Template for samaris documents

2.3Knowledge found outside Europe

2.3.1Information and recommendations from USA

The SAMARIS WP3 group, which includes an American partner (University of New Hampshire) has reviewed some recent documents from United States of America (USA).. The aim was to find existing knowledge of elements and methodology to assess the use and reuse of materials (including road construction and industrial by-products) in road pavements.

Important general information has been found in the reviewed texts from USA, which may be useful for our further work This chapter summarizes the important findings.

User guidelines from Federal Highway Administration (1998) cover nineteen materials from domestic, industrial, mining and road pavements. The purpose of the document is to assist those who have an interest in using and increasing their understanding of the types and by-product materials that may be recovered and used in pavement construction applications. FHWA-RD-97-148 (1998).

A report from the Association of State and Territorial Solid Waste Management Officials, “Beneficial Use Survey” pointed out that decision makers are discussing the meaning of beneficial use. There must be benefit to diverting what was previously considered waste for use in another location or application. The report states that in general, for a waste to be used beneficially the latter must have chemical or physical properties similar to the raw material it is replacing or, when incorporated into another product, its use must have some enhancing qualities to the final product which would distinguish that use from disposal.

Also, beneficial use of a waste must not be expected to result in adverse affects to human health or the environment. While there may be considerable confusion over when use of a waste is truly beneficial, the beneficial use of a waste would typically have one or more of the following characteristics: (1) used in a manufacturing process to make a product; (2) used as a substitute for a raw material or with other materials in a construction project; or (3) used as a substitute for a commercial product. ASTWMO (2000).

Apul et al (2002) state that water enters pavements despite efforts to prevent it, but the extent of pavement deterioration can be reduced by proper drainage and maintenance. The major water ingress routes are infiltration through the pavement surfaces (through joints and cracks) and shoulders, melting of ice during the freezing/thawing cycles, capillary action, and seasonal changes in the water table. In the literature the most emphasis is placed on infiltration through crack, joint and shoulders and drainage through edge drains. Use of an impermeable material to seal surfaces can slow (not prevent) infiltration. Sealing may also cause moisture accumulation within the asphalt concrete mixture by blocking evaporation. Drainage systems (permeable base, edge drains, and geo-textiles) are used to remove excess water that has entered the pavement.

Moisture in pavements increases or decreases after construction until equilibrium is reached. Seasonal moisture content variations and subsequent changes in pavement performance that occur after equilibrium are more pronounced in cold regions. Groundwater conditions may also influence pavement and especially subgrade water content if the ground water table is within approximately six meters from the surface. Apul et al (2002).

Comments from the SAMARIS WP3 group

The user guidelines from FHWA give a good overview of several alternative materials. For the further work there is a common agreement in the WP3 group about some of the recommendations, but the group needs to discuss to which level the recommendation can be incorporated in the SAMARIS proposal for a general methodology for the assessment of alternative materials. As an example the recommendations regarding the alternative material chemical and physical properties can be somewhat different, as far as the alternative material fulfils the functional requirements of the application into which it is used.

2.3.2USA frameworks found in reviewed documents

In 2001 the US Federal Highway Administration, FHWA, published a report: Framework for Evaluating Use of Recycled Materials in the Highway Environment. The report pointed out that although many by-product materials - such as recycled concrete material, recycled asphalt pavement, blast furnace slag, and coal fly ash - have historically been used in the highway environment, methods for evaluating the engineering and environmental suitability of such materials have not been formally developed.

Some State agencies have adopted regulatory or procedural frameworks for examining the potential for using recycled materials, but the absence of definitive methods of evaluation and specific criteria for determining the suitability of using such materials have in most instances limited the utility of these procedures.

The FHWA report presents a framework. It is developed by an expert group to present general methods for evaluating the engineering and environmental suitability of alternative materials of all types used in road construction. The framework is recommended and presented in a hierarchical flowchart in the Figure 2.4.

Figure 2.4. Evaluation framework flow process. Figure 2-1 FHWA-RD-00-140 (2001).
Following sections are extracts from the FHWA report. FHWA-RD-00-140 (2001).

The purpose of the evaluation framework is to articulate a logical process whereby a decision maker can evaluate a recycled materials utilization application and determine whether the proposed application is technically and environmentally feasible.

The framework presented is intended as a road map. The road map is intended to be a consensus-based document so that all parties in the decision-making process are aware of the evaluation procedure and the criteria that will be used to approve or reject the application.

Framework step 1

The first step in the framework process is selection of the applicant of a material and application. There are seven major application categories in the highway environment in which recycled materials have their greatest potential applicability. Table 2.1 lists recycled materials that have been used or have the potential for use, based on their engineering properties, in the seven major application categories previously described. As is evident in the table, many potentially recyclable materials have a number of potential uses. For instance, coal fly ash has been used as a mineral filler in asphalt paving, as mineral admixture in Portland cement concrete, as fill material in embankments, as pozzolan in stabilized base, and as a fine aggregate in flowable fill mixes.

Framework step 2

The second step in the framework process is the issues definition step. The purpose of this step is to identify all relevant historical activities, engineering and materials property data, environmental health and safety data, potential implementation issues, future recycling issues, and economic issues associated with the proposed material application. During this step an evaluation should be made to determine whether there are any readily apparent issues that could warrant rejection or modification of the proposed application. A flowchart that can be used to identify the key issues in any material-application proposal is presented in Figure 2.5.

Framework step 3 (Stage 1 in Figure 2.4)

The third step in the framework process is the screening step. The screening step includes screening procedures for engineering and materials properties, environmental, health, and safety, recycling, implementation, and costs. The purpose of the screen is to determine, on the basis of existing data, whether the proposed application can be approved without additional study.

Framework step 4 (Stage 2 in Figure 2.4)

The fourth step in the framework process is the laboratory testing evaluation. The testing evaluation is intended to characterize (1) the engineering and materials properties and (2) the environmental, health, and safety properties of the proposed recycled material and its application product.

During the development of the test plan, the decision maker will need to determine the criteria on which an approval will be based. Two approaches for evaluating the material properties are available. The first includes the use of ASTM or AASHTO specifications imposed by local jurisdictions (e.g., State Department of Transportations (DOTs)), and the second, which is most applicable when such criteria are nonexistent, is the use of a reference material (e.g., conventional construction material) to assess the relative engineering properties of the pro-posed material versus that of the reference material.

When testing new materials in highway construction applications, the passing or failing of one engineering property test may not warrant a rejection of the material, particularly if performance testing suggests that the final product (e.g., an asphalt pavement) will perform satisfactorily. There may be instances where the proposed material yields poor particle strength results, but in a blended matrix product the material performs in an acceptable manner. When a questionable situation arises, the decision maker can ultimately revert to Stage 3 field evaluations to resolve laboratory uncertainties.

Application	Recycled Material
Asphalt Concrete Pavement
Mineral Filler	Asphalt Plant Dust Sewage Sludge Ash Cement Kiln Dust	Lime Kiln Dust Coal Fly Ash
Asphalt Aggregate (Hot Mix)	Blast Furnace Slag Coal Bottom Ash Coal Boiler Slag Foundry Sand Mineral Processing Wastes Municipal Solid Waste Ash Nonferrous Slags	Petroleum Contaminated Soils Reclaimed Asphalt Pavement Roofing Shingle Scrap Scrap Tires Steel Slag Waste Glass
Seal Coat or Surface Treatment Aggregate	Blast Furnace Slag Coal Boiler Slag	Steel Slag
Asphalt Cement Modifier	Roofing Shingle Scrap Scrap Tires	Plastic
Portland Cement Concrete Pavement
Mineral Admixture or Cement Additive	Coal Fly Ash	Blast Furnace Slag
Portland Cement Concrete Aggregate	Reclaimed Concrete
Granular Base
Granular Base Materials	Blast Furnace Slag Coal Bottom Ash Coal Boiler Slag Combustor Ash Foundry Slag Mineral Processing Wastes Municipal Solid Waste	Nonferrous Slags Petroleum Contaminated Soils Reclaimed Asphalt Pavement Reclaimed Concrete Steel Slag Waste Glass
Stabilized Base
Stabilized Base or Subbase Aggregate	Coal Bottom Ash Coal Boiler Slag	Petroleum Contaminated Soils
Stabilized Base Supplementary Cementitious Material	Coal Fly Ash Cement Kiln Dust	Lime Kiln Dust Sulfate Wastes
Flowable Fill
Flowable Fill Aggregate	Coal Fly Ash Foundry Sand	Quarry Fines
Supplementary Cementitious Material	Coal Fly Ash Cement Kiln Dust	Lime Kiln Dust
Embankment and Fill
Embankment or Fill Materials	C&D Debris Coal Fly Ash Mineral Processing Wastes Nonferrous Slags	Petroleum Contaminated Soils Reclaimed Asphalt Pavement Reclaimed Concrete Scrap Tires
Landscaping Material
Soil Amendment, Top Cover, Mulch	Biosolids Wastewater Sludge Compost	Wood Chips C&D Wood Waste

Table 2.1: Potential uses of recycled materials in various applications. Table 2-1 FHWA-RD-00-140 (2001).


Figure 2.5: Issues evaluation steps. Figure 2-2 FHWA-RD-00-140 (2001).
Framework step 5 (Stage 3 in Figure 2.4)

The fifth step is intended to provide field-scale data on (1) engineering and materials properties and (2) environmental, health, and safety properties of the proposed recycled material and its application product. These data can then be compared with established performance criteria, with reference materials (e.g., a control section), or with appropriate standards or regulatory limits. The field testing stage is most applicable in situations where (1) the proposed recycled material has not been used historically so there is little or no field data, (2) there is little or incomplete historical data for the recycled material and more field data are needed, or (3) the proposed recycled material is being considered for new use in applications and there is no pertinent field data. FHWA-RD-00-140 (2001).

Eighmy (member of Samaris) and Magnee (2001) give following short description of the FHWA report: The framework was recently published by the FHWA to establish a logical and hierarchical evaluation process that all state can use either to develop a beneficial use determination process or to refine an existing process of this type. The purpose of this document is to help reduce barriers to the use of recycled materials and to facilitate the mitigation of successful practices across state boundaries.

Additionally, because the management and regulation of recycled materials use in the highway environment are jurisdictionally the responsibility of a state’s department of transportation (DOT) and its environmental protection agency (EPA), a major goal was to work with state DOTs and EPAs to develop a consensus approach that would encourage the two agencies to work together in the evaluation process. The process uses a series of stages that can each lead to approval or a beneficial use application from both engineering and an environmental perspective. It comprises issue definition, data evaluation, laboratory testing, and field tests. Eighmy and Magnee (2001).

Comments from the SAMARIS WP3 group

When looking for pre-existing frameworks for mechanical and engineering assessment of alternative materials, the WP3 group agreed that the most pragmatic and comprehensive one is the framework proposed by the FHWA. Therefore, the WP3 group will adopt the same approach as the one used by the FHWA (RD-00-140) report writers, to develop its proposal for the general assessment methodology. The FHWA report will be used as a basic document for further work.

Considering that most of the procedures and tests proposed in the FHWA framework have a equivalent at European level or at least at national level in at least one European country, the WP3 group’s proposal is to start by an assessment of the procedures and tests proposed in this framework with regard to the nine materials which the WP3 group already has chosen for further work.

The reliability of the tests proposed in the framework for these materials will be analysed for each application of the typical road structure that has been defined earlier.

Then, in a second phase, possible ideas of improvement of the FHWA framework will be investigated in other specialised frameworks for mechanical or environmental assessment of materials.

2.3.3Problems to be solved and research needed from the USA point of view

The report from Federal Highway Administration describes the facts described hereafter. Some recycled materials that may be proposed for use in a given application may have unique properties that do not readily lend the materials for testing as prescribed in the proposed test methods. For example, an applicant wishing to use scrap tire as an embankment material will have difficulty applying the test methods because of the relatively large size of the tire chips (25 to 75 mm), which cannot fit into the testing moulds. Examples of properties and corresponding tests that are unsuitable include permeability (AASHTO T215 or ASTM D5084), compressibility (AASHTO T216 or ASTM D4186), bearing capacity (AASHTO T193), and shear strength (ASTM D2850, ASTM D3080, and ASTM D4767). In such cases alternative methods may be needed or design conditions will have to be based on field experience and construction specifications and not lab testing. FHWA-RD-00-140 (2001).

Gardner and Eighmy (2001) state that there is a clear sense that the relative risk of using recycled materials requires further study. The ability to predict long-term environmental and physical performance is also crucial, and the ability to effectively share information, resources, and lessons learned, is also important. A number of research needs related to applications as well as research needs about “newer” recycled materials were identified.

There seems to be some consensus regarding the most needed areas of research summarized in the following points:

• 
  Risk-based evaluation and environmental impact assessment methods for recycled materials.
  

- How can we quantify this risk, and should it be done in a comparative manner (using which reference ?)?

- What are the appropriate laboratory or field tests that will enable quantification of risk in a reasonable and realistic manner?

- What is the appropriate, application-specific, framework with which to evaluate the environmental impact from laboratory or field testing programs?

• 
  Prediction of long-term physical and environmental performance of “new” construction materials.
  

- What are the appropriate tests to determine long-term structural, geo-technical, and environmental performance of a material that is new to the road construction industry?

- How can structural or environmental stresses be accurately accelerated in a laboratory or at a field site?

• 
  Synthesis of testing protocols, beneficial use determination procedures, acceptable risk parameters, leaching data, materials performance data across the 50 states is needed to reduce redundancy, eliminate inconsistencies, and facilitate specification and use of recycled materials in highway construction.
  
• 
  Research is needed on the highest volume use of recycled materials: in road construction and particularly as part of the pavement system. Materials include
  

- roofing shingles;

- mining waste;

- glass;

- dredged material;

- recycled concrete products; and

- reclaimed asphalt.

Applications include:

- all pavement system components (sub-base, base, and wearing course);

- large-volume structural and nonstructural fills; and

- concrete applications. Gardner and Eighmy (2001).

Apul et al (2002) focus on following needs for research:

• 
  Not much information exists on unsaturated hydraulic conductivity measurement techniques both in the field and in the lab. Development and standardization of unsaturated hydraulic conductivity techniques to be used for pavement studies is warranted.
  

• 
  More research is required on relative significance of ingress and egress routes; mainly crack infiltration, evaporation, and capillary rise. Apul et al (2002).
  

Comments from the SAMARIS WP3 group

Examples of properties and corresponding tests that are not suitable for all alternative materials (due to their great variety) include permeability, compressibility, bearing capacity and shear strength, which are described in the FHWA report, and this supports the findings on the European level.

The WP3 group agrees to several research needs, but the group will leave this to future research, as it is not possible to deal with it in the SAMARIS project.

The group will contribute, if possible, to clarify the research tracks useful for solving the problem: assessment of alternative materials for road construction.