John Douglas

Jean-Jacques Serrano

RISK ASSESSMENT FOR THE ROAD NETWORK IN THE FRENCH-ITALIAN BORDER REGION USING WEB SERVICES

Data Infrastructure for Risk Management' (ORCHESTRA, http://www.eu-orchestra.org/) being undertaken by BRGM, JRC and Ordnance Survey with the collaboration of local partners in the French-Italian border region between Nice and Genoa. The basis of the pilot is the evaluation of risk to the road network and the impact of road network disruption by, for example: earthquakes, landslides, floods, fires and chemical spills. Road closures can have a dramatic impact on the economic, social and functional life of a region and these impacts can spread far from the site of the blockage and, even, across international borders. The region chosen for this pilot project is especially prone to hazardous events and also, due to the lack of redundancy in the road network within the region, disruption to a major route can have a large effect. This pilot will seek to create a distributed network of web services that will access hazard, route and traffic information held within databases based at the data providers.

Once completed, users of the system developed during the pilot will be able to: simulate events leading to road blockage or disruption; calculate estimated traffic, alternative routes and their level of traffic; estimate additional costs (time and money) caused by the disruption, and the subsequent economic losses for the affected region; and run these simulations to identify pinch points within the road network and improve planning and prevention.

Potential end-users comprise: experts within the Piedmont and Liguria regions; transport and toll motorway companies; and national and regional administrations.

The key technical aspects addressed are: access to diverse data sources; risk assessment from multiple hazards; and use of semantics (ontologies) for efficient multilingual and crossorganisational database querying.

1.

Introduction

In today's rapidly changing world it is becoming more and more important that risk from natural and hazards with a human origin is correctly managed. Increasing urbanisation and the undertaking of high-value projects means that, in some areas, risk is increasing. In addition, due to climate change there is some evidence that the hazard level due to weather-related perils is becoming larger. As in all aspects of modern life information technology (IT) is playing an increasing role in risk management since it allows the undertaking of certain tasks and makes others easier to perform.

However, risk management in Europe and elsewhere is made more difficult by interoperability problems due to IT systems that cannot easily communicate with each other. Even those in organisations concerned with the same risk, e.g. two institutes concerned with different aspects of earthquake risk, may be running different computer systems. The problem is even worse when viewed across risk domains, e.g. IT systems concerned with industrial risk cannot often communicate with those concerned with earthquake risk, limiting the ability to undertake true multi-risk analysis. Multi-risk analysis is being increasingly recognised as an important tool because it gives a better overall picture of the level of and the interactions between risks in a region (e.g. [START_REF] Douglas | Physical vulnerability modelling in natural hazards risk assessment[END_REF]. In order to overcome these problems, users often must spend valuable time reformatting files, for example, to the detriment of undertaking more fundamental risk management tasks. In addition, this effort is, in some sense, wasted since, in all probability it will need to be repeated when data is sourced from another organisation or when a new IT system is developed. These interoperability problems limit the work that can be achieved since it is difficult to access and use existing data; data which cost much time and effort to collect.

In Europe, these problems arise not only across different types of risk, but also across regional and national borders. In addition to interoperability difficulties, language differences also become an issue. It is often important to undertake risk management across borders because impacts of events are not limited by human borders and actions undertaken to mitigate risk are also not contained by political boundaries.

In order to address these difficulties on a large scale considering the whole range of geographical data, an EC directive called INSPIRE (http://inspire.jrc.it) was launched in 2001. It is planned that this directive will be fully implemented by 2013 (implementation will begin in 2007). The directive is concerned with the setting up of a European Spatial Data Infrastructure, to implement metadata rules for data and services, to implement rules for harmonised spatial data specifications (exchange and update, ID systems, thesauri, key attributes, etc.) and to implement rules for network services (upload, discovery, view, download, transformation, etc.).

To develop these ideas into the field of risk management, a Framework Programme 6 Integrated Project (FP6 IP) called Open Architecture and Spatial Data Infrastructure for Risk Management (ORCHESTRA, http://www.eu-orchestra.org) was launched in September 2004. In the following section the ORCHESTRA project is briefly introduced. The following sections are then concerned with the pilot implementation of an ORCHESTRA system in order to aid in undertaking risk assessments for the road network in the border region of France and Italy.

2.

ORCHESTRA

ORCHESTRA involves 15 partners both from the risk management domain and from the IT industry. The purpose of the project is to design a platform-independent open service-oriented architecture (SOA) for risk management purposes, and implement it for Internet-based applications (web services) that can be called via the web to undertake a given process. They could be seen as subroutines located on the web to be used when needed by any user. The 'open' part of the project refers to the fact that the specifications of these services are being made public and free of charge so that they can be implemented by any interested party and can be accessed by all potential users. The actual procedure followed by the web service to perform the required task is not considered and is not specified; however, the inputs and outputs to the service and the actions it must undertake are specified. The philosophy behind this approach is that if the specifications are followed then risk management systems using these web services will be fully interoperable without needing to be created by a common entity. This philosophy has key advantages with respect to other approaches. For example, it is expected to favour the emergence of an operational market for risk management services in Europe, it eliminates the need to replace or radically alter the hundreds of already operational IT systems in Europe (drastically lowering costs for users), and it allows users and stakeholders to achieve interoperability while using the system most adequate to their needs, budgets, culture etc. (i.e. it has flexibility).

Interoperability of IT systems is a subject of much research and development in many countries. For example, the Open Geospatial Consortium (OGC) is an organisation that seeks to develop software standards in the field of systems concerned with geographical information. In addition, there are existing and under-development ISO and EC standards. ORCHESTRA bases its architecture on these standards and seeks to influence their development in order to make them applicable to risk management applications.

An additional advantage of the SOA approach in the risk management domain is that it allows applications to be updated with minimal effect on the services that call them. Procedures involved in risk management change often as experience is gained through disasters. Consequently it is important that the systems developed are agile allowing developments to be rapidly implemented in practice.

In the second half of the ORCHESTRA project four concurrent pilot projects concerned with different aspects of risk management in various European regions are being undertaken. The aim of these pilot projects is to validate the services and architecture developed during the course of the project and to demonstrate the results of the project to potential end users. In order to build on work already undertaken in earlier workpackages of the project and since it addresses truly multirisk and cross-border aspects, BRGM, JRC and Ordnance Survey decided to develop a pilot project based on the risk to the road network from different hazardous events, such as earthquakes, landslides and industrial accidents. The following sections briefly introduce the problem and the work being undertaken.

3.

Pilot project on risk assessment for the road network

Road transport plays an important role in the economic, functional and social life of a region. For example, roads enable the transport of commodities from their source (e.g. a factory) to the distribution centre (e.g. a shop) and the consumers from their homes to the distribution centre. Therefore, disruption to a road can have a dramatic impact and lead to extra costs, inconvenience and, within the post-event phase of the disaster cycle, difficulties in accessing affected communities. Roads can be disrupted (e.g. blocked) by a number of different events, for example: direct surface rupture or liquefaction caused by an earthquake, landslides (however caused), fire (forest or otherwise), floods, chemical incidences, avalanches, volcanoes and storms (through the falling of trees). [START_REF] Cova | Transportation Hazards, Chapter 17, Handbook of Transportation Engineering[END_REF] provide a good review of the types of hazard that can affect the road network and also their consequences. By focusing on the effect of an event, where the cause of the event is not specified, the proposed pilot is multi-risk. In addition, many of the services required to undertake the pilot are risk-neutral and can be used for various other projects.

As an example of the large impact that disruption to an important trans-frontier road can have, consider the closure of the Frejus road tunnel in the Alps between France and Italy due to a fire on 4 th June 2005, which killed two people. The average truck traffic each day through the tunnel was 3 800, all of which had to find alternative routes, such as through the Mont Blanc tunnel, which required a detour of about 200km. The tunnel accounts for about four-fifths of the commercial road traffic between France and Italy. The tunnel remained shut for about two months. This closure lead to large additional transportation costs. The three-year closure from 1999 to 2002 of the Mont Blanc tunnel due to another fire, which killed 39 people, was estimated to have cost the Italian economy 2.6 billion euros.

The area chosen for this project is the department of Alpes-Maritimes (06) in France and the Piedmont and Liguria regions in Italy, where BRGM and JRC already have good contacts with potential end users. The cross-border roads in this region, for example the E80 (A8 in France and A10 in Italy) motorway from Nice to Genova, pass through mountainous areas and feature many tunnels and viaducts. These make them particularly susceptible to hazards that block the road because it is not possible to easily by-pass or remove the blockage due to access difficulties. In addition, the mountainous relief in the region means the number of alternative routes is quite low.

Use cases

In this pilot project it is planned to implement six general well-defined procedures undertaken by end users (commonly called 'use cases' in IT parlance). It is expected that these six will test many aspects of the system and will demonstrate its ability to overcome current interoperability problems. Also the selected use cases involve varied interactions between different parties, e.g. different data providers and various end users. The following figure shows the relationships between the different use cases that will be considered and the following table gives brief details of these use cases. In order to aid with the implementation of these use cases their details have been transformed to Unified Modeling Language (UML). This pilot project is split into three phases of about six months each. Three use cases have been developed during Phase 1 and the final three more are being developed in Phase 2. Phase 3 concentrates on testing and improving the implemented system and installing it in the end users institutions.

ud Use Case M odel Find routes cut by a possible ev ent

Calculate cost of route unav ailability M otorw ay company

Regional authority DDE, Regional council, ...

Find the roads exposed to hazard

Hazard expert

Find alternativ e routes after a route is cut

Road transport company

Calculate losses of rev enue

Citizen

M aps of alternativ e roads

Calculate estimated time of unav ailability

Engineering company

M anages Consults «include» «include»
Relationships between the different use cases that are considered in the pilot project.

Use case Details Find roads cut by a possible event The end user retrieves data on the road network and the possible hazardous events in the region. Then they simulate the triggering of an event and the system is used to identify which roads will be cut by such an event. This information is stored for use by other use cases.

Find roads exposed to hazard

The end user collects data on the road network and maps of the level of hazard for different types of event (earthquake, landslide, flood etc.). From this information they compile an inventory of the roads that are at risk. Find alternative routes after a route is cut Firstly the user retrieves road and traffic information for the region. Next they collect information on which roads will be blocked by an event (e.g. from the first use case) and they indicate within the road network information where these blockages are. Finally the system calculates alternative routes for different types of traffic and stores these routes for future use.

Calculate estimated time of unavailability

This use case simply retrieves from an external source an estimate of the amount of time that a road will not be usable. This estimate is stored for later use.

Calculate loss of revenue

The user compiles information on the length of time that given roads will be unavailable (from the previous use case). Then they search for traffic that uses these roads and from combining these pieces of information arrives at an estimate of the loss of revenue to an industry due to the closure of the road.

Calculate cost of route unavailability

This use case combines information coming from previous use cases to estimate the overall economic cost of a road being unavailable. In the first step, the user collects information on the road network, the traffic that uses the unavailable roads and how long these roads will be unavailable for. From this information and the list of alterative routes for each traffic type the system computes an estimate of the cost of the road being blocked.

Data required

In order to accomplish the use cases described above it is necessary to access and process a number of different types of data, namely: hazard maps, catalogues of historical hazardous events, traffic data, road network data, political division data and topographical information. These data are accessed via the developed web services. Due to differences in the data structures and the languages used (French, Italian and English) between the various accessed information a simple WFS-X service has been developed in order to undertake the schema mapping and the language translation. The table below lists the various data that are employed to date within the pilot although there are plans to use data from many other sources. To aid in the search for relevant hazard maps the metadata of the maps used within the pilot are entered into the IGOS Geohazards GeoHazData metadata catalogue (http://www.igosgeohazards.org/). This metadata catalogue is being developed as a contribution towards the aims of the Group on Earthquake Observations (GEO).

Type of data

Calculation of affected area

Within this pilot it is necessary to estimate the roads that may be blocked by the occurrence of a particular event, e.g. an earthquake, landslide or flood, given in the catalogues listing the location and size of previous hazardous events. Ideally this would be performed by combining an estimate of the hazard with the vulnerability of each road to compute the expected damage. From this estimated damage the roads affected by the event could be computed. This could be performed using fragility curves (expressing the expected level of damage given a level of hazard), which are dependent on the road's vulnerability, for each type of hazard. However, except for earthquakes, there are difficulties in constructing fragility curves for other natural hazards and few such curves exist [START_REF] Douglas | Physical vulnerability modelling in natural hazards risk assessment[END_REF] Summary of hazards affecting the road network (after [START_REF] Cova | Transportation Hazards, Chapter 17, Handbook of Transportation Engineering[END_REF].

In Phase 1 of the pilot a simple scheme was employed to estimate the area affected by a hazardous event by simply assuming that the area is a circle that is a function of the size of the event depending on empirical relationships. In Phase 2 and 3 the area is more accurately estimated by making use of additional information. For example, in the case of the repeat of an historical earthquake (such as the destructive 1887 event in the region) the observed macroseismic intensities from the SISFRANCE database are used as input to a geospatial interpolation algorithm based on kriging in order to predict the area in which the road network could be blocked.

Digital rights managment

An important part of this pilot project is a consideration of data security and the handling of access rights to data -two growing issues in the creation of geospatial data infrastructures. In risk management, as in other domains, some data is sensitive (e.g. the locations of Seveso plants) and it is important that access to this data is well managed so that it can only be viewed by authorised users. In addition, there are important issues over payment and access rights to some types of information and services. All these important considerations will be investigated and will be implemented within the pilot in the following three step approach.

Phase 1: Open Access Services -initial integration of services with no authentication and authorisation. The objective of this phase is to build the initial pilot capability and test the implemented services.

Phase 2: Authentication and Authorisation Services -installation and configuration of the ORCHESTRA Service Network Architecture Services for authentication and service authorisation.

Phase 3: Prototype Digital Rights Management Capability -this stage will address the higher risk aspects of implementing technical measures to manage and protect the content owners' intellectual property. The content owners requirements will be understood during phases 1 and 2, and key elements of these requirements will be prototyped during this stage.

Client

So that the end user can easily make use of the services developed and the data collected during this pilot implementation a web-based client has been developed using MapBuilder v1.5 and BRGM libraries.

Interoperability experiment with a pilot of the FP6 WIN IP

It is planned to demonstrate the interoperability between this pilot and demonstrations of the system developed within the FP6 IP Wide Information Network (WIN, http://win-eu.org/), which has similar goals to ORCHESTRA. This experiment will consist of a use case scenario concerning a simulated event in the pilot region where the WIN demonstration will access and use results from the ORCHESTRA pilot on traffic re-routing and cost and time evaluations. In return, it is planned that this pilot will use services developed by WIN concerning, for example, multiple language thesauruses of risk concepts.

Conclusions

As in many aspects of IT, risk management is currently hampered by interoperability difficulties due to a variety of data formats, procedures, platforms etc. These difficulties are being addressed, on a general, scale by the ORCHESTRA project and, for specific cases, by a series of associated pilot projects. This brief article discusses the pilot project being undertaken by BRGM, JRC and Ordnance Survey concerned with assessing the risk to the road network in the France-Italy border region. The complete implementation of this pilot project should be completed by summer 2007 when the developed system will be demonstrated to end users and other concerned parties at a workshop to be held in the pilot region.

12.

  . A discussion of the computation of the risk to the road network from earthquakes is provided by D'Andrea et al. (2005). Cova & Conger (2004) present a more general discussion of risk to the road network from various hazards. The following diagram summarises the hazards affecting the road network. Within this pilot the main focus of interest are those in the second column (block or damage infrastructure) and those in the final column (create obstacles).

  The following table lists the web services and the implementations being used within this pilot.

	7.
			Data source
	Historical events	French	earthquakes:	SISFRANCE	http://www.sisfrance.net/
			French mass movements: BD Mvt http://www.bdmvt.net/
			French underground cavities : BD Cavités http://www.bdcavite.net/
			Italian earthquakes: INGV CPTI04 http://emidius.mi.ingv.it/CPTI04/
			Italian earthquake faults: INGV DISS http://www.ingv.it/DISS/
	Hazard maps	Maps for rockfall, subsidence, landslide and flooding hazard produced
			by BRGM for the Roya valley
	Traffic levels	French data: from the DDE and ESCOTA
			Italian data: data collected from various regions
	Road network	TeleAtlas
	Political divisions	IGN for France and Tele Atlas for Italy
	Topography	Tele Atlas and Demis
	6.	Services used
	Service		Implementation
	Feature Access Service	WFS of GeoServer
	Map and Diagram Service	ORCHESTRA
	Schema Mapping Service	WFS-X created by BRGM
	Authentication Service	ORCHESTRA
	Authorisation Service		ORCHESTRA
	Catalogue Service		IONIC
	User Management Service	ORCHESTRA
	Gazetteer Service		WFS-X and Gazetteer of BRGM + Geonames
	Processing Service		GRASS
	Cost Calculation Service	BRGM
	Route Calculation Service	JRC-IPSC

Acknowledgements

This work is co-funded by the European Commission's IST programme, under Unit G5 "ICT for the Environment", through the Integrated Project FP6-IST 511678 ORCHESTRA (see http://www.eu-orchestra.org). We thank the project coordinator, José Esteban, for his corrections.

13.


Sylvain Guignot
email: s.guignot@brgm.fr

Y Menard

S Touze

K Bru

Development of an Innovative Technique for Demolition Concrete Up-cycling: a Response to Mitigate GHG's Emissions and Natural Resources Depletion

Keywords: concrete, cement paste, aggregates, clinker, CO 2, recycling, fragmentation, pulsed power, environmental assessment

Concrete is the second most used material worldwide and the first used man-made material. Its production entails large emissions of GHG due to lime decarbonation during the clinkering process, as well as large consumption of non-renewable minerals and natural aggregates. Currently legislative pressure aiming at preserving natural resources is growing tighter on natural aggregates extraction, which motivates research for alternative raw materials in building concrete manufacturing. Among these materials, aggregates from waste concrete are the most promising as they already fulfill some of the physical and mechanical requirements for the use in concrete. One key point that has to be considered is the cement paste content at the aggregate surface, since it adversely affects the adhesion between the aggregates and their surrounding cement matrix in concrete, thereby resulting in concrete with low mechanical properties (). Current practices in concrete recycling consist in largely non-selective crushing and screening processes, which do not allow a straight separation between the clean aggregates and the cement paste.

The present study describes a high-voltage pulsed-power process of concrete fragmentation which enables to recover clean aggregates and hydrated cement paste (HCP). This HCP conveys valuable elements -Ca, Si, Fe, Althat would potentiallyreduce energy and natural resources consumption as well as CO 2 emissions of the clinker making process, if it were introduced in the raw mix of the clinker kiln. Overall environmental benefits of this up-cycling chain depend on the mineralogical composition of the cement paste, which in turn depends on the operational conditions of the concrete fragmentation process. To date, only scarce data are available to assess this recycling scheme. In this framework, our study tackle the subject by putting forward an experimental investigation of the pulsed-power process, coupled with a calculation methodology to assess the environmental benefits associated with the recycling of the obtained hydrated cement paste in clinker manufacturing. The proposed methodology leads the way to a comprehensive environmental assessment of concrete recycling schemes, based on a forthcoming LCA study that will make use of the results presented.

INTRODUCTION

Despite being the second most used material worldwide and the first used man-made material, concrete when recycled does not get a good press. Treated by means of low selective technics, the use of crushed concrete remains restricted to low added-value uses (most often as road base materials) since the produced aggregates are covered with a residual cement paste which impairs a good adhesion during a subsequent concrete reprocessing (Domingo-Caboet al (2009), Gómez-Soberón (2002a, 2002b)).At the present time, none of current technology allows recovering this cement paste, even though its unique composition and reactivity make it an ideal candidate for a clinker raw mix additive among all possible cementitious materials.Thus an additional benefit of crushing out clean aggregateswould be tolower natural resources depletion for Ca, Si, Fe and Al minerals bydirectly feeding clinker raw mix with a a high quality cement paste.

So asto estimate the potential of Recycled Cement Paste use in the raw mix, a calculation methodology has been developed tolink the raw mix composition with the CO 2 emissions and the energy consumption of the clinker process. The mineralogical composition of the RCP, its water content and its mean carbonation rate are taken into account in the calculation procedure. The raw mix composition is constrained by three specific parameters traditionally used by clinker manufacturer: the Lea and Parker lime saturation ratio, the silica ratio and the Kühlalumino-ferric module. The cement paste considered is produced by an innovative process for concrete recycling. This process includes an embrittlement step that uses the energy of high voltage pulses in order to induce a selective fragmentation of concrete waste blocks immersed in water. In addition to being a highly energy efficient technic, pulsed-power fragmentation is highly selective. This technology permits to recovermore hydrated and partly non-carbonated cement paste than a usual impact crushing for new clinker elaboration.

MATHEMATICAL MODELLING

General assumptions

Clinkerisation refers to the high-temperature reactionstaking place in a cement kiln, to dissociate CO 2 from CaCO 3 and combine the resulting CaO with silica, alumina and ferrous oxides to form clinker. The resulting powder is mostly composed of following compounds: 3CaO.SiO 2 (C3S), 2CaO.SiO 2 (C2S), 3CaO. In what follows we consider a dry clinker processing route in which raw materials are grinded and intimately blended before being pre-heated and sent to the kiln to form the clinker. We develop a mass-and enthalpybalance model to relate the clinkercomposition to the raw mill composition, and determine the variations in the energy consumption and the CO 2 emissions when part of raw mill is replaced by a hydrated cement paste.

Massbalance

In the model, raw materials consist of limestone (CaCO

Enthalpybalance

The enthalpy-balance model aims at estimating the variation in the energy consumed by the precalciner and the kiln when alternative raw materials are used. It assumes that the temperatures and the residence times in the pre-calciner and the kiln are not altered by the change in the raw mill composition. This implies that the various thermal losses around the equipments or associated with clinker and the transport of hot gases remainunchanged. In this configuration, the variation in the process specific energy ( S E ) is only contributed by the variation in the enthalpy of the reaction leading to clinker formation with recycled concrete, The term in bracket accounts for the thermic losses of the process without recycling, andis thus used as a reference value.

ck ref r H is the reference enthalpy for clinker formation using hydrated cement paste. In industrial plants of Portland cement dry processing, a mean value for E s,ref is 750 kcal per kg of clinker (Elkjaer, 1977).

The calculation of ck ref r H and ck r H are performed using the enthalpy of formation of the raw materials, the mineralogical phases of the clinker and the gases arising from the clinker formation -H 2 O and CO 2 (Table 1), according to the formula:

j , i j , F j i , F i ck r H . m H . m H 0 0 j m (resp. i m
) is the mass of reactants j (resp. of products i , clinker and gases). 0 i , F H stands for the enthalpy of formation of species i per unit mass.

All calculations are performed at 298 K, since to date no data were found concerning the sequence of reactions accounting for the thermal decomposition of the hydrated cement paste into reactive materials inside the kiln.

CO 2 emissions

CO 2 emissions resulting from the coal combustion in the kiln can be calculated (Eq. 3) and summed with the emissions from the dissociation of calcite (Eq. 4).

Cement paste substitution in raw mix for clinker production

Several criteria can be usedto control the quality of the clinker made from recycled concrete, and to precise the range of values allowed for the proportions of recycled concrete in the crude materials.

On a mineralogical point of view, a clinker formulation dedicated to a standard Portland cement must meet the following requirements, expressed in weight percent: 45.0 < C3S < 79.7, 5.7 < C2S < 29.8, 1.1 < C3A < 14.9, 2.0 < C4AF < 16.5 (Taylor, 1997). These values correspond to the main oxides composition in clinker: Lime saturation ratio represents the ratio of total lime content to the lime content which entirely combines with SiO 2 , Al 2 O 3 and Fe 2 O 3 . A high SR meansahigh silica content at the expense of flux agents, resulting in an impaired clinker burnability. Alumino-ferric ratio gives an indication of the formation of the C3A phase: below a value of 1.5, only alumina combines with iron oxide and only C4AF is formed. Lastly, the total of the four major oxides is considered to show very little variation, due to the fact that most cement plants use raw material from reliable sources that limit the variability of the minor and the major constituents. Therefore, the following sum is taken as a constant: (Eq.7)

20.0 < SiO 2 < 24.3 %, 3.7 < Al 2 O 3 < 7.1, 1.7 < Fe 2 O 3 < 5.
The mean value for t found after a review of six Portland cement plants by [START_REF] Moore | Chemical control of Portland cement clinker[END_REF]

EXPERIMENTAL

Experiments are performed on concrete wasteusing two different technologies: an impact crusher, which is widely used for concrete recycling, and an innovative technique based on pulsed power fragmentation. The objectiveis to evaluate the feasibility of the pulsed-power route to induce a selective fragmentation of the concrete.

The initial material is composed of 18wt per cent of hydrated cement paste and 82wt per cent of a mixture of silica sand and aggregates. This latter mixture is made up of 40wt per cent of -2 mm sand and 60wt per cent of 2-20 mm aggregates.

The impact crushing is performed on a Hazemagimpactor with a rotation speed of 290 rpm.The pulsed power fragmentation is performed on a laboratory device designed by Selfrag Company (Switzerland). The material is loaded into a 0.2 dm 3 bowl filled with tap water and whose bottom consists of a counter electrode.

Results

Table 2 summarizes the preliminary results. The chemical characterization is currently under way and will be given on the oral presentation.

Table 2 According to these results, the cement paste content shows similar values throughout the tests, i.e with a crushing or a pulsed power configuration (52 -49 -48 %wtrespectively). The amounts of fines produced with fragmentation are at least equivalent to the one produced with the usual crushing process, around 3 wt per cent. This value corresponds to the direct outlet of the concrete crushing/fragmentation processes and would beincreased by adding an attrition step on both processes to recover more fines.In the case of selective electrofragmentation, the embrittlementpreferentially occurs at aggregates surface and not within.

Thus, less aggregates particles are likely to be produced during the attrition stage; therefore, the quality of the fines fraction recovered could be improved. Tests are currently under progress to support this assumption. With more stringent conditions of fragmentation (conf.2) the fines amount reaches 10 wt per cent. The energy consumptions are almost the same and remains low, around 1 kWh/t of materials.

MODEL IMPLEMENTATION

Two cases are considered, with and without recycled concrete.In both cases, the solid combustible is a dry bituminous coal with a lower heating value of 8500 kcal/kg. The air required for the combustion is supposed to be dry.The raw mixesare assumed to be dry when they enter the preheater of the clinker production process. In the case of no recycled concrete use, raw materials are the pure minerals considered previously: (Olivier, 1969). Table 3 gives the corresponding composition. chemical characterization of the cement pastes obtained at the outlet of a pulsed power fragmentation process and associated downstream processes. To evaluate the environmental benefits in using pulsedpower in place of impact crushing for concrete waste treatment, a comprehensive comparison will be drawn and will include the various consumptions and emissions of both processes, withoutsidesteppingthe reuse of the cleaned aggregates generated along with the cement paste in the pulsed power process for new concrete production. This forthcoming evaluation will performed according to a LCA methodology, that will make use of the theoretical and experimental results given in the present study. Enthalpies of formation for reactants and products involved in clinker processing. [1] :

limestone (CaCO 3 ), kaolinite (2.SiO 2 .Al 2 O 3 .2H 2 O),

TABLE CAPTIONS

CEMDATA07 data base, see Lothenbachet al (2008), Matscheiet al (2007) and

Möschneret al (2008). [2] : Barinet al (1977). [3] : Barinet al (1993). [4] : Barinet al (1989). [5] :

Frenkelet al (1994). [6] : Landoltet al (2002).

Material 0 i , F H , 298 K (kJ.kg -1 ) C3S [1]
-12 855 C2S [1] -13 419 C3A [1] -13 189 C4AF [1] -10 453 C3AH6 [1] -14 656 C3FH6 [1] -10 642 C3ACScH12 [1] -14 067 C3S2H3 [2] -13 970

Al 2 O 3 (

 3 C3A), 4CaO.Al 2 O 3 .Fe 2 O 3 (C4AF), with final lime content below 1 wt per cent.

  the weight proportion of combustible burnt to achieve the formation of 1 kg of clinker, coal C y is the carbon molar contents in the combustible, are the weight proportions of CaCO 3 , recycled concrete, clay, and iron ore in raw materials and sand CaCO y 3 is the limestone content of sand.

  Heating Value of the combustible.

  7 and 61.0 < CaO < 68.0 %. These ranges of acceptable values are interrelated according to various characteristic ratios stemming from the mechanistic description of clinker formation in kiln. Main ones are the Lea and Parker formula for lime saturation ratio ( LaP), the Kühlalumino-ferric( MK ) and silica ratio ( SR ). Associated ranges of acceptability are:

  is 0.96. Considering the dependence of CaO, SiO 2 , Al 2 O 3 and Fe 2 O 3 content on the proportions of the crude materials and on the part of HCP in the recycled concrete, fulfilling these previous inequalities brings a range of acceptable values for each main constituent in the crude materials. In what follows, the proportions of crude materials (CaCO 3 , clay, iron ore and recycled concrete) are expressed in term of the previous characteristic ratios, given (Eq.6) and the mass conservation of CaO, SiO 2 , Al 2 O 3 and Fe 2 O 3 along the reaction path between the crude materials and the clinker. Considering the content of these latter species in the recycled concrete as parameter values, this approach leads to 4 equations with 4 parameters and 3 variables, whose range of variation are known. Setting the parameters values, the determination of theacceptable range of variation for the crude materials proportions consist in calculating the absolute minima and maxima of each of the 4 equations. A Sequential Quadratic Programing algorithm is implemented in MATLABand is used to solve the equation system.

A

  second electrode is fixed on the upper part of the bowl, and a high-voltage current is discharged onto concrete blocks. The electrical breakdown of solids takes place when the voltage of the pulse exceeds the electrical strength of the mineral matrix. High voltageaffected concrete blocks are splitted along grains interfaces characterized by different permittivity and/or electrical conductivity. Operating parameters are the working electrode gap, the number of pulses, the pulse frequency and the voltage.Each experiment consists of several batches (450 g each) to treat at least 10 kg of material.Two configurations are tested: conf.1 (working electrode gap: 30 mm, number of pulses: 5, voltage: 110 kV) and conf.2 (working electrode gap: 30 mm, number of pulses: 15, voltage: 125 kV).The amounts of fine particles produced at the outlet of both fragmentation devices are obtained by manual sieving (-2 mm). The cement paste content (assumed to be similar to the insoluble content) is obtained after an acid digestion of the recovered fine particles, performed by contacting the solid with an18.5 wt percent hydrochloric acid solution in a ratioliquid:solid 3:1during 4 h.

  silica (SiO 2 ) and goethite (Fe 2 O 3 .H 2 O). In the case of recycling, same raw materials are used (except for silica) and the Recycled Concrete is made up of silica Sand composed of 99 wt per cent of SiO 2 , and 1 wt per cent of Fe 2 O 3 .Given the experimental results, the model is implemented considering a fine fraction made of RC HCP y 50 wt per cent of a hydrated cement pasteand 50 wt per cent of silica sand. To remedy the temporary lack of information concerning thecontents of chemicals in the cement paste, calculations are made with literature data

Fe

  3 , clay (kaolinite: 2SiO 2 .Al 2 O 3 .2H 2 O), iron oxide ore (Fe 2 O 3 .H 2 O) and Recycled Concrete (RC), composed of Hydrated Cement Paste (HCP) and sand (S).FollowingOlivier (1969), the HCP is assumed to be composed of residual Ca(OH) 2 and the 4 following

	mineralogical phases:
	C3S2H3 : 3CaO.2SiO 2 .3H 2 O
	C3AH6 : 3CaO.Al 2 O 3 .6H 2 O
	C3FH6 : 3CaO.Fe 2 O 3 .6H 2 O
	C3ACScH12 : 3CaO.Al 2 O 3 .CaSO 4 .12H 2 O
	The mean contents of anhydrous compounds in the clinker -CaO, Al 2 O 3 , FeO and SiO 2 -are estimated by
	mass conservations of the initial reactants.

Table 1 -

 1 Enthalpies of formation for reactants and products involved in clinker processing

Table 2 -

 2 Amounts of fines produced by a usual impact crushing and the pulsed-power fragmentation process

Table 3 -

 3 Mineralogical and chemical compositions of the recycled concrete used in the model implementation

Table 4 -

 4 Estimation of minerals amounts, emissions of CO2 and enthalpy of clinker formation in the case of no recycling in the crude materials, and recycling of a mixture hydrated cement paste/sand : 50/50 wt per cent.

	clk
	F

H : enthalpy of clinker formation. S E : specific energy.

TABLE 1

 1

Table 3

 3 Mineralogical and chemical compositions of the recycled concrete used in the model implementation

	Mineralogical	Chemical
	Composition	Composition
	CaCO 3	0	CaO	25.59
	SiO 2	49.50	SiO 2	58.23
	Fe 2 O 3 .H 2 O	0.50	Al 2 O 3	2.19
	C3S2H3	24.89	Fe 2 O 3	1.69
	C3AH6	4.35	MgO	0.60
	C3FH6	3.25	Na 2 O+K 2 O	0.30
	C3ACScH12	6.17	CO 2	6.60
	Ca(OH) 2	10.51	H 2 O	10.32

Table 4

 4 Estimation of minerals amounts, emissions of CO 2 and enthalpy of clinker formation in the case of no recycling in the raw materials, and recycling of a mixture hydrated cement paste/sand : 50/50wt per cent.

				clk
				F
	Raw Materials	wtper cent relative to clinker	Clinker wt per cent relative to clinker
			No recyling	Recyling Equal modules	Recyling Lowest CO 2		No recyling	Recyling Equal modules	Recyling Lowest CO 2
	CaCO 3	121.7	107.9	104.9	C3S	57.9	56.8	54.5
	2.SiO 2 .Al 2 O 3 .2H 2 O	16.5	14.8	10.3	C2S	21.2	21.2	27.8
	SiO 2	14.9	(-)	(-)	C3A	12.4	12.4	7.4
	Fe 2 O 3 .H 2 O	3.1	2.5	2.9	C4AF	8.3	8.3	9.6
	Recycled cement paste	(-)	26.5	33.0
	CO 2 emissions	wt per cent relative to clinker	Modules for clinker characterization
			No recyling	Recyling Equal modules	Recyling Lowest CO 2		No recyling	Recyling Equal modules	Recyling Lowest CO 2
	Raw materials	53.5	47.5	46.2	LaP	0.94	0.94	0.90
	Coal combustion	26.5	26.7	25.8	MK	2.36	2.36	1.50
	Total	80.0	74.2	72.0	SR	2.44	2.44	3.00
	Enthalpy
			No recyling	Recyling Equal modules	Recyling Lowest CO 2
	clk F H for 1 kg	1623 kJ	1575 kJ	1479 kJ
	clinker
	Specific Energy
	E	S	2945 kJ	2897 kJ	2801 kJ
	for 1 kg clinker

H :enthalpy of clinker formation. S E : specific energy.

ACKNOWLEDGEMENTS

The authors wish to thank the the French Research Agency ANR for its financial support through the COFRAGE project (ANR-Ecotech 2009), as well as all the partners of the project (Picheta, Colas, CNRS -IMS, Selfrag AG and INPT -LGC). The authors gratefully acknowledge the contribution of G. Baudet to this work.

Table 3 Given the contents in CaO, SiO From these values, and a given case of clinker processing without recycled cement paste, Table 4 describes the results of mix proportions calculations obtained in two cases : (i) when modules with recycled cement paste are equal to modules without recycling, and (ii) when the biggest reduction in CO 2 emissions is targeted (this corresponds to the minimum value allowed for raw CaCO y 3 ). Table 4 According to the results, the specific energy consumption is reduced by 3per cent when recycled concrete is used and clinker with equal module is formed. Total calcite content in a recycling targeting the lowest possible CO 2 emissions corresponds to a calcite introduction in the raw mix of 107.9 weight parts,or similarly a decreaseof14per cent in calcite consumption, along with small reductions in iron ore and kaolinite minerals.

CONCLUSIONS

On the basis of theoretical calculations, the present study proves that reusing the cement paste contained in concrete waste as a raw constituent for clinker processing,lowers the CO 2 emissions as well as the mineral resources consumption. The exact potential substitution in the raw mix will be refined with the forthcoming

Table 2

Amounts of fines produced and associated content of cement paste by an usual impact crushing and the pulsed-power fragmentation process