How geosynthetics contribute to improve infrastructures

Geosynthetics help connect people

Roads and railways are of utmost importance for the development of any country. Not only economic growth and climate action but also social development heavily dependent on infrastructure (UN 2015). The following subsections show how geosynthetics help improve road networks, railways, and bridges.

Using geosynthetics to improve road networks

Paved roads are designed and constructed to allow safe, efficient, and economical transportation of passengers and commercial traffic. To achieve these objectives, pavement degradation induced during construction and operation of the pavement must be kept within acceptable limits. Due to the systematic traffic of heavy vehicles, climatic conditions, and the mechanical properties of the materials used in road construction, the service life of road pavements may thus be shorter than expected.

In this scenario, geosynthetics are effective in the following ways

1. Mitigation of reflective cracking in asphalt mixes: Over time, repeated loading and varying weather conditions cause cracks and joints in the pavement to manifest in the new pavement, a phenomenon known as “reflective cracking”. A reflective crack propagating through a new pavement surfacing can make the new surfacing vulnerable to water intrusion and early failure. In this case, geosynthetics reinforce, separate, stiffen, and comprise a barrier (Zornberg 2017a).
2. Separating: A major cause of failure of pavements built on resilient foundations is the contamination of the aggregate base material by the underlying resilient subgrade. Even a small number of fines contaminating a granular layer can negatively affect the structural response of the granular layer due to reduced base layer thickness, which reduces road life (Zornberg 2017a). A geotextile placed between a fine-grained subsoil and a coarse-grained base course can minimize contamination of the base course by fine particles pumped from the subsoil under repeated traffic loads (Bourdeau and Ashwamy 2012) and allow the basecoat to stay “clean”. ‘, which retains its strength and drainage characteristics (Perkins et al. 2012).
3. Stabilization of flexible road foundations: the reinforcement provided by geosynthetics is often essential to allow the initial construction. The presence of a weak subgrade can lead to localized shear failure in the subgrade, which creates significant deflections in the various overlying layers of the pavement (Zornberg 2017b).
4. Provide lateral drainage of pavements: In pavements, water flow can be induced by pore pressure generated in the subgrade by traffic load. In the absence of a suitable filter, fines retained in the subgrade can be carried by pore water into the base. The key to this application lies in the geosynthetic’s ability to filter fines without clogging (Perkins et al. 2012). Drainage is also important because the presence of moisture in the base and/or foundation layers of a pavement is detrimental, compromising the mechanical properties of these soils (Zornberg 2017b). Adequate drainage of a pavement is expected to extend the life of the pavement system by a factor of two to three compared to a similar pavement with inadequate drainage (Perkins et al. 2012).

Geotextiles and geogrids have also been successfully used to separate, filter, drain or reinforce soils from unpaved roads (Bourdeau and Ashwamy 2012).

Geosynthetics connecting people via railways

Railways are also important for connecting people and improving improvements in certain places. For example, about 7,000 km of railway tracks in India (out of 60,000 km) rest on weak foundations, which lead to ballast penetration and result in multiple losses, such as additional maintenance costs for the tracks and the rolling stock, speed restrictions, higher fuel consumption, and passenger discomfort. Rehabilitating and strengthening these tracks can help remove speed restrictions (Venkatappa Rao 2016). In this context, geotextiles ensure the separation between the different layers to prevent the fines of the support from being pumped into the granular layers, which would reduce the resistance and the drainage capacity of these layers. The separation of the different layers is therefore a function of geosynthetics in this context. Good drainage is essential to avoid deterioration of the track and can be improved by using a drainage geocomposite (IGS n.d.d).

Finally, the key functions of the sub-ballast are stress drainage and absorption to dissipate stresses from wheel loads to acceptable values ​​at the sub-base. A geotextile can accomplish this by separating the subsoil from the overlying material to avoid ballast contamination. Additionally, a geogrid can provide lateral containment and thus reduce shear stresses in the subsoil below.

Bridges

GRS Full Bridge technology combines the technologies of GRS Full Bridge and retaining walls with an FHR facing. The first step in building a full GRS bridge is to build a pair of GRS walls. After deformation of the supporting soil and backfilling of the GRS walls, the FHR facings are made by pouring concrete in place on the face of the wall wrapped in a geogrid reinforcement. Finally, a continuous beam is constructed with both ends embedded into the top of the FHR facings. The beam is also connected to the top of one or more intermediate pillars, if they are built (Tatsuoka et al. 2014). GRS integral bridges have virtually no bumps in the approach embankments and suffer no structural damage to the facing due to seasonal thermal expansion or girder contraction, while their stability against floods, tsunamis and seismic loads is very high. These characteristics are attributed to the stepwise construction of the FHR liner, which is firmly connected to the geogrid layers (Yonezawa et al. 2014). GRS integral bridges are now the standard for railways in Japan. They are suitable options for rail and road bridges in many places around the world.

Towards a new global society

Science and technology have had an undeniable effect on the world. Today, no sphere of human life is spared by science. Previous sections have highlighted this phenomenon by focusing on how developments in geosynthetics science and engineering affect land management and enable physical connections between people. While we all agree on the essential role played by science and technology, we are less and less sure of the criteria to adopt to guide its applications. Science itself is unable to dictate the human qualities required to guide our use of the Earth (Thuan 2013). This is where values ​​are paramount.

Setting values

What are the values? A compass to think about and a guide to action. They are characterized not only by the fact that value systems endure, but also by the fact that they influence not only individuals but also societies. Values ​​have value; they represent what is non-negotiable for an individual or a group of individuals (Lenoir 2012). As a Frenchman, I am influenced by the national philosophers often quoted in this Giroud lecture. Readers are of course encouraged to broaden their thinking beyond the preliminary approach developed here and incorporate their own philosophy and worldview. Lenoir (2012) suggests that six values ​​could serve as a basis for the construction of a new civilization on a planetary scale, not based solely on market logic but on what, in various forms, has constituted the base of civilizations around the world. world. world and which is shared by all: beauty, truth, justice, respect, love and freedom. Through a dialogue of cultures, a reformulation of values ​​must contribute to building a global civilization based on universal values ​​integrating local singularities. But what meaning should be given to these six values? And how are they expressed in the cosmos of geosynthetics? A brief overview is given in the following sections.

Beauty

In India, beauty is considered the reflection of the perfect ordering of the World, as is the case with Chinese or Greek thinkers. If there is a formal beauty attested by art, architecture and natural forms, there is also a form of ideal and transcendent beauty which goes beyond the canons of beauty to come closer to the supreme divinity. Kant (2015) writes that when we talk about beauty, we enter the realm of universality. Beauty is the absolute represented in a relative way, the infinite represented in a finite way, eternity represented in a temporal way (Comte-Sponville, 2006).

Geosynthetics blend into the local environment

Some authors in the field of geosynthetics make explicit references to beauty. For example, some structures reinforced with geosynthetics may be seeded with grass or the beds may be filled with live plants during installation. Once the plants grow, the structure becomes a beautiful green home for insects and other animals from the local environment. Additionally, geosynthetics allow builders to use natural elements in combination with reinforcement tools, providing better, more economical performance and beautiful results (Man et al. 2010). This is also the case with geosynthetic reinforced soil embankments, as mentioned by Christopher (2014), which can be arranged according to the natural environment to provide an aesthetic advantage over retaining structures. Lawson (2016) mentions that geotextile bags for liners, which can be made in appropriate colors, can blend in aesthetically with beach environments.

Another effort to showcase the beauty of geosynthetics is the promotional video for the 7th International Conference on Geosynthetics (Nice, France), which features a fashion show where top models are dressed in geosynthetics (geotextiles, geogrids, geomembranes). Other similar initiatives originated courtesy of manufacturers and were presented, for example, at the 10th International Conference on Geosynthetics in Berlin.

More recently, the IGS Photo Contest was designed to finally compile an excellent collection of photos showcasing the exceptional work of IGS members. One of the challenges of this conference was to illustrate the different sections with “beautiful” images, and several photos from the IGS photo competitions were used for this purpose. These competitions have been extended to other countries or parts of the world, such as Brazil, North America, France and South Africa.

Beautiful theories in geosynthetics

Beauty in science is the physical beauty of the world, not just the visual beauty that stands out, but also the beauty inspired by the coherence and order of the world (Thuan 2013).

Unlike beauty in art, the beauty of a theory is not relative, it does not depend on eras or cultures; it is universal. A beautiful theory must be simple in the assumptions and axioms that support it, which is also a form of elegance. According to Thuan (2013), the last quality of a beautiful theory is to make beauty and truth coincide; it conforms to Nature.

In an effort to rework this definition, Jean-Pierre Giroud thought it best to first define the word “theory” for a technical field. According to Giroud, a theory is an abstract description that aims to represent reality. In our field, abstraction is necessarily represented by mathematical equations and accompanying text. Because the number of experiments we can conduct is limited, a theory has the power, through mathematics, to extrapolate what we learn from a limited number of experiments to an infinite number of cases. A theory therefore not only explains observations but also predicts future events, which makes it essential for design purposes. This is the characteristic that makes a theory useful: it is the basis for accurate predictions. However, this alone does not make the theory beautiful.

Giroud also says that a good theory must deal with an important subject and encompass various phenomena or be related to a complex mechanism. A beautiful theory must be elegant and therefore simple, especially if it describes complex phenomena. The main characteristic of a good theory can be its enlightening effect: it must clarify things for the user, allow him to understand the phenomenon in question. The parameters must therefore be clearly identified and their impact must be assessed in an immediately understandable way. Moreover, originality is also an important characteristic of a good theory. Finally, among the theories he has developed, Giroud proposes two theories from the field of geosynthetics that he finds attractive: (i) the theory of the development of wrinkles in geomembranes and (ii) the filtration criterion, by putting the emphasis on the criterion of retention (the monumental theory on filtration juxtaposes various theories).

Truth

The notion of truth is diverse and refers to various orders: (1) knowledge, including scientific knowledge, (2) ultimate truth, (3) stable benchmarks to guide one’s life and (4) alignment between reality and the way we describe it. If the first two orders are perhaps less consensual, the last two seem more universal. Alongside the concept of alignment between facts and discourse, specific to Western civilization, another complementary expression of truth has emerged in Asia, that of truth as coherence (Piorunski 1998; Lenoir 2012). In short, a proposition is true not only if it conforms to reality but also if it is consistent with other propositions that are part of the same paradigm. Through this approach, truth can be linked to a way of life, to human experience (both social and inner) and to our relationship to the world. The truth is what allows us to direct our lives.

Thuan (2013) states that the goal of science is truth. Science approaches truth asymptotically, including in the geosynthetics cosmos: research conducted today is increasingly precise and allows for increasingly precise description and analysis of specific phenomena, as illustrated by the most publications.

Truth is also a concern when it comes to adhering to ethical rules and the veracity and originality of published data. The editors of IGS’s two official journals, Geosynthetics International and Geotextiles and Geomembranes, have made tremendous continuous efforts over the past decades to ensure quality publications through a peer review process. Similar review processes are also in place for the organization of regional or international conferences. Such criteria are necessary and must be maintained to continue to ensure the credibility of the information produced in the field of geosynthetics. According to the IGS Code of Ethics, no member of the IGS will knowingly make a false statement or false information.

Justice

Justice aims to establish laws, equality between humans, peace, sharing of land and wealth (Lenoir 2012). Although justice is one of the most constant and rooted values ​​in all the cultures of the world, the challenge is to bring it to life in our actions. Svami Prajnanpad, an Indian sage, says that justice is a law of exchange, that is why it is so difficult. He who gives before he takes or is ready to give as soon as he takes, who considers all others as himself from the depths of himself and considers no one as a stranger to him, is on the path of justice (Comte- Sponville 1997).

SDG 16 emphasizes justice, which is one of the three values ​​along with freedom and respect to feature in all 17 goals. SDG 16 states that national and local institutions should be accountable and deliver fairly to all without demanding bribes. No planetary civilization can be sustainable without justice being implemented at all levels of social life (Lenoir 2012).

Giroud (2006) argues that no existing research company would have treated polymer scientists and geotechnical engineers, textile or plastics manufacturers and earthmoving contractors, civil engineering and material suppliers. No existing society would have provided an open forum for civil engineers and the plastics industry as the IGS does. Justice is thus rendered to the members of the IGS, and the pursuit of justice is what has enabled the IGS to achieve international consensus.

During election periods, IGS Chairs never fail to encourage recommendations from people at the various seats to try to ensure good representation from all parts of the world on the IGS Board. Furthermore, the direct election of IGS members has historically led to a good balance of constituencies within the IGS Council, both geographically and professionally (Zornberg 2012).

Each IGS chapter has access to a dedicated web page on the IGS website, can contribute to each issue of IGS news, and can compete for the selection of nominees for the awards or to organize a regional conference or international.

The IGS also contributes to improving environmental justice. According to the Lancet Commission on Pollution and Health (The Lancet Commission 2017), pollution and pollution-related illnesses are often a reflection of environmental injustice, which is the inequitable exposure of poor, minority and deprived populations. their rights to toxic chemicals, contaminated air and water, unsafe workplaces and other forms of pollution. The concomitant and disproportionate affliction of these populations by pollution-related diseases amounts to a violation of their human rights. A fundamental principle of environmental justice is that all people and communities are entitled to equal protection by environmental and public health laws and regulations.

International development organizations, including United Nations agencies, multilateral development banks, bilateral funding agencies, private foundations and non-governmental organizations, have important responsibilities in pollution control and disaster prevention. pollution-related diseases that complement and extend the role of governments. These agencies should raise pollution prevention up the international development and global health agenda and dramatically increase the resources they devote to pollution control (Lancet Commission on Pollution and Health (The Lancet Commission 2017 )). In this case, a better sharing of the resources produced by the IGS would undoubtedly contribute to increasing environmental justice in the world. This is the option chosen by the French chapter of the IGS, which gives free access to their website and to references on the state of the art on the use of geosynthetics (in French and in English). And free should not be considered synonymous with worthless when it brings more justice.

The geosynthetics community is looking for ways to educate engineering students about geosynthetics and make them aware of the usefulness of geosynthetics. Dixon et al. (2017) mention the IGS sustainability film as a good example of IGS teaching materials. This film, as well as the IGS leaflets, have been translated into several languages, facilitating their appropriation. Short courses and training lectures are also available at international conferences.

A successful IGS initiative is the EtE program. The main objective of this program is to ensure that every student graduating from an undergraduate engineering program receives a basic exposure to geosynthetics. One way to implement this action is to provide educators with the knowledge and tools to help them integrate geosynthetic topics into their engineering curricula. EtE events provide participating teachers with a wealth of resources to support this mission. Such events have already been organized in Argentina, Portugal, Poland, the United States, the Philippines , Indonesia, China and Brazil. The IGS provides equal support to all chapters for the organization of an EtE event.

Respect

Lenoir (2012) says that at the heart of respect for the other is the recognition that the other, whether an individual or a group, must have a space where dreams and aspirations can be expressed. Respect is the recognition that each individual has the right to make their own choices in life and should be respected in their choices for who they are.

This value is expressed through the golden rule, which I express here according to Confucius: “What you don’t want done to you, don’t do to others”. The Golden Rule appears in different forms in Hinduism, Buddhism, Jainism, Zoroastrianism, Judaism, Christianity and Islam.

In his speech to members, Tatsuoka (2006) advocated for more and better local activities and communications in local languages ​​through local organizations and local collaborations in addition to the international activities of the IGS. Chapters are thus encouraged to develop along paths that they define themselves, the objective being that their development is adapted to local conditions. The chapters thus have the possibility, following the minimum directives given by the IGS, to develop and to organize at their convenience meaningful events in their country.

As mentioned earlier, the IGS is a society in which groups as diverse as polymer scientists and geotechnical engineers coexist, textile or plastic manufacturers and earthmoving contractors and civil engineering consultants and material suppliers. This coexistence is possible because respect is offered and each individual or company has the possibility of developing according to its own axis of development. Respect is all the more important when different research teams are working on similar topics from different approaches that can benefit each other, and when different manufacturers coexist and produce geosynthetics from the same product family (geotextiles , geomembranes, geogrids, GCL, etc.) .

Respect is the basis for ensuring this coexistence and the development of the IGS. In accordance with the IGS Code of Ethics, no member of the IGS shall make abusive, racist, sexist, homophobic, ageist, discriminatory or otherwise inappropriate comments or derogatory or stereotypical remarks about any ethnic group, political , social or religious or of a particular gender.

Love

At the most collective level, there is a form of love that is found to varying degrees in all cultures; namely compassion. Compassion can be defined as an expression of love towards people in a state of suffering, misfortune, injustice, and therefore in a situation of weakness (Lenoir 2012). Compassion is what we express when one of the IGS chapters loses a member. We collectively share the pain with local chapters, friends and family.

We also express our compassion when one of our locals is dealing with a natural disaster. Unfortunately, many such disasters occur every year and local people receive messages of support from our community around the world. Certainly, one of these events that has marked us a lot is the great earthquake and tsunami in Tohoku which gave rise, beyond expressions of sympathy, to the organization of dedicated sessions in conferences all over the world. , which can be interpreted as a sign of compassion. from the organizers. The ultimate resource is people – especially capable, spirited, hopeful young people endowed with freedom – who can exercise their will and imagination for their own benefit and for the benefit of the rest of us as well (Simon 1995).

The IGS board, under the impetus of its president Jorge Zornberg, approved in December 2012 the creation of the young members of the IGS (Zornberg 2013). The idea of creating this committee was born after the scholarship students of the IGS 2009-2012 expressed their interest in getting more involved in the IGS. Consequently, the founding members of this committee of young members are the scholarship students of the IGS for the years 2009-2012. The IGS has dedicated time, energy and money to support the creation and development of this committee in what I consider to be a show of love to these young members who have now freely entered the action.

Freedom

The theme of freedom in the modern Western world has evolved towards the autonomy of individuals, the emancipation of the group and the rejection of arbitrariness (Lenoir 2012). It is on this basis that the United Nations emphasizes the right to freedom of information and expression in private and in public. People should have the freedom to contribute to decisions that affect their lives. Fundamental freedoms must be protected, in accordance with national legislation and international agreements.

The concept of freedom is complementary to the concept of availability which has developed in Asia. If freedom implies a choice, availability is equivalent to dissolving any position, not taking sides, being entirely “open” and not making any a priori projections, which allows nothing to be missed (Aeschiman 2015).

Within the IGS, each member is free to express their opinions and to act and behave as they see fit, provided they respect the IGS code of ethics. This is demonstrated by the IGS approach to organizing regional or international conferences: the IGS provides a useful checklist, although local organizers have a great deal of flexibility. A clear example of this culture occurred during the debate over whether to hold the Eurogeo 6 conference in Istanbul, which involved security issues, or move it to Slovenia. The organizer, Erol Güler, won a decision by a show of hands, with the full support of the IGS board. The technical commissions created by the IGS on soil reinforcement, barrier systems, filtration, hydraulics and stabilization, also enjoy the freedom to do their own work and schedule meetings at their convenience.

Young scientists need in-depth training in their field, but they should also be encouraged to look beyond the boundaries of their field and work in partnership with others to meet real-world challenges. Too often, the incentive structure of promotions and job security causes future generations of scholars to look inward to address academic issues limited to their disciplines instead of looking outward to seek partnerships. and addressing societal challenges (Myers 2017). The freedom granted to young members of the IGS made them an exception to this trend. They have taken full advantage of their freedom and are now fully contributing to the IGS council meeting in many ways. They organize themselves, as evidenced by their reporting in the IGS news, and they initiate events, workshops and interactions with senior members. A particularly poignant example of their organization is the IGS Young Member Paper Competition at the 11th International Conference on Geosynthetics in Seoul. The IGS Young Members also held their very first photo contest in 2018 and a logo background in 2019. I see very few limits to the initiative of these young members given the freedom they enjoy.