Papers by Keyword: Durability

Abstract: The addition of silicon-aluminium materials can improve the strength of geopolymers, but its effect on the durability of geopolymers has not been confirmed. In this paper, chemical corrosion resistance and freeze-thaw cycle tests were carried out on fly ash geopolymer and metakaolin/mineral slag-fly ash geopolymer, and the reaction mechanism was determined by microscopic analysis. In the chemical corrosion resistance tests, three groups of specimens were immersed in different corrosive solutions, and the corrosion resistance of the specimens was measured by testing the compressive strength and quality change of the specimens immersed in the solution for different times. The results show that the addition of silicon-alumina materials can improve the chemical corrosion resistance of geopolymers in a certain extent, and the mineral slag shows better improvement effect. In the freeze-thaw cycle tests, three groups of materials were put into the freeze-thaw test machine, and their freezing-thawing resisting performance was measured by testing their mass loss rate and compressive strength after different cycles. The results showed that the strength loss of the specimens was improved with the addition of the silicon-aluminium materials, but the mass loss rate of the specimens became higher with the addition of metakaolin.

Abstract: This study investigates the durability performance of local fly ash as a supplementary cementitious material (SCM) in reinforced concrete. In this paper the effect of the fly ash on the durability of reinforced concrete under combined chloride-sulfate penetration has been investigated. Two mixes made by tow formulations: a control mix made of ordinary cement OPC (M1) and a mix substituted with 17% of fly ash (M2) exposed to combined chloride-sulfate attack. The durability performances of these concrete mini pipes were experimentally investigated and evaluated by electrochemical impedance spectroscopy (EIS). The results indicate that the concrete pipe substituted with fly ash shows a high mechanical polarisation resistance compared to the traditional concrete pipe. Moreover, the EDS analysis and visual inspection confirm the results found by the electrochemical measurements. Ultimately, the fly ash as a SCM could improve the service life of reinforced concrete pipe in combined chloride-sulfate attack.

Abstract: The basic material used for advancement in concrete is often composed of essential limiting materials such as concrete, fine aggregate, coarse aggregate, and water. Solid waste management is one of the most important tactics in today's total collection situation. As expected, an effort was made to decrease usual resources and conserve the environment. To increase the strength of concrete, Sodium Silicate (Na₂SiO₃) is added in the amounts of 5%, 10%, 15%, 20%, 30%, 35%, 40%, and 45% by weight of cement. The study entails investigating the effect of adding sodium silicate in various quantities on setting time, workability, and compressive strength. When sodium silicate is added to concrete, there is a significant increase in workability and durability, according to the literature. Setting time and compressive strength were studied, and it was shown that using sodium silicate as a substitute for cement improves workability and durability. When Sodium Silicate is added to concrete buildings, the content of calcium hydroxide drops while the content of calcium silicate hydrate (C-S-H gel) increases as compared to untreated concrete structures. Because the expansive and insoluble C-S-H gels partially fill the micro-pores, micro-voids, and micro fractures in the concrete structures, the sodium silicate-based concrete sealers are basically surface hydrophilic agents. Because of the production of C-S-H gel, the amount of water in the mix is reduced as compared to a traditional one, as is the initial setting time. Sodium Silicate is transformed into a binding agent as well as a superplasticizer after the reaction.

Abstract: Saline soil is an inferior and special material consisting of fine soil particles and possesses poor engineering properties. The swelling, salt heaving, and corrosive behaviors of this soil render it unsuitable for pavement construction due to its deteriorating effects. To use this soil as a subgrade material in the roadway, this soil needs to meet various engineering standard criteria such as deformation, sulfate reduction, strength, and durability for use as subgrade material. Hence, the soil underwent careful stabilization using designed proportions of chemical additives such as lime and slag-based materials. The paper studied the feasibility of using slag-based materials (by-products of the steelmaking process) such as ground granulated blast furnace slag (GGBFS) and basic oxygen furnace slag (BOFS) with lime in stabilizing sulfate-saline soil. On this premise, four designed mixtures, which include saline soil (control), [soil+6% lime], [soil+4% lime+2% (50% GGBFS+50% BOFS)], and [soil+4%lime+2% (70% GGBFS+30% BOFS)] for use to determine their various geotechnical and durability properties. The experimental program for determining these properties included proctor compaction, unconfined compressive strength, three-dimensional (3-D) swelling, and dielectric constant tests. As a result, the laboratory test findings have revealed that adding GGBFS and BOFS to the lime-treated saline soil decreased the maximum dry density, enhanced the strength parameter, and reduced the soil's volumetric swelling and moisture susceptibility.

Abstract: The key drivers of the growing interest in the recovery of local materials, particularly land and waste plants, are low-cost building materials, thermal comfort, decreased energy consumption, and decreased carbon dioxide polluting emissions. This work's primary objective is to test a bio-sourced composite material that takes the form of a block of unfinished soil that has been stabilized with cement and blended with wheat straw. This study is being done with the objective of examining the impact of this fiber at different weight percentages (0, 2, 3%, and 4%) on the mechanical behavior, durability, and thermophysical properties of the produced blocks. The results obtained indicated an increase in thermal conductivity, from 2.75 W/mK for the blocks without wheat straw fiber to 0.398 W/mK for those getting 4% of the wheat straw fiber, signifying an improvement in thermal insulation. While retaining the low performance threshold required by the earth construction standard, this improvement was accompanied by an average decrease in mechanical performance.

Abstract: The research investigated the chemical, mechanical and durability of composites developed from aluminum slag. Aluminum slag is a hazardous residue product of secondary Aluminum smelting. The objective of this research was to study the chemical and geotechnical properties of Al slag. To investigate the stabilization of Al slag with fly ash and GBFS binder to enhance the pozzolanic reaction. Lastly, to study the properties of developed composites and recommend the application. Aluminum slag can be categorized as black or white, with the black dross (slag) having low metal concentration and a granular-like appearance comparable to sand. White dross (slag) has a high metal concentration and contains small quantities of oxides and salts, forming huge blocks. Aluminum slag is a by-product of the foundry industry that is deposited in landfills, causing pollution such as soil, air, and groundwater contamination, as well as affecting human health. Aluminum slag recycling has become more popular in recent years, and it can now be used to make concrete and bricks instead of cement. When compared to properties obtained from composites produced from cement, Aluminum slag improves several properties of the material in this study. Properties such as compressive strength, workability, and durability of the material are found to be improved. At 40% binder and cured at 80°C, the mortar sample made from Al slag, GBFS binder, and fly ash had the highest unconfined compressive strength (UCS) of 24 MPa. The optimum number of days for curing was found to be 14 days. Based on the overall research, it can be concluded that Aluminum slag produced from the foundry industries can be stabilized with fly ash and GBFS binder to produce bricks and concrete

Abstract: Carbon nanotubes (CNTs) have been studied as a reinforcement material for cementitious composites, with promising results. Incorporating CNTs into cement-based materials enhances the composites' mechanical, thermal, and electrical properties, as cementitious materials have limited applications due to their strain capacity and less tensile strength. CNTs have high tensile strength and modulus, along with excellent electrical conductivity. These features make them ideal for construction materials. Using CNTs in cement-based composites can improve the durability and sustainability of construction materials and provide new opportunities for advanced applications in the construction industry. The addition of CNTs to cement-based materials can improve mechanical performance, improve fire resistance and reduce carbon dioxide emissions. The incorporation of CNTs in cementitious composites is a promising area of research with significant potential for use in the construction industry. The current study's findings are expected to provide insight into the new material and its glamorous scopes for application as construction materials.

Abstract: Due to the shortcomings of waste bricks, they cannot be used repeatedly. The brick powder can partially replace cement for construction production, which can solve the problem of cement energy consumption. This paper studies the influence of brick powder on the performance of cement-based materials. The research shows that the water absorption effect of brick powder and the friction force are the two main factors affecting concrete. Energy dispersive spectrometer, inductively coupled plasma mass spectrometry and compressive strength tests show that the addition of brick powder leads to the increase of silicon/calcium. inductively coupled plasma mass spectrometry shows that although brick powder dissolves in the early stage, the volcanic ash effect is weak. The results of mercury intrusion porosimetry and ultrasonic pulse velocity are consistent with the compressive strength. When 5 % is added, it shows excellent durability. In addition, with the increase of age, the durability will not decrease significantly. Since the brick powder only needs to be ground to avoid the related process of cement, good economic and environmental benefits can be obtained with the increase of substitution rate.

Abstract: The worldwide interest in coral concrete stems from its use in reef engineering, where it is a composite material made by combining saltwater and coral. This analysis examines the components, mechanical characteristics, and durability of coral concrete. The micro hardness of the interfacial transition zone in coral concrete is significantly greater than that of normal concrete. However, it is found that the coral concrete has less compressive strength than standard concrete hence, the durability of standard concrete is also longer than this concrete. However, the addition of fibres to coral concrete improves the splitting tensile strength and flexural strength significantly. Inadequate cementation of the components hinders the performance of coral concrete because of the porous and brittle nature of coral aggregates. Further investigations can be carried out for underwater engineering applications and sea constructions by selecting appropriate coral aggregate type and developing mix design procedure to produce the high-strength coral concrete.

Abstract: Comparative analysis of two models for predicting residual resource of polymer composite, one proposed by specialists from RS Technologies Inc and the other proposed by Institute of Oil and Gas Problems SB RAS (Russia), was carried out to obtain service life of composite poles for power transmission lines manufactured by RS Technologies Inc (Canada) for cold climate of Republic of Sakha (Yakutia). Models are based on experimental studies of strength of materials during accelerated and full-scale climatic tests. The difference lies in the presence of parameters of climatic zone and test methods in the first model, while the second model considers changes in physical and mechanical properties and structure of materials during aging under conditions of full-scale exposure and accelerated climatic tests. Comparison of results of predicting the durability of fiberglass products in cold climate of Yakutsk (Russia) according to Institute of Oil and Gas Problems SB RAS model and similar products in Calgary (Canada) climate (the closest in terms of climate conditions) according to RS Technologies Inc model showed the same results. Service life of composite support material was approximately 120 years with specified level of permissible decrease in characteristic property index of 75% of the original.