Effect of Bentonite Content and Hydration Time on Mechanical Properties of Sand–Bentonite Mixture

The bentonite is commonly used mixed with soils for groundwater retention and waste contaminant facilities. The incorporation of bentonite could significantly reduce hydraulic conductivity. In this study, the effects of bentonite content, hydration time and effective confining pressure on the static properties of a sand–bentonite mixture were studied using experimental and numerical methods. Firstly, a large number of drainage static triaxial tests on the sand–bentonite mixture with various bentonite contents were conducted. The test results show that the increase in bentonite content and hydration time leads to a slight decrease in shear strength and initial tangent modulus of the sand–bentonite mixture. The presence of bentonite reduces the shear shrinkage and dilatancy trend of the mixture. The cohesion of the mixture increases with the increase in bentonite content and hydration time, but the internal friction angle decreases correspondingly. The hydration of bentonite on the surface of sand particles changes the contact form between particles. The bentonite slurry between pores of the sand skeleton also affects the mechanical behavior of the sand–bentonite mixture. Then, a series of 3D discrete element models were established for numerical simulations of drainage static triaxial tests. The numerical model parameters were calibrated by experimental results. The meso-mechanism of bentonite content affecting the mechanical behavior was revealed according to the contact force distribution between particles. The research results are helpful to understand further the mechanism of bentonite on the mechanical properties of the sand–bentonite mixture.

A Comprehensive Review on the Characteristics, Challenges and Reuse Opportunities Associated with Produced Water in Fracturing Operations

Amid the rise in energy demand over recent years, natural gas from tight reservoirs has been targeted abundantly around the globe by different oil operators. Hydraulic fracturing technology has been instrumental in the successful exploitation of energy from tight formations. The process is associated with enormous usage of water. Hydraulic fracturing requires as little as 500,000 gallons of freshwater, and up to 6 million gallons per well depending on the type of well and the number of stages treated. Now operators, as well as service companies worldwide, have shown a desire to use produced water in field operations to enhance economics and reduce their environmental footprint. Reusing produced water in field operations appears to be a win-win proposition by transforming the industry's biggest waste product into a resource. This paper highlights the recent findings in published articles about formulating a fracturing fluid from produced water as a base fluid. The rheological properties and fluid performance requirements, such as proppant carrying capacity, mixing, fluid efficiency, ability to crosslink and break, and cleanup after treatment, will be evaluated in detail. This paper identified the critical parameters associated with high TDS fluids (produced water) such as pH, hydration time, ionic strength, and suspended solids, collected the corresponding optimal ranges for these parameters in laboratory tests, and reported some of the validity of the findings under actual conditions in field trials around the world. Most studies demonstrated the feasibility of using untreated produced water as a base fluid for crosslinked gel-based hydraulic fracturing. Through adjusting the hydration time, the gel loading, and the amount of breakers applied, it is conceivable that crosslinked gels with optimal rheological characteristics can be formulated with untreated produced water. Multiple generations of guar- and CMHPG-based crosslinked fracturing fluids, developed with 100% untreated produced water, exhibited optimal viscosities exceeding 200 cp at 40 s−1 for at least 60 minutes. The ability to provide fracturing fluids with high-salinity produced water can be a successful water conservation approach and an attractive solution for enhancing operation economics. Some studies indicated that using produced water can be better than freshwater because the produced water is more compatible with the reservoir and may be less likely to cause conditions such as salinity shock, which can damage the formation. More studies are needed to understand the associated technical challenges further.

The Influence of Rice Protein, Hemp Protein and Transglutaminase Addition on the Quality of Instant Fried Noodles

The goal of this study was to determine the effect of rice and hemp protein addition together with transglutaminase on the quality and fat content of fried instant noodles. The following parameters have been analyzed during this research: the amount of water, fat content, hydration time, color and texture parameters. The evaluation of sensory parameters before and after cooking of instant noodles has been performed. It can be concluded that the addition of TGase significantly decreased the fat content; the recipe with a 3% hemp protein addition with TGase in an amount of 2% was the most promising solution to obtain a low-fat product. On the other hand, the better consumer acceptance levels were observed for the rice protein addition (1%) with 2% TGase. It seems that the most promising product is the sample with a 5% addition of rice protein with 2% TGase-a reduction in the fat content by 30% (from 25% to 16%). The addition of rice protein, hemp protein and TGase reduced the fat content of the instant noodles in comparison to the control sample. The additives used had an impact on the L*, a* and b* color parameters. All instant noodles obtained during the research process were characterized by a short hydration time, which did not exceed 5 min. During the sensory evaluation, analyzed samples of the instant noodles obtained scores higher than 4.2 points on a five-point scale.

Experimental Study of the Mechanical and Microstructure Characteristics of Coal Gangue Road Stabilization Materials Based on Alkali Slag Cementation

To accelerate the resource utilization of coal gangue and meet the strategic requirements of carbon neutralization, alkali-activated, slag-cemented coal gangue is applied in the preparation of solid waste-based road stabilization materials. Here, the cementation characteristics and microstructure characteristics of alkali-activated, slag-cemented coal gangue road stabilization materials are studied using the alkali equivalent and coal gangue aggregate ratio as experimental variables. The results show that with the increase in alkali equivalent from 1% to 7%, the unconfined compressive strength of the alkali-activated coal gangue road stabilization material initially increases and then decreases, with 3% being the optimal group in terms of stabilization, the aggregate ratio of coal gangue increases from 70% to 85%, and the 7-day unconfined compressive strength of the stabilized material decreases approximately linearly from 8.16 to 1.68 MPa. At the same time, the porosity gradually increases but still meets the requirements of the specification. With the increase in hydration time, a large number of hydration products are formed in the alkali slag cementation system, and they are closely attached to the surface of and interweave with the coal gangue to fill the pores, resulting in the alkali slag slurry and coal gangue being brought closer together.

Insight into the Interaction between Water and Ion-Exchanged Aluminosilicate Glass by Nanoindentation

This work aims to explore the interaction between water and ion-exchanged aluminosilicate glass. The surface mechanical properties of ion-exchanged glasses after different hydration durations are investigated. The compressive stress and depth of stress layer are determined with a surface stress meter on the basis of photo-elasticity theory. The hardness and Young’s modulus are tested through nanoindentation. Infrared spectroscopy is used to determine the variation in surface structures of the glass samples. The results show that hydration has obvious effects on the hardness and Young’s modulus of the raw and ion-exchanged glasses. The hardness and Young’s modulus decrease to different extents after different hydration times, and the Young’s modulus shows some recovery with the prolonging of hydration time. The ion-exchanged glasses are more resistant to hydration. The tin side is more resistant to hydration than the air side. The results are expected to serve as reference for better understanding the hydration process of ion-exchanged glass.

Effect of Different Hydration Time on Carbonation Degree and Strength of Steel Slag Specimens Containing Zeolite

Steel slag partially substituted by zeolite (SZ) was beneficial for improving the compressive strength and carbonation degree of SZ specimens after a combined curing (hydration and then carbonation) process due to pozzolanic reaction between them. By previous work results, the zeolitic substitution ratios of 5 wt.% and 15 wt.% in steel slag specimens (SZ5 and SZ15) gained the optimum compressive strength and carbonation degree, respectively, after 1 day hydration and then 2 h carbonation. This study investigated the effect of previous hydration time (1, 3, 7, 14, and 196 days) on carbonation degree and strength of SZ specimens after subsequent carbonation curing. Two zeolitic substitution ratios (5 wt.% and 15 wt.%) were selected and pure steel slag specimens were also prepared as controls. Compressive strength results revealed that the optimum hydration curing time was 1 day and the optimum zeolitic substitution ratio was 5 wt.%. The pozzolanic reaction happened in SZ specimens was divided into early and late pozzolanic reaction. In the late hydration, a new mineral, monocarboaluminate (AFmc) was produced in SZ15 specimens, modifying the carbonation degree and strength further. And the mechanism of pozzolanic reaction in early and late hydration in SZ specimens was explained by several microscopic test methods.