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The aim of this report is to investigate systems thinking and use it to analyse the nature of work for an elevated water construction and also to implement essential systems to guarantee quality of work to the client as well as provide safe working conditions to employees working for this construction company
1.0. Systems’ thinking
Systems’ thinking is defined as an approach to problem solving by viewing “problems” as parts of an overall system rather than reacting to specific part, outcomes or events. One of the best ways of solving problems using systems’ thinking is to model a problematic scenario into simple input-output system. The input-output system consists of;
- Input – things to be converted by the conversion process
- Output – things produced or created as a result of the conversion process
- Constraints – elements that limit the conversion process
- Opportunities – sub product of conversion process which benefits another process
- Mechanisms – personnel, equipment and technology used in conversion process
- Conversion process- is an activity which uses a mechanism to convert an input into an output under certain constraints while offering opportunities for other conversion process.
|Figure 1 – Input-Output Model|
This is the construction process by which the specific locations of structures to be constructed are located in the site. The input of this process is the bare land and the output will be the location of the structural elements to be constructed such as columns. The mechanisms used in this process are skills of surveyors and surveying equipment. The main constraints of this process are the difficulty to locate points due to possible weather conditions and uneven topology of the construction site.
Construction of the base
This is the construction process by which the foundation for the water tank is constructed. The inputs for this process are the bare lands with marking of perimeter of foundation and construction materials. The outputs will be the foundation of the water tank. The mechanisms used in the process are the skills of labour, excavating machinery, steel bar bending machines and concrete mixer. The main constraints will be unforeseeable adverse weather conditions and unexpected ground conditions and the opportunities are the fact that the workshop setup to make concrete and to bend reinforcement steel can be used for other construction process like construction of columns and beams.
Construction of columns and beams
This is the construction process by which columns and beams for the water tank is constructed. The inputs for this process are construction materials and formwork and the output is the columns and beams of the water tank. The mechanisms used in the process are the skilled labour, steel bending machines and concrete mixer. The constraints are unexpected adverse weather conditions and the fact that there are many mistakes that can be made in the dimensions of structures and when mixing of concrete.
This is the process by which the concrete is protected from loss of moisture and kept within a reasonable temperature range so that the concrete can reach it complete strength. The inputs for this process are water and concrete and the output is fully cured concrete structure. The mechanisms used in the process are the curing techniques like ponding and spraying. The constraints are the fact that hot weather can decrease moisture content of concrete due to evaporation.
This is the process by which harm caused to the surrounding environment due to the construction process is reduced to appropriate levels or eliminated altogether. Input for this process is the surrounding environment and the output is the surrounding environment with minimum change due to the construction. The mechanisms used are environmental protection techniques such as recycling waste materials and proper disposal of construction waste. The constraints are the extra costs that occur for proper environmental protection and this can delay construction too. Opportunities are the fact that cleaner environment paves way for a more sustainable future and recycling construction waste can reduce the overall cost of construction.
2.0. Systems to control the appropriate level of strength and accuracy of concrete
During the construction process there are three main places where the strength and the accuracy of the concrete is decided; during manufacturing of cement and admixtures, during mixing of concrete and during curing of concrete.
- Manufacturing of cement and admixtures is not a part of the actual construction process therefore there is a possibility that the materials bought is of low quality.
- The construction process is fairly large hence it requires many batches of concrete with different composition of aggregates and admixtures which can lead to mistakes in mixing of concrete which in turn can affect the strength of the concrete.
- After the laying of the concrete its moisture level must be controlled to make sure the concrete reaches its maximum strength. If the moisture level is not properly controlled the concrete strength will reduces and form cracks and also its permeability will increase which can affect the long-term strength of reinforced concrete structures
Different concrete testing methods and quality control mechanisms can be used in a systematic way to ensure that appropriate levels of strength and accuracy of concrete is achieved at each stage of construction. The system of quality control can be made chronologically and using feedback loops so that mistakes at each level can be detected and rectified.
- Cube test – this is used before construction to find the compressive strength of concrete. This has to be performed 7 days before construction using the cement bought for concreting. This should be carried according to BS EN 12390-1:2012. This is used to check if bought materials is of good quality
- Slump test – this is used to test the workability and stability of concrete and to ensure uniformity between different batches of similar concrete. This should be carried out according to BS EN 12350-2:2009
- Windsor probe test – this is a penetration test used to find the strength of concrete after construction. This should be carried according to BS 1881-207:1992. This is to check if final structure has concrete with required strength.
- Concrete curing – ponding and regular spraying of water are methods of concrete curing which is used to make sure concrete is cured properly
|Figure 2 – System for quality control of cement|
By following the above procedure it is possible to control the quality control system to achieve appropriate level of strength and accuracy of concrete. The company must appoint a qualified technical officer to be in charge of each test so that chances of error in the tests can be minimized
3.0. Health and Safety hazards
During the construction process the workers are exposed to many health and safety hazards therefore there is significant need for a safe work system to identify and to reduce the risk to an acceptable level or to eliminate it altogether. Below are some of the possible health and safety hazards pertaining to this construction process and their Risk rating;
|Table 1 – Impact assessment|
|Table 2 – Risk likelihood assessment|
|Within the bounds of possibility||1|
|A rare occurrence||2|
|Not very likely||3|
|A 50% chance||4|
|Table 3 – Risk Assessments|
|Falling objects from above||4||4||16|
|Collapse of form work or false work||4||4||16|
|Trips and falls||3||4||12|
|Injuries from hand tools||3||3||9|
|Exposure to hazardous chemicals||4||1||4|
|Exposure to high vibration||1||3||3|
|Inhalation of dust||1||3||3|
Risk rating = Impact x Likelihood of risk
Risk assessment is the determination of quantitative or qualitative value of risk related to an existing situation and a recognized hazard. A risk assessment involves identifying the hazards present in any undertaking and then evaluating the extent of the risks involved while taking into account existing precautions
According to ICTAD Conditions of Contract major contracts clause 17.1 and clause 17.2 the contractor is responsible for any injury or sickness of any person whatsoever arising out of or in the course of the construction process. The possible hazards, the construction stage likely to occur in and their prevention methods are listed below;
Table 4 – Risk prevention methods
|Hazards||Construction stage||Prevention methods|
|Falling objects from above||During construction of superstructure||Prevented by wearing hard hats and steel toe boots|
|Collapse of formwork and falsework||Likely in all stages of construction||A competent engineer with adequate training and experience in designing false work and form work should be appointed.|
|Excavation collapse||During excavation for base||Vehicles and heavy machinery shouldn’t be kept near the excavation. Fix retaining walls during deep excavation.|
|Trips and falls||Likely in all stages of construction||Can be prevented by labeling trenches, pits or any other surface that can cause workers and to slip or trip|
|Electric shocks||Likely in all stages of construction||Avoid using electrical equipment in damp conditions unless they are specially designed for those conditions. make sure that the wires of equipment are not damaged|
|Injuries from hand tools||Likely in all stages of construction||Prevented by making sure the worker has enough training to use the tool and by making sure the tool is maintained properly and is in mint condition.|
|Exposure to hazardous chemicals (e.g. Cement and admixtures)||Likely in all stages of construction||If skin contact with these substances is inevitable, suitable protective clothing and gloves should be worn. Washing of hands after work and skin care are essential to prevent dermatitis. However, solvents should never be used to clean hands or other body parts|
|Exposure to high vibration||Most likely during excavation for base||Where possible, low vibration tools should be used. They should also be properly maintained so that they are balanced and have no loose parts. Wearing anti-vibration gloves can also reduce the harmful effect of vibration.|
|Inhalation of dust||Likely in all stages of construction||By the use of dustproof masks.|
It is the responsibility of the contractor to employ a health and safety representative who will look into the hazards pertaining this construction and implement suitable prevention method. Also according to ICTAD Conditions of contract major contracts clause 18.3, the contractor is responsible for insuring all personnel against injury.
By following the ICTAD condition and by implementing suitable prevention methods for each health and safety hazard it is possible to create a proper safe work system so that the risks can be reduced to an appropriate level or eliminated altogether.
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