plastering.
Curing Concrete
All exposed concrete surfaces shall be sprayed with a curing compound after removal of shutters or the following
day afyer casting in the case of slabs
Before placement of formwork on construction joints, surfaces shall be cleaned of all dirt, shavings,
loose stones and laitance.
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6. Quality Control
Item Control Tolerance Check
Formwork Measuring forms -20mm ~ +20mm Inspection
Concrete (class A) Sampling and Testing slump : 1002.5cm Inspection
Compressive Cube Strength 26.25 N/mm2 ==>
Concrete (class A) Inspection
Test (28days) 30N/mm2
7. Safety Control
To wear helmet, work suite or overalls while working. Workmen on batch plant to wear dusk masks and ear plugs.
Workmen working on heights to wear body harness.
Checks to be made that there are no people working within radius of moving equipment or moving machine.
Good communication to be mantained between pump operator and concrete placing gang leader.
Workmen to excerise caution when operating vibrator near formwork and scafolding.
Adequate lighting will be provided for concrete finishing during night time.
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