ASTM International

ASTM International, originally known as the American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services. The organization’s headquarters is in West Conshohocken, Pennsylvania, about 5 miles northwest of Philadelphia.

ASTM predates other standards organizations such as BSI (1901), DIN (1917) and AFNOR (1926), but differs from these in that it is not a national standards body, that role being taken in the USA by ANSI. However, ASTM has a dominant role among standards developers in the USA, and claims to be the world’s largest developer of standards. Using a consensus process, ASTM supports thousands of volunteer technical committees, which draw their members from around the world and collectively develop and maintain more than 12,000 standards.

ASTM International publishes the Annual Book of ASTM Standards each year in print, CD and online versions. The online version was available by subscription and cost was based upon usage. For 2008, the complete set of books or CDs cost almost USD $9000 and included 81 volumes.

ASTM standards

The standards produced by ASTM International fall into six categories:

* the Standard Specification, that defines the requirements to be satisfied by subject of the standard.
* the Standard Test Method, that defines the way a test is performed. The result of the test may be used to assess compliance with a Specification.
* the Standard Practice, that defines a sequence of operations that, unlike a test, does not produce a result.
* the Standard Guide, that provides an organized collection of information or series of options that does not recommend a specific course of action.
* the Standard Classification, that provides an arrangement or division of materials, products, systems, or services into groups based on similar characteristics such as origin, composition, properties, or use.
* the Terminology Standard, that provides agreed definitions of terms used in the other standards.

The quality of the standards is such that they are frequently used worldwide.

The Annual Book of ASTM Standards covers 15 sections of interest plus a master index:

1. Iron and Steel Products
2. Nonferrous Metal Products
3. Metals Test Methods and Analytical Procedures
4. Construction
5. Petroleum Products, Lubricants, and Fossil Fuels
6. Paints, Related Coatings, and Aromatics
7. Textiles
8. Plastics
9. Rubber
10. Electrical Insulation and Electronics
11. Water and Environmental Technology
12. Nuclear, Solar, and Geothermal Energy
13. Medical Devices and Services
14. General Methods and Instrumentation
15. General Products, Chemical Specialties, and End Use Products
16. Index to all sections and volumes

ASTM Standards can be purchased as a digital library subscription or individually from qualified standards providers. When maintaining a large standards library, sometimes it is best to purchase a digital subscription to stay current on standards and in compliance with all copyright laws.

Four collections are now available via a dynamic, online portal. EHS Professionals can procure licenses to a Biodiesel portal (which includes the latest ASTM D6751-08 standard), Due Diligence aka Vapor Intrusion portal, Department of Transportation portal, or a Custom Collection portal that can be purchased by section and/or volume across disciplines or the entire compilation in its entirety.

AASHTO

AASHTO, the American Association of State Highway and Transportation Officials, is a standards setting body which publishes specifications, test protocols and guidelines which are used in highway design and construction throughout the United States. Despite its name, the association represents not only highways but air, rail, water, and public transportation as well.

The voting membership of AASHTO consists of the Department of Transportation of each State in the United States, as well as that of Puerto Rico and the District of Columbia. The United States Department of Transportation, some U.S. cities, counties and toll-road operators, most Canadian provinces as well as the Hong Kong Highways Department, the Turkish Ministry of Public Works and Settlement and the Nigerian Association of Public Highway and Transportation Officials have non-voting associate memberships.

The American Association of State Highway Officials (AASHO) was founded on December 12, 1914. Its name was changed to American Association of State Highway and Transportation Officials on November 13, 1973. The name change reflects a broadened scope to cover all modes of transportation, although most of its activities are still specific to highways.

While AASHTO is not a government body, it does possess quasi-governmental powers in the sense that the organizations that supply its members customarily obey most AASHTO decisions. It is an example of a general tendency in the American style of government to outsource many governmental functions to nongovernmental organizations, whose decisions are then routinely ratified by appropriate government agencies.

Some noteworthy AASHTO publications are:

A Policy on Geometric Design of Streets and Highways, often called “The Green Book” because of the color of its cover. This book covers the functional design of roads and highways including such things as the layout of intersections, horizontal curves and vertical curves.
Standard Specifications for Transportation Materials and Methods of Sampling and Testing.
In addition to its publications AASHTO performs or cooperates in research projects. One such project is the AASHO Road Test, which is a primary source of data used when considering transport policies and the structural design of roads. Much of AASHTO’s current research is performed by the National Cooperative Highway Research Program (NCHRP) which is administered by the Transportation Research Board (TRB) of the National Research Council.

The AASHTO Materials Reference Laboratory (AMRL) accredits laboratories. AMRL accreditation is often required to submit test results to State DOTs. For example, a contract for the construction of a highway bridge may require a minimum compressive strength for the concrete used. The contract will specify AASHTO Test Designation T22 “Compressive Strength of Cylindrical Concrete Specimens” as the means of determining compressive strength. The laboratory performing T22 will be required to be accredited by AMRL in that test.

AASHTO coordinates the numbering of Interstate Highways, U.S. Highways and U.S. Bicycle Routes.

Measures to avoid cracking in fresh concrete

Generally, the contractor shall allow for all necessary measures to monitor and avoid cracking in fresh hydrating concrete, regardless the size or volume of the pour. Such measures shall be to the satisfaction of the Engineer and shall be such that maximum surface crack width on hardened concrete measure immediately after the pour does not exceed 0.004 times the nominal cover of the main reinforcement.

The contractor shall allow for and provide approved instrumentation for the measurement of internal temperature changes in large pours. The maximum concrete temperature at the point of delivery shall not in general exceed the lower of either 37 degree C, or 6 degree C above the prevailing shade temperature in accordance with the recommendations of ACI. The limiting internal temperature differential measured across the extreme faces of concrete mass shall not exceed 25 degrees C at any time.

Curing of hardened concrete shall be executed in accordance with the curing specification. Generally, the element surface shall not be cooled to dissipate heat from the concrete. Curing methods, such as the wetting of heated concrete elements exposed to prolonged and direct radiation, which induce temperature gradients within the concrete mass are strictly prohibited.

For large pours, the contractor shall allow for and take extra precautions to reduce concrete temperature gradient and to prevent the loss of surface moisture. Such measures include but are not limited to:

• Keeping all mix constituents shaded where possible to reduce their temperatures in the stockpile

• Cooling of mixing water and/or replacing part or whole of the added water with ice.

• Reducing the cement content by the use of admixtures (but not below that required for the durability)

• Using a cement with a lower heat of hydration

• Injecting liquid nitrogen after mixing of concrete

• Restring the time between mixing and placing of the concrete to not more than 2 hours

• Providing approved surface insulation continuously over all exposed surfaces to prevent draughts and to maintain uniform temperature through the concrete mass

• Initiating curing immediately after final tamping and continue until the approved surface insulation system is fully in place

• Providing shade to the concrete surface to prevent heat gain from direct radiation.

If the surface exhibits crack after compaction, it shall be retamped to close the cracks while the concrete is still in plastic stage.

Shotcrete for Stabilisation and Lining

 

Stabilisation using shotcrete

Shotcrete is the perfect material for excavation stabilization. Its unique flexibility in the choice of application thickness, material formulation (fiber), output capacity, very early strength development (dry and/or wet) and the ability to respray at any time makes shotcrete the complete material for excavation stabilization.

A distinction is made between full excavation and partial excavation according to the load-bearing properties and stability of the substrate. Excavation is by drill and blast or mechanical methods. In line with the old saying about tunneling: “It is dark in front of the pickaxe”, preliminary bores or narrow pilot tunnels often precede the main construction in difficult ground conditions. These exploration tunnels are then incorporated in the excavation of the future tunnel or used as parallel tunnels for many different purposes. In all these applications shotcrete is used for stabilization if the excavated face is not sufficiently stable. A thin base course in the form of a fine skin can be built up very quickly with sprayed concrete. If the load-bearing properties of the shotcrete are not sufficient, it is strengthened with reinforcement (fiber/steel reinforcement). By using steel rings and mesh, shotcrete becomes the lattice material between the beams.

By using bolts, the load-bearing properties of the shotcrete skin can be linked to the increased load-bearing properties of the substrate near the excavation. If there is high water penetration and/or heavy fracturing of the rock, injection and preliminary waterproofing with gunite and drainage channels will create the conditions for applying the shotcrete layer.

Like all construction methods, underground construction has evolved historically on a regional basis. What is different about building underground is the varying geological conditions in the different regions. Because of this and the variety of projects involved (in cross section and length), different methods have developed. In partial excavation, these are basically the new Austrian Tunneling Method (ATM), the German core method and the Belgian underpinning method. The full section is divided into smaller sections which are each temporarily stabilized and are only joined to form the full section at the end. In the full excavation application, partially and fully mechanized tunnel systems have a huge potential for development. In the longer term the constraints on use will be reduced solely to the economics of tunnel boring machines (TBM). Shotcrete application systems will be permanently installed on tunnel boring machines.

 Lining using shotcrete

The final lining of a tunnel is the permanently visible visiting card of the tunneling contractor. The exception is a final lining with paneling. Inner lining concrete (shell concrete) and shotcrete are both used for a durable final lining. The higher the specifications for the evenness of the concrete finish, the more likely it is that a lining of structural concrete with interior ring forms will be used. Formed interior finishes are also considered to be aesthetically superior. Although new and additional installations are necessary on a large scale for this lining, the cost can be offset by the economics of the interior ring concrete, depending on the length of the project.

This work demands massive inner ring moulds and the machine technology for concrete delivery, compaction and moving the forms. Conventionally produced concrete requires considerable compaction work because inner lining concrete generally has a substantial wall thickness. Accessibility is usually difficult, which means that so-called form vibrators are used, although they have a limited depth effect and are therefore very labour-intensive and subject to wear, which also results in significant additional noise pollution. An important innovation may be the use of self-compacting concrete (SCC) which replaces the whole mechanical compaction process and has a free-flowing consistency which enables to fill these forms completely.

Without the maximum evenness specifications, shotcrete is also suitable for the final lining. Before installation of the waterproofing membrane, the shotcrete surface is often leveled as smoothly as possible with a finer gunite, which greatly improves the conditions for laying the waterproofing membranes without wrinkles.

10 Goals for Advanced Project Management Training

Professional project managers seeking certifications often discover that there remains so much more to learn about the subject. Some managers bank on the power of actual experience to strengthen their know-how; however there is something that the knowledge of structured approaches offers that mere hands-on experience can’t. Given the many learning opportunities available, how can program and project managers choose the right path that will further improve their skills? Improvement and Skill Building, One Step At A Time
We, as individuals, need to employ the principle of continuous improvement. We have a broad culture of self-help and personal improvement, but not everyone has adopted the approach, and almost everyone could do even better. Just as so many practice personal self-improvement with the assistance of self-improvement books, motivational materials, attending motivational seminars, and more, it is virtually the same thing in the realm of project management skills. Advanced project management skills simply are taking everything we know, and then some, to the next level by becoming aware of new ideas and incorporating them into our own best practices.
Continuous Improvement
Let’s look at an example of how we can improve our ability to run meetings. We all know that the best way to do this is to practice, but, then again, it must be good practice. It is true that practice makes perfect, but “perfect practice” is what brings home the bacon. If we find ourselves in meetings on a regular basis, the best way to improve those skills and become a more “advanced project manager” is to try to raise our awareness, apply, adopt, and internalize one or two new ideas for continuous improvement on a daily basis.
For example, in meetings, setting a time limit for the meeting is a good technique. If you have not been doing that, or if you are not satisfied with how effectively you have been doing it, simply try to adopt this one single technique, master it, and integrate it into your common best practices. You might then want to tackle the idea of improving something like facilitation skills to enable everyone to contribute in an optimal way in solving problems in meetings. The key is to mark an area for improvement, to seek information on it to acquire one or two practical objectives, and to begin to put into practice.
Advanced project management training can help greatly in this process of personal and professional continuous improvement. Firstly, this will help us recognize and deal with different types of issues. It can heighten our awareness of what happens in certain situations and how to cope. It can help us to become aware and to develop strength at exercising many nuances of soft skills in our day to day project management practice.
Getting beyond meetings, project managers may identify any of the following areas and more for self improvement in the journey to more advanced project management skills:
1. Improve understanding of project and organizational finance.
2. Learn more techniques for communicating with people from different cultures.
3. Develop a deeper understanding of the unique perspectives of the various workforce generations that might make up your team.
4. Identify opportunities for leveraging outsourcing on projects, and also identify the risks and pitfalls of the outsourcing approach.
5. Adopt a more thorough understanding of issues surrounding telecommuting, and techniques and pitfalls in this evolving environment.
6. Build more advanced consultative skills for working as an external consultant, having worked within a single company for many years.
7. Become more effective at managing technical employees, a unique workplace challenge.
8. Broaden your scope of understanding of project management by expiring related methodologies, Bodies of Knowledge (BOKs), and frameworks, such as PRINCE2 or Six Sigma.
9. Seek to better understand the evolving field of knowledge management in organizations.
10. Develop a formal understanding of the strategic planning process, which provides the input to portfolio management and guide project and program selection.
This list of 10 possibilities for advancing one’s project and program management skills is actually a short one. When it comes to advancing project management skills, the sky is the limit, and the opportunities are virtually endless. There are a nearly infinite number of different types of challenges that a project or program manager faces, and whether by reading books, listening to selected speakers, taking classroom or online courses, and even hiring a coach, there is a lot of opportunity to improve, and many ways to do it.

Specification for Mixing Concrete

 

Concrete shall be mixed at the construction site, at a central mixing plant, in a truck mixer, or by a combination of central plant and truck mixing. Hand-mixing may be used only when approved by the Engineer. No concrete shall be mixed, placed, or finished when the natural light is insufficient, unless an adequate and approved artificial lighting system is operated.

Mixing at site of concrete construction

Concrete shall be mixed in a batch mixer of the type and capacity approved by the Engineer. Mixing time shall be determined by the Engineer in accordance with Method of Test for Variation in Unit Weight of Air Free Mortar in Freshly Mixed Concrete. When results of the above tests are not available, the mixing time shall be longer than 1 1/2 minutes after all the materials have been introduced into the mixer, but in no case shall the mixing time exceed three times the mixing time prescribed above.

Charging of water into the mixer shall begin before the cement and aggregates enter the drum. During mixing, the drum shall be operated at speeds specified by manufacturers. Pick-up blades in the drum of the mixer which are worn down 20 mm or more at any part must be replaced.

The volume of a batch shall not exceed the manufacturer’s rated capacity of the mixer without written permission of the Engineer. No mixer whose rated capacity is less than a one-bag batch shall be used.

Concrete shall be mixed only in such quantities as are required for immediate use, and concrete which is not of the required consistency at the time of placement shall not be used. Re-tempering of concrete will not be permitted. Entire content of the mixer shall be removed from the drum before materials for the next batch are placed therein. Upon cessation of mixing for a considerable length of time, the mixer shall be cleaned thoroughly. Upon resumption of mixing, the first batch of concrete material placed in the mixer shall contain sufficient sand, cement, and water to coat the inside surface of the drum without diminishing the required mortar content of the mix.

Central plant mixing

Mixed concrete shall be transported from the central mixing plant to the site of work in agitator or non-agitator trucks approved by the Engineer.

Agitator trucks shall be equipped with a water-tight revolving drum, and shall be capable of transporting and discharging concrete without segregation. The agitation speed of the drum shall be between 2 and 6 revolutions per minute. The volume of mixed concrete permitted in the drum shall not exceed the manufacturer’s rating nor exceed 70% of the gross volume of the drum. Upon approval of the Engineer, truck mixers may be used in lieu of agitator trucks for transportation of central plant mixed concrete. Gross volume of agitator bodies, expressed in cubic metres, shall be as determined by the mixer manufacturer. The interval between introduction of water into mixer drum and final discharge time shall be a maximum of 45 minutes unless the use of additives has been approved. Depending on the type and usage of the approved additives this interval may be extended up to a maximum of 2 hours.

During this interval the mixture shall be agitated continuously. Bodies of non-agitator trucks shall be smooth and water-tight. Covers shall be provided when needed for protection against rainfall. The non-agitator trucks shall deliver concrete to the work site in a thoroughly mixed and uniform mass. Uniformity shall be deemed satisfactory if samples from the one-quarter and three-quarter points of the load do not differ more than 25 mm in slump. Placing of concrete shall be completed within 30 minutes after introduction of mixing water into the cement and aggregates or if admixture is used at a time to be determined by the Engineer.

Truck mixing

Concrete may be mixed in truck mixers of approved design. Truck mixing shall be in accordance with the following provisions. The truck mixer shall be either a closed, water-tight, revolving drum or an open-top revolving-blade or paddle type. It shall combine all ingredients into a thoroughly mixed and uniform mass, and shall discharge the concrete with satisfactory uniformity. A maximum difference of 25 mm between slumps of samples from the one-quarter and three-quarter points of the discharge load shall be deemed satisfactory.

Mixing speed for revolving drum type mixers shall not be less than 4 revolutions per minute of the drum nor greater than a speed resulting in a peripheral velocity of the drum of 1 metre per second. For the open top type mixer, mixing speed shall be between 4 and 16 revolutions per minute of the mixing blades or paddles. Agitation speed for both the revolving-drum and revolving blade type mixers shall be between 2 and 6 revolutions per minute of the drum or mixing blades or paddles. The capacities of truck mixer shall be in accordance with the manufacturer’s ratings except that they shall not exceed the limitation herein. Standard for normal rated capacity, expressed as percentage of the gross volume of the drum, shall not be more than 50% for truck mixing and 70% for agitating.

The concrete shall be delivered to the site of the work and discharge shall be completed within 45 minutes after the introduction of the mixing water into cement and aggregates unless the use of additives has been approved by the Engineer. Depending on the type and usage of the approved additives this interval may be extended up to a maximum of 2 hours During this interval the mixture shall be agitated continuously. When the concrete is mixed in a truck mixer, the mixing operation shall begin within 30 minutes after the cement has been mixed with the aggregates. Except that when intended for use exclusively as agitators, truck mixers shall be provided with a water measuring device which will measure accurately the quantity of water for each batch. The delivered amount of water shall be within plus or minus 1% of the indicated amount when the tank, if mounted on the truck mixer, is satisfactorily and practically level.

Hand mixing

Hand mixing will not be permitted, except in case of emergency, without written permission from the Engineer. When permitted, it shall be performed only on water-tight mixing platforms made of metal, etc. Concrete shall be turned and returned on the platform at least six times and until all particles of the coarse aggregate are covered thoroughly with mortar and the mixture is uniform.

Curing Concrete

Immediately after forms have been removed and finishing completed, all concrete shall be cured by one of the following methods. The Engineer will specify the concrete surface which may be cured by either method.

Curing concrete using Water method

The entire exposed surfaces other than slabs shall be protected from the sun and the whole structure shall be covered with wet burlap, cotton mats, or other suitable fabric for a period of at least seven days. These materials shall be kept thoroughly wet for the entire curing period. Curbs, walls, and other surfaces requiring a rubbed finish may have the covering temporarily removed for finishing, but the covering must be restored as soon as possible. All concrete slabs shall be covered as soon as possible with sand, earth or other suitable material and kept thoroughly wet for at least seven days. This covering material shall not be cleared from the surface of the concrete slabs for a period of twenty one days. If wood forms are allowed to remain in place during the curing period, they shall be kept moist at all times to prevent them from shrinking.

Membrane forming curing compound

All surfaces shall be given the required surface finish prior to application of the curing compound. During the finishing period, the concrete shall be protected by the water method of curing. Membrane curing compound shall be applied after the removal of forms, or after the disappearance of surface water. It can be sprayed or applied to the concrete surface by means of an applicator in one or more coats at the rate instructed by the manufacturer. Should the membrane seal be broken or damaged before the expiration of the curing period, the damaged area shall be immediately repaired by the application of additional membrane material. The Contractor’s proposals for the use of liquid membrane curing compound and the locations shall be subject to the approval of the Engineer.

Introduction to Sprayed Concrete

 

Sprayed concrete is an excellent tool for stabilization and support of structures in a very short time and for concrete application without using any molds. Sprayed concrete is also the interaction of man, machine and concrete. Sprayed concrete is a high-performance material which functions only as well as these “three components of success”. Man, personified in the work of the nozzle man, requires great technical skill and dedication to the job. The operator must be able to rely fully on the machine and the sprayed concrete material. It is the interaction and quality of these components that finally determines the success of the sprayed concrete application.

In times of rapidly increasing mobility and limited space, the need for underground infrastructure continues to grow. Sprayed concrete has an important role in this requirement. This method is economically outstanding and almost unlimited technically, making it obvious answer.

Sprayed concrete (or shotcrete)  is a single technical term that covers different components of a complete technology:

1. The sprayed concreting process
2. The material sprayed concrete
3. The sprayed concrete system

These three components define a complete technology which has a long tradition, huge potential for innovation and a great future. The material sprayed concrete is a concrete mix design that is determined by the the requirements of the application and the specified parameters. As a rule, this means a reduction in the maximum particle grading to 8mm or  maximum 16mm, an increase in the binder content and the use of special sprayed concrete admixtures to control the properties of the material. Sprayed concrete was used for the first time in 1914 and has been permanently developed and improved over recent decades.

There are now two different sprayed concrete processes:

• dry process sprayed concrete
• wet process sprayed concrete

The main mix requirements focus on the workability (pumping, spraying application) and durability; they are:

• high early strength
• the correct set concrete characteristics
• user-friendly workability (long open times)
• good pumpability (dense-flow delivery)
• good sprayability (pliability)
• minimum rebound

The sprayed concreting process designates its installation. After production, the concrete is transported by conventional means to the process equipment. Sprayed concrete or sprayed mortar is fed to the point of use via excess-pressure-resistant sealed tubes of hoses and is sprayed on and compacted. The following methods are available for this stage of the process:

• the dense-flow process for wet sprayed concrete
• the thin-flow process for dry sprayed concrete
• the thin-flow process for wet sprayed concrete

Before being sprayed, the concrete passes through the nozzle at high speed. The jet is formed and the other relevant constituents of the mix are added, such as water for dry sprayed concrete, compressed air for the dense-flow process and setting accelerators when required. The prepared sprayed concrete mix is the projected onto the substrate at high pressure which compacts so powerfully that a fully-compacted concrete structure is formed instantaneously.  Depend on the setting acceleration, it can be applied to any elevation, including  vertically overhead.

The sprayed concrete process can be used for many different applications. Sprayed concrete and mortar is used for concrete repairs, tunnelling and mining, slope stabilisation and even artistic design of buildings. Sprayed concrete construction has various advantages:

• application to any elevations because sprayed concrete adheres immediately and bears its own weight
• can be applied on uneven substrates
• good adhesion to the substrate
• totally flexible configuration of the layer thickness on site
• reinforced sprayed concrete is also possible (mesh/fibre reinforcement)
• rapid load-bearing skin can be achieved without forms (shuttering) or long waiting times

Sprayed concrete is a flexible, economic and rapid construction method, but it requires a high degree of mechanization and specialist workers are essential.

Total Quality Control in Construction

Quality control in construction typically involves insuring compliance with minimum standards of material and workmanship in order to insure the performance of the facility according to the design. These minimum standards are contained in the specifications described in the previous section. For the purpose of insuring compliance, random samples and statistical methods are commonly used as the basis for accepting or rejecting work completed and batches of materials. Rejection of a batch is based on non-conformance or violation of the relevant design specifications. Procedures for this quality control practice are described in the following sections.

An implicit assumption in these traditional quality control practices is the notion of an acceptable quality level which is a allowable fraction of defective items. Materials obtained from suppliers or work performed by an organization is inspected and passed as acceptable if the estimated defective percentage is within the acceptable quality level. Problems with materials or goods are corrected after delivery of the product.

In contrast to this traditional approach of quality control is the goal of total quality control. In this system, no defective items are allowed anywhere in the construction process. While the zero defects goal can never be permanently obtained, it provides a goal so that an organization is never satisfied with its quality control program even if defects are reduced by substantial amounts year after year. This concept and approach to quality control was first developed in manufacturing firms in Japan and Europe, but has since spread to many construction companies. The best known formal certification for quality improvement is the International Organization for Standardization’s ISO 9000 standard. ISO 9000 emphasizes good documentation, quality goals and a series of cycles of planning, implementation and review.

Total quality control is a commitment to quality expressed in all parts of an organization and typically involves many elements. Design reviews to insure safe and effective construction procedures are a major element. Other elements include extensive training for personnel, shifting the responsibility for detecting defects from quality control inspectors to workers, and continually maintaining equipment. Worker involvement in improved quality control is often formalized in quality circles in which groups of workers meet regularly to make suggestions for quality improvement. Material suppliers are also required to insure zero defects in delivered goods. Initally, all materials from a supplier are inspected and batches of goods with any defective items are returned. Suppliers with good records can be certified and not subject to complete inspection subsequently.

The traditional microeconomic view of quality control is that there is an “optimum” proportion of defective items. Trying to achieve greater quality than this optimum would substantially increase costs of inspection and reduce worker productivity. However, many companies have found that commitment to total quality control has substantial economic benefits that had been unappreciated in traditional approaches. Expenses associated with inventory, rework, scrap and warranties were reduced. Worker enthusiasm and commitment improved. Customers often appreciated higher quality work and would pay a premium for good quality. As a result, improved quality control became a competitive advantage.

Of course, total quality control is difficult to apply, particular in construction. The unique nature of each facility, the variability in the workforce, the multitude of subcontractors and the cost of making necessary investments in education and procedures make programs of total quality control in construction difficult. Nevertheless, a commitment to improved quality even without endorsing the goal of zero defects can pay real dividends to organizations.