Discussion of "compaction and strength behavior of tire crumbles-fly ash mixed with clay" by Akash Priyadarshee, Arvind Kumar, Deepak Gupta, and Pankaj Pushkarna

The dimensional analysis concept was successfully extended to the clay–tire crumbles–fly ash CBR problem, thereby leading to the development of a simple and practical dimensional model capable of predicting the CBR (at both unsoaked and soaked conditions) as a function of the mixture’s basic index properties, i.e., stabilizer content, initial placement (or compaction) condition, specific surface area, grain-size distribution, and curing time. The predictive capacity of the proposed dimensional model was examined and further validated by statistical techniques. The proposed dimensional model contains a total of four model (or fitting) parameters, which can be calibrated with little experimental effort and further implemented for predictive purposes. The model parameters can be adequately estimated by a total of four unsoaked or soaked CBR tests. Four scenarios consisting of the clay soil with no additives, a desired clay–tire crumbles mixture (no fly ash), a desired clay–fly ash mixture (no tire crumbles), and a desired clay–tire crumbles–fly ash mixture are recommended for the calibration phase. The choice of tire crumbles and fly ash contents are arbitrary; however, from a statistical perspective, median contents are expected to yield a more reliable estimate of the model parameters (Mirzababaei et al. 2018)

Assessment of clay soil fabric using scanning electron microscope (SEM)

This paper introduces the way of assessing the soil fabric using outlines given by Collins and McGown (1983).The physical and mechanical properties of soils depends particularly on their fabric. At micro levels, the fabric of a soil sample consists of different elemental particles as well as it does at visible range of view. The arrangements of elementary particles and their sizes and shapes predict its mechanical behavior and characteristics. One of the best ways to recognize the fabric of a soil sample is to utilize scanning electron microscope. In this paper first the fundamental alphabets of scanning electron microscopes are explained then the soil fabric classification system given by Collins and McGown is fully described. Three clay soil sample were selected. Six specimens were prepared for swelling test, three of them without any treating agents and remains were treated with apolymeric agent. After applying swelling test according to ASTM D-4546 the samples were scanned using scanning electron microscope (SEM) and 18 micrographs were taken. For clarifying the terms used in the classification system, all micrographs were fully interpreted

Discussion on “Effects of lime addition on geotechnical properties of sedimentary soil in Curitiba, Brazil” [J Rock Mech Geotech Eng 10 (2018) 188–194]

The present discussion aims at complementing the original work published by Baldovino et al. (2018) by outlining a novel point of view. In light of the inherent limitations associated with the empirical model suggested in the original article, the dimensional analysis technique was introduced to the soil-lime strength problem, thereby leading to the development of simple and physically meaningful dimensional models capable of predicting the unconfined compressive and splitting tensile strengths of compacted soil-lime mixtures as a function of the mixture's index properties, i.e. lime content, initial placement (or compaction) condition, initial specific surface area and curing time. The predictive capacity of the proposed dimensional models was examined and validated by statistical techniques. The proposed dimensional models contain a limited number of fitting parameters, which can be calibrated by minimal experimental effort and hence implemented for predictive purposes. © 2018 Institute of Rock and Soil Mechanics, Chinese Academy of Science

Carpet waste utilisation, an awakening realisation : a review

Waste generated from pre-and-post consumer waste is becoming a concerning issue both with the manufacturers and the disposal authorities. Light-hearted attitudes of carpet manufacturers towards waste less than a decade ago are rapidly changing as burden of storage, transportation and disposal costs are biting into company budgets. This review paper will explore waste generation and its accumulation from source to end-product and highlights some of the innovative approaches adopted by manufacturers, researchers around the world and in particular those attempted by University of Bolton

Reduction of swell pressure of expansive soils using some polymeric additives

The main objective of this study is to evaluate the effect of three polymeric additives on swelling properties of expansive soils. Three clayey soil samples were used in this study. One of them are of moderate and two of them are of high plasticity index. Furan, Methyl Metha Acrylate (MMA) and Vinyl Acetate (VA) have been used as three polymeric additives in this study. In order to evaluate the effect of these polymers on swelling pressure of afore mentioned soil samples firstly a series of swell pressure tests (using ASTM-D4546) were applied on untreated soil samples at optimum water content. Then each untreated soil sample was mixed with each of the polymers at three different dosage and swell pressure tests were applied at optimum water content. The results showed significant reduction in swelling pressure of these soils. It is also appeared that the efficiency of these polymers to reduce the swell pressure of expansive soils depends on the plasticity index of the soil, type of polymer and the percentage which is used

Analysis of strip footings on fiber-reinforced slopes with the aid of particle image velocimetry

This paper provides results of a comprehensive investigation into the use of waste carpet fibers for reinforcement of clay soil slopes. The interaction between laboratory scale model slopes made of fiber-reinforced clay soil and surface strip footing load was examined. Results for the influence of two variables, namely fiber content and distance between the footing edge and the crest of the slope, are presented and discussed. The particle image velocimetry (PIV) technique was used to study the deformation of the slope under the surface loading. The front side of the tank was made of a thick Perspex glass to facilitate taking accurate images during the loading stage. To study the stress induced in the slope under footing pressure, excess pore-water pressure and total stress increase were measured at predetermined locations within the slope. The results showed that fiber reinforcement increased the bearing resistance of the model slope significantly. For instance, inclusion of 5% waste carpet fiber increased the bearing pressure by 145% at a 10% settlement ratio. - See more at: http://ascelibrary.org/doi/abs/10.1061/(ASCE)MT.1943-5533.0001758#sthash.LF8FejRf.dpu

X-ray computed tomography imaging of fibre-reinforced clay subjected to triaxial loading

The strength evolution of fibre-reinforced soils has often been examined experimentally using conventional soil testing techniques and numerically by modelling the physico-mechanical behaviour of the soil-fibre interface. Although fibre reinforcement provides a surplus strength to the soil, its real strength contribution is highly dependent on the re-orientation of fibres within the spatial domain of the compacted soil under loading. In this study, a series of unconsolidated undrained triaxial tests were carried out on miniature fibre-reinforced clay samples and the 3D architecture of the fibres before and during the loading was visualised using an intensive image processing technique. This research for the first time investigates the mechanism of fibre re-orientation, spatial distribution, displacement and tortuosity in a randomly fibre-reinforced clay at different stages of loading using an advanced X-ray computed tomography (CT) imaging facility. The results showed a high degree of anisotropic distribution of fibres (i.e. both in spatial location and angles in XZ/XY planes) that is further intensified upon loading

Comparisons of the resilient moduli of asphalt mixes containing recycled materials through empirical and experimental methods

The stiffness of asphalt mixes is a fundamental property that plays an important role in determining the performance of asphaltpavement under traffic loading. The resilient modulus (stiffness) of asphalt mixes can be either determined using laboratory experiments orpredicted through empirical methods based on asphalt components’properties. This paper characterized the effect of recycled materialsincluding recycled construction aggregate (RCA) and glass on the resilient modulus of asphalt mixes using both an empirical methodand a series of laboratory experiments. In addition, the resilient moduli obtained from different methods for different asphalt mixes werecompared, and the accuracy and reliability of different empirical methods were discussed accordingly. The outcomes indicated that in cases inwhich the value of resilient modulus cannot be obtained experimentally, empirical equations cannot well predict the actual resilient modulus.Furthermore, the addition of RCA and glass at a certain amount was shown to improve the resilient modulus of the asphalt mix. This may beattributed to the basic properties of RCA due to its smaller flakiness index and particle shape compared with virgin aggregates. These twoparameters significantly affected the final performance of asphalt mixes

Polymers for stabilization of soft clay soils

In this study, the influence of two chemical additives, (i.e., poly(vinyl alcohol), PVA and 1,2,3,4 Butane Tetra Carboxylic Acid, BTCA on the engineering properties of an expansive clay soil is investigated. The effect of polymers on the unconfined compression strength of soil samples prepared at maximum dry unit weight (i.e., 16.2 kN/m 3 and 17% water content) and a lower dry unit weight (i.e. 10.8 kN/m 3 and 48% water content) was evaluated. PVA and BTCA added at dosages of 0.1% to 1.5% and 0.1% to 0.5% respectively to both compacted soil samples and cured for 1 and 14 days. The results of unconfined compression tests on clay soil samples stabilized with different PVA and BTCA contents cured for 1 and 14 days indicated that such hydrophilic polymers improve the compression strength of both dense and soft clay soils significantly and their strength even increases with curing time. However, the efficiency of the additives is highly dependent on the unit weight of the soil. Furthermore, the durability of stabilized samples was also examined using soaking tests and results revealed that these polymers improve the durability of clay soils once they are soaked under water. © 2017 The Authors

Effect of polymers on swelling potential of expansive soils

This paper introduces new soil stabilisers for reducing the swelling potential of expansive soils. In this study three different polymers (Furan, Poly(methyl ethacrylate) (PMMA) and Poly(vinyl acetate) (PVA)) were utilised as soil stabilisers. For evaluating the effect of these polymers on swelling potential and microfabric of expansive soils, three soil samples of high plasticity index were selected. First the engineering, chemical and mineralogical characteristics of the untreated soils were determined, and three different pairs of dry density and water content (dry of optimum, optimum and wet of optimum) were chosen, from standard Proctor compaction curve. Treated soil specimens were prepared at 3%, 5% and 10% of furan content and 1%, 3% and 5% of polymethyl methacrylate and polyvinyl acetate content. The addition of polymethyl methacrylate and polyvinyl acetate can also diminish the swelling potential of soil specimens, but to alesser degree. The addition of additives produced aggregations and clay-granular matrices within the fabric, which reduced the swelling potential of the soil samples