Sustainable reuse of coal mine waste : experimental and economic assessments for embankments and pavement layer applications in Morocco

This paper examines the potential reuse of coal mine waste rocks (CMWR) as an alternative material for road construction to conserve the natural resources and sustainable management of mining waste. The investigation was conducted through the determination of the chemical, mineralogical, geotechnical properties, and acid mine drainage formulation of CMWR as well as economic feasibility. An economic case study confirmed the workability of CMWR reuse in a radius of 29 km around their dumps. Results confirmed that weathered CMWR can be successfully used as a sustainable alternative material for creating embankments

Numerical Investigation to Quantify the Rate of Damage within Mortar Bituminous Materials: Modeling of Cracks Initiation and Propagation

Asphalt concrete is highly used to construct pavement layers in the civil engineering field. It is defined as a complex medium composed of aggregates (inclusions), mortar (matrix) and air void. The mortar itself is a mixture of fillers, sand and bitumen. Furthermore, mortar is the phase that links the coarse aggregates. In general, fracture of asphalt concrete occurs within mortar or among aggregate-mortar interface. Therefore, two types of fracture can be identified, i.e., adhesive and cohesive damages. The first type is occurred among the interface of aggregate-mortar. The second is taken place within the mortar. This paper presents numerical investigations of the damage initiation and stiffness degradation within the asphalt concrete matrix. Numerical simulations were carried out to investigate, firstly, how damage is initiated and developed, and then, to simulate how cracks can be initiated and propagated within this material. Cohesive finite elements method was adopted to simulate fracture. For adhesive damage, the model was represented by one rectangular aggregate that is linked to the asphalt concrete thanks to a thin layer of the mortar. For cohesive damage, the model was considered as a thick layer of the mortar in between two coarse aggregates. The applied loading was derived from the speed of traffic vehicle. A comparative analysis between four mortars was conducted. The effect of loading and the type of mortar on damage initiation and stiffness degradation will be shown. Moreover, the initiation and propagation of cracks as function of loading and stiffness modulus will be illustrated

Numerical Simulation of Fracture at Asphalt Mastic Materials

International audienceIn this paper, numerical simulations have been conducted to investigate how damage initiates and propagates at mastic materials. Mastic is known as the matrix component of asphalt concrete. The 2D specimen digital model has been created by using a layer of mastic material which is inserted between two coarse aggregate. Cohesive elements have been inserted into mastic to simulate crack initiation and propagation. The effects of loading and stiffness modulus will be investigated. Many important conclusions will be given

Effects of Roasting Temperature and Time on the Chemical Composition of Argan Oil

This work aimed at assessing the effects of roasting temperature and duration on chemical composition of argan oil. Thus, argan oils extracted from almonds roasted at different temperatures (75-175°C) and times (10-30 min) were analyzed and compared to a control. The physicochemical parameters (acidity, peroxide value, and absorbance at 232, 270 nm) increased slightly and the fatty acid composition did not show significant variation, regardless of roasting temperature and duration. The browning index increased significantly for temperatures greater than or equal to 100°C. The tocopherols content significantly decreased with roasting temperature and time (from 977.9 to 305.2 mg/kg after roasting at 175°C for 10 min). However, fluctuations are noted as a function of temperature. The phospholipids content increased with roasting temperature and time (from 0.198 % to 1.370 % after roasting at 175°C for 30 min). The decrease in the tocopherols content would be due to their thermolability. The increase in phospholipids and tocopherols content could be explained by better extractability. The results obtained make it possible to conclude that a roasting at 125-150°C / 10 min would allow the development of the organoleptic properties of the oil, notably its hazelnut flavour, without compromising its oxidative stability

Micromechanical modeling of the interfacial zone in hot mix asphalt through use of a heterogeneous numerical method

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Numerical Investigation to Quantify the Rate of Damage within Mortar Bituminous Materials: Modeling of Cracks Initiation and Propagation

International audienc

Modelling of asphalt mixes based on X-ray computed tomography and random heterogeneous generation

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Adoption of Asphalt Binder Performance Grades for Morocco Considering Climate Change

International audienceThis study deals with the development of asphalt binder performance grading (PG) distribution maps of Morocco and the assessment of climate change effects on pavement design (structural impact), energy consumption, and CO2 emissions (environmental impact). The PG maps were made at the current time (2020) as well as at future times (2050 and 2080) considering climate change. To achieve this aim, the weather data of 30 cities, including maximum and minimum daily air temperatures, were analyzed for temperature zoning over the last 35 years (1985 to 2020). Prospective temperatures between 2050 and 2080 were estimated using a time series analysis. Pavement temperature was then determined using LTPP and SHRP models. Results revealed different asphalt binders PG from PG52-10 to PG76-10 and PG64-16 depending on the selected reliability. The diversity of climate in Morocco may explain this variety of asphalt binder PG. Furthermore, time series analysis showed no changes in the PG distribution map of 2050 compared with the 2020 map, while the map was changed in 2080. The structural and environmental investigations showed that the asphalt layer should be increased by 0.22 cm for each 1 °C temperature increase to maintain the same pavement performance. So, more than 1500 BTUs of energy will be consumed per meter square of the asphalt layer. In addition, ignoring the climate change effect on asphalt pavement decreases the lifetime of pavement by about 6.23 to 31.73% for 1 and 6 °C of temperature increase, respectively

Fractional viscoelastic modeling of modified asphalt mastics using response surface method

International audienceThe main aim of this study is to develop prediction equations of asphalt mastic fractional model parameters based on the fractional model parameters of asphalt binder, taking into consideration many parameters including, styrene–butadienestyrene (SBS) and polyphosphoric acid (PPA) modification, modifier’s dosage, volume filling rate of siliceous filler, and test temperature. Experimental tests were conducted on original, SBS- and PPA-modified asphalt binders and asphalt mastics fabricated with these binders by using a dynamic shear rheometer device to achieve this aim. The asphalt mastic samples were fabricated considering a couple of volume filling rates of siliceous filler: 18 and 35%. Then, a fractional viscoelastic and the generalized Maxwell model were implemented and compared to describe the viscoelastic behavior of binder and mastic samples. The results showed that the fractional viscoelastic model could accurately predict the viscoelastic behavior of the original and modified asphalt mastic using fewer parameters compared to the well-known generalized Maxwell model so that the fitting accuracy of all samples is more than 0.99. In addition, the response surface methodology (RSM) was used to develop the prediction equation between the parameters of modified asphalt binders and the correspondent asphalt mastic fractional model. R2 values of SBS and PPA prediction models for fractional model coefficients are between 0.89 and 0.96. The predictive models presented a high accuracy so that mastic parameters with asphalt binder parameters, additive’s percentage, temperature, and volume filling rate can be achieved