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Khandani, Atapour, Yousefi Rad, Khosh,
Volume 17, Issue 3 (12-2023)
Abstract

Backfill materials used to fill underground mines are a type of engineered material whose particle size distribution (PSD) directly affects their mechanical and physical properties. According to the authors' review, there is no comprehensive standard for the properties of aggregates used in underground mine backfill materials. In this paper, the particle size ranges and particle size distribution curves of various mine backfill materials, including hydraulic backfill, paste backfill and rock backfill, have been reviewed. The available data on different types of backfill materials were collected. Based on the collected data, the smallest particle size, the largest particle size and the PSD curve ranges for each type of backfill material were determined. Then the characteristics of the particle size distribution curve of each backfill material, including the mean particle diameter (D50), the uniformity coefficient (Cu) and the curvature coefficient (Cc), were calculated.  The results of the analysis of the PSD curves for paste backfill, hydraulic backfill and rock backfill materials showed that the particles in rock backfill and paste backfill had the largest and smallest sizes, respectively. Finally, the particle size distribution characteristics of a new backfill material prepared from construction and demolition waste (CDW backfill) are presented and compared with the particle size distribution of each of the conventional backfill materials. The results indicate that the PSD curve of the CDW backfill lies at the upper limit of the range of the particle size distribution curve of hydraulic backfill and at the lower limit of the range of the particle size distribution curve of rock backfill.
 

Miss Faeze Majidi, Dr Mohammad Fathollahy, Engineer Habib Rahimi Menbar,
Volume 17, Issue 3 (12-2023)
Abstract

Aggregate is the main component of concrete and plays an essential role in the quality of concrete. Alkaline silicate reaction (ASR) is one of the most important reactions in concrete that can lead to concrete destruction. Aggregates containing active silica are responsible for this reaction, and the higher the amount, the greater the expected volume of reactions. The rate of increase of the reactions with changes in the amount of silica aggregates is part of the subject of this research. In this regard, a material was selected as the base material from the mountain quarry, and the necessary tests were performed on it by adding silica aggregates, 5, 10, 15, and 20 percent, the ASR test was performed on them according to the ASTM C1260 standard; The results showed that the expansion of the samples will increase by 0.01, 0.02, 0.04 and 0.06% respectively. Next, for the effect of microsilica on ASR, 5, 10, 15, and 20% were added to the materials and the results showed that microsilica reduced the expansion of the samples by 0.009, 0.014, 0.022, and 0.032 respectively and the increase of 20% of microsilica has reduced the expansion of the samples by 50%.

Dr Mohammad Fathollahy, Engineer Habib Rahimi Menbar,
Volume 18, Issue 4 (12-2024)
Abstract

In order to produce strong and durable concrete, it is essential to accurately assess the alkali reactivity potential of aggregates. Alkali reactions occur gradually over time and are therefore often overlooked in the early stages of a project.. This research investigates the alkali-aggregate reaction (AAR) potential of concrete aggregates. Petrographic analysis of aggregates, based on ASTM C295, is a simple and rapid method for identifyingminerals that may react with the alkalis in cement. In this study, susceptible aggregates were identified through petrography, and then the accuracy of the results and the importance of petrographic analysis were verified using laboratory methods (ASTM C586 and ASTM C1260) to select suitable materials with minimal cost and time before designing the concrete mix. The results indicate that carbonate aggregates may contain silica and have alkali reactivity potential, necessitating the use of ASR testing methods as well. In addition, the results demonstrate that petrographic analysis is an effective and valuable method for identifying minerals with alkali reactivity potential.

Majid Taromi, Abbas Eftekhari, Jafar Khademi Hamidi, Mahdi Saeidi,
Volume 19, Issue 3 (12-2025)
Abstract

The Sabzkuh Water Conveyance System was planned as an inter-basin water transfer project in the Sabzkuh region of the Chaharmahal and Bakhtiari province, a tributary of the Karun River. Initially, the project included a diversion dam, an open canal, and a tunnel. However, in the initial feasibility studies, the potential environmental risks to the Choghakhor lagoon, ecosystem and regional groundwater resources were not given sufficient consideration.Only due to land acquisition problems in the Chahartagh forest area, the tunnel route was changed and the channel was also removed. Consequently, the project was scaled down to comprise only a diversion dam and a 11-kilometre-long tunnel. This is while the geological and environmental risks of the project area were not fully investigated in the selection of the final route. After 484 meters of excavation, the Solaqan fault was encountered and a sudden inrush of water with a flow rate of 100 liters per second and the liquefaction of the excavation front caused the TBM to get stuck. Subsequently, the drainage of water caused the drying of the Aloqareh spring and the depletion of the Shirkoshteh spring, and negative environmental and social consequences for the region. To release the TBM, two side galleries were constructed and grouting and drainage were carried out. Ultimately, the tunnel excavation operation was stopped due to the problems that arose. The challenges that arose in this project indicate the need for a comprehensive study and planning in the selection of the route and TBM, as well as environmental, economic and social assessments at all stages and examining their interaction with each other.

Eng. Mohammad Hossein Jowlar, Dr. Mashalah Khamehchiyan, Dr. Mohammad Reza Nikudel, Dr. Asghar Azadi,
Volume 19, Issue 3 (12-2025)
Abstract

Over the past three decades, research into the factors influencing the development of gypsum karsts has become an active and growing area of study. The mechanically weak nature of gypsum, along with its rapid dissolution and deformability, contributes to the formation of gypsum karsts, voids, and caverns in regions where gypsum deposits are present. This process can significantly undermine geotechnical stability by reducing bearing capacity and increasing settlement. This issue is particularly critical in heavy industrial settings such as petrochemical facilities, where large storage tanks and other infrastructure are founded directly on the ground surface. Consequently, identifying and assessing these processes is essential for the design, construction, and maintenance of engineering projects. This study assesses subsurface gypsum karsts within the Masjed Soleyman Petrochemical site using an integrated geophysical and geotechnical approach. Ground Penetrating Radar (GPR) was employed across 24 profiles totaling 2,307 meters, also geotechnical data were obtained from 113 boreholes drilled to depths of 20–40 meters. Following data analysis, 32 occurrences of subsurface gypsum karsts were identified at depths ranging from 4 to 36 meters. Subsequently, surface water drainage patterns were analyzed and digitized from historical Corona satellite imagery (1968). In parallel, groundwater levels and flow direction maps were generated using data from electric probe depth finder measurements in boreholes. The integration of these datasets revealed that most gypsum karsts are concentrated in areas where groundwater tends to accumulate and flow. Finally, groundwater sampling and chemical analysis revealed an average sulfate concentration of approximately 1,480 ppm, indicative of a severe sulfate exposure environment.


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