Papers by Keyword: Pore Size Distribution

Abstract: The rate of transport of liquids in porous environment is crucial engineering problem. It has importance in many fields like chemical engineering, hydropedology, economic geology and also in building materials science. The intensity of a liquid transport in porous body can be analyzed be means of three concepts – sorptivity, permeability and diffusivity. The approaches applied in field of porous rocks are discussed. Water absorption coefficients of set of sedimentary rocks of wide porosity range were determined experimentally and the relationship between them and specific pore volume of rocks was found.

Abstract: Recycled finely crushed brick appears to be a suitable additive to lime or cement binder in render mixtures. This waste material indicates good pozzolanic properties and actively takes part in formation of chemical bonds in materials structure. The main objective of this paper is to find an appropriate ratio of waste crushed brick that is used as a replacement of other constituents represented by lime hydrate and silica sand. Besides it aims to find out a perspective utilization of such a waste material. Finely crushed brick originates from the production of thermal insulating brick blocks which is ecologically and economically advantageous. In this work, results of measured material parameters of render mixtures with different replacement ratios of binder (lime hydrate) and simultaneously filler (silica sand) by finely crushed brick are presented. Among the studied parameters basic physical properties (measured by water vacuum saturation method and by helium pycnometry), characterization of pore system (by mercury porosimetry) and thermal characteristics are presented.

Abstract: Aerogels are porous materials with potential applications in fields ranging from thermal insulation, catalyst support, filters, electrical storage, components in optical devices, mechanical damping all the way to drug release. However, careful reliable characterization is the base for both, understanding of fundamental structure - property relationships as well as a directed development of materials and composites for specific applications. The review therefore addressed severe problem upon aerogel characterization that have been identified in the past and presents reliable non-destructive alternatives and novel methods that can be applied for the characterization of aerogels as well as their gel precursors.

Abstract: Melt-blown nonwoven fabric is a kind of excellent fiber filter media in the field of air filtration, which has the characteristics of high specific surface area, small pore size, high porosity, superfine fiber, low pressure drop and high filtration efficiency. In this paper, the microstructure characteristics of pore diameter and pore size distribution of polypropylene melt-blown nonwoven, and the relationship of micropore structure and filtration characteristics, continuous dust holding test were studies by using instruments of Microscope, Capillary Flow Porometer and TSI 8130 Auto Filter Tester.

Abstract: This work aimed to examine the influence of carbonation on the water sorption isotherms of cement materials. Two types of normalized CEM I and CEM II Portland cement mortars were carbonated at 20°C, 65% relative humidity and 20% of CO₂ concentration for 32 days. The pore size distributions determined from the water sorption showed a reduction in microporosity and a slight increase in the mesoporosity. The pores clogging due to formation of calcium carbonate was highlighted by the reduction of the quantity of adsorbed water and the decrease in the hysteresis isotherms. We also studied the coupling effect between carbonation and humidification-drying cycles. The results of this study also indicated that the humidification-drying cycles coincide only from the second cycle because of a difficult evacuation of water during desorption, even at low humidity.

Abstract: On the base of the former research of mercerization of pulp fibers, SEM, XRD and Automated Surface Area & Pore Size Analyzer were used to characterize surface morphology, crystalline property, and specific surface area and the pore size distribution of fibers. The results show that the fiber cell wall swelling, degree of crystallinity decrease and specific surface area and pore size distribution increase after mercerization.

Abstract: SEM and Automated Surface Area & Pore Size Analyzer were used to characterize surface morphology and specific surface area and the pore size distribution of fibers. The results showed that specific surface area and pore size distribution increase after ultrasonication. The ash content of the composites of ultrasonic treated fiber is larger than the untreated fiber, and the magnetic properties show a good superparamagnetic behavior.

Abstract: For determination of compressive strength of bedding mortar used in historic masonries, a promising moderately-destructive technique is double punch test (DPT). DPT consists of loading prismatic samples of mortar (about 4×4×1 cm³) by means of two circular steel platens (typically 2 cm diameter) and then calculating mortar compressive strength as the ratio of the failure load to the cross section of the circular platens. In this study, the influence of mortar sample thickness and mortar sample capping on the reliability of results obtained by DPT was systematically investigated. The influence of sample thickness was assessed by comparing DPT results obtained for samples with 5, 10, 15 and 20 mm thickness with compressive strength determined by testing reference 4 cm-side cubes. Different mortars were considered (cement, lime-cement, natural hydraulic lime), in order to investigate a wide range of mortar mechanical characteristics. The influence of surface capping was evaluated on a lime-cement mortar by comparing compressive strength determined on reference cubes with strength obtained by DPT on proper samples, without capping and after capping with rubber, gypsum and cement. The results of the study indicate that sample thickness substantially influences mortar compressive strength determined by DPT, which may vary by up to three times depending on sample thickness. A good estimation of the actual mortar compressive strength was obtained when samples with thickness similar to the loading platens diameter were tested, which suggests that choosing the size of the loading platens for DPT based on the thickness of mortar joints under investigation may be an effective way for obtaining reliable estimations. As for the influence of surface capping, in those cases where no mortar sample regularization is possible, because of the poor quality of the mortar, the results of the study indicate that sample capping actually seems necessary in order to avoid significant underestimations of mortar compressive strength. Considering the higher practicality offered by gypsum with respect to rapid-setting cement for surface capping, the use of gypsum seems preferable.

Abstract: Carbon Nanotubes (CNT) have emerged and gained great interest for research in many applications because of their unique specific characteristics such as having high porosity, high surface area and the existence of a wide spectrum of surface functional groups through chemical modification. Multiwalled carbon nanotubes (MWCNT) is a type of CNT that comprises of multiple layers of concentric cylinders. The overall study of this research work is to modify MWCNT to become a good adsorbent that can adsorb CO₂ at its optimum capacity. In order to make MWCNT as an efficient adsorbent, surface treatment on pristine MWCNT is necessary to overcome the hydrophobicity issue by the introduction of carboxyl group. Upon the surface treatment, functionalization of MWCNT with 3-Aminopropyl triethoxysilane (APTS) was conducted to obtain the attachment of amine group that will assist MWCNT in adsorbing CO₂. The surface treatment and functionalization process undergone by MWCNT changed the physical properties of MWCNT such as the surface area, pore volume, and pore size distribution. These properties can be determined using surface area and pore analyzer (SAP). Sample that treated with the mixture of nitric and sulfuric acid (HNO₃/H₂SO₄) and functionalized with APTS gives the lowest surface area (22.07 m²/g) and pore volume (0.06 cm³/g). The pore size distribution also decreases due to the most presence of functional group onto the surface of modified MWCNT. This research paper is focusing on the effect of surface area, pore volume, and pore size distribution on the modified MWCNT.

Abstract: Hygric transport properties belong to a group of important characteristics from a construction design point of view. Since a content of water (at whatever state) could lead to degradation processes of materials whether by phase changes or by chemical reaction (with any component of water contained), it is important to know an amount of water which can get into the pore structure of a material. Studied materials in this workwere sandstones. Several types of these clastic sedimentary rocks were chosen and experimental determinations of basic physical properties as well as hygric transport parameters were performed. From the achieved results,it is obvious that the main influence on hygric transport characteristics has the open porosity, in particular the pore structure.The higher porosity is the higher amount of water can be transported through the sandstones.