Components Of Material Management Construction Essay
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Published: Mon, 5 Dec 2016
The decision to purchase starts with the decision to build or to produce depending on the type of product an organization produces. The construction industry’s product is a tangible structure that can either be residential house, school, hospital, office building, recreation center, sport complex, or roads, bridges, dams, sewers, railways, airport runways, pipe lines, etc. To produce the end result of the effort to construct, different resources are required by an organization. These resources are manpower, money, machineries, and most importantly material. It is estimated that 60-70 percent of a project direct costs accounts for material cost. Therefore material procurement is an important aspect of every construction work, and worth planning earlier when the decision to construct starts. Planning material procurement starts with identifying and estimating the amount of materials needed, evaluating the availability of the material in market, selecting the reliable source for obtaining the material, and answering questions on the problem of transportation and storage of the material on site throughout the construction period of the project. This is to avoid unwanted or extra cost incurred as a result of poor material management process.
Material management function starts from office where likely constraints associated with every type of resource needed to build the prospective project can be sorted out. It further extends to construction site where practical implementation of the plans and schedules developed during the initial planning stage of the material procurement is needed. Construction site layout of temporary facilities such as office, staff canteen, security shed, material stores, position of crane, and temporary walkways largely affects the movement of workers and material delivery vehicles. And the proposed position of permanent structures within the project site cannot be affected because of temporary facilities. This put a challenge on the project manager who must study the activities likely to happen on site and provide solution to anticipated risk and inconveniences that arises due to poor arrangement of site temporary facilities. With careful positioning of temporary site facilities, material delivery can be easier, accident can be minimized, access to material of work can be faster and ultimately the speed of construction process can be increased.
2.0 Literature review on material management
The procurement of material of work is the reason for which an organization should maintain a competent material procurement department. The primary function of this department is to plan the quantities of the materials needed at a particular time, identify the source of purchasing the materials and initiate the process, planning of inventory and control, ensures quality control measures are taken, and maintain a steady flow of material to avoid shortage during the construction period. Other function of the department includes coding and classification of material, maintaining good record of the movement of material right from delivery to storage and use, and observing the current trends in purchase system and market availability of construction materials.
2.1 Components of Material Management
Contractors are bound to cut expenditures and make even more profit if adequate attention is given to material and equipment planning, scheduling and control. Therefore profitable contracting requires sound material management. It is found that bout 60-70 percent of a project direct cost is incurred on material and equipment. Construction projects are undertaken to finish within a specific time, cost, and quality. To this end number of people, material, machineries and equipment are needed collectively to tackle the individual activities that together make up the whole project. Although projects are classified into two; Infrastructure and Building projects both requires a common resource depending on the size and complexity of the project. On a large building project such as multi-storey building as well as highways construction, the typified equipment used are machine excavators, heavy bull dozer and number of trucks for carting away surplus excavated material, and transporting aggregates, cement, blocks, reinforcement bars, timber, etc. to the project site. Other materials used in building type project are sanitary appliances, surface finishes such as marble, granite, ceramic tiles, plaster board, paints, etc. Material management is composed of series of activities that must be collectively identified, planned, organized, implemented, and monitored and controlled. These are:-
Handling and Transportation
Receiving and Inspection
Storage and Warehousing.
Purchasing: When the need for material arises, the material procurement or purchasing department makes an inventory of the material, sometimes refer to as Material Indent and send to the selected supplier. This is termed as Purchase order/ Material Enquiry. Initially, the supplier’s quotation had been received and reviewed by the purchasing department.
It is also the sole responsibility of the department to negotiate price with suppliers and select the most reliable one in terms of quality of product, delivery time, and lowest purchase cost. Upon receiving purchase order from the contractor, the supplier makes available all the materials in the correct quantity and quality before transporting to the contractor who receives the goods in his own store. The materials supplied to the contractor are often accompanied by consignment notes indicating the types and quantity of the material loaded, and usually this happen within a short time having confirming before placing the order that the materials needed are available in the supplier’s store. However in some cases, the contractor has to follow up order especially if time is against the project. This is known as Expediting by Contractor. Expediting can be done through phone calls, email, fax or any means of communication available.
Material Handling and Transportation: Difficulties can be encountered with handling and transporting materials to the project site especially large fragile materials such as interior glass partitions. Handling materials should start from the point of uploading onto transporting vehicle through maneuvering of the vehicle around busy area to have to reach the project site, and downloading and storage. It further extends to proper positioning in the store till the period when the material can be incorporated into structure or component. Material handling and transportation procedures are not limited to fragile items only. Long and heavy materials such as steel column, galvanized steel angle iron for steel trusses, reinforcement bars, precast concrete components, bricks/blocks and cement bags are almost first line items needed onsite, and deserves careful handling both offsite and onsite. Some materials applicable to a particular trade may be required at a time when other trades are busy working. For example aggregates can arrive at the project site when steel fixers/iron benders are fabricating reinforcement bars. And the truck may have to pass across the iron workers before reaching the designated point of delivery. To avoid such an incident, the planners should take consideration of all materials likely to be required within the time other trade workers are working. This ensures smooth interaction between workers of different professionalism onsite.
Receiving and Inspection: Different types of materials of work are being delivered on site prior to construction work begin or as the work proceeds. Some materials are fragile such as glass panel, asbestos, ceiling board, wooden and plastic door panels etc. while others are of metallic or aluminum nature e.g. door and window frames, steel columns, reinforcement bars, burglar proof etc. Other materials that are directly tipped onsite include aggregates, bricks/blocks, and cement. Whatever type of material needed onsite must be received and ascertained by site manager or the clerk of work upon arrival of delivery. Materials are prone to breakage and or damage in the cause of transportation. Similarly shortage can occur mistakenly as materials are being uploaded from the supplier’s store. However, as a precaution to ensure quality control, proper record of the number of materials received and inspection of their qualities is necessary. This ensures security of expenditure since shortage and broken items are necessarily wastage. Efficient material record also documents the material movement in and out of store for use. It shows the material destination from the store including date and signature of the receiving person e.g. masonry foreman. Three important documents received by the store officer are copy of purchase order from the purchasing department, supplier’s advice document, and consignment notes. This enables the store officer to organize and plan for clearances of material. Where materials received are from internal divisions e.g. from contractor’s central store to the site store the document involved are usually Material transfer and Return to store Notes.
Storage and Warehousing: Competent and experience staffing is needed to perform the activities of storing materials. Although aggregate materials may not require warehousing, some materials such as sanitary appliances, glass panels, door and window frames, electrical equipment such as air conditions, ceiling fans, room heaters, water heaters, and interior finishing materials such as floor tiles, wall tiles, carpets and rugs etc. requires storage within an enclosed storeroom to safeguard the material against loss, theft or pilferage, damage, etc. Nevertheless, in some cases material deterioration may occur in the cause of keeping materials in store. For example heavy materials placed over a fragile material can result to breakage. Therefore a designated operation of store personnel that takes into account downloading deliverables, good positioning and proper arrangement in the store should be maintained. Also good storage practice ensures that materials to be used early are kept closer to the store entrance for ease of access to the material in order to avoid displacing other materials before reaching the needed item. And frequent rotation of materials around storeroom should be avoided as it leads to breakage or damage of materials.
2.2 Objectives of Material Management
The goal of operating any business entity is to make profit over the goods or services it offers. In this respect, construction business is not an exception. The goal of the investment made on plants and machineries, expenditure on material of work and payment of staff and lobour wages is to make a reasonable profit at the end of every project work. At the inception of every project work, there is gradual absorption in the use of materials to form components. The components makes up a structure and the structure makes up the whole building. However the total quantity of all the materials needed to build a project must not be obtained at hand before work starts, rather the materials will be supplied daily or periodically as scheduled by the project management team. This requires efficient planning of inventories, effective buying and purchasing strategy, good storage and inventory control, timely supply and distribution of materials, and maintaining the harmonious relationship between the supplier and the customer.
2.3 Function of Material Management
The function of material management can be divided broadly into primary and secondary functions. Primarily it aims at planning material of work required, purchasing which includes selecting the reliable supplier, ensuring the availability of material at the designated point, and ascertaining and maintaining the steady flow in material supply. The secondary function has to do with proper recording of material through coding and classifications of the materials to ensure proper record are kept both for receiving and using of material. The other secondary functions of the material management deals with the assessment of difficulties in handling and transportation of the material. This challenges the project management team with need to adopt systematic implementation of their plans at all level of the management organization. Ultimately it requires strict monitoring and control.
2.4 Problem of Material Management
There are number of problem associated with material management. The problems may be associated with structure of an organization, storage space requirement, delivery problem, lack of security, market availability of materials, legislation etc. These problems are examined in details below:
Organization Structure: Good organization structure that properly defines roles and responsibility of the individuals at all level is likely to support material management purpose. The coordination and communication between estimating department, research and development department, purchasing department, and plant and machineries department should be maintained at highest level. Where there is poor coordination and communication, internal memo/notes cannot reach an intended destination. For example when there is plant breakdown e.g. excavator is not working due to mechanical problem and the plant and machineries department did not alert engineering department about the problem until the time when soil excavation is needed. Or quantity of materials such as cement is low in the store without informing the purchasing department by the store officer.
Storage Space: Large number of materials is required depending on the magnitude of the project. And the term storage space implies both enclosed and open space that can be used to keep materials of work safe until the need for it arise. All materials need protection against many threats such as pilferage, theft, damage or loss. Material such as aggregates, bricks/blocks may not require enclosed storage protection than proper outdoor positioning and stacking. However, other materials such as reinforcement bars, steel columns, timber, and galvanized steel for trusses must be protected against contact with water in order to avoid rust/corrosion. The size of proposed building may occupy 60% of the total project site, enabling the remaining 40% to be used for temporary access and site facilities. In such case, the planners must arrange for periodic delivery of certain materials to avoid cluttering the space, and maintain constant operation to keep the surrounding area clean.
Problem of Delivery: Not withstanding material order is placed early, a situation exist in which material can not arrive on time. This may be due to a problem on the side of the supplier. And certain specialized materials may not be available within the proximity of the construction site. The material must be transported possibly from another city e.g. hot rolled or cold rolled materials. Eventually worker must be left redundant and time is being wasted.
Security Problem: Security of materials onsite is of paramount importance. Gradual pilferage and theft are issues of concern to the project managers. Loss of materials through pilferage and theft represent financial lost to the project as a whole, and in the end it increases the cost of the project. Materials are prone to be stolen despite being in store. And some materials as earlier mentioned may not require indoor storage. Therefore, a well designated vigilante must be maintained 24 hours onsite.
Availability of Materials on Market: Steady flow of materials throughout project duration is among the primary function of material management. However, this can be affected by market availability of the material of work. Occasionally manufacturers can run out of raw material or be affected by government policy to the extent that production may have to be slow or suspended. Unavailability of materials of work on market can affect material management by either increasing competition in material purchase or delay the general work progress.
Legislation: Domestic manufactures are not likely capable to satisfy construction industry’s need for raw materials. This is true no matter how develop a country is, certain products must be imported from another country. Example of these materials can be specialist hot rolled items, structural members such as steel I section columns, galvanized steel angle iron, air conditions, heaters, wall tiles, floor tiles, etc. and government policy on importation can affect the flow or availability of material on market. Another example can be seen in the price of labour to be used for government projects. Construction labour costs are divided into two; government price, and the price determined by other labour unions such as bricklayers union, steel fixers union, etc. All labour cost whether union cost or government cost can be influenced by the act of legislative committee who are responsible for monitoring and controlling the aspect in a particular country.
3.0 Relations of the Existing site layout to position of Material/Site facilities
Construction sites are bound to face trouble not only technically related, also management related difficulties results into unwanted situation that affect time and cost. Site-based management can make a significant improvement in the cost and time saving during the construction process without involving mass of additional work. Among the important tasks of site management is the site layout planning. Without effective and systematic approach to site planning, extensive time loss and cost overruns could result especially in large projects, where the number of manpower, subcontractors, and equipment involved are high. A detailed planning of the site layout and location of temporary facilities can enable the management to make considerable improvement through minimizing travel time, waiting time, and increasing workers morale by showing better and safer work environment.
Existing Site Layout: Contrary to the above idea, the existing site layout shows concrete batching plant, timber, materials 1, material 2, temporary building, waste materials, reinforcement, scaffold store, store 1, store 2, and temporary road with little information to fully identify the use of the facilities. It further located the concrete batching plant quite away from any storage facility. Waste material is situated behind the temporary office. And finally the project site does not contain security room and toilet. The major short coming of the existing site layout is lack of proper definition of the site facilities, whether the store is for cement or tools, what sort of material can be stored in the facilities named ‘Material’, as both do not convey ideal information that indicates the type of materials to be stored.
Assuming the current position of the temporary facilities is to be maintained, the lead time of concrete work must be slow due to large distance between the concrete batching plant and stores. There is proposed two units of 2-storey building as shown on the site layout, however no provision for tower crane that hoist materials of work to high rise area. Waste material facility should not be too far from the center where most construction activities takes place, this is true in order to encourage the site sanitarians in keeping the site free of scraps that can cause injuries e.g. cut off pieces of metal or timber, broken asbestos, long span aluminum roofing sheet, etc. The temporary walk ways in the existing site layout does not lead up to the spaces between both semi-detached and double storey twin buildings. Following rainfall, the surrounding site area is likely to become bog and muddy, thus inconveniencing traffic around the site.
4.0 Anticipated problems to be encountered on the existing site layout
Most engineers have the impression that site planning can be undertaken simultaneously as the work proceeds day by day. It is important to know that condition of project site will be the condition in which workers live for the duration of the project. Thus, careful pre-planning is imperative. Since construction labour cost constitutes 30-40 percent of project total cost, it is important to realize that significant cost saving will be achieved if the labour force moves freely and quickly within the project site. With free and quick progress of labour force, large amount of work will be done in a day. Conversely, lack of free movement slows rate of production by obstructing the cycle time of material delivery to workers.
4.1 Anticipated Problem
Strictly speaking, the existing site layout contradicts the general site management idea. Construction projects are to start on a specific date and end on a specific date. Consequently, individual activities in the project are given expected starting and finishing time. Unless the activities are on schedule, the project will not finish on the time it is expected to finish. And unless production is maintained at highest speed level, the individual activities would not meet the schedule. To maintain production at highest speed level, access to material of work must be uninterrupted. Interruption to material access is caused by different reason including the distance through which the material must pass before reaching the final production point. The following problems should be anticipated by the site manager:-
Laydown Space: The site layout does not consider simple laydown space for materials such as aggregates, bricks/blocks, etc. which do not require enclosed space for storage. Also for materials which are arranged to be periodically brought to site such as pile for foundation and precast concrete components. If bored pile foundation is to be used for the double-storey building and the scheduled work force is that only 80 piles can be driven into the soil per day. There bound to be problem for space to stack these items upon delivery before they are used.
Plant & Equipment Wrongly Located: The concrete batching plant located far away from any storage facility indicates how far workers need to travel in order to bring material of work to the batching plant. The batching plant and the material stores are located in two opposite sides of the project boundary. This apparently increases the cycle time for the production of wet concrete mix. The ideal procedure for casting wet concrete should not suggest any delay in the production cycle which can be achieved by keeping all the materials needed closer to the batching plant. When materials are closer to production point, the number of labourers needed to be supplying the materials can be reduced because of the short cycle distance than they otherwise have to cover assuming the material is far away. Consequently, the amount of money that must be paid for lobour is reduced.
Poor Location of Temporary Building/ Site Office: It is important to locate temporary site office closer enough to be able to monitor the site activities probably by looking through the window. However, it is equally important to locate the office where noisy construction activities can be avoided as much as possible. The location of the temporary office as shown on this existing site plan seem to be too close to construction activities especially vibration and sound produced by jetting down pile into the ground. Large magnitude of vibration and sound is produced during hammering pile down into the ground, and dust flew up when drilling and chiseling holes on concrete or wooden components. Thus the office is also too close that dust may be entering into the building as a result of such activities.
Inadequate Space between The Existing Site Facilities: The existing facilities such as temporary building, reinforcement, scaffold store, waste material, material, and store are located too close to one another. The effect of this can be manifested by the need for material delivery to the store between ‘waste material’ and ‘materials’. Locating site facility in a confined space do not allow delivery vehicle to reach the location of the facility. And in the extreme it results into double handling of the material by having to off-load temporarily before arranging for workers to move the material to its final destination. Double handling should be avoided as much as possible as it waste time, and often attracts petty charges which when accumulated can make a reasonable amount of money.
Insecurity: The major problem to be faced by the site manager comes from the complete omission of the provision for site security shed. Materials, plant and equipment are never to be taken home by workers nor always brought from high rise areas down to store and locked up, and the next morning they are taken up again. This is tedious. It is a good practice if small electric tools such as drilling machine, welding machines can be left where they have been used today for instance on 2nd floor, and tomorrow the work continues without need for taking it up again. However, this can only be proven good practice if constant day and night security of the material is maintained in the construction site. Material pilferage by labourers is another reason for maintaining security on site.
Omission of Staff Canteen: Notwithstanding workers are always busy onsite, provisions should be made for location of temporary staff canteen. Omission of this facility on this project site may cause workers to travel some distance for need of water, cigarette, mints, cake, etc. and when this happens, automatically the work is retarded.
Lack of Temporary Toilet: The provision of this seemingly less important site facility is almost necessary in every project site. Site management personnel, visitors, members of statutory agencies, and workers are bound to require toilet to ease themselves of their demand. It is impracticable while work is on progress for a worker to seek to go back home or anywhere away from the project site for the need of toilet. Therefore temporary site toilet should be among the site planners’ focus when design temporary site facilities.
5.0 Proposed New Site Layout
The architectural drawings of a project indicate among other things, the proposed position of the individual structures within the scope of the project work. Invariably, this position must be maintained and never to be altered because of the need for temporary site facilities such as material stores, security shed, staff canteen and toilets, site office, position of crane, etc. It is the project manager’s responsibility to examine the activities that take place in the cause of construction work and provide viable alternative that maintain the proposed position of the structures as well as proper location for the temporary site facilities. In achieving this, number of factors deserves consideration. These are lead time of individual activities on the project, ease of access to material of work, activity cycle time, raw material delivery, safety of workers, types of materials, and space requirement for laydown purpose and free interaction.
Site Security Shed: Among the important site facilities is security shed as it provides shelter for site security personnel against weather. It can be constructed of timber, metal/aluminum, tent leather, and even masonry materials such as brick/block, and stone defending on the decision of the project management team. Security shed is almost provided in every type of building project whether it is office building, commercial building, school, hospital, etc. therefore it is advantageous to build the facility once and for all. Building security shed using temporary material like timber, metal etc. can be considered as waste of money and time since the temporary one must be replaced by the permanent structure to serve the same purpose at the end of the project work.
The most suitable position for locating security facility is always by the main entrance of the building, since security personnel are to monitor any movement in and out thereby looking after the properties in and around the building. In this respect, site security building is no exception. Its position has to be by the site main entrance. And it should be properly sited to allow clear coverage of reasonable locations both left and right. Specifically to this project, the security building should be by the right side of the entrance. This is because the left side is a proposed double-storey structure, and can block proper view of the semi-detached structures at the opposite side due to double-storey height of the building. Conversely, positioning the facility at the right hand side enhances proper viewing of the facade of the double-storey, as well as reasonable view of the semi-detached structures.
Material Store: There can be number of stores on site defending on the type of material to be kept in the store. Site material stores do not need to be located all in one position. The location has to be based on the type of material in the store, distance between the store and the point of using the stored items, and accessibility by the delivery vehicle. All material stores must be accessible to the material delivery van, and be close enough to ease difficulty in removing items out of the store. Inaccessibility of store location result into double handling a situation where materials need to be temporarily off-loaded before moving the same into the store. This is time consuming and attracts expenses.
Waste Material Store: Waste is being generated in the course of executing works onsite. Therefore daily waste management should be designed and maintained throughout the project duration. Site waste can be broken stones, blocks/bricks, empty cartons, cut-off pieces of metal, aluminum, timber, etc. which is no longer needed or seen as valuable. Defending on the site manager’s decision, waste can be stored as salvaged items which can subsequently be sold for recycle purpose. However, not all onsite waste can be salvaged for recycling. Waste such as paper cartons and polythene e.g. for tiles, sanitary and electric appliances are best disposed up by taken them away to any refuse collection point nearby, since it is not needed for recycle. This type of waste may not require enclosed storage facility. A simple laydown waste collection point can be satisfactory before they are disposed-off. Only solid non-combustible waste e.g. cut-off metal as piling material, steel angle iron, steel sections, rebar etc. can be stored in waste material facility before they are removed for recycling.
The best practice for onsite waste collection is to collect the generated waste on daily basis just at the point it occurs. Since different trades are working at different places around the project site, it can be difficult to set a single point for waste collection. The waste collected from all points can be taken to central waste collection facility from where the accumulated wastes from all the project activities are moved out of the project site. For example, waste can be generated at 2nd floor, 3rd floor, 4th floor, and ground floor respectively. The waste collected at each floor should be packed and brought down to the central waste collection point. Like material store, the proper location for central waste collection should always be accessible by both vehicle and workers to increase morale in dumping and subsequent removal away from the project site.
Scaffold Store: There are different types of scaffold designed to serve different purpose. These are independent tie scaffold, bird cage, slung scaffold, mobile tower scaffold, and putlog scaffold. The independent tie and bird cage scaffolds are specially designed for external works, covering from ground floor up to high rise areas to enable painting, plastering, glazing, and external electric work. They are mounted immediately on arrival, and once mounted do not need to be dismantled until the end of the project. Such scaffold does not need to be kept on site; ideally they can
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