Properties of concrete mortar incorporating recycle pulverized sandblasting waste as additives

Sandblasting waste is a by-product obtained from the ship maintenance industry which is rich in silica content. This waste has a smaller particle size compared with typical sand and contains a high prevalence of impurities, so it is categorized as toxic and hazardous materials based on Indonesian Law. Furthermore, it also has not been efficiently harnessed, with most of it being relegated to disposal in waste landfills. To solve those problems, this research aimed to reduce the waste by reuse and recycle the sandblasting waste. In this study, the Pulverized Sandblasting Waste (PSW) used as additives in concrete mortars. Prior to use as an additive in mortar, the sandblasting waste was pretreated using chemical and mechanical processes. The mechanical pre-treatment was performed by pulverization for 8 and 12 h, later called PSW8h and PSW12h, respectively. Eleven mixture proportions were designed with constant Cement and w/c ratio. The PSW was added to the mortar specimens with a percentage of 0-5% from the weight of Cement as an additive. The test performed in this study includes compressive strength, Strength Activation Index (SAI), porosity, water absorption, and flexural test. The experimental results show that adding PSW into the mortar can enhance compressive and flexural strength. Furthermore, the results indicate that mortar with PSW has significantly lower porosity and water absorption than the control mixture. Using PSW with finer particle size shows better results in mechanical and durability properties of mortar, especially in concrete compressive and flexural strength.

Geological and engineering appraisal of hydraulic frac sand in some Egyptian localities as a proppant of oil well drilling

Sand that comprises high purity silica grains, in large percent, is of the best naturally occurring grains that can be used as proppants during hydraulic fracturing processes. Proppants are used to increase formations' permeability; to increase reservoirs' productivity, or to reopen plays and utilize unconventional reservoirs. The potentiality of these grains to be used as frac proppants is determined according to certain physical, mechanical, petrographical and chemical evaluations that include particle size analysis, acid solubility, turbidity, bulk density, crush resistance and hardness, sphericity and roundness, mineral and chemical composition. This study shows the evaluation of the silica sand samples collected from Malha Formation in Wadi El Dakhal, Eastern Desert; Naqus Formation in Wadi Qena, Eastern Desert; and Bahariya Formation at Gabal El-Dist area in Bahariya Oasis, Western Desert, Egypt. The samples were examined according to frac sand international standards. The results showed the potentiality of the tested samples to be utilized as frac sand proppants. Wadi El-Dakhal and Wadi Qena studied areas possess very promising samples for frac sand production. But, the quality of Wadi El-Dakhal samples is somewhat better than that of Wadi Qena samples. The samples of Gabal El-Dist in Bahariya Oasis are relatively less to achieve the requirements; however, they can be utilized in shallow depths.

The assessment testing of the studied samples revealed a good results and verifying the standard requirements, where SiO₂ content is 89.1% in Wadi Qena, 99.3 % in Wadi Dakhal and 78.1% in Gebel El Dist, crush resistance at 5000 psi gives fine percent 4.71 W.Q, 6.78 W.D, and 14.11 B.O, turbidity readings raining from 100.5 to 133.25 NTU, the grain roundness are rounded to sub rounded, and grain size distribution range is 30/50 to 40/70 grading (710 um to 210 um).

Foam injection for enhanced recovery of diesel fuel in soils: Sand column tests monitored by CT scan imagery

The use of surfactant foam for the remediation of diesel fuel, a Light Non-Aqueous Phase Liquid (LNAPL), was investigated in sand column experiments using X-ray Computed Tomography (CT). A preliminary series of tests were carried out on six surfactant candidates in order to measure their physical properties, including critical micelle concentrations and interfacial tensions (IFT) with the LNAPL. Batch tests for foam stability were carried out with and without added LNAPL, in order to measure the half-life of foam columns produced with each surfactant candidate. Foam flow-rate co-injection tests were carried out for each surfactant candidate in 405 cm³ sand columns contaminated with LNAPL at residual saturation. These tests revealed that a 1:1 mixture of sodium dodecyl sulfate and cocamidopropyl betaine, injected at a total volumetric flow-rate (Q_foam) of 45 mL/min, resulted in successful generation and propagation of foam within the contaminated porous medium. Finally, two sand column tests, carried out respectively under high- and low-pressure conditions, were imaged with a CT-scanner in order to compare and contrast foam morphology evolution as well as the LNAPL desaturation dynamics involved in both scenarios. The saturation profiles extracted from CT images provided valuable new insights.

Fluorine removal and calcium fluoride recovery from rare-earth smelting wastewater using fluidized bed crystallization process

As a regulated pollutant, fluorine compounds affect the health of millions of people all over the world. Their removal using a fluidized bed reactor (FBR) through crystallization process is a new method. Instead of chemical precipitation, which produces large amounts of sludge-containing wastewater hard to recover and treat. In this work, FBR was applied to a typical rare-earth smelting wastewater containing fluorine. Influence of different seed materials, seed size, and seed amounts on the fluorine removal and calcium fluoride recovery in the FBR were studied. When silica sand was used as the seed crystal and the amounts reached 30g, the concentration of fluorine in the actual wastewater decreased to 8.2 mg L^-1 or lower. The removal efficiency of fluorine and recovery ratio of calcium fluoride were obtained as 93.79% and 89.45%, respectively. The particle size of recovered calcium fluoride was about 1.5mm. The results show that FBR with silica sand as seed crystal is a feasible and economical method for removing fluorine and recovering calcium fluoride from rare-earth industrial wastewater.