Petrographic and geochemical features of Gimo marble, Gole area, Kurdistan Region, Iraq: constraints on its protolith's origin and depositional environment

It is essential to identify marbles' petrographic and geochemical characteristics to determine the palaeo-environmental settings where their carbonate protoliths formed. The petrogenesis of massive Gimo marbles in the Gole area, Kurdistan Region of northeast Iraq, was investigated in this study through a combination of field mapping, petrographic, and geochemical techniques. Petrographic examination of these marbles reveals that mineral compositions are similar in all samples, with both homeoblastic and mosaic textures occurring, in addition to opaque grains that provide evidence of mineralization. Geochemical analyses show that the average calcium carbonate content of the marble is 94.96%; hence, the marble is lithologically characterized as a pure calcite marble. In most samples, the silica content was below 2 wt.%, with high values related to quartz veinlets. A range of geochemical indices and Post-Archean Australian Shale (PAAS–normalized rare earth element (REE) patterns) suggest that the limestone protolith was deposited in a shallow, near-shore marine environment on a continental margin, with very low input of detrital material. The negative Ce anomalies indicate that the protoliths of the Gimo marbles were carbonate rocks of a sedimentary origin.

Geochemical investigation of hydrocarbon generation potential of coal from Raniganj Basin, India

Methane content in a coal seam is a necessary parameter for evaluating coal bed gas, and it poses an environmental risk to underground coal mining activities. Keeping in pace with comprehensive studies of coal bed gas, 12 coal samples were selected from the Sitarampur block of Raniganj Coalfield for analysis. The Petrographic examination illustrated that significant values of reactive macerals present in samples demonstrate that organic matter is dominated by the prominent source of aromatic hydrocarbons with a minor proportion of aliphatic hydrocarbon, which falls in the region of (Type III) kerogen, confirms the suitability for the potential of hydrocarbon generation. “A” factor (aliphatic/aromatic bands) and “C” factor (carbonyl/carboxyl bands) value concluded that the sample has the lowest aromaticity and the highest hydrocarbon-generating potential, which was also validated by the Van Krevelen diagram. The Van Krevelen diagram plots between the H/C and O/C ratio indicate that coal samples lie in the type III kerogen, and bituminous coal (gas prone zone) is present in the block, which is confirmed by the cross-plot between desorbed and total gas (cc/g). The in situ gas content values are high enough to produce methane from coal beds. The overall study concludes that the Sitarampur block from Raniganj Coalfield is suitable for hydrocarbon generation and extraction.

Petrographic and Mechanical Analyses of Selected Granitic Rock Deposits in Ado-Ekiti, South-West Nigeria.

In this study, the petrographic and mineralogy of selected granitic rocks on their physical and mechanical strength were evaluated. Granitic rock samples sourced from seven locations were analyzed to investigate their mineral micro-texture and compositions using petrographic examination and X-ray diffraction (XRD) analysis respectively. Mechanical properties including compressive strength and hardness of the examined rocks were performed following ASTM D7012–10 and EN 1534 standards. Their physical properties in term of specific gravity, porosity and water absorption were examined following ASTM C97/C97M. Results show that the predominant minerals in rock samples are quartz and kaolinite. Stress-strain curve displays plastic fragmentation after initial fracture in most granitic rock samples with rock samples from Olorunda Zone 9 and Olorunda Zone 2 exhibiting superior plastic deformation over a wide strain elongation. Their physical properties were within the acceptable range for construction applications.

Petrophysical Investigation of Hydrocarbon Generation Potential of Coal from Raniganj Basin, India

Methane content in a coal seam is a necessary parameter for evaluating coal bed gas, and it is a threat to underground coal mining activities from environmental aspects. Keeping in pace with comprehensive studies of coal bed gas, the authors had selected 12 coal samples from the Sitarampur block of Raniganj Coalfield. The Petrographic examination illustrated that significant values of reactive macerals present in samples demonstrate that organic matter is dominated by kerogen Type III, making it suitable for hydrocarbon generation. “A” factor (aliphatic/aromatic bands) and “C” factor (carbonyl/carboxyl bands) value concluded that the sample has the lowest aromaticity and the highest hydrocarbon-generating potential, which also validated by the cross plot between atomic H/C and O/C. The plots between the H/C and O/C ratio in the Van Krevelen diagram indicate that the coal samples lie in the type III kerogen, and bituminous coal (gas prone zone) is present in the block, which confirmed by the cross plot between desorbed and total gas (cc/g). The in-situ gas content values are high enough to produce methane from coal beds. The overall study concludes that the Sitarampur block from Raniganj Coalfield is suitable for hydrocarbon generation and extraction.

Assessment of AAR and Sulfate Attack on Wadi Gravel Concrete after 4 Years in Service

Wadi gravel is a local aggregate in Qatar that could contribute to enhanced sustainability by replacing expensive imported gabbro. The material needs to be processed before use to reduce sulfate content to acceptable levels. The paper presents the performance assessment of three full-scale buildings, variously made with 50% and 100% Wadi gravel and conventional gabbro concretes. Site monitoring up to four years in service demonstrated the strength development with age and resistance to the aggressive exposure conditions in Qatar. The Wadi gravel concrete exhibited at least similar performance to the gabbro concrete, and excellent durability as defined in national construction specifications. The paper provides initial long-term assessment and builds on previous publications by the authors, for initial assessment of Wadi gravel concrete. In an earlier investigation by the authors, a difference was observed between the concrete prism expansion test results of RILEM AAR-4.1 and BS 812-123. Wadi gravel was classified as potentially reactive in the more accelerated RILEM AAR-4.1 and of low reactivity in the more realistic exposure BS 812-123. Petrographic examination of the hardened concrete after four years in service has shown no evidence of cracking or signs of distress or deterioration and confirmed the BS 812-123 interpretation of alkali-silica reactivity of Wadi gravel concrete. The results obtained in this investigation provide more confidence for the wider and efficient use of Wadi gravel in structural concrete.

Long-Term Durability of Cold Weather Concrete : Phase II

Recent laboratory results confirm that it is possible to protect concrete from freezing solely using chemical admixtures and indicate that the amount of admixture required may be significantly less than previously recommended. Researchers have also verified that admixture-based freeze protection can produce concrete that is durable to winter exposure for a minimum of 20 years, through petrographic examination of core specimens obtained from past field demonstrations. Freeze protection for concrete using chemical admixtures alone has been an area of active research for 3 decades; however, the most recent methodology recommends very high addition rates of accelerating and corrosion inhibiting admixtures, which result in significant challenges, including slump loss, rapid setting, and potentially excessive temperature rise. As part of a laboratory study, researchers systematically varied the dosage of freeze protection admixtures used in concrete cured in a 23 °F environment. Preliminary findings indicate that a 50% reduction in admixture dose maintained adequate freeze protection and resulted in compressive strengths exceeding those of room-temperature controls at 7 and 28 days. The combination of improved handling, reduced cost, and verified durability associated with the use of admixtures for freeze protection makes a compelling case for broader adoption of this technique in winter operations

Investigation on the Mechanical Properties and Microstructure of Eco-friendly Mortar Containing WGP at Elevated Temperature

The properties of mortars containing waste glass powder (WGP) as a cement substitute for sustainable construction at various high temperatures were investigated. For this purpose, specimens from four mixtures with WGP at various percentage levels of 0, 5, 10 and 15% were prepared and exposed to the specified temperatures. After that, the compressive and flexural strength were determined at high temperatures. The mass loss was also measured by weighing the samples before and after exposing to the high temperatures. The microstructure of mortars was analyzed by petrographic examination. Based on the obtained results, incorporation of WGP as partial replacement of cement could improve strength characteristics of the mortars at the elevated temperatures up to 17%. Also, the optimum ratio of cement replacement level was found to be 10%. In addition, the petrographic images of the mortars showed that at the same time with the strength loss of specimens, the red discoloration of WGP occurred that is attributed to the oxidation of iron compounds that starts at temperatures above 200 °C.