Conference Agenda

<p>Sand is generally used as a backfill in geosynthetics reinforced soil structures such as foundations, embankments, pavements, retaining structures, and vast quantities of sand being consumed by these structures. The massive demand for sand by construction industries faces problems related to granular material cost and availability. These industries also face the dumping problem of demolition wastes due to the demolition of old and damaged structures such as buildings and roads, as they generated construction waste in bulk. This waste imposes enormous pressure on landfills and also created pollution in the environment. The utilization of construction and demolition materials has environmental and economic benefits that provide alternative backfill material and reduce waste on the earth. The present study investigates the applicability of natural and commercial geogrid with demolition waste. A series of consolidated undrained triaxial tests were conducted to check the feasibility of construction and demolition materials with reinforcement. The hexagonal and square aperture shape bamboo grid is used as a reinforcement. A 50mm diameter bamboo grid was placed in the cylindrical sample made of construction and demolition waste. The specimen dimensions were 75 mm diameter and 150 mm length in different height; single at the center, double layer at 1/3^rd height, triple-layer at 1/4^rth height. The triaxial tests were conducted on confining pressure of 50, 100, and 150 kPa.The experimental results show that the bamboo grid provides an apparent cohesion to the construction and demolition materials and increases internal friction angle.</p>

<p>Asphalt mixtures overlays are used to an existing road pavement (flexible or rigid) when the structural or functional conditions of the pavement have reached an unacceptable level of failures. Most of the overlays are designed to fatigue and rutting damages. Pavements that are structurally rehabilitation after the placement of the overlay and that are adequately designed to rutting and fatigue damages may illustrate cracking patterns after a short period of time that is similar to those that existed in the old pavements. This damage is known as “reflective cracking.” Although reflective cracking is the most common distress mechanisms in rehabilitated pavements, it is rarely predicted in the asphalt overlay design. Findings of studies among various interlayers, showed that the performance of asphalt pavements is improved if reinforced by geosynthetics, in terms of retarding the reflective cracking in asphalt overlays.</p>

<p>As a technical community we are currently tasked with finding a replacement for the surfactant (Igepal CA-630) used in the stress cracking tests per ASTM &amp; CEN norms-test methods. As of 2021, the EU no longer allows the sale of Igepal CA 630 to people in production industries (i.e., large quantities) due to eco-issues/concerns and that it may cause immune-mediated blood-brain barrier disruption. This is apparently a REACH directive not a law.  </p>

<p>Trying to be proactive, we know that there are hundreds of commercially available non-ionic surfactant in the family of octylphenoxypolyethoxyethanol which are candidates for this substitution. Unfortunately, all have unique characteristic that will affect stress cracking in HDPE differently. As such the Geosynthetic Insitute (GSI) has embarked on an international collabrative effort to establish a new REACH accetable replacement stress cracking surfactant. This paper will summarized the effort and illustrate results from a massive round robin program.</p>

<p>Several large-scale laboratory tests were conducted on multi geosynthetic specimens to assess damage effects from ultra-light weight foamed glass aggregates versus ASSHTO #57 stone. When geotextile or geogrid design strengths are needed for geosynthetics used in reinforcement applications, one needs to define the Long-Term Design Allowable strength.</p>

<p>In regards to the Partial Factor of Safety for installation damage, we have a very good handle on how reinforcement geosynthetics behave with conventional soil and aggregate. Installation damage is the loss of strength properties resulting from the act of installation. In some situations, where aggressive backfill and heavy equipment are used in construction, the resultant loss of strength can be significant. Cases have been reported where only 30% of the original strength properties remain after installation (AASHTO Task Force 27). Although this high loss level is unusual, it points out the need to address installation conditions.</p>

<p>Relatively new to the USA market are AeroAggregates. These Ultra-Lightweight Foamed Glass Aggregates are produced from 100% post-consumer recycled glass. The aggregates have a highly frictional surface that are combined with low unit weight, inertness, high permeability, and insulating properties. As such these foamed glass aggregates are ideal as lightweight backfill used in conjunction with geosynthetic reinforcing elements.</p>

<p>It is our intention to present a comprehensive data set of results from this full-scale performance evaluation.</p>

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<p>Deinking sludge ash (DSA) and deinking sludge (DS) represent the main waste from recycled deinking paper pulp production in a paper industry. Their mixtures were used in this research to develop a composite with the proper geomechanical properties for the backfill of the GRS retaining structure. Several mixtures with different contents of DS and DSA were initially tested to develop an optimal composite. Moderate alkalinity (pH approx 12) of the composite was observed. Thus, a long time durability of geogrid was also tested among other geosynthetic-soil interaction properties.</p>

<p>The chosen composite was used as a backfill material of the retaining wall structure built in the south part of Slovenia, near the railway line, for landslide stabilization. All laboratory and field tests confirmed the required physical characteristics and that the environmental requirements are being reached.</p>

<p>The European Association of Geosynthetic product Manufacturers (EAGM) commissioned ETH Zürich and ESU-services Ltd. to quantify the environmental performance of commonly applied construction materials (such as concrete, cement, lime or gravel) versus geosynthetics for 4 cases. Geosynthetic materials are used in many different applications in the civil and underground engineering. In most cases, the use of geosynthetic material beneficially replaces the use of other construction materials. To this end a set of comparative life cycle assessment studies are carried out concentrating on various functions or application cases. The environmental performance of geosynthetics is compared to the performance of competing construction materials used. Further new cases are evaluated since 2020. This paper presents the results of a case with a Filtration function (the construction of a filter where geosynthetics are used is compared to the case of mineral filter) in a river construction with a typical geotextile filter in comparison to a gravel/sand filter. The study shows benefits in sustainable constructions using geosynthetics.</p>

<p>This paper focuses on the use of geosynthetics as internal reinforcements in mechanically-stabilized tire derived aggregate (MSTDA) walls. Topics that will be addressed are the interaction between tire derived aggregate (TDA) and different geosynthetics from pullout testing, compression of the TDA under both self-weight and surcharge loading, and facing element design. Advantages of using MSTDA walls over conventional mechanically-stabilized earth walls will be discussed, including the light-weight fill aspects and the flexibile response during earthquakes. </p>

The number of scrap tyres is growing all around the world due to increasing number of vehicles. This creates significant environmental and economic concerns. Recycling and reusing scrap tyres in engineering projects is an alternative way to deal with these concerns. Recycled tyres are commonly mixed with soils in different proportions. This paper presents a series of laboratory experiments on sand-rubber mixtures (tested with seven different volumetric rubber fractions ranging from 0% (pure sand) to 100% (pure rubber)) under one-dimensional cyclic loading at different stress levels. It is aimed to investigate the behaviour and response of mixture with increasing rubber fraction under different cycle loads. The results indicate that one-dimensional characteristics of mixtures depends on rubber fraction. The applied cycle load also affects the response of mixtures. The results of cyclic oedometer tests were analysed and the effect of applied vertical stress on the remanent deformation were discussed.

<p>Construction and Demolition (C&amp;D) Waste is a priority stream due to the large amounts generated and, simultaneously, their high potential for re-use and recycling. C&amp;DW are usually defined as the residues from the operations of construction, reconstruction, maintenance and demolition of buildings and other civil infrastructures.</p>

<p>The work herein presented is part of a broader study aiming to assess the feasibility of replacing the soils typically used in the construction of geosynthetic reinforced structures (embankments and retaining walls) by fine grain recycled aggregate from C&amp;DW. However, it should be pointed out that one of the main questions of using geosynthetics in ground applications is their durability. This aspect is particularly significant if a recycled aggregate is being used.</p>

<p>This paper presents the mechanical, chemical and environmental degradation induced by a fine-grain recycled C&amp;DW on the short-term tensile behaviour of a uniaxial high density polyethylene (HDPE) geogrid, used commonly in reinforced steep slopes and retaining walls. In order to study the chemical and environmental degradation a damage trial embankment (2m×3m in plant) was constructed using C&amp;DW as filling material. The damage caused by the mechanical actions during installation was also simulated by laboratory mechanical damage tests. For comparison purposes, geogrid samples were also exposed to a natural soil.<br />Wide width tensile tests were performed on geogrid samples exhumed from the trial embankment after 12 months, on laboratory damaged samples and on intact samples. Their short-term tensile behaviour is compared. Scanning electron microscope (SEM) images of intact and exhumed specimens are also presented.</p>

<p>In recent decades, several studies and applications of recycled Construction and Demolition (C&amp;D) waste have been reported in the literature. Although encouraging results have been achieved by different researchers worldwide, most of the studies are focused on the short-term behaviour of the recycled C&amp;D materials. In fact, the knowledge related to the long-term behaviour of these alternative materials is still fairly limited. This paper summarizes the main results of the research project CDW_LongTerm - Valorisation of Construction and Demolition Wastes in geosynthetic reinforced structures - Prediction of long-term behaviour. This research project has involved mixed fine-grain recycled aggregates obtained from non-selected C&amp;D waste, which correspond to the recycled materials actually available on Portuguese market. Changes on the geotechnical and geoenvironmental behaviour of different recycled C&amp;D materials induced by real weather conditions and other agents (such as, compaction or wet-drying cycles), the durability and creep behaviour of the geosynthetics, the long-term behaviour of geosynthetic/C&amp;D material interfaces and the long-term performance of a full-scale model have been studied. Demonstrating that geosynthetic-reinforced structures constructed with C&amp;D materials are perfectly capable to maintain their good behaviour throughout the design working life, this project will contribute to promote the valorisation of C&amp;D waste, particularly the fine-grain fraction with low market acceptance for other applications such as pavement base layers and concrete production, and therefore contribute towards a more sustainable and environmentally friendly Europe.</p>