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The aim of this study was to present the problem of durability of structural lightweight concrete made of a sintered fly ash aggregate. The issue of durability was researched for 12 concrete series in terms of their water absorption, water permeability, and freeze-thaw resistance. Additionally, the microstructure of several concretes was analyzed w...
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... the case of one concrete series (2d), which did not reveal any signs of frost damage after 150 cycles, an additional 50 cycles of freezing and thawing were carried out on half of the specimens. The scheme of freeze-thaw cycles used in this research is presented in Figure 3. After the freezing and thawing cycles, the appearance of the specimens was assessed for cracks, and the weight and strength losses were determined. ...
Context 2
... the case of one concrete series (2d), which did not reveal any signs of frost damage after 150 cycles, an additional 50 cycles of freezing and thawing were carried out on half of the specimens. The scheme of freeze-thaw cycles used in this research is presented in Figure 3. After the freezing and thawing cycles, the appearance of the specimens was assessed for cracks, and the weight and strength losses were determined. ...
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The use of supplementary cementitious materials (SCM) as partial replacement of ordinary Portland cement is widely accepted in the construction industry. The adverse environmental impact of producing cement is mitigated through the reduced production of cement due to the use of SCM. In addition, SCM such as fly ash, silica fume, and slag, impart ma...
Citations
... 20 Although these materials fulfill certain applications in some ways, the composites have poor mechanical strength, durability, density, and other properties. 21,22 In order to overcome the shortcomings of traditional filled lightweight concrete, millimeter and micrometer sized lightweight functional fillers (LWFs) such as EPS, HGMS, and expandable thermoplastic microspheres are widely used. Coal gangue ceramic lightweight aggregate concrete is made by converting coal gangue into low-density ceramic aggregate to make low-density lightweight aggregate concrete. ...
Reducing the structural load and operational energy consumption of buildings is a trend in the development of the construction industry, and lightweight concrete has become a research hotspot because of its dual characteristics of low density and high strength. In this paper, a three-step method is used to prepare lightweight concrete composites. In the first step, basalt fiber powder was adhered to polystyrene foam ball expanded polystyrene spheres (EPSs) by the “ball rolling method” to obtain basalt fiber reinforced epoxy composite balls. In the second step, the epoxy resin composite ball and the configured cement matrix are filled into a prefabricated mold. Finally, the lightweight concrete specimens were overlaid, pressed into shape, and cured for 28 days. By changing the volume ratio, size, and wall thickness of the epoxy composite balls, as well as the length and content of basalt fibers, the lightweight concrete was exhibited a reduction in density and increase in strength. The results showed that the smaller the epoxy composite spheres and the larger the wall thickness are, the higher the compressive strength of the material for a certain volume ratio of epoxy composite spheres will be. The addition of appropriate hollow glass beads can reduce the number of pores in the matrix, but excessive hollow glass beads will reduce the bonding force of the concrete matrix. Basalt fibers not only improve the strength of EPSs but also serve to connect matrix–matrix and matrix–epoxy composite spheres.
... In conclusion, the compressive strength of the concrete is related to the aggregate strength, the matrix strength, and the bonding strength between the aggregates and the matrix. These factors also influence the splitting tensile strength of lightweight concrete [18,66,67]. This can explain why the strong correlation exists between the splitting tensile strength and the compressive strength of CFAA concrete in Section 3.1.2. ...
Cold-bonded Fly Ash Aggregate (CFAA), as an alternative to natural coarse aggregates, can prepare more lightweight, economical, and sustainable concrete. However, CFAA concrete has insufficient durability, which hinders its application in a salt-corrosion environment. Nanosilica (NS) has an advantage of high activity and is generally used as an efficient mineral admixture in engineering. This study aims to improve the strength and durability of CFAA concrete by incorporating NS. To this end, compression tests, splitting tensile tests, and microscopic analyses were performed to investigate the mechanical properties of the concrete containing different NS dosages. Subsequently, the dry–wet and freeze–thaw durability tests were conducted to evaluate the salt-corrosion resistance and the frost resistance in the water, Na2SO4 solution, and Na2CO3 solution. The results show the compressive and splitting tensile strength peak at 2 wt% NS dosage. In this instance, the concrete has an optimum microstructure and exhibits desirable salt-corrosion resistance in the late stage of dry–wet cycles. During freeze–thaw cycles, NS could improve the frost resistance of the concrete but scarcely diminished internal damage under sulfate attack. The study explores the long-term performance of NS-modified CFAA concrete, providing a simple and effective method to mitigate the concrete deterioration in a harsh environment.
... In this investigation, M10 NaOH molarity was used. In general, the much-reduced durability of LWAC compared to NWAC should not be identified with its significantly higher water absorption [26]. Graphical representation of water absorption percentage as shown in Figure 19. ...
This research is to replace natural coarse aggregate as 20%, 40%, 60%, 80%, and 100% respectively, by weight in an M20 grade geopolymer concrete. The geopolymer concrete with different mixes is subjected to fresh, hardened, and durability tests. Utilization of thermal ash aggregates increased the slump and compressive strength of geopolymer concrete by about 15% and 9% respectively. Whereas the slump and compressive strength of geopolymer concrete decreased by about 30% and 38% respectively by using 100% Lightweight Expanded Clay Aggregate (LECA). Density reduction in geopolymer concrete was found by using both thermal ash aggregate and lightweight expanded clay aggregate for about 9% and 28% respectively. Thermal ash aggregate decreased the density of geopolymer concrete up to 1850 kg/m³ and improved the strength up to 24.50 N/mm², on the other side using lightweight expanded clay aggregate, the density of geopolymer concrete drastically decreased up to 1250 kg/m³ with a huge decrease in strength up to 14 N/mm². Other mechanical test results showed similar variations with respect to the compression test results. To ensure the durability of lightweight geopolymer concrete for mixes of GPC, TM5, and LM2 conducted tests like acid resistance, sulphate resistance, salt resistance, water absorption, accelerated corrosion, and sorptivity test.
Keywords
Geopolymer concrete; green concrete; thermal ash aggregate; lightweight expanded clay aggregate, durability
... Artificial aggregates from fly ash with the addition of superplasticizer (SP) have high mechanical properties and durability with compressive strengths of 25-83.5 MPa [12][13][14][15][16]. Meanwhile, the addition of 100% fly ash and SP increased the compressive strength by 4.97 at 28 days and 31.32% at 90 days [17] Other researchers also tested the effectiveness of artificial aggregates using fly ash on the mechanical properties of concrete using fly ash. ...
The amount of fly ash waste is increasing, causing environmental and storage problems. One solution is to utilize the fly ash as an artificial aggregate. This research focuses on getting the right formula for mixing fly ash, cement, and superplasticizer (SP). The tests carried out were compressive strength at 3, 14, 28, and 56 days. The results showed that the best composition with a ratio of cement: fly ash of 1:4 added with a superplasticizer of 1.2% by weight of the mixture resulted in a compressive strength of 79 MPa at 56 days of age.
... The use of SFA in concrete can reduce its density and make them more eco-friendly [4]. SFA are porous, which permits ingress of cement paste into its voids and makes a better bond with it, thus making concrete strong and durable [5]. ...
This study reports experimental and numerical studies on the flexural behaviour of sustainable fibre reinforced lightweight hollow core slabs (FR-LWHCS). An innovative and sustainable LWHCS is proposed for structural applications using a lightweight concrete mix of 1800 kg/m 3 density, previously developed by authors. Full-scale precast LWHCS specimens are cast and tested under flexure using a four-point loading configuration. A high shear span to depth (a/d) ratio of 10 is chosen to have flexure dominant behavior. FR-LWHCS is made using sintered fly ash aggregate (SFA) as coarse aggregate and monofilament macro synthetic fibres of different volumetric fibre dosages (0.4 % and 0.6 %). A small dosage of micro synthetic fibres of 0.02 % by volume is also added to arrest shrinkage cracks. Two control slabs, one constructed with lightweight concrete and the other with conventional normal density concrete, are tested. The digital image correlation (DIC) technique is used to track the cracks and failure modes. A 3D finite element analysis is performed to supplement the test results. Test results show that FR-LWHCS satisfies all the structural requirements, leading to economy and sustainability. FR-LWHCS with 0.6 % fibre dosage performed better than hollow core slabs made of normal density concrete. Though the addition of fibres did not considerably increase peak load, a minimum dosage of fibre addition is warranted in LWHCS to improve the serviceability performance. Fibre addition significantly improved the strain energy absorption.
... Several researchers have confirmed that LC has increased shrinkage due to its low modulus of elasticity, which rises by up to 50% (Kahn and Lopez 2005, Domagala 2020, Tian et al. 2015. Different factors (such as time dependence, outdoor temperature, and humidity levels) can help lower shrinking rates. ...
... Otherwise, the LC has a higher rate of creep than the OC. However, the rate of creep is higher in the LC than in ordinary concrete, and it is also similar for higher classes and dense concrete (Domagala 2020, Tian et al. 2015. Furthermore, low density of lightweight concrete typically results in less desirable mechanical properties than dense concrete. ...
The building sector has seen a huge increase in the use of lightweight concrete recently, which might result in saving in both cost and time. As a result, the study has been done on various types of concrete, including lightweight (LC), heavyweight (HC), and ordinary concrete (OC), to understand how they react to earthquake loads. The comparisons between their responses have also been taken into account in order to acquire the optimal reaction for various materials in building work. The findings demonstrate that LWC building models are more earthquake-resistant than the other varieties due to the reduction in building weight which can be a curial factor in the resistance of earthquake forces. Another crucial factor that was taken into study is the combination of various types of concrete [HC, LC, and OC] in the structural components. On the other hand, the bending moments and shear forces of LC had reduced to 17% and 19%, respectively, when compared to OC. Otherwise, the bending moment and shear force demand responses in the HC model reach their maximum values by more than 34% compared to the reference model OC. In addition, the results show that the LCC-OCR (light concrete column and ordinary concrete roof) and OCC-LCR (ordinary concrete for the column and light concrete for the roof) models' responses have fewer values than the other types.
... The findings showed that specimens made with coarser aggregates and SF performed better than those made with smoother aggregates [17]. The durability of FA and aggregate-based structural lightweight concrete was studied for their water permeability, absorption, and freeze-thaw resistance to determine their long-term applicability in the construction industry [18]. Capillary penetration and water absorption were significantly decreased by the addition of Calcium Stearate (CS). ...
The study compares the durability of Natural Zeolite with Metakaolin, Silica Fume, and Fly Ash on high-strength concrete. 300 concrete specimens were tested for compressive strength before and after an acid attack, modulus of elasticity, water absorption, and rapid chloride permeability. 5%, 10%, and 15% of the cement were replaced with cementitious elements while maintaining the same quantity of Natural Zeolite. In this investigation, the water-cement ratio was maintained at 0.35. After 28 days, the specimens were tested for durability. Samples of all mixes were TG/DT and FTIR tested. The optimal percentages of cementitious materials that resulted to the maximum durability enhancements were reported as the study results. Experimental results showed that Natural Zeolite and Metakaolin strengthened the durability of concrete. All the data show that 5% Natural Zeolite with 10% Metakaolin performs well. Good R2values and appropriate independent variable coefficients suggested that the regression findings for high-strength concrete durability were accurate. The P values of all models were less than 0.005 and the F values were statistically significant and appropriate; therefore, the generated models predict concrete's strength with authenticity. Doi: 10.28991/CEJ-2022-08-10-019 Full Text: PDF
... These technologies should ensure minimal impact on the environment [1,2], propose solutions for improving the energy efficiency of buildings [3], reducing CO2 emissions using renewable energy [4,5], and utilise modern structural materials [6]. One of the most commonly used materials in construction is concrete [7] for which ongoing development of innovative research is observed, aimed at improving its design in obtaining appropriate properties and durability [8,9], and methods for the evaluation of achieved results [10]. Among the trends developed worldwide, the high-performance fibre-reinforced concrete (HPFRC) group is worth mentioning [11]. ...
The paper refers to studies of the structure of high-performance concrete with polypropylene fibre at different dosages. The authors see a research gap in the study of the effect of adding polypropylene fibre on the parameters of concrete exposed to high temperatures. The study takes into account the thermal effect—groups of samples were heated to 200 °C, 400 °C and 600 °C. The authors carried out basic tests to describe the changes in density, ultrasonic tests, uniaxial compression strength tests and tensile tests by splitting. The positive effect of polypropylene fibres is mainly observed between 20 °C and 200 °C. The melting of polypropylene fibres causes a delay in the development of micro-cracks in the structure of these concretes compared to HPC. Adding polypropylene fibres to the mixtures also increased the speed of ultrasonic wave propagation in the medium. The research was deepened with tomographic imaging. A description of the splitting surface was carried out. The results of tensile by splitting tests clearly show an increase in the relative failure area for unheated concretes in proportion to the number of fibres used. Changes in splitting surfaces under the influence of temperature are graphically illustrated. Furthermore, differences in the samples under the influence of heating at high temperatures are presented. Finally, the porosity development of all sample groups before and after heating at all temperatures is described.
... Heidrun floating platform, Norwegian Sea), stadiums (e.g. Volkswagen Arena, Wolfsburg, Germany), etc. (Nadesan and Dinkar 2018;Domagała 2020). European and American standards specify guidelines for the use of LWA in concrete masonry unit, structural concrete, insulating concrete, etc. (DIN EN 13,055, 2016;ASTM C331/C331M-17, 2017; ASTM C330/ C330M-17A, 2017; ASTM C332-17, 2017). ...
Low density, fire resistance and good thermal insulation properties of lightweight aggregate concrete (LWAC) have drawn the attention of engineers and researchers for its widespread application. However, the LWAC still found limited application in the construction industry. For conventional application of LWAC, knowledge of different attributes of its behaviour is needed, and thus the presented review investigates the comprehensive studies on LWACs incorporating lightweight aggregates (LWAs) i.e. oil palm shell, lightweight expanded clay aggregate (LECA), fly ash-sintered (FS) and pumice, along with supplementary cementitious materials (SCMs). Firstly, the physico-chemical, morphological and mineralogical characterization of different LWAs is presented, followed by critical review on fresh, hardened, durability and thermal properties of LWACs vis-a-vis normal weight concrete. Furthermore, research works conducted on the development of LWACs using LECA, fly ash and micro-fine slurry powder (MSP) are discussed. Research findings show that LWAC prepared with LECA as coarse and fine aggregate along with 25% fly ash + 10% MSP as cement replacement exhibits good mechanical and thermal properties. Overall, it has been envisaged that LWACs, because of their techno-economic and environmental advantages, are supposed to capture a major share in the building industry in the twenty first century. Basically, the scientific contribution of the present work is to provide the knowledge base and scientific basis for further research in this area and lay the foundation for the development of the guidelines to use LWACs.
... In addition to these advantages, lightweight concrete has better durability properties [10] than standard concrete, including higher frost resistance, fire resistance, and seismic loading. This has led to the widespread use of lightweight concrete in many countries to construct high-span bridge decks [11] and multistory buildings [12]. ...
In the modern construction industry, lightweight aggregate concrete (LWAC) is often used to produce load-bearing structural members. LWAC can be up to 40% lighter by volume than normal strength concrete. However, the lack of adequate numerical models often limits the practical application of innovative building materials such as lightweight concrete in real projects. The present study conducted a comparative numerical deformation analysis of a full-scale bridge deck slab and girder. Using the physical model proposed by the authors and the finite element software ATENA, the deformations of full-scale lightweight and traditional reinforced concrete elements under the short-term effects of permanent and variable loads were compared. Depending on the safety and serviceability limit requirements, it was found that the amount of longitudinal reinforcement in lightweight reinforced concrete elements could be reduced compared with that in standard reinforced concrete elements with the same parameters. The results of the numerical analysis showed that the deformation analysis model proposed by the authors could serve as an alternative tool for the design of lightweight concrete flexural members with the selection of optimum geometric and reinforcement parameters limited by the stiffness condition.
