DURABILITY PLANNING AND SUSTAINABILITY FOR NEW PROJECTS
Authors: Dr. Emad A. Abu-Aisheh
ABSTRACT The exposure conditions of reinforced concrete in the Arabian Gulf region constitute a severe environment, which makes reinforced concrete most vulnerable to deterioration and the weakest link in terms of durability. The main factor affecting the durability of reinforced concrete structures in the Arabian Gulf is steel reinforcement corrosion due to chloride attack. Around the world, infrastructure facilities are designed and constructed on the basis of direct costs and minimum standard requirements, without explicit consideration of maintenance and depreciation over its service life. Proper design, operation, and management of infrastructure must deal with every facet of its service life, including: feasibility studies, design, construction, operation, maintenance, repair and rehabilitation, and finally decommissioning and disposal of the system; after it has outlived its useful life. Durability planning is a crucial process in the design of new infrastructure. It is the process that gives confidence in the ability of the construction materials to meet a nominated design life. This process involves four main stages; environmental exposure assessment, determination of the likely modes and the rates of degradeation, selection of suitable materials of construction and operation, and maintenance planning. This article discusses the basic concepts involved in infrastructure durability and sustainability. The article also looks at the processes involved in durability planning, the resources available for durability assessments, and discusses a durability challenge from a recent mega-infrastructure project.
INTRODUCTION Reinforced concrete structures in the Arabian Gulf region show significant deterioration due to corrosion of reinforcement, sulfate attack, salt weathering, and non1 structural cracking . The poor durability performance of concrete is attributed to several interactive factors. High temperatures, wide daily and seasonal fluctuations of heat and humidity regimes, usually high prevalence of chloride and sulfate salts, inadequate specifications and poor construction practices, all act interactively to cause noticeable concrete degradation within an alarming short span of 5-10 years.
Durability plans prepared by independent durability specialist consultants are now a requirement for many major projects in several countries, including Australia. Such plans provide the basis for durability design to ensure that the project structures and elements will achieve the design life requirements in the expected exposure conditions using the materials, construction methods, workmanship, and maintenance proposed. Durability Plans cannot be prepared in isolation. They need to take into account the proposed construction methods, element shape and orientation, longterm exposure, maintenance methods, quality control, operating risks, and detailed design. Consequently, the Plan must be developed through interaction with the client, designer, contractor and other sub-contractors. At the start of the project it is necessary to lay out the process for the assessment of the durability during the entire project duration. The planning process involves four main stages: environmental exposure assessment, determination of the likely modes and rates of degradation, selection of suitable materials of construction, and operation and maintenance requirements for the design life. The durability planning process utilizes a variety of local and international standards, physical site inspection and testing, extensive construction material testing, and also involves interaction with the design teams from all engineering and science disciplines. On well planned projects, this process starts in the concept design phase and usually continues throughout the design and construction and into the operation and maintenance phase. This article attempts to explain briefly the basis behind sound durability planning for new infrastructures to achieve sustainable infrastructures, focusing mainly on concrete structures.
DURABILITY, SUSTAINABILITY AND DESIGN LIFE Durability is defined as the design of a structure or facility to meet the design life requirement — by material selection, degradation management, monitoring, 2 inspection and maintenance . A structure is considered durable when it performs satisfactorily and maintains an acceptable appearance as long as the owner and the user need the structure. A commonly used definition of the design life of a SAUDI ARAMCO JOURNAL OF TECHNOLOGY
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project element is the period of time after the date of practical completion, during which the item is expected to operate within its specified design parameters without 3 replacement, refurbishment or major maintenance . The design life of all elements of an asset may not be the same and often depends on the ease with which an element of the structure may be replaced or refurbished without significant disruption to the operation of the structure. For the everyday buildings and normal structures, the national codes and regulations will have defined society's service life requirements — often not explicitly but implicitly through the standards and codified design requirements. It is often forgotten that complying strictly with the performance requirements stated in codes and standards will only provide the minimum quality and performance acceptable to society, and the assumed service life — when strictly complying with the Australian concrete standard AS 3500, the British standard BSI BS EN 206-1, the European concrete standard Euorocode 2 and the Canadian concrete standard CSA A23.3-04 — is generally only 40 to 50 years. For many special structures, additional requirements must be satisfied for truly long-term performance and service life of the structures. This aspect is often completely overlooked by owners and clients. The term ―sustainable‖ can be defined as ―avoiding 4 depletion of natural resources .‖ Sustainable structures should strive to conserve natural resources and minimize waste (be an efficient, minimalist design, avoiding extravagant architectural statements), minimize the embodied energy in the structure (appropriate selection of materials and material sources for the functional demands of the project), and have a long life with minimal maintenance input. Sustainability objectives for infrastructure projects are best accomplished by ensuring durable structures with long service life and low maintenance, which on a whole-of-life basis, minimizes material consumption over the long-term. It is likely that such a structure also has the lowest whole-of-life economic cost. To illustrate this point, this article cites two recent projects designed to have an extended life in an aggressive environment. The Southern Seawater Desalination Plant, Fig. 1a, is required to last 100 years. Coatings, metal roofs, electrical and mechanical elements have a substantially shorter design life, and are expected to be replaced during the life of the bridge 5 asset . Figure 1b is the Gateway Bridge Arterial, crossing the Brisbane River in Queensland, Australia. Most elements of the new bridge are designed for and is expected to last 300 years. Again, the road wearing surface, noise and traffic barriers and bridge bearing may have a substantially shorter design life, and are expected to be replaced during the life of the bridge 4 asset . Elements with shorter design lives are required to be designed for ease of maintenance or replacement during the life of the asset. The purpose of durability planning is to provide assurance to all stakeholders that all materials — used SAUDI ARAMCO JOURNAL OF TECHNOLOGY
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Fig. 1a. Photo depicting the Southern Seawater Desalination Plant in Western Australia.
Fig. 1b. Photo of the Gateway Bridge Arterial crossing the Brisbane River in Queensland, Australia.
in the construction and manufacture of the structure and associated equipment — will remain serviceable for the duration of the life of the structure.
DURABILITY PLAN DEVELOPMENT AND IMPLEMENTATION Durability plan process and implementation involves seven major steps: 1. Durability Review Process 2. Verification of each Element‘s Durability 3. Incorporation of Durability Requirements in the Design 4. Durability Requirements during Construction 5. Operation and Maintenance Requirements 6. Durability Plan – Project Works Report – Addendum 7. Birth Certificate
The information gathered above can be summarized in a technical file or report called a Birth Certificate (step 7). The Fédération Internationale du Béton (fib), New Model Code Chapter 2, defines a Birth Certificate as: A document, report or technical file (depending on the size and complexity of the structure concerned) containing engineering information formally defining the form and 6 the condition of the structure after construction .
ENVIRONMENTAL EXPOSURE The first major step in durability planning is to understand the environment for which the infrastructure is being designed. It is also important to know if the atmosphere contains aggressive species from nearby industries. The degree of degradation may vary from insignificant to severe depending on the material exposed. It is important to fully understand which aggressive elements are present in each exposure zone. Many of the standards used in the design of large structures provide nominal classification of the environment. American Concrete standards typically use classifications S0, S1, S2, S3 for Sulfate exposure, C0, C1 and C2 for corrosion protection of reinforcement; P0 and P1 for low permeability requirements. But standards that deal with steel or other metal structures use terms like mild, moderate, and severe or designations like C1 to C5. It should also be noted that the environmental classifications are not consistent between materials, and for concrete elements the classification also varies with the required design life. The difference in classification is a result of the reaction different materials have with an environment. As an example, the interior columns, beams, and slabs of an office building are subjected to an insignificant deterioration in accordance with ACI 318 exposure environments — exposure classifications that apply to this environment are S0, F0, P0, C0. Another example is a pile in a marine structure subjected to seawater splash — wetting and drying — in the Arabian Gulf. In this case, the pile is subjected to severe deterioration in accordance with ACI 318 — exposure classifications that apply to this environment are P1, C2 (or C3), S2 (or S3) and F0. A single element of a structure may be exposed to a variety of environments. For example, a bridge pile in a creek may be exposed to the atmosphere, the water, a buried environment, and possibly a tidal zone depending on the location of the creek. Often, the most aggressive environment needs to be considered for the entire element to ensure that the element can be readily constructed. The most important design rule for minimizing corrosion is to ensure that all water (whether from rain, splash, condensation and the like) can drain from the element substrate and that there is no propensity for ‗―ponding.‖ Consequently, flat roofs or roofs with a low slope are generally subject to the most severe corrosion conditions as well as a significant level of damage from
particulate dropout, pollution and UV radiation. Vertical walls generally receive less exposure to the prevailing weather than the roof and suffer less deterioration, but can still be subject to corrosion. Exposed areas that are subject to pollution and/or deposition by marine salts but not washed by rain, such as wall relief and overhangs, will show increased corrosion. Typically, sheltered areas may also show enhanced corrosion if they are subject to increased ―time of wetness‖ due to condensation, which is not controlled by direct sunlight. Atmospheric The atmospheric environment — whether an exposed external, sheltered external or an internal atmospheric environment, contains a multitude of elements, pollutants and varying levels of humidity — may contribute to the degradation processes of exposed materials. There are a few factors which predominantly affect the degradation of construction materials. The most common elements that affect concrete structures are aerosol salt, usually chloride based salts, sulfur dioxide (SO2) and carbon dioxide CO2. For all materials, one of the crucial parameters in determining the extent of degradation is the time of wetness. The time of wetness is essentially the period of each day in which there is sufficient moisture in the air to sustain the degradation processes occurring on the surface of the material. In a marine environment, chloride ions are the most aggressive species. Buried Buried environments are complex with no one element or property of the soil indicating how buried elements will react with the soil. The corrosivity of the buried environment for steel structures is primarily dependent on many factors including: pH, chloride content, sulfate content, resistivity, oxygen concentration, water content of the soil, presence of active sulfate reducing bacteria and the type of soil (e.g., organic content). For concrete structures, the aggressiveness of the soil is primarily dependent on a slightly different selection of factors including: pH, chloride content, sulfate content, total alkalinity calcium content, magnesium content, Langelier Saturation Index, and the presence of acid sulfate soils or potential acid sulfate soils. In the buried environment it is necessary to determine not only the concentration of aggressive elements in the soil, but the replenishment rate or inflow rate to enable a long-term as well as a short-term estimate of degradation rates. Where the buried elements form components of a tunnel structure, it is important also to assess the effect of water pressure. The affect of other aggressive substances on concrete are discussed in the German Standard DIN 7 8 4030 and in the American Standard ACI 201.2R .
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Immersed Immersed environments can range from relatively benign to severely corrosive toward steel and concrete. The corrosivity depends on a number of factors including: pH, dissolved salts (chlorides, sulfates), dissolved carbon dioxide, flow rate, pollution, and dissolved oxygen. In some environments, microbiological organisms can greatly accelerate the rate of corrosion (e.g., accelerated low water corrosion). The effect of these parameters is similar to those previously listed. External Influences Aside from the physical aspects of the environment that cause degradation to materials, there are other influences — particularly within the buried and sometimes the immersed environment — that also affect the rate of degradation of materials. The most common of these detrimental external influences are drainage currents from Direct Current (DC) railways and tramways, and stray current from adjacent Cathodic Protection (CP) systems. Stray current corrosion from these two sources is most common in buried steel structures, particularly pipelines, however, it has occasionally been observed in reinforced concrete structures. Changes to the Exposure Environment The exposure environment may be changed in several ways: 1. Mode of construction: The boring process for cast insitu pile in alluvial soil may expose potential acid sulfate soils (PASS) allowing conversion to aggressive acid sulfate soils (ASS). If a driven pile has been used in preference to the bored pile, the exposure to oxygen and the resultant conversion to ASS is less likely to occur. 2. Operation or maintenance of the infrastructure: Example 1 – In a long road tunnel, the buildup of exhaust fumes may result in a drastic increase in CO2 levels, SO2 and other gases, which increase the corrosivity of the atmospheric environment. Example 2 – Chemical spills also cause a significant change to the exposure environment. 3. Climate change – This is a large subject on its own and will not be discussed here. Physical Assessment of the Environment Testing to confirm exposure conditions is an important part of the durability process. Testing must occur within the corridors of the project at the location where the structure is to be built. This is particularly important for buried environments as soil is not particularly homogenous over large distances or with depth, so testing needs to be conducted at multiple locations within the project boundaries. SAUDI ARAMCO JOURNAL OF TECHNOLOGY
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For buried structures, including piles, pipelines and basements of buildings, it is necessary to sample and test both the soil and the groundwater at the depth at which the structure will be buried.
MODES OF DEGRADATION OF REINFORCED CONCRETE The service environment places a durability ―loading‖ on an asset and, depending on the construction materials, quality of workmanship during construction and the level of ongoing maintenance, the asset undergoes progressive deterioration or degradation, until unacceptable damage occurs. The mode of degradation is specific to the service environment and the construction material under consideration. Reinforced concrete can degrade by reacting with the environment such that either the concrete matrix loses cohesion and strength or the steel reinforcing rods corrode. The two most common modes of degradation are chloride ingress and carbonation, both result in 1, 9 corrosion of the steel reinforcement . Chloride induced corrosion predominantly occurs in splash and tidal zones and to a lesser extent in the immersed zones of marine structures. Carbonation induced corrosion most commonly occurs in the atmospheric zone of structures exposed to industrial pollution and road tunnel environments. The most important part of the structure protecting it against ingress of aggressive substance is the concrete cover. The quality of the concrete cover and the minimum concrete cover thickness are the values normally used when calculating the expected service life — based on assumptions regarding the penetration of de-passivating and corrosive substance to the reinforcement. It is evident that the quality of the outer concrete layer — or the concrete cover — and the cover thickness becomes the one single most important quality determining parameter. This is the only rational way of performing a quantified service life design for new concrete structures — and a residual service life design for existing structures. Concrete can lose cohesion and strength through chemical reactions with sulfates and acidic ground water, and contact with acid sulfate soil or soft flowing ground water. The extent of degradation of the concrete matrix from these causes can be difficult to estimate, so the concrete mix is usually enhanced to prevent attack. The enhancement of the mix may include: An increased cementitious content, lower water content, an increased density or the addition of supplementary cementitious materials. In addition to reacting with the environment, the service life of the concrete can also be reduced by thermal cracking during the construction process.
RATE OF DEGRADATION The next stage in the durability planning process is to determine the estimated rates of degradation that are likely in each exposure category in which the structure is
exposed. Degradation rate information can be obtained from published data from long-term in-situ monitoring or from concrete predictive modeling used with a computer model to increase accuracy in predicting future performance. Concrete durability and rate of degradation depends largely on the ease (or difficulty) with which fluids in the form of liquid (water), gas (carbon dioxide, oxygen) or ions (chlorides, sulfates) can migrate through the hardened concrete mass. Concrete is a porous material, therefore, moisture movement can occur by flow, diffusion or sorption. We are concerned with all three, but generally the overall potential for moisture and ion ingress in concrete by these three modes is referred to as its permeability. The durability of concrete is influenced or controlled by the type, number and size of 9 pores present . Low porosity/permeability/penetrability of concrete to moisture and gas are the first line of defense against: acid attack, sulfate attack, corrosion of steel embedment and reinforcements, carbonation, alkali-aggregate reaction, frost damage, and efflorescence, just to name a few of the most prominent concrete degradation mechanisms. When concrete is submerged, water ingress can also be assisted by an external head of water pressure. The rate of this pressure ingress is resisted by the density of the concrete. This property is measured by testing the concrete's permeability (the property of saturated concrete). An excellent source of information is provided by existing structures adjacent to the project site and exposed to the environment of interest. Asset owners may have sufficient information including as-built drawings, duration of exposure and maintenance history, to enable estimation of corrosion rates in specific environments. Under exceptional circumstances, testing may be permitted on adjacent structures to gain degradation rates. Predictive Modeling for Concrete Structures The standards governing concrete structure, specifically ACI 318-08 and ACI 350, only provide guidance on requirements for durability for a number of general environments. Sufficient consideration must be given to a number of environments — encountered in the durability planning processes — including: Chloride contaminated soil or water (other than seawater), atmospheres high in carbon dioxide, and hollow leg (water on one side and air on the other). The degradeation caused by these environments includes chloride and carbonation induced corrosion. The deterioration of concrete structures involves an initiation phase (T0), a preliminary propagation phase (T1), a secondary propagation phase (T 2) and a final propagation phase (T3), Fig. 2. The end of the preliminary propagation phase is the point at which the corrosion has resulted in initiation of longitudinal cracks
Fig. 2. Events related to the service life, and detailing of the 10 propagation phase .
though minimal damage has occurred to the structure. The damage escalates in the secondary propagation phase and the end of this phase is marked by the longitudinal cracks reaching the aesthetic limit of 0.3 mm in width. The damage further escalates during the final propagation phase, spalling occurs and the unacceptable loss of structural capacity occurs at the end of this phase. In the durability planning for a new structure the goal of modeling is to ensure that during the design life period for the structure, the deterioration does not pass beyond the preliminary propagation phase (T 0). The available models for the deterioration of concrete resulting from either chloride ion ingress or carbonation of the cover concrete only predict the duration of the initiation phase (T0). The period of preliminary propagation is usually estimated based on corrosion rates of steel reinforcement in specific environments. Moderately dry concrete exposed to high levels of CO2 may carbonate fairly quickly but the rate of corrosion may be significantly slow, to give in some circumstances, a T 1 period of 4050 years. In marine environments, the T 1 period may be as short as 10 years or less. Although significant research is still required to provide sound modeling of the T1 phase, using the initiation period to estimate the design life will produce an unnecessarily conservative design particularly in some carbonation environments. Modeling shall also be conducted to estimate the likely early age of the thermal cracking of sections of concrete due to the heat of hydration during the curing process. CIRIA C660 is a commercially available model that can successfully be used to predict early age thermal cracking. Chloride Ingress Modeling Even though several transport mechanisms play a role in the ingress of chloride ions into concrete, the majority of models for chloride ion penetration are based on Fick‘s Second Law of Diffusion for uncracked concrete. The SAUDI ARAMCO JOURNAL OF TECHNOLOGY
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diffusion equation is modified to incorporate the time dependent changes that occur with the chloride diffusion coefficient. The goal of the modeling is to estimate the depth of cover of concrete that will prevent the critical concentration of chloride ions diffusing to the depth of the reinforcing steel during the design life of the structure. For chloride modeling, the design life period is equated to T0 as the propagation period is relatively short in comparison with the initiation period. The critical concentration of chloride ions is typically 0.06% by weight of concrete. The critical concentration is defined as the concentration at which corrosion is initiated, independent from any damage to the structure. Life 365 is commercially available software based on ACI 365.1R for predicting service life of structures based 11 on chloride ingress and carbonation modeling . A key missing-point in research is the corrosion in RC flexural members (that normally include cracks) subjected to chloride attacks. Ignoring cracks in research on reinforcement corrosion can only produce incomplete, flawed and in most cases, misleading results. A very representative example is the initiation of corrosion in RC flexural members in a chloride-laden environment, in which a misperception has been prevalent for a long time that it takes 20 - 30 years for corrosion to start (based on Fick‘s Second Law). There has been 12 convincing evidence published , that in RC flexural members subjected to chloride intrusion; the initiation of reinforcement corrosion is a matter of short periods of time, e.g., months, not years. Carbonation Modeling The rate of carbonation is dependent on a variety of factors including the concentration of carbon dioxide, moisture content of the concrete, concrete mix, curing process, exposure conditions, size and distribution of the pore in the concrete and connectivity of the pores. Unlike corrosion of reinforcement in chloride contaminated concrete, the rate of propagation of corrosion in carbonated concrete may be relatively slow. So the goal for the carbonation modeling is to estimate the cover required to prevent the propagation of corrosion exceeding T2 during the design life of the structure. As the modeling only predicts the time to corrosion initiation, a sound knowledge of the corrosion rates in carbonated concrete under various environmental exposure is required. Modified versions of Fick‘s Second Law of Diffusion are usually used to estimate the corrosion initiation phase in carbonated concrete. A number of different models have been developed over the years. The most appropriate model is the Comité Euro-International du 13 Béton (CEB) model , which incorporates a number of the factors that govern carbonation including mix design, 14 curing and CO2 concentration . The CEB model provides a greater flexibility to adjust the model to suit the specific environment than other models that are available.
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PROVISIONS TO ENHANCE THE DURABILITY OF CONCRETE STRUCTURES 1. Interaction between durability design and execution. Already at the design stage, possible means of construction shall be considered and fixed, as this will influence the durability design. 2. Concrete specification shall be performance based to achieve the durability requirements for a specific project. Performance based specifications are becoming more common and are quantified by the use or adaptation of test methods that measure the principal chloride/carbon dioxide transport mech15 anism for specific exposure conditions . 3. Robustness in design and construction. One of the main obligations of the conscious designer is to adapt the design to the conditions under which the structure is to be constructed, operated and maintained to avoid structures being sensitive to variations in the assumed qualities. A degree of robustness in the design can be very advantageous with respect to the future performance and durability of the structure. 4. Selection of greater cover to reinforcement in aggressive environments and the use of correct spacers. The spacer material should have a good bond to the concrete and should have similar hygrothermal deformation characteristics as concrete. In this respect, plastic spacers are not compatible with the surrounding concrete. 5. The use of various good quality supplementary cementitious materials, such as pulverized-fuel ash (PFA), ground granulated blast furnace slag (GGBS), microsilica (MS) (also known as silica fume) and metakaolin (MK) refines the pore structure of concrete, achieving less permeable and chemical resistant concrete. 6. Provision of electrical continuity for reinforcement in substructure elements in more aggressive environments, to enable future cathodic protection installation if required. 7. Good detailing to enable compaction of concrete, along with good vibration and subsequent curing during construction, to ensure a dense layer of cover concrete. 8. The use of self-compacting concrete (SCC) is a concrete mix — where the placing and compaction has minimal dependence on the available workmanship on site — that would improve the quality of the concrete in the final structure. 9. Use of controlled permeability form liners (CPFL). The most important part of the structure protecting it against ingress of aggressive substance is the concrete cover, also considered the "skin" of the structure. CPFL has proven effective in enhancing the denseness of the outer mm and cm of the cover by reducing the water-cement ratio and improving the curing of this outer concrete layer. 10. Use of permeability reducing admixtures. The use
of an admixture — characterized by hydrophobic and pore-blocking ingredients (HPI) — appeared to considerably improve concrete durability with respect to chloride induced corrosion in concrete mixtures. These admixtures could be one of the solutions to chloride induced corrosion of steel reinforcement in concrete structures in very aggressive environments. The effectiveness of two typical commercially available permeability reducing admixtures, one characterized by crystal growth and the other by an HPI, were recently 16 studied . Experimental chloride concentrations of concrete specimens exposed to a simulated coastal environment were reported. The results were in favor of using HPI, whereas the inclusion of a crystal growth admixture seemed to have almost no detectable effects.
CONCLUSIONS Durability design is a complex subject and only a flavor of the issues has been provided in this article. For key infrastructure planning, the following issues must be considered:
Assessment of exposure severity based on proper statistical methods. Design based on anticipated deterioration mechanisms and material performance. Durability design based on the lowest economic life cycle costs. Specification of appropriate quality control tests. Specification of appropriate inclusion of sensors for monitoring performance. Appropriate use of risk assessment to determine testing and monitoring requirements and durability confidence levels.
On major projects, a full durability plan, prepared by a specialist durability consultant, will provide a degree of assurance that the structures will meet their expected design life; without the need for repairs that could be expensive, and even more costly, in terms of effect on operations. Durability planning starts in the tender submission phase of a project and continues throughout the design and construction phase. The majority of the durability planning process occurs in the detailed design phase. This article mainly discussed the durability planning processes associated with corrosion and deterioration of concrete as these are the most common durability problems in infrastructure. A summary of the durability processes was presented in this article. Finally, the competence to fully understand the durability related problem complex and to achieve optimized integrated performance based designs of concrete structures will have to start with adapting this into the engineering education curriculum. A new design paradigm is needed for the design and execution of
concrete structures. This is a precondition for concrete structures to increase competitiveness, and therefore remain the solid and reliable foundation for future societal prosperity.
ACKNOWLEDGMENTS The author would like to thank the management of Saudi Aramco for permission to publish this article. This article was previously presented and published in the proceedings of the International Conference on Future Concrete, Doha, Qatar, November 1-3, 2010, pp. 59-70.
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BIOGRAPHY Dr. Emad A. Abu-Aisheh joined Saudi Aramco in February 2009 as a Structural and Civil Materials Engineer working in the Consulting Services Department. Prior to joining Saudi Aramco he was leading the concrete technology and structural dynamics unit of WorleyParsons, Australia. Emad also served as lecturer and research scientist at the University of Melbourne, Victoria, Australia, Curtin University, Perth, Australia, Virginia Tech, Blacksburg, VA and the Higher Colleges of Technology, Abu Dhabi, U.A.E. He has over 22 years of experience in structural engineering and concrete technology split between academia, research and industry. Emad‘s specialty fields include: durability, concrete technology, structural engineering, repair and waterproofing of concrete structures, liquid retaining structures, modal testing of civil structures, structural health monitoring, NDT of civil engineering structures, and finite element modelling. He has 19 world-class publications and over 40 technical engineering reports in the areas of structural dynamics, durability, concrete technology and NDT. In 1986, Emad received his B.S. degree and in 1987, he received his M.S. degree, both in Civil Engineering from the University of Mississippi, Oxford, MS. He received his Ph.D. degree in 2003 in Civil Engineering from the University of Melbourne, Victoria, Australia. Emad is a member of several international organizations, including the American Concrete Institute.
