Porosity, Permeability and Microstructure of Foamed Concrete Through Sem Images

Abstract

This paper examined the foamed concrete (FC) for permeability of total and capillary water absorption, at 28 days of air sealed curing. The microstructure of 15 selected FC specimens was investigated to determine permeability in relation to porosity and density using Scanning Electron Microscopy (SEM) images. The FC specimens of the densities (1100, 1600, and 1800) kg/m3 were made using fine sand and brick aggregates with toner and MK inclusion as additives. The microstructural investigation of the FC revealed, porosity measure as a percentage ratio of the area under investigation to be in the range of (39.65 to 77.7) %. The pore size is in the range of (0.01 to 70) µm, depending on the type of additive, for the mixes containing toner and MK, it is in a fine range of (0.01 to 10.0) µm. For the FC specimens, the finer the pore size, the less permeable and the stronger it is. Permeability is porosity and strength dependent, whereby high porosity leads to high permeability and low compressive strength for FC mixes made with sand or brick only with no additive inclusion. Meanwhile, the FC mixes made with the inclusion of additives, such as the toner and MK20 mixes, showed an evenly spread net of independent air voids with a regular shape within their matrix, which is beneficial in decreasing permeability. Therefore, besides the porosity and strength, the fineness of the pore matrix and the shape factor of the pores are two other key factors in controlling permeability. Toner and MK20 inclusion can enhance the capillary water absorption to reach almost water tight. Besides, MK30 and MK50 inclusion displayed adverse effect on permeability. Depending on the type of filler, the additive, and the percentage ratio of the porosity of the FC matrix at (1600 and 1800) kg/m3 densities, it is possible to produce FC with compressive strength between (55.1 and 30) N/mm2.

An Integrated Approach to Using Sheep Wool as a Fibrous Material for Enhancing Strength and Transport Properties of Concrete Composites

“…Lower water absorption in reinforced specimens indicates lower environmental harm, confirming the matrices’ lower permeability. With the addition of fibers beyond 2%, due to the uneven distribution of fibers in the concrete matrix, the volume of pores increased, consequently reducing the concrete density and providing more space in the matrix to absorb water and a higher water absorption rate [ 41 , 42 ]. The findings show that raising the fiber volume fraction changed the distribution and size of air voids in the matrices.…”

“…In contrast, De Schutter et al [ 44 ] confirmed that a higher porosity volume in the concrete matrix causes increased sample degradation due to a higher water absorption rate. Shawnim et al [ 42 ] found that an uneven spreading of large holes might increase permeability, leading to greater water absorption.…”

Investigating The Load Carrying Capacities of Lightweight Foamed Concrete Strengthen with Fiber Mesh

“…Thus, the load-carrying capacity in compression is primarily a function of the density. Besides, Shawnim & Mohammad [20] highlighted that at the higher densities, the compressive strength is not influenced by the distribution of air voids, but rather by the more uniform distribution of voids. Lim et al [21] also mentioned that the production of LFC with finer sand results in a more uniform distribution of air voids compared to coarse sand.…”

Optimizing of the Cementitious Composite Matrix by Addition of Steel Wool Fibers (Chopped) Based on Physical and Mechanical Analysis

“…García et al posited that the air void content in a mixture depends mainly on the percentage of the clusters of fibers in the mixture [28], while Schutter et al [29] noted that a more porous generated CCM results in increased degradation of a sample, caused by increased overall water absorption. Shawnim et al [30] pointed out that the uneven distribution of large-sized pores can lead to high permeability, resulting in increased water absorption, while Ramamurthy et al [31] observed that smaller air voids result in lower porosity and vice versa. Figure 5 confirms that increasing the fiber fraction beyond 4% resulted in altered air void distribution and sizes in the CCM.…”