Mahmoud Al-Tamimi

This research aims to investigate the durability and behavior of Jordanian oil shale ash (OSA) as a substitute material for ordinary Portland cement (OPC) and Portland Pozzolana cement (PPC) in mortar under sulfate attack. Mortar samples with replacement ratios of 0%, 10%, 20%, and 30% of OSA were utilized in this investigation. The study is divided into two stages. In the first stage, the effect of OSA replacement on the mechanical properties and hardening time of mortar samples is examined over a curing period of 3, 7, 14, and 28 days using potable water. The second stage focuses on studying the durability of mortar samples with the aforementioned OSA replacement ratios. These mortar samples are fully immersed in a sodium sulfate solution with a concentration of 5% and subjected to wet and dry cycles for degradation at 1, 6, 12, 18, 24, 30, and 36 days. Various analyses were conducted, including compressive strength testing, SEM analysis, mass loss measurement, ultrasonic pulse velocity assessment, relative dynamic modulus of elasticity (RDME) evaluation, and visual inspection. For OPC-based mortars, compressive strength ranged from 44.00 to 49.75 MPa (0% OSA), 42.88 to 48.29 MPa (10% OSA), 44.50 to 50.88 MPa (20% OSA), and 31.00 to 36.53 MPa (30% OSA). For PPC-based mortars, compressive strength ranged from 36.00 to 42.32 MPa (0% OSA), 39.73 to 43.60 MPa (10% OSA), 44.97 to 46.06 MPa (20% OSA), and 22.35 to 28.18 MPa (30% OSA). Specimens with 0%, 10%, and 20% OSA showed continued increases in compressive strength, UPV, and RDME throughout exposure, while 30% OSA specimens showed deterioration after 24 days (OPC) and 18 days (PPC), with mass losses increasing from 0.52% to 8.4% (OPC) and 0.75% to 7.8% (PPC). The results indicate that while moderate OSA replacement (up to 20%) may be viable under sulfate exposure, 30% replacement leads to significant deterioration. However, the absence of non-sulfate controls prevents definitive separation of continued hydration from sulfate resistance. These findings provide practical guidance for the use of OSA in sulfate-prone environments.

This research intends to investigate and analyze the usage of Jordanian oil shale ash (OSA) as a replacement material for ordinary Portland cement and pozzolanic cement in mortar. To start, oil shale was collected from the Wadi Al-Shallala location, crushed, sieved and burned at 800 °C for 24 h. OSA partially replaced the ordinary Portland and pozzolanic cements with ratios of 10%, 20%, and 30%. This research looked into the effect of cement substitution on the standard consistency and hardening time for cement paste. The water contents as well as beginning and final hardening times increased due to the higher replacement ratios of the cements. Also, pozzolanic activity index (PAI) along with scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) testing and mechanical properties (compressive and flexural strengths) of mortar with both types of cement substitution were evaluated. The compressive strength and flexural strength were checked following 3, 7, 14, 28, 56 and 90 days of curing, while (SEM) was conducted just at 28 days old with a 20% replacement ratio in mortar specimens. Results show that 20% OSA substitution for ordinary Portland cement or Pozzolanic cement raises compressive strength and flexural strength, plus provides better morphology. Thus, oil shale is seen as a natural pozzolanic material that increases efficiency in cement mixtures.

Background: One of the best-studied subjects in the area is gold mineralization, and researchers have focused on the veins, their direct weathering products, or fluid inclusion analyses. Abu Khusheiba gold deposits in Jordan were characterized as epithermal deposits, and the wadi sediments below were investigated in some studies. Although epithermal mineralization is confirmed at Wadi Abu Khusheiba, part of the southern Jordanian Aheimer Volcanic Suite, the source of mineralizing fluids is uncertain. Among the most critical scientific issues is whether the fluids are magmatic, meteoric, or mixed, and what it would mean for gold deposition and resource potential. Moreover, the area lacks comprehensive geochemical and isotopic studies that would reveal fluid evolution, styles of alteration, and metal transport mechanisms. Stable isotope research (e.g., oxygen) in conjunction with mineralogical studies can shed light on mineralization sources and environments – addressing an important knowledge gap. Economically, fluid evolution knowledge is required to evaluate the future gold exploration potential of the Abu Khusheiba area. Results: In accordance with stable isotope data (δ¹⁸O: 10.8 to 16.4‰), the fluids have a magmatic source with negligible meteoric water interaction. The evidence for a low-sulfidation epithermal system with constant state hydrothermal conditions comes from banded colloform quartz textures and potassic alteration. Such evidence enhances regional mineral exploration strategies as well as new ore-forming process understanding.

Petrological, geochemical, and biostratigraphical investigations have been conducted on seventy-nine samples from four selected sections in Jordan to understand the factors that influenced the enrichment and deposition of massive phosphorite deposits. The calcareous nannofossil marker species Broisonia parca constrica and Reticulofenestra bisecta, from the assigned sections 1 and 2 (Hawar and Al Dhahikiyya), were indicative of the Campanian and Eocene periods, respectively. The enrichment of some ecological marker species such as Kamptnerius magnificus indicates that there were cold periods during phosphate precipitation. All thin sections of the phosphate samples are of grainstone and packstone textures and are composed of skeletal fragments and peloids. Skeletal fragments appeared to be the main component of Hawar phosphates with the existence of peloids, while peloids were the component in sections 2 and 3 (section 3: Al Hisa). At least three intervals of high phosphorous values appeared in the Hawar section, showing variations in the Ca and Nd isotopes and in the terrigenous inputs. Four periods of phosphate enrichment are observed in Sections 2 and 3. These are deep water circulation periods of the early and late Campanian period, interrupted by two periods of submarine and continental weathering. Deep water circulation was initiated during cooling in the Campanian period and indicated by high phosphorous and Ca isotope components and a decline in terrigenous indicators (Al, Si, Ti, and Fe). Submarine weathering during warmer deep-sea periods is indicated by a rising Nd isotope ratio when many of the igneous provinces were subjected to weathering. Continental weathering took place in the warmer periods, with the hydrologic cycle and enhancement of terrigenous indicators (Al, Si, Ti, and Fe) being observed. The effect of the hydrologic cycle was at its highest in the south during the Campanian period and in the Eocene, as both represented shallower settings.