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This work focuses on the effect of the incorporation of marine shell waste in different mass substitution rates in geopolymer mortars as an efficient solution to overcome the problems related to this waste. In this paper, Lebanese metakaolin was used as the primary clay source of aluminosilicate for the geopolymer mortars. Then, a mass substitution of metakaolin with shell waste was drawn in terms of structure, synthesis mechanism, and parameters delimiting their performance. The chemical properties of all constituents were investigated using X-ray diffraction analysis and X-ray Fluorescence. Also, the microstructure analysis was observed by implementing a scanning electron microscope (SEM). The compressive strength and elasticity modulus were measured as two fundamental mechanical properties of geopolymer samples by highlighting the impact of curing conditions (non-heated and heated) after passing 1, 3, 7, 28, 90, 120, 180, and 360 days and the various substitution rates (0–20%). The results showed that the curing conditions and the various substitution rates of metakaolin with marine shells affected the microstructure and mechanical properties. Adding shell waste reduced the compressive strength for both non-heated and heated samples and slightly increased the elasticity modulus up to 10% for non-heated and for heated curing conditions. While the final compressive strengths of non-heated samples are greater than heated ones, the rate of achieving a specific compressive strength is more rapid for heated samples. An environmental and economic analysis showed that assuming an equal transportation cost, replacing metakaolin with an average amount of 10% seashell waste reduces the energy usage by 7% and the price by 2% to produce 1 ton of geopolymer and preserves the non-renewable sources of Kaolin clay and solves the problems related to seashell waste deposits. [ABSTRACT FROM AUTHOR]

This 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. [ABSTRACT FROM AUTHOR]

This paper aims to study the use of Lebanese raw kaolin in the formulation of geopolymers (GP) mortars based on an experimental and numerical approach. Two classes of GP mortars were prepared: the first contained sodium (Na)-based alkali activator, while the second was prepared by adding potassium (K)-based activators. A microstructural characterization was realized before and after the calcination of the raw material. Mechanical characterization of the mortars was conducted by highlighting the impact of the two alkaline solutions used, on tests performed on days 1, 3, 7, 28, 90, and 120. Simultaneously, a three-phased heterogeneous numerical modeling (matrix, aggregates, pores) was used to obtain specific characteristics not accessible experimentally. As main results, the experimental work showed that the binding solutions' nature and samples' aging affected the microstructure and, consequently, the mechanical properties. K-based geopolymer mortar presents higher values of mechanical strength than Na-based geopolymer mortar. Moreover, an asymptotic behavior is observed in mechanical characteristics at about 90 days. The numerical results confirmed that micro-defects and porous network have an important impact on Young's modulus values as well as the presence of the sand phase. The mechanical characteristics of pure binder samples were also obtained numerically. These samples contain natural defects and pores leading it impossible to obtain experimentally the desired characteristics. This work and the associated results confirm that Lebanese raw material can be considered as a sustainable construction material solution for Middle Eastern countries. [ABSTRACT FROM AUTHOR]

The huge amount of wastes is produced annually from the phosphate extraction process which causes environmental problems in terms of energy and pollution. Using these wastes for producing asphalt mixtures can be a cost-effective and eco-friendly solution for managing them. The aim of this study is to investigate the feasibility of using phosphate wastes for fabrication of bituminous materials. Furthermore, the study objective is to discover the most effective waste to be included in asphalt mixtures. These wastes were acquired from the phosphate extraction plant, Ben Guerir city, Morocco. Phosphogypsum, fly ash, and dry phosphate sludge were the materials selected to be used as filler. Four samples were prepared, including an original asphalt binder as well as phosphogypsum, fly ash, and phosphate sludge asphalt samples. Classical characterization, viscous flow, frequency, and temperature sweep tests were carried out on these samples. The results showed that the viscous flow behavior of the asphalt binder containing phosphogypsum and fly ash wastes has been substantially more improved compared with binder with phosphate sludge filler. It was also shown that phosphogypsum waste enhances the mechanical properties of asphalt binder as well as its performance against rutting more than fly ash and phosphate sludge wastes. [ABSTRACT FROM AUTHOR]

Asphalt binder resistance to permanent deformation considerably influences total pavement resistance to rutting at the high service temperatures. To improve asphalt shear strength against rutting resistance, researchers have been used various modifiers and recently the use of waste materials as binder rheological enhancement agents is paid lots of attention. In this study, waste toner was adopted as an anti-rutting enhancement agent, and then neat asphalt binder was modified by waste toner at four dosages: 4, 8, 12 and 16% based on asphalt binder's weight. The effectiveness of binder modification by waste toner to improve asphalt binder and mixture's resistance to permanent deformation has been assessed by means of different methods: the Superpave specification parameter, G*/sinδ, and the multiple stress creep and recovery (MSCR) test for asphalt binder and wheel track test for asphalt mixture to determine the rut depth for a certain number of loadings. Results showed that adding toner to neat asphalt binder can meaningfully enhance the anti-rutting performance of asphalt binder and subsequently asphalt mixture. Moreover, increasing the dosage of toner up to 12% in the modified asphalt binder amplifies the trend of rutting resistance improvement. [ABSTRACT FROM AUTHOR]