Composite Building Materials Research Articles

Towards Sustainable Composite Building Material: Integrating Lime with Slag for reduced mortar Thermal Conductivity

Lime Based Mortar became very popular due to its outstanding features of flexibility, permeability and low carbon emissions. However, lime’s characteristic delayed setting, late hardening time, low mechanical strength, among others, overshadowed significance of its outstanding features, thereby putting its overall use into decline, particularly, with the 19th century Portland Cement discovery. This study therefore aims at reviving lime usage through a sustainable lime composite, by integrating an industrial by-product, Ground Granulated Blast Furnace Slag (slag) with lime, in form of lime-slag mortar, with a view to reducing the mortar thermal conductivity. The methodology involved mortars with the same Binder/Aggregate (B/A) mix ratio (1:3) using five separate volumetric compositions of ‘slag-lime’ binders (i.e. 1:1, 1:2, 1:3, 2:1 and 3:1). Physical properties of the mortars involving their Water/Binder (W/B) ratios, Air Contents and Bulk Densities were recorded. Comparative evaluations of the compositions in hardened state, involving thermal conductivities were carried out at specific intervals through a twelve-month curing period. These were partly monitored through assessments of the composites’ microstructural behaviours over a six-month period. Results of the investigation show that addition of slag to mortars facilitate slightly larger pores with increased porosities. However, these effects are minimal (i.e. from 23.42% to 25.37% porosity) when slag content is at equal volumetric content with lime. A general reduction (not in a linear trend) in the thermal conductivities of the mortar with increasing slag content was observed, cumulating in 25% decrease in the composites having thrice volumetric content of slag, relative to lime. Composite’s reduced thermal conductivity would be of utmost importance in construction especially, where material’s limited thermal conductivity property is of utmost importance.

Towards Sustainable Composite Building Material: Integrating Lime with Slag for reduced mortar Thermal Conductivity

Lime Based Mortar became very popular due to its outstanding features of flexibility, permeability and low carbon emissions. However, lime’s characteristic delayed setting, late hardening time, low mechanical strength, among others, overshadowed significance of its outstanding features, thereby putting its overall use into decline, particularly, with the 19th century Portland Cement discovery. This study therefore aims at reviving lime usage through a sustainable lime composite, by integrating an industrial by-product, Ground Granulated Blast Furnace Slag (slag) with lime, in form of lime-slag mortar, with a view to reducing the mortar thermal conductivity. The methodology involved mortars with the same Binder/Aggregate (B/A) mix ratio (1:3) using five separate volumetric compositions of ‘slag-lime’ binders (i.e. 1:1, 1:2, 1:3, 2:1 and 3:1). Physical properties of the mortars involving their Water/Binder (W/B) ratios, Air Contents and Bulk Densities were recorded. Comparative evaluations of the compositions in hardened state, involving thermal conductivities were carried out at specific intervals through a twelve-month curing period. These were partly monitored through assessments of the composites’ microstructural behaviours over a six-month period. Results of the investigation show that addition of slag to mortars facilitate slightly larger pores with increased porosities. However, these effects are minimal (i.e. from 23.42% to 25.37% porosity) when slag content is at equal volumetric content with lime. A general reduction (not in a linear trend) in the thermal conductivities of the mortar with increasing slag content was observed, cumulating in 25% decrease in the composites having thrice volumetric content of slag, relative to lime. Composite’s reduced thermal conductivity would be of utmost importance in construction especially, where material’s limited thermal conductivity property is of utmost importance.

Research on Thermal Insulation Properties of Plant Fiber Composite Building Material: A Review

The annual output of crops in China is about 900 million tons. Improper handling of large amounts of straw waste increases the negative impact on the environment. Recently, many scholars have studied the rational use of crop straw, and found that straw was rich in plant fiber, which combined with some kinds of building materials could be used to produce new green composite building materials. The composite building materials are more environment friendly and economical than the traditional materials, which can greatly improve the wall insulation performance. However, there are numerous factors affecting the thermal insulation performance of composite building materials. Conducting an in-depth analysis of the main factors and trends influencing the thermal insulation performance of composite building materials is necessary. This paper firstly introduced the current situation and existing problems of crop straw waste utilization, then discussed the influence of main factors on the thermal insulation properties of composite building materials. According to the analysis, the straw content is the most principal factor affecting the thermal insulation performance of composites. In a certain value range, the thermal conductivity of the composites decreases with the increase of straw content and the decrease of moisture content. Composites produced with pretreated plant fiber have better thermal insulation performance than composites without pretreatment. The thermal conductivity value of the composites decreases with increase in fiber length. Based on the research of functional rule of various influencing factors on the thermal insulation performance of composites, composite building materials with better thermal insulation performance could be obtained.

Cement-based composites with waste expanded perlite - Structure, mechanical properties and durability in chloride and sulphate environments

Implementation of fine, dusty materials generated during the production of expanded perlite is a challenge from the waste disposal point of view. However, after proper treatment, it is possible to use them in the composite building materials manufacturing where they can play a role of so-called pozzolanic additive, strengthening setting and hardening process when mixed with cement. In this study waste expanded perlite – Portland cement composites were exposed to the action of sodium chloride, sodium sulphate and magnesium sulphate solution. The results show that the durability of cement composites with waste expanded perlite is significantly improved; the lifecycle of these materials would be markedly enhanced. Due to the pozzolanic reaction between the vitreous aluminosilicate component of perlite and calcium hydroxide released from cement clinker, the phase assemblage of hardened cement matrix is changed towards the partial replacement of calcium hydroxide by the C-S-H phase. The amount of calcium hydroxide is therefore markedly reduced, as well as the pore refinement and compact microstructure of products is observed. As a consequence, the compressive strength increases, the permeability of final material decreases. Therefore the durability of Portland cement - perlite mortars is significantly improved. The reference mortars with cement subjected to the sodium and magnesium sulphate started to expand after 200 and 100 days of curing respectively. They were destroyed after about a year, while the samples containing 20% of WEP exhibited no expansion after 5 years of storage in corrosive solutions.

Experimental Investigations on the Performances of Composite Building Materials Based on Industrial Crops and Volcanic Rocks

Interdisciplinary and sustainability represent the main characteristics of this paper due to the fact that this research is offering a connection between two main areas—agronomy and construction, by using hemp shiv for the design of new building materials, which can increase the sustainability level of the building industry. For this reason, the main scope of this study is based on the investigation of a new category of composite building materials—lightweight mortars based on hemp shiv, volcanic rocks and white cement—which contribute to a positive environmental impact and help to increase indoor comfort. A complex report was carried out on two segments. The first one is focused upon the characteristics of the raw materials from the composition of the new materials, while the second segment presents a detailed analysis of these composites including morphological and chemical investigation, pyrolytic and fire behavior, compression and flexural strengths, and acoustic and thermal characteristics. The proposed recipes have as a variable volcanic rocks, while the hemp and the binder maintain their volumes and properties. The results were analyzed according to the influence of volcanic rocks on the new composites.

Reaction of Spot Radioactive Source with the Energy of 661.7 KeV on the Modification in the Structure of Surface Layer of Metal Composite Material

This paper presents the results of studies of the composite metal radio-protective building material by method of atomic-force probe microscopy, before and after its irradiation with gamma rays of 661.7 keV and absorbed dose up to 2 MGy. Composite metal material is based on the filling of hematite iron ore concentrate and aluminum matrix. This composite material has high technical (physical and mechanical) and radio-protective proprieties. The composite is planned to be employed as a bearing structure at various nuclear facilities.

Composite building materials from natural fibers/ agro-forest residues

Interest in using renewable resources such as natural fibers and agro-forest residues as reinforcements/fillers in polymer matrices has grown considerably for making wood alternatives in view of their low cost, easy availability, saving in energy and pollution free-production. In this paper, an overview on the global perspective of natural fiber reinforced composites has been outlined with reference to their applications in buildings. Researches carried out on polymer composites based on natural fibers and agro-forest residues are briefly reviewed in terms of their physico-mechanical properties and performance characteristics. During fabrication, 30-50 wt % sisal/jute fibers in laminates/sheets, 50-60 wt % rice husk in extruded/injection moldings and ~95 wt % pine needles in boards have been used. The sandwich composites used in the doors ( jute laminate face, and polyester-urethane foam core) have a density of 500-610 kg/m3 and exhibited ~1.5% weight loss when exposed to termites according to ASTM D 3345. Based on the results, sisal/jute composite panels/ door shutters, shuttering plates, rice husk/plastic profile frames and pine needle composite boards have been successfully manufactured at pilot plant scale. Techno-economics and sustainability issues related to these composites have also been discussed in order to develop confidence among users and entrepreneurs. A comparative assessment between the properties of these newly developed products and commercial specification gives a clear guideline for users about their suitability in large scale adaptation in practice.

Thermal insulation and acoustic building composite materials based on expanded obsidian

In modern conditions, one of the ways allowing the construction company to be competitive in the market is the use of modern high – quality and, at the same time, cheaper building materials. Many technogenic formations, in particular solid waste are valuable technological raw materials and can be involved in technological redistribution in order to obtain composite building materials. In the production of crushed stone, sands from lithoid pumice and perlite, it is advisable to produce separation and separate obsidian. In this case, the separated obsidian turns into production waste. The expantion of obsidian will allow to obtain a large porous ultralight material and thereby solve environmental issues – recycle production waste. On the base of expanded obsidian, it is possible to obtain new types of effective composite thermal insulation and acoustic materials (cellular concretes and acoustic plasters), which have high performance properties and expand the range of effective building composite materials.

Microbiological corrosion of building materials

The research results in the field of microbiological corrosion of building materials of domestic and foreign experts are presented. It is shown that microorganisms cause corrosion of concrete on cement and other binding metal and other materials. Metals in the order of decreasing the rate of biocorrosion are arranged in the following row: aluminum, mild steel, zinc, brass, copper, stainless steel. Concrete, due to its high surface activity, is capable of adsorbing a wide variety of substances, including microorganisms: bacteria and mycelial fungi. Among bacteria, nitrifying agents, thionic, iron and silicate bacteria and others participate in the corrosion of cement concrete (mainly due to their acid secretions). According to the data of a number of authors, on the surface of stone building materials mycelial fungi of the genera Penicillium, Aspergillus, Trichoderma, Cephalosporium prevail. Biodeterioration in this case mainly comes down to the disruption of cohesion of constituent components as a result of exposure to mineral or organic acids, as well as enzymes and due to chemical reactions between the cement stone of solutions and concretes and the waste products of microorganisms. The compositions of bituminous composites at various ratios of the materials used without inclusion in the composition of fungicides showed non-fungal resistance and non-fungicide. Comparison of concrete on gypsum and phosphogypsum binders showed that samples on a phosphogypsum binder overgrow microorganisms somewhat more, wood materials are subject to significant biodeterioration at high humidity. Biodegradation of wood occurs mainly due to the use of mushrooms as food sources of cellulose, lignin and other components. Synthetic polymers and materials based on them are significantly superior to natural polymers in biostability. However, under certain operating conditions, they are damaged by biological agents. Biological damage to plastics, as well as other materials, occurs simultaneously with their aging under the influence of external physical and chemical factors (ultraviolet radiation, water, temperature changes, etc.). Additives that are usually always present in polymer compositions (fillers, plasticizers, stabilizers, antioxidants, modifiers, pigments, etc.) significantly affect the biostability of polymeric materials. One of the effective ways to increase the biostability of composite building materials is the introduction of fungicidal additives in their composition. It is also shown that of great importance in increasing the durability and increasing the life of some building structures (metal products, communications, underground pipelines and some others) is their protection by paint and varnish coatings.

Thermal conductivity of composite building materials: A pore scale modeling approach

In this article the effective thermal conductivity (ETC) of a wide range of multiphase porous building materials has been estimated numerically. The numerical random generation macro-meso pores (RGMMP) method, which is based on the macroscopic statistical information, such as the porosity, volume fraction of macro-meso pores, is used here for the reconstruction of microstructures of various porous building materials. The distribution of macro-meso pores and their sizes are controlled by core distribution probability and porosity. The lattice Boltzmann method equipped with the conservation of energy and suitable boundary conditions at multiple interfaces is adopted for the numerical solution of energy transport equations through the porous media. After comparison with the benchmark of some theoretical solutions and existing experimental observations, it is employed for the estimation of ETC of different multiphase building materials. The resultant predictions through proposed model accord much better with the existing experimental data than the values obtained through traditional theoretical models. Moreover, comparison of the current reconstruction method, RGMMP, with previously proposed Quartet Structure Generation Set (QSGS) method indicated that predictions with present model is more accurate than those obtained with QSGS. Finally the method is applied for analyzing the variation of ETC with temperature and found that value of thermal conductivity rises with increase in temperature for all the mentioned building materials.

Modelling the hygrothermal behaviour of cement-bonded wood composite panels as permanent formwork

This paper reports on the hygrothermal behaviour of a new bio-based composite building material, based on recycled wood fibres used as eco-aggregate within a cementitious matrix. A coupled heat and moisture transfer was established through the material and resolved numerically with a model developed herein. Relative humidity and temperature were chosen as driving potentials. The hygric and thermal properties of the material were analysed and then used as input parameters in the model. The accuracy of the latter was verified by comparing the simulation results with experimental hygrothermal tests, from which the moisture buffering value (MBV) could be determined. The MBV showed that the wood-cement composite material might contribute to improve the indoor thermal comfort and be relevant for low-energy building design.

Components of solid municipal waste in construction compositions

The effectiveness of chemical, thermal, mechanical and complex methods of disposal of polymer waste was analyzed. The results of studies aimed at the development of the composition of a thermoplastic binder using polymeric municipal waste, taking into account the sample sizes of various components in waste sorting complexes, are presented. The binder is filled with mineral powders and shredded wood waste. Received compositions are used for the manufacture of construction products with a long life cycle. Standard methods for determining the properties of products for constructional purpose, the parameters of the fillers were used. Compositions for the manufacture of polymer-mineral composite building materials are offered. The optimal parameters of filling and dosage of functional additives are established.

Evaluation of components influence of fillers in building materials on their physical characteristics by means of computer data analysis

The article presents an analysis of the dependence of the strength characteristics of new polymer-mineral composite building materials on the percentage of mineral filler components. The influence of the main components that are not included in the noncrystalline phase of the samples under study on the physical and mechanical properties of the materials under study was evaluated. The results showed that the use of substances with a high content of crystals with perfect splitting without crystals with imperfect splitting as fillers for a polymer composite could contribute to the production of building materials with high strength characteristics. These results can be used to assess the joint influence of components on both the physical characteristics already considered and others.

The effect of structuring composite building materials

A mechanism for structuring the dispersion-filled composite materials by the example asphalt concrete is considered in this paper. The effect of an abrupt increase in the strength and water resistance of the material is conditioned the manifestation of intermolecular interaction forces, is shown, which occurs during the formation of binder films between dispersed aggregate particles with a thickness comparable to the radius of action of intermolecular attraction forces. It was established that the structuring of asphalt concrete is manifested when the thickness of the liquid interlayers between the particles of the mineral powder is about 10-7 m, which allows to attribute the effect to the category of nano effects. The technology of industrial production of structured material based on pelletizing is proposed. The test results of the new material are presented. The possibility of using the developed technology for the disposal of industrial waste is shown.

Experimental determination and fractal modeling of the effective thermal conductivity of autoclave aerated concrete (AAC) impregnated with paraffin for improved thermal storage performance

Autoclave aerated concrete (AAC) was incorporated with paraffin to form novel composite building materials with improved thermal storage capacity. The composite samples were prepared by impregnating RT28 paraffin into three types of AAC with different porosities. The effective thermal conductivity of the paraffin/AAC composites was measured at both 20 °C and 35 °C, while the paraffin was in solid and liquid phases, respectively. A fractal model was developed to predict the effective thermal conductivity of the composites. Both the experimental results and model predictions showed that the thermal conductivity increases with raising the paraffin content, leading to deterioration of the thermal insulation performance of pristine AAC. The volumetric heat capacity of the composites was also measured to derive the thermal effusivity, which serves as a measure for thermal storage performance of building materials. To reach a compromise among the various considerations, it was suggested that an intermediate paraffin content, about two thirds of the saturated level, is appropriate for all samples because it is unnecessary to fully impregnate the AAC samples with paraffin at the cost of reducing the insulation performance and increasing the risk of paraffin leakage upon melting.

Application of Water-Dispersed Quantum Dots to Crack Monitoring in Smart Composite Materials

Heterostructurally engineered CdZnSeS@ZnS quantum dots (QD) materials are synthesized through surface modification involving ligand exchange, changing the surface chemistry from hydrophobicity to hydrophility. The hydrophilic characteristics of the CdZnSeS@ZnS QDs are exploited in the artificial monitoring of the cracks present in the smart composite building materials. The synthesized CdZnSeS@ZnS QDs demonstrate that the average sizes of CdZnSeS and CdZnSeS@ZnS QDs are 9.5 and 12.7 nm, respectively. The presence of ZnS shell (~1.6 nm) functions as an effective physical barrier in order to enhance the stability of QDs against environmental changes such as the ligand exchange process. The optimized CdZnSeS@ZnS QDs, exhibit high-quality fluorescent features with a peak emission wavelength of 525 nm. The current work chose the shape memory alloy(SMA)/cement composites as a model system of cement-based materials, due to its applicability to self-healing functions mediated through shape memory alloys immersed into the cementitious matrix. The SMA/cement composites are subjected to the hostile mechanical loading, leading to mechanical defects, cracks and subsequently were heated to heal cracks mechanically generated. The insertion of aqueous QD solutions to the recovered SMA/cement composites is evaluated in terms of structural health monitoring. Unlike the previous crack monitoring approaches, the water-dispersed QD materials demonstrate the facilitated infiltration to the crack networks and the effective monitoring capability with the aid of highly luminescent quantum dots. The unique features are discussed with the main emphasis on the hydrophilic properties of the CdZnSeS@ZnS QDs. The aqueous QD solution approach is proven to be suitable for monitoring complex cracks and self-healing features in smart composite materials which will be employed in buildings and infrastructures.

An Experimental Programme on Fibre Reinforced Concrete made with OPC, Fly Ash and Metakaolin

Most commonly used composite building material in construction industry is Concrete due to ease of construction and its properties like compressive strength and durability. The basic ingredient of Concrete having adhesive nature is Ordinary Portland Cement(OPC). OPC is being replaced with Fly Ash and Metakaolin as these mineral admixtures possess pozzolanic properties which credit for strength gain and cost reduction in concreting. In this investigation, OPC is replaced up to 40% with Fly Ash and Metakaolin for M35 grade of Fibre Reinforced Concrete(FRC). Natural sand is replaced completely with Manufactured sand (M-sand). Steel fibres @ 1% of binder are used. Mechanical properties like compressive strength and split tensile strength at 7 days and 28 days age are tested. Additionally durability tests like water absorption and sorptivity after 28days curing are conducted. The test results indicated that 30% replacement of OPC was optimum for strength criteria, workability of Concrete was decreased with increase in replacement of OPC with Fly Ash and Metakaolin together.

Soil degradation due to pollution by oil and oil products and the development of a way to prevent them

Soil degradation and, as a result, desertification is a global phenomenon, but in Kazakhstan it is feltmost acutely. The main causes leading to desertification and adverse environmental changes includechemical contamination of the soil. Local and regional chemical pollution of soils is observed near citiesand industrial enterprises, open-pit mining of mineral resources. The dominant group of chemical pollution will be oil itself, gas accompanying it, waste and underground mineralized water. The problem ofdetoxification, cleaning and restoring the properties and fertility of soils polluted with oil and oil productsin order to prevent soil degradation is an important and most pressing issue at present. The main idea ofthe work is to create a solar complex for processing oil and gas waste with the development of fundamentally new solutions in the technological scheme for processing oily waste.In world practice, various methods of cleaning soil and water from oil pollution are applied: mechanical, physicochemical and biological. Not all of them are safe and effective. To solve the problemsof anthropogenic pollution by oil and petroleum products, photothermal methods during cleaning toremove the hydrocarbon portion of the soil. The authors have created a solar system and developed away to prevent soil degradation with the production of petroleum products.The scientific novelty of the work lies in the use of various types of solar constructions in the recycling and utilization of oily wastes, ensuring maximum separation of hydrocarbons from oil wastes, without prejudice to their chemical structure, in the manufacture of modern composite building materials,ensuring the intensification of hardening processes.The results show that an environmentally friendly method has been developed for cleaning oilpolluted soils, soils and oil sludge. This method solves an important environmental problem of cleaningoil-polluted soils, soils and oil sludge, helps restore and prevent the degradation of natural complexes,reduces pollution of the soil layer and water bodies. This will allow utilizing oil barns and sludge collectors in all oil-producing regions using solar energy.Key words: soil degradation, technogenic desertification, oil pollutants, land reclamation, soilcleaning.

Mechanical properties of the gypsum composite reinforcement with wooden fibers

The gypsum is one of the most often used materials in the civil engineering. Very often it is applied in the form of plasterboards without any reinforcement, for example, cladding boards are unusable as supporting construction. To improve the mechanical properties of plasterboards, fibrous materials such as cellulose or glass fiber are added. Reinforcement of gypsum with fibers improves in particular the flexural and shear strength. The main purpose of the research is to clarify whether natural wooden fibers could be used as the reinforced of composite gypsum building materials. Wooden fibers are used as a blown or board thermal insulation. This article presents the results of tests aimed at determining the mechanical and physical properties of gypsum composite reinforced with wooden fibers. The effect of the reinforcement on the strength properties as a compressive strength, flexural strength was verified on a series of test specimens. The results of the tests have shown that the reinforcing of gypsum composite has an impact on the mechanical-physical parameters.

CLAY CONSTRUCTION COMPOSITES BASED ON CHEMICALLY ACTIVATED RAW MATERIALS AND ORGANIC CONNECTORS

Objectives. The aim of this work is to study the theoretical aspects and technological possibilities of chemical activation and modification of organic clay raw materials of the Volga region in organic additives to obtain composite building materials based on previous work on the development of clay cement composites.Method. In connection with the high physicochemical activity of clay and cement with respect to organic additives and mineral salts, expressed in the high adsorption activity and sensitivity of hydration processes, studies of the structure of clay were studied separately from cement. To determine the change in pH value of suspensions from clay and clay cement raw materials, the role of the influence of ECA products of treatment of aqueous-salt solutions of sodium chloride and ACF resin was studied.Result. The results of the tests showed that by changing the pH values of the clay cement samples by the products of electrochemical activation of water-salt solutions, it is possible to actively influence the active centers of the surface of clay particles. The adsorption and capacity of the cation exchange of clay raw materials are reduced when they are modified with acetone formaldehyde resin.Conclusion. The studies carried out to study the structure formation and the nature of the effect of the pH of the system environment on the process of the condensation of the ACF resin create the prerequisites for further research in the field of soil consolidation, their stabilization and enhance-ment of operational parameters.