Antimicrobial Efficiency of Metallurgical Slags Suitable for Construction Applications

The chapter deals with studying antimicrobial efficiency of granulated blast-furnace slag with fineness of 340 (1Sa) and 520 m2/kg (1Sb), air-cooled blast-furnace slag (2S), demetallized steel slag (3S), calcareous ladle slag (4S) and copper slag (5S), respectively. The efficiency has been tested on G+ bacteria—Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus; G− bacteria—Pseudomonas aeruginosa, Escherichia coli, Serratia marcescens; yeasts—Rhodotorula glutinis, Candida albicans; filamentous fungi—Penicillium funiculosum, Aspergillus niger, Alternaria alternata, Chaetomium globosum, Cladosporium herbarum, Trichoderma viride. The efficiency has been determined by dilution methods in agar media for that reason the resulting concentration of slags has been 10, 20, 40 and 60%, respectively. The antibacterial efficiency decreased as follows: S4 > S3 > S2 > S1a = S1b > S5, whereas anti-yeast efficiency decreased as follows: S4 > S1a = S1b = S3 > S2 > S5. Filamentous fungi were selectively sensitive to slags, that way there is approximate order of efficiency S4 > S3 = S1a = S1b > S5 > S2. Application of metallurgical slags into construction materials provides them increasing biodegradation resistance

Recycled cellulose fiber reinforced plaster

This paper aims to develop recycled fiber reinforced cement plaster mortar with a good workability of fresh mixture, and insulation, mechanical and adhesive properties of the final hardened product for indoor application. The effect of the incorporation of different portions of three types of cellulose fibers from waste paper recycling into cement mortar (cement/sand ratio of 1:3) on its properties of workability, as well as other physical and mechanical parameters, was studied. The waste paper fiber (WPF) samples were characterized by their different cellulose contents, degree of polymerization, and residues from paper-making. The cement to waste paper fiber mass ratios (C/WPF) ranged from 500:1 to 3:1, and significantly influenced the consistency, bulk density, thermal conductivity, water absorption behavior, and compressive and flexural strength of the fiber-cement mortars. The workability tests of the fiber-cement mortars containing less than 2% WPF achieved optimal properties corresponding to plastic mortars (140-200 mm). The development of dry bulk density and thermal conductivity values of 28-day hardened fiber-cement mortars was favorable with a declining C/WPF ratio, while increasing the fiber content in cement mortars led to a worsening of the water absorption behavior and a lower mechanical performance of the mortars. These key findings were related to a higher porosity and weaker adhesion of fibers and cement particles at the matrix-fiber interface. The adhesion ability of fiber-cement plastering mortar based on WPF samples with the highest cellulose content as a fine filler and two types of mixed hydraulic binder (cement with finely ground granulated blast furnace slag and natural limestone) on commonly used substrates, such as brick and aerated concrete blocks, was also investigated. The adhesive strength testing of these hardened fiber-cement plaster mortars on both substrates revealed lime-cement mortar to be more suitable for fine plaster. The different behavior of fiber-cement containing finely ground slag manifested in a greater depth of the plaster layer failure, crack formation, and in greater damage to the cohesion between the substrate and mortar for the observed time.Web of Science1411art. no. 298

Characterization of cement composites based on recycled cellulosic waste paper fibres

Nowadays, there is paying an attention to the utilization of natural, renewable and biodegradable resources of raw materials of lignocellulosic character, residues from agricultural crops and wood processing as well as waste from papermaking industry in building composite materials preparing. Also recycled fibres coming from waste paper are considered as valuable material. The objective of this study is to utilize these recycled cellulosic fibres into cement composites and characterise their impact on resulting physical and mechanical properties of fresh and hardened cement composites. Manufactured cement composites contained 0.2%, 0.3% and 0.5% addition of cellulosic fibres. In fresh fibre cement mixtures reduction in workability with increasing amount of cellulose fibres was noticed. Density as well as compressive and flexural strength of 28 and 90 days hardened fibre cement composites was tested. Distribution of cellulosic fibres with 0.5% addition in hardened fibre cement composites was also observed. The results of density determination of 28 and 90 days hardened fibre cement composites showed reduction in their values related to weight lighter concretes. Compressive strengths of fibre cement composites have shown decreasing character with increasing added amount of cellulosic fibres into the mixture up to 0.5%. Maximal decrease in compressive strength values was observed in composites containing 0.5% of cellulosic fibres. However, obtained strength parameter values of hardened composites had satisfying results for their application in construction as nonload bearing building material.Web of Science8136736

Characterization of manmade and recycled cellulosic fibers for their application in building materials

The aim of this study was to characterize two types of cellulosic fibers obtained from bleached wood pulp and unbleached recycled waste paper with different cellulose content (from 47.4 percent up to 82 percent), to compare and to analyze the potential use of the recycled fibers for building application, such as plastering mortar. Changes in the chemical composition, cellulose crystallinity and degree of polymerization of the fibers were found. The recycled fibers of lower quality showed heterogeneity in the fiber sizes (width and length), and they had greater surface roughness in comparison to high purity wood pulp samples. The high purity fibers (cellulose content > 80.0 percent) had greater crystallinity and more homogeneous and smooth surfaces than the recycled fibers. The presence of calcite and kaolinite in all of the recycled cellulosic fibers samples was confirmed, whereas only one wood pulp sample contained calcite. The influence of the chemical composition was reflected in the fiber density values. Changes in the chemical composition and cellulose structure of the fibers affected the specific surface area, porosity and thermo physical properties of the fibers. More favorable values of thermal conductivity were reached for the recycled fibers than for the wood pulp samples. Testing the suitability of the recycled fibers with inorganic impurities originating from the paper-making processes for their use as fillers in plastering mortars (0.5 wt.% fiber content of the total weight of the filler and binder) confirmed their application by achieving a compressive strength value of 28 day-cured fiber-cement mortar required by the standard as well as by measured more favorable value of capillary water absorption coefficient.Web of Science7111145112

Basic Physical – Mechanical Properties of Geopolymers Depending on the Content of Ground Fly Ash and Fines of Sludge

The binding potential of fly ash (FA) as a typical basic component of building mixtures can be improved in mechanical way, which unfolds new possibilities of its utilization. This paper presents the possibilities of preparing the geopolymer mixtures based on ground (dm = 31.0 μm) FA, used in varying percentages to the original (unground; dm = 74.1 μm) one. As a modification, fine-grain sludge from the process of washing the crushed aggregates was used as filler in order to obtain mortar-type material. The basic physical-mechanical properties of mixtures are presented and discussed in the paper, focusing on time dependence. The following standard tests were executed after 2, 7, 28, and 120 days: density, total water absorption, flexural strength, and compressive strength. Ground FA provided for positive effect in all tested parameters, while incorporation of fine portion of sludge into the geopolymer mixture does not offer a significant technical profit. On the other hand, it does not cause the decline in the properties, so the environmental effect (reduction of environmental burden) can be applied through its incorporation into the geopolymer mixtures

Study of thermal analysis of cellulose fibres using into building materials

This paper provides the investigation of thermal analysis of cellulose fibres which will be used into building materials as a partial filler replacement. Cellulosic fibres come from two various sources: bleached wood pulp and unbleached waste paper whereas these natural fibres have different cellulose contents and another manufacturing process. Natural fibres have been widely used as reinforcing fillers in composite materials in recent years. As a result, they are subjected to thermal degradation during composite processing. It is thus of practical significance to understand and predict the thermal decomposition process of natural fibres and the knowledge will help better design the composite process and estimate the influence on composite properties by the thermal decomposition of natural fibres. The results obtained from the thermal analysis of cellulosic fibres showed differences in their thermal decomposition and also differences in the weight loss due to their chemo-mechanical treatment, the presence of impurities and CaCO3 originating from filler in paper making

The investigation of concrete’ biodeterioration in sewer pipes, case study

The activity of microorganisms plays a very important function in the whole spectrum of degradation processes such as corrosion of metals and concrete, the plugging of the pipeline and filters in consequence of the biofilms creation or the efficiency reduction of heat exchangers. The microorganisms that cause microbiologically influenced corrosion of concrete are ubiquitous in the environment and they produce either organic or inorganic acids that can dissolve and disintegrate the concrete matrix. This paper is focused on the concrete biocorrosion’s study in real sulfuretum conditions — in a sewer pipe with wastewater in Košice city. Concrete samples with addition of 5 and 10% of coal fly ash respectively as well as reference samples without coal fly ash addition were used for the experiment. The weight changes and surface changes of concrete samples were valuated after 4-month exposition to the real sulfuretum influence. The concrete biodeterioration studies in sewer pipes suggest the analogical biodegradation processes for all samples, whereby the composition of concrete and duration of aggressive environment influence are also important

Biocorrosion of concrete sewer pipes

Biocorrosion of natural and synthetic materials is an irreversible biochemical process, where a significant participation of bacteria societies takes place. The biocorrosion of concrete sewer pipes is caused mainly by the sulphuric bacteria and sulphate-reducing bacteria (SRB) forming a part of the biological circulation of sulphur and its compounds in biosphere. The aim of this work was to simulate a biocorrosion and to study the effect of simultaneous action of Acidithiobacillus thiooxidans ( A.t. ) and sulfate-reducing bacteria on concrete samples under model conditions. The biocorrosion effect has been proved and a further study is planed

The mould resistance of carbide lime by-products from deposits

The article deals with testing and evaluating the mould resistance of carbide lime by-product from deposits in comparison with the effect of reference conventional slaked lime. The mould resistance of limes was tested on a mixture of mould such as Gliocladium virens, Paecilomyces variotii, Penicillium funiculosum, Chaetomium globosum, and Aspergillus niger as well as evaluated according to the method stated in the technical standard STN 724310: 1993. The evaluating scale for mould resistance is from 0 up to 5 in the fungal growth degree (FGD). The FGD value 0 stands for no fungal growth comes about and construction materials and products have the microbiostatic effect against filamentous fungi. The experiments confirm the microbiostatic effect against mould of carbide lime by-product from deposits as well as reference conventional slaked lime; however, the microbicidal effect against mould has not been confirmed at all; the inhibiting area-zone-did not form on the agar growth media around the tested samples. Application of carbide lime by-product from deposits ensures increased mould resistance of construction materials with the microbiostatic effect against mould in accordance with technical standard STN 724310: 1993.Web of Science73102582257