Structural and textural characterization of Brassica carinata biochar to investigate its potential industrial applications

This study investigates the microstructure of lime-treated clayey soils using mercury intrusion porosimetry (MIP) and environmental scanning electron microscopy (ESEM) analyses. Parameters that were varied include lime percent (3, 6, 9%), curing duration (7, 28 days and 1 year), soil pulverization level and mellowing period (1 and 24 h). All samples were compacted at optimum water contents using standard Proctor compaction energy. The 34 MIP and several ESEM analyses conducted on these samples showed that lime content and curing duration had significant impact on the resulting microstructure. MIP results, presented as mercury intrusion curves, total porosity values and pore size distribution histograms revealed that lime stabilization changed the microfabric of clayey soils through a dynamic pore refinement process. Although increases in pore sizes and porosities were observed in the short term (up to 28 days), after a curing period of 1 year, considerable decreases in pore sizes and porosities were noted. A novel “Pore Size Amplification Factor”, (PSAF) was calculated to determine the amplification and/or deamplification of different pore size ranges compared to the untreated soil. ESEM analyses confirmed that while the addition of lime to clayey soils initially increased pore size within the microstructure, over time, as the pores became partially or even completely blocked, the pore sizes reduced. Pores of different sizes and cementation within and on the particles were visible. ESEM findings also showed that pore shapes were not always circular as is assumed in MIP analyses. The results of this study add valuable insight into the time related changes in the microfabric of lime-treated soils.

Pore structure description of mortars containing ground granulated blast-furnace slag by mercury intrusion porosimetry and dynamic vapour sorption

Microstructural evolution of cemented paste backfill: Mercury intrusion porosimetry test results

Optimizing accelerated carbonation of carbon-eating concrete on early age microstructure and durability improvement

3D pore analysis of sedimentary rocks

Synergistic effects of ettringite-based expansive agent and polypropylene fiber on early-age anti-shrinkage and anti-cracking properties of mortars

Sorption isotherms for four gases (N2, A, Kr and CO2), commonly used in specific surface area and pore structure measurements, have been accurately determined on a number of clay mineral and oxide systems.Specific surface areas obtained by application of the BET theory to these isotherms illustrate the extent to which the apparent cross-sectional areas for these sorbed gases vary with surface structure, exchangeable cation and microporosity.V-n plots for nitrogen adsorption on these materials using nitrogen adsorption on crystalline materials of large crystal size as a standard isotherm provide appreciable ranges of linearity in each case. The specific surface areas obtained from these straight line plots agree well with the corresponding BET values. The linearity of these plots for illite clays indicates the absence of capillary condensation and that adsorption in slit-shaped pores takes place largely by the formation of physically adsorbed layers on the surfaces.Much larger BET specific surface areas were obtained from carbon dioxide sorption at 196 K on goethite, hematite and gibbsite than from nitrogen, argon and krypton sorption at 78°K. It is suggested that enhanced sorption of CO2 into microporous regions of the oxides, inaccessible to the other gases. occurs in a similar fashion to that frequently observed for coal and charcoal materials. V-n plots for CO2 sorption in these materials using that for an illite clay as a standard isotherm, support this conclusion.Considerably lower BET specific surface areas were obtained for CO2 sorption on kaolinite than were obtained for nitrogen, argon and krypton sorption. The shape of the V-n plots for CO2 sorption on kaolinite compared with illite suggest that an initial specific adsorption of CO2 on the kaolinite is followed by a change in state with the completion of this layer, allowing normal multilayer formation to proceed.

This work reports the results of structural analysis in novel dextran-acrylate (dexT70-VA) hydrogels generated chemoenzymatically. Porous structure as well as hydrogel surface and interior morphologies were evaluated by mercury intrusion porosimetry (MIP), nitrogen adsorption (NA), and scanning electron microscopy (SEM) analyses, as a function of the degree of substitution (DS), and initial water content used in the preparation of the hydrogel. MIP analysis showed that the overall networks were clearly macroporous with pore sizes ranging from 0.065 to 10 microm. As expected, the average pore size decreased as DS increased and as initial water content decreased. Moreover, the porosity values ranged from 75 up 90%, which shows that these hydrogels present an interconnected pore structure. Nitrogen adsorption analyses showed that the specific surface area of dexT70-VA hydrogels increased either by increasing the DS or by decreasing the initial water content of the hydrogel. SEM results revealed that the surface of hydrogels with lower DS presented either a porous structure or a polymeric "skin" covering the pores, whereas hydrogels with higher DS were totally porous. Furthermore, the interior morphology varied according to the DS and the initial water content of the hydrogels. Finally, the average pore size was also determined from the swelling of hydrogel using a theoretical model developed by Flory-Rehner. The comparison of the SEM and MIP results with the ones obtained by the equilibrium swelling theory of Flory-Rehner shows that this approach highly underestimates the average pore size.

Study on fine-toned fly ash content for lightweight strain-hardening cementitious composites (LSHCC) with low fiber content

Biochar is a carbon-rich material whose properties vary depending on the feedstock, pyrolysis condition, and heating rate. It possesses high water-retention properties, making it suitable for amending natural soil in landfill cover for green and sustainable development. The landfill cover may also undergo uneven settlements in the long term due to several loading and environmental conditions. Therefore, it is important to carry out a detailed study on the compressibility, hydraulic conductivity, and compressive strength of landfill cover layers considering long-term effects such as prolonged curing and wetting–drying cycles. Hence, in the current study, these hydromechanical properties of bamboo biochar–amended soil (BAS) were investigated. Series of one-dimensional oedometer and unconfined compressive strength (UCS) tests were performed on bamboo biochar (BB) mixed with low plastic clay (CL) and silty sand (SM) in five proportions (i.e., 0, 1, 2, 3.5, and 5%). Mercury intrusion porosimetry (MIP) and field emission scanning electron microscopy (FESEM) tests were carried out to find out microstructural changes in the samples. In CL soil, the addition of up to 2% BB reduced compressibility and hydraulic conductivity while enhancing UCS values; however, higher dosages led to reverse outcomes. In contrast, BB addition (1–5%) in SM soil resulted in a continuous increase in compressibility and hydraulic conductivity, along with a decrease in UCS values. The UCS values increased with an increasing curing period and decreased with wetting–drying cycles in both soils amended with biochar. MIP and FESEM analysis revealed efficient filling of pores and reduction of void space in CL soil up to 2% BB addition. Thus, CL soil amended with BB ensures enhanced material stability, suggesting its potential suitability for landfill cover applications.

The lacustrine shale in the second member of the Kongdian Formation (Ek2) is the most significant target of shale oil exploration in the Cangdong Sag, Bohai Bay Basin, China. To investigate the occurrence mechanisms and to reveal the influencing factors of shale oil mobility in Ek2, a series of analyses (X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), total organic carbon (TOC) analysis, Rock-Eval pyrolysis, low-temperature nitrogen physisorption (LNP), mercury intrusion porosimetry (MIP), and multiple isothermal stage (MIS) pyrolysis) were conducted on samples collected from well cores in the Cangdong Sag. The results show that the lithofacies can be categorized as laminated felsic shales, laminated and massive mixed shales, and laminated and massive carbonate shales. The shales were characterized by a high organic matter abundance and moderate thermal evolution with good to excellent hydrocarbon generation potential and contained a high abundance of Type I and II1 kerogens. Laminated felsic shales and laminated mixed shales, compared with other lithofacies, had clear advantages in the amount of free hydrocarbon that can be volatilized from the rock (S1), the oil saturation index (OSI) value, and the free oil and movable oil content. LNP, MIP, and MIS pyrolysis analyses show that the residual shale oil mainly occurred in pores with diameters smaller than 200 nm, and the pore diameter when residual oil occurred in some laminated shale samples could reach 50 μm. The lower limits of the pore diameter where free oil and movable oil occurred were 7 and 30 nm, respectively. The mobility of shale oil is controlled by the shale oil component, thermal maturity, TOC content, and pore volume. The results herein provide a basis for the evaluation of optimal shale oil intervals.

Microstructural evolution of saturated normally consolidated kaolinite clay under thermal cycles

To promote the effective recycling of waste ceramic tiles and alleviate the shortage of natural river sand, this study systematically investigates the strength and durability of concrete incorporating recycled ceramic fine aggregate (RCFA), herein referred to as RCFA concrete, at water-to-binder (W/B) ratios ranging from 0.25 to 0.45. The RCFA was produced by crushing waste ceramic tiles characterized by low water absorption. As indicated by experimental results, RCFA concrete exhibits improved compressive strength and enhanced resistance to freeze–thaw cycles and chloride ion penetration compared to natural aggregate concrete. However, the beneficial effects of RCFA diminish at lower W/B ratios. Furthermore, the incorporation of RCFA significantly reduces autogenous shrinkage and alleviates the decline in internal relative humidity, with these effects being more pronounced at lower W/B ratios. Conversely, RCFA increases drying shrinkage at the W/B ratio of 0.45, although this negative effect is mitigated as the W/B ratio decreases. Mercury intrusion porosimetry and scanning electron microscopy analyses reveal that RCFA improves concrete performance by reducing microporosity and enhancing the interfacial bonding between fine aggregates and hydration products.

The presence of residual non-aqueous phase liquid (NAPL) in low-permeability lens aquifers of ten results in a “tailing” effect, ecological deterioration and poor sustainability, which is a primary factor contributing to remediation failures at NAPL-contaminated sites. This issue is largely due to the poorly understood mechanisms by which NAPL residuals interact with low-permeability lens aquifers. To elucidate these mechanisms, this study conducted a series of column experiments, varying the permeability contrast (Kmn), lens sizes (ϕ), and hydraulic gradients (I). Complementary techniques such as mercury intrusion porosimetry and particle size analysis were employed to characterize the aquifer and lens materials. The data obtained include the residual NAPL saturation (Sr), groundwater flow velocity (V), pore size distribution, particle size, and gradation under different experimental conditions. Sensitivity analyses using range and variance analyses identified the following order of effect on NAPL residuals in low-permeability lens aquifers: Kmn > ϕ > I. Correlation analyses further suggest that the governing mechanisms are predominantly mediated by changes in the average particle size, macroporosity (pores > 60 μm), mesoporosity (pores = 30~60 μm), and microporosity (pores = 2~30 μm), as well as abrupt changes in pore size at the interface between the lens and the aquifer, in addition to V. This study can provide a theoretical basis for green, low-carbon, and sustainable development, such as pollution remediation and ecological environment security.

Thermally induced phase separation (TIPS) based methods are widely used for the fabrication of porous scaffolds for tissue engineering and related applications. However, formation of a less-/non-porous layer at the scaffold’s outer surface at the air–liquid interface, often known as the skin-effect, restricts the cell infiltration inside the scaffold and therefore limits its efficacy. To this end, we demonstrate a TIPS-based process involving the exposure of the just quenched poly(lactide-co-caprolactone):dioxane phases to the pure dioxane for a short time while still being under the quenching strength, herein after termed as the second quenching (2Q). Scanning electron microscopy, mercury intrusion porosimetry and contact angle analysis revealed a direct correlation between the time of 2Q and the gradual disappearance of the skin, followed by the widening of the outer pores and the formation of the fibrous filaments over the surface, with no effect on the internal pore architecture and the overall porosity of scaffolds. The experiments at various quenching temperatures and polymer concentrations revealed the versatility of 2Q in removing the skin. In addition, the in vitro cell culture studies with the human primary fibroblasts showed that the scaffolds prepared by the TIPS based 2Q process, with the optimal exposure time, resulted in a higher cell seeding and viability in contrast to the scaffolds prepared by the regular TIPS. Thus, TIPS including the 2Q step is a facile, versatile and innovative approach to fabricate the polymer scaffolds with a skin-free and fully open porous surface morphology for achieving a better cell response in tissue engineering and related applications.