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Presentation of my projects in modeling domain
Presentation of my projects in modeling domain
- Aggregates exploitation and transport flow (France)
- Artisanal Gold Mining (Burkina Faso)
**    Paper Award
- Ultra-pure Quartz exploitation (Madagascar)
- Collective management of animal wastes (La Réunion)

Aggregates exploitation and transport flow in France

(Unsigned photos: © BRGM)

1- Background and issues

aggregates kindWhat are aggregates?

Aggregates are unconsolidated materials used for two principal purposes all over the world:
- as one of the main components of concrete being used as elementary grains associated to cement,
- as bases of road or railway infrastructures (foundation, ballast).
aggregates sources

 The aggregates are retrieved from two principal sources:
1- alluvial deposits (sand and gravel) which are unconsolidated and easy to extract, both on-shore and off-shore, often sorted by sedimentation processes and with naturally rounded grains.
2- hard rocks such as sandstone, limestone, crystalline rocks, that need to be crushed and produce angular grains of different sizes.  Crushed, recycled, concrete is regularly proposed as a possible substitute but often fails to meet the market demand for the specific physico-chemical nature of natural rocks.

Exploitation issues

As aggregates are low value materials, any additional treatment or transport adds significantly to the price of the final product.  For the modern society two main issues are continuously in conflict:
- the population refuses quarries (the aggregate exploitation sites) close to their places of living; 
- the producing companies are obliged to realize short transportation distances for the large volumes of material to remain economic (gas price, trucks...) and comply with environmental legislation (noise, dust, degradation of roadways).

aggregates transportThe above conflict of issues is becoming a major stake for the next years and is intrinsically related to the more general problem of aggregate supply, also exposed in France. Experts in the field of aggregate production and consumption announce potential shortages in the supply of bulk aggregates to the large centres of urban development in the near future.  The zones with strong consumption of materials and the location where aggregates can be extracted from their geologically determined deposits do not have any reason to always coincide.

Socio-economic factors and demographic trends determine the aggregate demand but aggregate resource sites close to growing towns are more and more often exhausted or their access is disabled to favour other land-use occupation activities, e.g. to preserve natural suburban spaces or to allow agriculture.

Social and economic impacts

aggregates transportIf the economic impact of industrial activities can be measured thanks to parameters such as the sales turnover, the benefit, the dividends... the socio-economic impact is less standardized. It is above all apprehended by the activity generated in term of employment.

Moreover, it is by employment that an industrial company is anchored to a territory, in spite of the current tendency to disunite the economic entity from its social reality. If the reasons which leads to the establishment of an extractive company are basically related to the context with gitologic knowledge, the anchoring of the company on the territory appears ex post by generated employment (direct, indirect and induced).

At global level, with an annual production in the EU25 of 3 billion tons, an average consumption of 5 to 15 tons of aggregates per capita per year, an estimated employment of 250,000 jobs, and a total value of 35 billion €, the sector of aggregate production and consumption in the EU is the largest macro-regional market in the world.

The socio-economic impacts are not limited to employment. In a thorough approach, it would be relevant to consider the social repercussions via externalities which may be positive (revitalization of a career to a base of leisure after exploitation), or negative (transformation of a career to a discharge).

2- Modelling & Simulation

In order to anticipate the access to aggregates beyond current schemes and on a long term basis ranging from 15 to 30 years in France, two modelling projects, MEGG and ANTAG, in which I am involved, have token place at BRGM. These projects adopt two complementary approaches:
- MEGG, in which aggregates activities are analyzed at micro/meso level. It uses multiagent system approach, and bottom-up design scale (from departmental/regional to national scale).
aggregates flow model- ANTAG, in which aggregates activities are analyzed at macro level. It uses dynamic system approach and top-down design scale (from national to regional/departmental scale)

During a first stage, the objective consists in an understanding of the current or short-term planned mechanism in the field of the aggregates supply, consumption, transport mode and flow. A chock of the model with real world is necessary.

During a second stage, the objective consists, via prospective simulation, in an elaboration of scenarios of careers closing (diagrams of rupture) and then in attempting to answer the following questions:
- what might be the socio-economic and environmental effects of these careers closing in the long term ?
- what might be the best possible reorganizations in terms of aggregates supplying ?
- where would be the best adapted location to open other productions ?

The idea also is to find an optimization of the mechanism of transportation accordingly.



With regards to MEGG, the socio-economy field is used to supplement the panorama of the aggregate network in the prospect of sustainable development. At that stage, Seine-Maritime was selected like pilot department. In particular, we have chosen to concentrate on the aggregate careers of the sector of Anneville-Ambourville (see photos).


Nevertheless, taking into account the availability of data, the jump of scale towards the region of Haute-Normandie may be necessary to process certain data of the production network.

The methodological exercise of collecting economic and social data as well as their coupling with more traditional data (geological and technical-economic ones) will then be a ground of research privileged for the definition of indicators applicable to the territorial management of the extractive activities in France.


sdageWith regards to ANTAG, France is divided into 6 geographical areas according to the SDAGE decomposition. These areas are :
- Artois Picardie
- Seine Normandie
- Loire Bretagne
- Adour Garonne
- Rhône Méditerranée
- Rhin Meuse

Inside these areas, we manipulate aggregate data about production, consumption, transportation and flow inside a region or between regions.

Current stage

MEGG and ANTAG are ongoing projects. Modelling and simulations results will be presented later…

Note that the two projects are administratively independent (in BRGM calendar terms) and as such, they progress in a parallel way. However, the idea of coupling the two modelling approaches is really planned in the future.

(Unsigned photos: © BRGM)