Showing items 1 - 6 of 6

Improving expansive clay subgrades using recycled glass : resilient modulus characteristics and pavement performance

- Yaghoubi, Ehsan, Yaghoubi, Mohammadjavad, Guerrieri, Maurice, Sudarsanan, Nithin

  • Authors: Yaghoubi, Ehsan , Yaghoubi, Mohammadjavad , Guerrieri, Maurice , Sudarsanan, Nithin
  • Date: 2021
  • Type: Text , Journal article
  • Relation: Construction and Building Materials Vol. 302, no. (2021), p.
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  • Description: The scarcity of sound soils, especially in urban areas, often forces engineers to construct the pavement on problematic subgrade soils such as expansive clays. The associated cost involved in replacing the existing problematic soil is avoided by adopting treatment techniques. In this study, a type of high plasticity expansive clay was mixed with 10, 20, and 30% sand-size recycled glass (RG) as a non-chemical soil treatment approach. An extensive investigation comprising experimental works, numerical modeling, and pavement performance analysis was undertaken. After determination of the physical properties of clay and RG, resilient modulus characteristics of clay and the three clay-RG mixtures were carried out through an experimental program. Subsequently, the obtained resilient modulus data sets were incorporated into a finite element analysis program in order to analyze the stress-strain response of pavement models founded on clay and RG-treated subgrades. The compressive and tensile strains achieved through the analysis of the pavement models under traffic loads were next used to compare each pavement model with respect to fatigue and rutting performances. The experimental results showed up to a 113% increase in resilient modulus of clay by the addition of 30% RG. The outcomes of the analysis on pavement systems modeled using the experimental input showed a considerable reduction in compressive and tensile strains by treating the clay subgrade with RG. Consequently, the strain reduction exhibited a significant increase in fatigue life and rutting life of pavements founded on RG treated clay subgrades. The outcomes of this research aim to encourage the construction industry to consider the utilization of environmentally clean recycled aggregates, such as RG, for improving subgrades with problematic soils and hence, promote sustainable construction materials and approaches. © 2021 Elsevier Ltd

Inspection of open-pit mine drainage characteristics with a horizontal borehole camera

- Perdigao, Cristhiana, Dyson, Ashley, Yaghoubi, Mohammadjavad, Baumgartl, Thomas

  • Authors: Perdigao, Cristhiana , Dyson, Ashley , Yaghoubi, Mohammadjavad , Baumgartl, Thomas
  • Date: 2021
  • Type: Text , Conference paper
  • Relation: 14th Baltic Sea Region Geotechnical Conference, BSGC 2020 Vol. 727
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  • Description: Horizontal bores and drains are crucial infrastructures for maintaining the stability of large open-pit mines. Induced deformations as the result of mining activities and the infiltration of water from large surface catchments during heavy rain events can cause the build-up of pore water pressures in brown coal batters. This can potentially lead to catastrophic slope failures. Horizontal boreholes and drains are commonly installed at shallow inclines and typically range in length from 150 to 400 metres. Due to complexities in surveying lengthy horizontal bores, the long-term internal properties of these structures are poorly understood. In this research, a specialised horizontal borehole camera was developed to observe a range of factors influencing borehole performance including the identification of fractured or jointed material, borehole geometry and features, and locationally dependent water outflow and drainage paths. Investigations were undertaken at an operational brown coal mine in the Latrobe Valley, located in Victoria, Australia. Features observed on the profile of horizontal bores are discussed, with an emphasis on providing in-situ material characterisation and for the purposes of maintaining stable mine batters. © Published under licence by IOP Publishing Ltd.

Shear strength properties and stress–strain behavior of waste foundry sand

- Yaghoubi, Ehsan, Arulrajah, Arul, Yaghoubi, Mohammadjavad, Horpibulsuk, Suksun

  • Authors: Yaghoubi, Ehsan , Arulrajah, Arul , Yaghoubi, Mohammadjavad , Horpibulsuk, Suksun
  • Date: 2020
  • Type: Text , Journal article
  • Relation: Construction and Building Materials Vol. 249, (2020)
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  • Description: This research evaluates the engineering properties of waste foundry sand (WFS) as a sustainable construction material. In this research study, extensive laboratory experiments, including X-ray fluorescence (XRF), pH value, particle size distribution, California bearing ratio (CBR) and consolidated drained (CD) direct shear and CD triaxial tests were conducted. In addition, for the comparison purpose, a similar testing program was applied to a control material, namely sand sized waste recycled glass (RG), which is an accepted construction material for geotechnical and pavement construction projects. Results indicated that although the strength properties of WFS were lower than those of RG, the WFS could meet the required characteristics to be used in applications such as engineering fill and road embankments. The outcomes of this research aim to increase the market demand for WFS as a solid waste by improving the construction industry's confidence in its performance. Using WFS as an alternative to natural sands in the construction activities can potentially have significant positive environmental impacts through reducing CO2 emission, as well as preventing the expansion of landfills for the disposal of WFS. © 2020 Elsevier Ltd

Temperature and duration impact on the strength development of geopolymerized granulated blast furnace slag for usage as a construction material

- Arulrajah, Arul, Maghool, Farshid, Yaghoubi, Mohammadjavad, Phetchuay, Chayakrit, Horpibulsuk, Suksun

  • Authors: Arulrajah, Arul , Maghool, Farshid , Yaghoubi, Mohammadjavad , Phetchuay, Chayakrit , Horpibulsuk, Suksun
  • Date: 2021
  • Type: Text , Journal article
  • Relation: Journal of Materials in Civil Engineering Vol. 33, no. 2 (2021), p.
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  • Description: Through the process of extracting iron from iron ore, a by-product is generated known as granulated blast furnace slag (GBFS). Traditional stabilization methods such as cement stabilization are not entirely sustainable options. This research investigates the engineering properties of geopolymer-stabilized GBFS and their viability for usage as a construction material. A combination of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) was used as the liquid alkaline activator (L) along with low-carbon pozzolanic binders, namely, fly ash (FA) and slag (S). The L was prepared with a Na2SiO3:NaOH ratio of 70 30 and binders were added up to 30%. The effect of different curing regimes on the strength of geopolymerized GBFS was evaluated using scanning electron microscopy (SEM) and unconfined compressive strength (UCS) tests. The effect of both the temperature and duration of curing had a vital role in the strength development of the mixtures. The test results indicated that the combination of FA+S as a geopolymer binder could perform better than FA or S alone. With the lowest UCS value of 7.8 MPa and highest value of 43 MPa, all the geopolymer-stabilized GBFS were found to be suitable for a variety of civil and construction applications. © 2020 American Society of Civil Engineers.

The effects of initial static deviatoric stress on liquefaction and pre-failure deformation characteristics of saturated sand under cyclic loading

- Liu, Zhiyong, Qian, Jiangu, Yaghoubi, Mohammadjavad, Xue, Jianfeng

  • Authors: Liu, Zhiyong , Qian, Jiangu , Yaghoubi, Mohammadjavad , Xue, Jianfeng
  • Date: 2021
  • Type: Text , Journal article
  • Relation: Soil Dynamics and Earthquake Engineering Vol. 149, no. (2021), p.
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  • Description: Initial static deviatoric stress can affect the liquefaction behaviour and deformation characteristics of saturated sand under cyclic loading. A series of cyclic triaxial tests were performed on a saturated sand consolidated under a constant vertical stress but different lateral stresses. The dependence of failure mechanism, liquefaction resistance, and stiffness evolution of the sand on initial static deviatoric stress ratio was investigated on medium dense to dense sand samples (Dr = 0.44 to 0.82). The pre-failure deformation and the direction of strain accumulation were analysed under different static deviatoric stress ratios. The results indicate that under cyclic loading with stress reversal condition, the effective mean stress in the samples could reduce to zero, which leads to cyclic mobility failure and completely loss of stiffness due to liquefaction. The stress state after cyclic loading could be above critical state line. Under non reversal loading condition, however, the effective mean stress cannot reduce to zero and therefore the samples fail under shear due to large strain accumulation. In this condition, the stress state at the end of the cyclic loading is approximately at the critical state line and hardly affected by initial deviatoric stress. The failure resistance of medium dense to dense sand is not greatly affected by initial static deviatoric stress until it is large enough to meet non-reverse loading condition. The ratio of axial stain to excess pore water pressure accumulation (or Δϵacc a/Δϵacc v) increases with the average static deviatoric stress ratio ηav. The strain accumulation direction roughly follows the flow rule of Modified Cam Clay model, independent of relative density and failure mechanism. © 2021 Elsevier Ltd

Utilisation of alkaline activated industrial by-products in deep soil mixing

- Yaghoubi, Mohammadjavad, Arulrajah, Ar, Disfani, Mahdi, Horpibulsuk, Suksun, Bo, Myint, Leong, Melvyn

  • Authors: Yaghoubi, Mohammadjavad , Arulrajah, Ar , Disfani, Mahdi , Horpibulsuk, Suksun , Bo, Myint , Leong, Melvyn
  • Date: 2017
  • Type: Text , Conference paper
  • Relation: Seventh International Conference on Geotechnique, Construction Materials and Environment, Nov. 21-24, 2017, ISBN: C3051, Mie, Japan p. 96-101
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  • Description: The use of deep soil mixing (DSM) technique in deep ground improvement projects has increased over the past decade due to being more cost-effective and easier to implement compared to other techniques such as piling, for structures subject to low to medium loads. Currently, Portland cement, lime and their combination are being used as the most common binders in DSM. However, due to the economic and concerning environmental disadvantages of using these binders, there is a need for new environmentally friendly cementing materials. This research attempts to find a way to use stockpiles of industrial by-products, such as fly ash (FA) and slag (S), as new green binders; consequently, reducing the carbon footprint in ground improvement projects. Different contents of FA and S, activated by liquid alkaline activator (L), were added to a soft marine soil to evaluate the changes in its behaviour as well as its microstructure. In addition, mixtures with cement (C), lime (Li) and their combination were prepared and tested for comparison. Binders were added at contents of 10, 20 and 30%, by dry soil mass, and samples were cured for 7 days. The results revealed that these new binders significantly increased the strength and stiffness of the soft soil, and they can be a suitable replacement for C and Li. The optimum mixture was found to be CIS+5% FA+15% S, within the range of binder, L and water content studied in this research. Moreover, recycling FA and S would substantially limit the expansion of landfill sites.
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