Volume of permeable voids

The experiment is completed in two phases. In the first phase, the effects of different NC contents on the compressive strength of mortar and concrete are evaluated. The optimum NC content that exhibited the highest compressive strength is selected to be included in HVFA concretes and mortars to evaluate its effects on early age (e.g., at 3 and 7 days) and later age (e.g., up to 90 days) compressive strengths. The mixture proportions of mortars and concretes used in this phase are shown in Tables 11.2 and 11.3, respectively. The second phase was designed to study the effect of optimum NC (i.e., 1 wt%) on water sorptivity, volume of permeable voids (VPV), chloride permeability, porosity, and chloride diffusion of HVFA concretes containing 39 and 59 wt% FA and cured at 28 and 90 days. 

The existed straight relationship between the compressive strength and density. Also, the existed inverse relationship between the compressive strength, density and absorption, volume of permeable voids. 

The compressive strength increase as the addition of SF increases. However, the diy density tends to also increase due to the relatively high specific gravity. Also, absorption and volume of permeable voids decrease as the addition of SF increases. These happen due to the micro filling effect and pozzolanic reaction of SF contributed to a denser microstmcture. 

Diatomaceous Silica Filter aids of diatomaceous silica have a dry bulk density of 128 to 320 kg/m (8 to 20 Ib/fU), contain paiiicies mostly smaller than 50 [Lm, and produce a cake with porosity in the range of 0.9 (volume of voids/total filter-cake volume). The high porosity (compared with a porosity of 0.38 for randomly packed uniform spheres and 0.2 to 0.3 for a typical filter cake) is indicative of its filter-aid ability Different methods of processing the crude diatomite result in a series of filter aids having a wide range of permeability. 

Specific gravity, apparent The ratio of the weight in air of a given volume of the impregnable portion of a permeable material (that is the solid matter including its permeable pores or voids) to the weight in air of an equal volume of distilled water at a stated temperature. 

The subject of study in this case is permeability of regular or irregular 2D and 3D lattices that have some distinctive property. It can be, for example, the lattice of sites formed of different phases, A and B, and the problem is reduced to an establishment of interconnectivity of the system through phase A or B (in one of the phases there can be void). In other examples, there can be problems with the introduction of additional phases that regulate heat transfer or electrical conductivity of the catalyst, or additives, which are introduced into the volume of the catalyst, and further are dissolved or burned off to form a system of transport pores. In the latter case, the percolation approach allows estimations of a volumetric part of the additive that is necessary to form... 

Preferred fluid migration pathways are influenced by porosity and permeability, sedimentary sequences, facies architecture, and fractures. Porosity is a measure of pore space per unit volume of rock or sediment and can be divided into two types absolute porosity and effective porosity. Absolute porosity (n) is the total void space per unit volume and is defined as the percentage of the bulk volume that is not solid material. The equation for basic porosity is listed below ... 

All voids in the subsurface medium are classified as porosity. When pore spaces are interconnected so that water can flow between them, the medium is said to be permeable. The actual openings that permit water flow are referred to as effective porosity. Effective porosity is calculated as the ratio of the void spaces through which water flow can occur to the bulk volume of the medium (expressed as a percentage) as follows ... 

Apparent Density and Apparent Specific Gravity. Apparent density is the weight of a unit volume of a porous solid including any air which may be entrapped in the pores or interstices (impermeable voids) but not between the grains (permeable voids). This value would be identical with abs d of a material contg no voids (permeable or impermeable), but otherwise it is smaller than the abs d... 

Permeability. Although wood is a porous material (60—70% void volume), its permeability (ie, flow of liquids under pressure) is extremely variable. This is due to the highly anisotropic shape and arrangement of the component cells and to the variable condition of the microscopic channels between cells. In the longitudinal direction, the permeability is 50 to 100 times greater than in the transverse direction (13). Sapwood is considerably more permeable than heartwood. In many instances, the permeability of the heartwood is practically zero. A rough comparison, however, may be made on the basis of heartwood permeability, as shown in Table 3. 

Two terms, permeable and porous, can be distinguished. Porosity relates to the proportion of free space in a material. A low-density wood or cellular foam is porous in that it contains a large void volume. A permeable material, on the other hand, is defined in terms of the ease of fluid flow. If the cells are interconnected then air/water can escape when compressed and the material is porous and permeable (a sponge). A material is porous and impermeable where the cells are closed and the... 

Annealing a porous membrane (particularly one which contains a nonsolvent capable of functioning as a plasticizer) produces a decrease in void volume and permeability and, because pore size is... 

Most solid powders contain a certain void volume of empty space. This is distributed within the solid mass in the form of pores, cavities, and cracks of various shapes and sizes. The total sum of the void volume is called the porosity. Porosity strongly determines the important physical properties of materials, such as durability, mechanical strength, permeability, adsorption properties, and so on. The knowledge of pore structure is an important step in characterizing materials and predicting their behavior. 

These macroscopic measurements of gas trapping are confirmed by visual observations in transparent etched-glass micromodels and bead packs (24—26, 41). Trapped foam severely reduces the effective permeability of gas moving through a porous medium by blocking all but the least resistive flow paths. Hence, trapped gas reduces the void volume of the porous medium available for flow. Thus, higher flow resistances are measured, and lower permeabilities to gas are computed. This trapped gas accounts for some, but not all, increased resistance to flow. 

---