High Strength Lightweight Concrete Research Articles

Development of an eco-friendly high-strength lightweight concrete using pre-treated coconut shell aggregate and ground-granulated blast furnace slag

Development of an eco-friendly high-strength lightweight concrete using pre-treated coconut shell aggregate and ground-granulated blast furnace slag

Reinforcing effect of CNT on the microstructure and creep properties of high-strength lightweight concrete

Demand for precast high-strength lightweight concrete (HSLC) has recently increased for cost benefits. This study aims to explore the reinforcing effect of carbon nanotube (CNT) on the microstructure and creep properties of HSLC. A total of four types of HSLC mixture were applied by securing two target properties (a compressive strength of 120 MPa and a density of 2000 kg/m3; a compressive strength of 80 MPa and a density of 1600 kg/m3) through steam curing with high temperature (90℃), considering a combination of lightweight materials and CNT utilization as variables. Lightweight aggregates operated internal curing (IC) more effectively than hollow microsphere, improving the pore structure of HSLC and leading to the formation of hydration products, especially calcium silicate hydrate (C-S-H). The efficiency of lightweight aggregate on IC was proven through nanoindentation testing, identifying that no unhydrated particles were observed in the specimen incorporating only lightweight aggregate as lightweight material, while unhydrated particles made up 8–19% of the total phase volume with hollow microsphere incorporation. The utilization of CNT enhanced the microstructure of the cement matrix by filling pores and inducing formation of ultra-high-density (UHD) C-S-H, improving the creep resistance of HSLC. Furthermore, CNT bridging suppressed redistribution of C-S-H caused by C-S-H slip, resulting in approximately 49% of the total specific creep compared to conventional high-strength concrete (HSC). The fédération internationale du béton (fib) model is considered to derive the creep properties of HSLC, since it indirectly applies the impact of lightweight material utilizing its oven-dried density.

Development of geopolymer-based lightweight high-strength concrete and properties at different temperatures

In the current study, a green and high-strength lightweight concrete is developed. Geopolymer-based lightweight concrete (G-LWC) is an innovative green building material that combines the advantages of geopolymers and lightweight concrete. Building upon existing research, to achieve low density, a lightweight aggregate, expanded glass powder (EGP), is used, resulting in the development of geopolymer-based lightweight high-strength concrete (G-LWHC) with a compressive strength exceeding 100 MPa. The influence of different EGP content and fiber admixtures on its density and mechanical properties is also studied, and its performance after exposure to high temperatures is analyzed from both micro and macro perspectives. The research results indicate that the incorporation of EGP significantly reduces the concrete density while also decreasing its compressive strength. G-LWHC exhibits significant temperature-induced ductility, with RT,150D increasing by 142.80% and 258.02% after exposure to 600 °C and 800 °C, respectively, compared to room temperature conditions. The addition of fibers has the most notable impact on improving the concrete's flexural strength. The developed G-LWHC exhibits characteristics of being lightweight, high-strength, and resistant to high temperatures, maintaining residual strength even after exposure to 800 °C.

Possibility of production high strength lightweight concrete containing organic waste aggregate and recycled steel fibers

Abstract This study combines two types of waste materials to achieve sustainable lightweight concrete (LWC) including agricultural and industrial wastes that hold high potential to reduce global environmental pollution. A novel application of 35% treated date seed (DS) wastes as partially replaced by volume to natural coarse aggregate in producing sustainable LWC was investigated. Calcium hydroxide solution was utilized as a treatment to extract cellulose from the achieved hemicelluloses of the DS. Fourier transform infrared spectroscopy was utilized to analyze the structural characteristics of the isolated cellulosic samples before and after treatment. Then different volume fractions of steel fibers (0.5, 0.75, and 1%) recycled from scrap tires were added to the LWC with 35% DS. Several experimental tests, including slump test, compressive strength, oven-dry density, split tensile strength, flexural strength, and water penetration depth, were carried out in this investigation. The results demonstrate that concrete containing 35% DS and reinforced with 1% recycled steel fibers show enhancement in the compressive, tensile, and flexural strengths by about 15.2, 32.6, and 58.2%, respectively, and reduces the permeability by 16.1% relative to the reference concrete mixture.

Evaluation of the Properties of High Strength Lightweight Concrete with High Temperature History

In this study, we evaluated the compressive strength and ultrasonic velocity based on the temperature and age of ordinary aggregate and lightweight aggregate concrete (30 and 60 MPa) and examined their correlation. The unit weight and compressive strength of ordinary aggregate and lightweight aggregate concrete were measured to evaluate the mechanical properties and examine the correlation between ultrasonic velocity and compressive strength. The W/B ratio was set at 0.41 and 0.28, and measurements were made at 1, 3, 7, 28, 56, and 91 days. The physical properties were evaluated at 23, 100, 200, 300, 500, and 700 ℃. In all test specimens, compressive strength and ultrasonic speed increased with age; and the higher the temperature, the lower the compressive strength and ultrasonic speed. By analyzing the correlation between ultrasonic velocity and compressive strength, a strength prediction equation in the form of an exponential function was found. Moreover, from the error rate test, we confirmed that the strength prediction equation generally had an error rate of 15% or less.

Carbonation of Shale Ceramsite High-Strength Lightweight Concrete Incorporating Graphene Oxide

The growing demand of concrete for improving durability has stimulated extensive research on graphene oxide (GO). Carbonization, as an irreversible deterioration, should be paid more attention to high-strength lightweight concrete (HSLWC) with the characteristics of porous structure. In this study, the effect of different low content of GO on the carbonation depth of HSLWC made from shale ceramsite was experimentally investigated. Subsequently, the effect of GO on pore distribution of HSLWC was analyzed. Four groups of grade 60 HSLWC were designed for comparative experiments, in which 0.00%, 0.01%, 0.03% and 0.05% (by weight of cement) GO were added, respectively. The results indicated that GO could effectively reduce the carbonization depth of HSLWC. When GO content was 0.05%, the carbonization depth was reduced by approximately 23%. The main reason was that GO not only reduce the total porosity but also refine the pores, thus improving the carbonization resistance of HSLWC.

An innovative multi-objective optimization approach for compact concrete-filled steel tubular (CFST) column design utilizing lightweight high-strength concrete

Incorporating sustainability into Concrete-Filled Steel Tubular (CFST) columns' optimization can enhance efficiency and sustainability in construction. Discrepancies in international standards for ultimate load capacity computation in compact CFST columns under eccentric loading, particularly with lightweight high-strength concrete, pose challenges. This research compile a dataset of compact CFST columns, evaluating design codes (AISC 360-16, Eurocode 4) against experimental results. Besides, a comprehensive finite-element model predicts compact CFST column performance, investigating axial force-moment (P-M) interaction behavior with respect to the material strength ratio (fy/fc′). In the second phase of the study, an ANN model, incorporating input parameters, estimates axial load capacity, facilitating multi-objective optimization for optimal CFST column geometry. The results confirmed that Eurocode 4 outperforms AISC 360-16 in experimental axial capacity predictions (Nuc/Nuc,theoretical) where, the mean and standard deviation for Eurocode 4 were estimated at 1.07 and 0.22, respectively, compared to 1.21 and 0.29 for AISC 360-16. Besides, statistical metrics confirm the precision of the ANN model, particularly with high-strength concrete, promising efficiency in future computational intelligence-based structural design platforms.

Experimental Investigation into Lightweight High Strength Concrete with Shale and Clay Ceramsite for Offshore Structures

Experimental Investigation into Lightweight High Strength Concrete with Shale and Clay Ceramsite for Offshore Structures

Development of high-strength lightweight concrete by utilizing food waste digestate based biochar aggregate

The application of carbon-negative biochar in cement composites can effectively reduce carbon emissions of construction materials. In this study, low-carbon composites were tailored with high volume of food waste digestate (FWD) biochar aggregate. The biochar was customized at different temperatures with the goal of enhancing the properties of cement-based composites. Backscattered electron microscopy (BSEM) images show that FWD biochar with a grey circle shape exhibited strong bonding with the cement matrix. Nano-indentation results indicate that the two statuses of FWD biochar showed visco-elastic and elastic-plastic modes of deformation, respectively. The FWD biochar aggregate prepared at higher pyrolysis temperatures (i.e., 650 °C and 750 °C) has higher elastic modulus (up to 11.4 GPa), which can be applied to make biochar blocks with higher strength and lower density compared to the biochar pyrolyzed at 550 °C. As a result, FWD 750BC blocks could reach 28-d compressive strength of 57.8 MPa and density of 1.77 g cm−3, which fulfilled the requirements of high-strength lightweight aggregate concrete. Hence, this study established a foundation to utilize FWD biochar as an aggregate in high-strength biochar construction materials.

Structural benefits of using carbon nanotube reinforced high-strength lightweight concrete beams

Recently interest in lightweight concrete (LWC) has increased for its cost effectiveness and design reduction, however it has low resistance to external forces. Carbon nanotube (CNT) was incorporated to overcome this disadvantage and achieve high-strength in LWC. The structural response of CNT reinforced high-strength lightweight concrete (HSLC) beams was investigated considering specimen size, tensile reinforcement ratio, and stirrup spacing. As the tensile reinforcement ratio increased from 0.008 to 0.019, yielding and peak load of specimens improved by 92% and 73%, respectively. Interestingly, nanocrack bridging induced by CNT increased the ductility index of reinforced HSLC beams compared to conventional reinforced HSC and LWC beams in the low longitudinal reinforcement index range. At the end, a flexural design model for CNT reinforced HSLC beams was proposed and validated. This study aims to reinforce feasibility by providing both a basic reference for structural response and a cost analysis of CNT reinforced HSLC.

High Strength Lightweight Concrete, using Scoria and Mineral Admixture

High Strength Lightweight Concrete, using Scoria and Mineral Admixture

Efficient mix design method for lightweight high strength concrete: A machine learning approach

The application of lightweight high strength concrete (LWHSC) is becoming popular due to its superior mechanical properties and lighter weight nature. As a result, it offers advantages in terms of faster construction and cost effectiveness. However, achieving both high strength and lightweight is quite challenging as LWHSC possesses unique characteristics that require different mix design methods compared to conventional concrete. Additionally, the lack of appropriate mix design guidelines limits the usage of LWHSC. Therefore, appropriate tools are necessary to develop effective mix design methods for LWHSC, especially when aiming for high strength. In this study, four machine learning (ML) algorithms, namely support vector regressor (SVR), multilayer perceptron (MLP), gradient boosting regressor (GBR), and extreme gradient boosting (XGB), were applied to comprehensively analyse LWHSC mixes and provide effective prediction models to carry out mix design. To focus on the upper high strength margin of lightweight concrete (LWC), an experimental database consisting of 403 datasets with 28-day compressive strengths greater than 60 MPa and oven dry densities less than 2000 kg/m3 was developed from an extensive literature survey to predict the compressive and splitting tensile strength of LWHSC. The results demonstrated that all ML models predicted LWHSC strengths well with optimum hyperparameter combinations. Among them, GBR outperformed the other three models with an accuracy of less than 5% and 10% in predicting the average compressive and splitting tensile strengths, respectively. Furthermore, partial dependence plots (PDP) and individual conditional expectation (ICE) plots were provided to visualise the correlation between mix compositions and LWHSC strengths.

Development and characteristics of novel high-strength lightweight core-shell aggregate

The need for high-strength lightweight concrete for cost-effective and energy-efficient building construction drives the need to develop high-strength lightweight aggregates. In this study, a novel high-strength lightweight core–shell aggregate (HLCSA) was developed and compared with commercial available artificial lightweight aggregates (LWAs). The loose bulk density, water absorption, and crushing strength of the developed aggregate were optimized by changing the water/binder ratio of the shell, core materials, shell/core ratio, and curing methods and time. XRD, TGA, and X-CT were utilized to analyze the hydration degree, microstructure, and pore structure of the shell and core of the core–shell aggregate. The results showed that a suitable water/binder ratio of 0.20–0.22 for the shell and a core material (cenosphere) were optimal for producing the HLCSA. The size, loose bulk density, crushing strength, and strength efficiency of the pelletized aggregate were all found to increase with the shell/core ratio. The curing method and curing time played an important role in affecting the crushing strength. The microstructure and porosity of HLCSA analyzed by optical microscopy and X-CT showed that it was a hollow shell structure with a porous core that was well coated by a dense shell, which ensued the high strength and lightweight features at the same time. The developed HLCSA (with shell/core of 1.6) had a crushing strength of 6.93 MPa and a loose bulk density of 834 kg/m3 with a high strength efficiency of 8,309 Pa·m3/kg, which was much higher than the common commercial LWAs.

Influence of vacuum infiltration on mechanical properties of polymer concrete filled with lightweight ceramic aggregates

In this paper, the influence of vacuum infiltration of lightweight ceramic aggregates as fillers in polymeric concretes was described. In the first stage of the investigation, a set of ceramic aggregates with a high open porosity of about 27% was produced on the basis of industrial wastes. Ceramic aggregates with a size of 2 to 4 mm, hereinafter referred to as granules, were produced using contaminated glass cullet waste and coal shale. The effectiveness of granule infiltration with epoxy resin in the production of polymer concrete with high mechanical strength and relatively low mass compared to traditional concrete was discussed. The compressive strength of polymer concrete, where the aggregates were infiltrated with resin, is 87 MPa, and the polymer concrete, in which the vacuum infiltration process was not used, reaches a compressive strength of approximately 42 MPa. The resulting concrete, due to its density, is classified as a lightweight high-strength concrete.

Effect of Graphene Oxide on compressive strength of Shale Ceramsite high strength lightweight aggregate concrete

The use of shale ceramsite to produce high-strength lightweight concrete (HSLWC) in the construction industry is an effective method for sustainable development and environmental protection. The growing demand for HSLWC has stimulated the development of nanomaterials to further enhance mechanical properties. This study investigated the effect of graphene oxide (GO) on the properties of HSLWC with shale ceramsite as a coarse and fine aggregate, including workability, density, compressive strength, and energy dispersive spectrometer (EDS) test. The control mixture was designed according to the standard of grade 40 high strength concrete, and four groups of mixtures were prepared by adding doses of GO at 0.00%, 0.02%, 0.04% and 0.06% by weight of cement to the control mixture. The experimental results showed that HSLWC with the 28-day compressive in the range of 43-54 MPa and the oven dry density of 1705-1783 kg/m3 could be produced by using shale ceramsite and shale pottery sand as coarse aggregate and fine aggregate, respectively. Simultaneously, adding a low content of GO to HSLWC could slightly increase the density, rationally reduce the slump, and significantly enhance the compressive strength. The EDS results showed that the reason for the increase in compressive strength was that GO could accelerate the cement hydration process and regulate the crystal morphology of the cement.

Axial tensile behavior of hybrid steel-polypropylene fiber reinforced high-strength lightweight concrete

In practical engineering, concrete materials are mainly damaged by tension, especially for high-strength lightweight concrete (HSLC) whose tensile performance is not as satisfactory as ordinary concrete under the same compressive strength. Adding fibers is one of the most effective methods to improve the tensile properties of concrete. In this study, the tensile behavior of hybrid fiber reinforced HSLC was investigated through direct tensile test. The tensile stress-strain curve was obtained and the tensile toughness was calculated. Furthermore, the cracking process was measured and captured synchronously by digital image correlation (DIC) measurement. The results indicated that hybrid fibers enhanced the tensile properties of HSLC at both micro and macro levels. Polypropylene fibers increased the tensile toughness of HSLC by inhibiting the propagation of micro-cracks. Steel fibers improved the peak stress, peak strain, and tensile toughness of HSLC by extending the propagation path of macro-cracks and restraining the increase of the width of macro-cracks. According to the test results, an equation for the axial tensile stress-strain curve of the hybrid fiber reinforced HSLC related to fiber characteristic parameters was formulated, which can be used as a reference for engineering design.

Effect of Pre-Soaking Treatment Method of Plant-Based Aggregate on the Properties of Lightweight Concrete—Preliminary Study

This research investigates the effect of pre-soaking treatment on plant-based aggregate using a wet grout binder to formulate a high-strength lightweight concrete (HSLWC). Surface modification utilising a novel grout soaking technique with various water-to-cement (w/c) ratios has indicated a new method of approach for the recent development of lightweight plant-based aggregate (LWPA). In this experiment, the fresh and hardened properties of modified LWPA lightweight concrete were assessed by verifying their workability, densities, compressive and split tensile strengths towards the modulus of elasticity. The results showed that pre-soaking plant-based lightweight aggregate (w/c: 0.6, 0.8, 1.0 and 1.2) slightly increased the density of the samples compared to untreated LWPA. The oven-dry density of treated and untreated LWPA is controlled in the range of HSLWC. The outcomes indicated that the workability of the surface-modified LWPA is significantly improved: up to 40% in 6 min for the (TDS)/0.6 sample compared to the original LWPA. The mechanical properties of the LWPA concrete with the surface modification method exhibit a substantial increment of compressive strength, split tensile strength and the modulus of elasticity; recorded at 22%, 26% and 34%, respectively. Significantly, the findings from this experiment reveal that the pre-soaking treatment method on LWPA is shown to be a highly recommended technique in improving interfacial bonding while maintaining its performance as one of the most promising solutions to improve the properties of lightweight concrete.

Prediction Model and Mechanism for Drying Shrinkage of High-Strength Lightweight Concrete with Graphene Oxide.

The excellent performance of graphene oxide (GO) in terms of mechanical properties and durability has stimulated its application potential in high-strength lightweight concrete (HSLWC). However, more attention needs to be paid to the long-term drying shrinkage of HSLWC. This work aims to investigate the compressive strength and drying shrinkage behavior of HSLWC incorporating low GO content (0.00-0.05%), focusing on the prediction and mechanism of drying shrinkage. Results indicate the following: (1) GO can acceptably reduce slump and significantly increase specific strength by 18.6%. (2) Drying shrinkage increased by 8.6% with the addition of GO. A modified ACI209 model with a GO content factor was demonstrated to have high accuracy based on the comparison of typical prediction models. (3) GO not only refines the pores but also forms flower-like crystals, which results in the increased drying shrinkage of HSLWC. These findings provide support for the prevention of cracking in HSLWC.

Effect of Graphene Oxide on the Mechanical Properties and Durability of High-Strength Lightweight Concrete Containing Shale Ceramsite.

An effective pathway to achieve the sustainable development of resources and environmental protection is to utilize shale ceramsite (SC), which is processed from shale spoil to produce high-strength lightweight concrete (HSLWC). Furthermore, the urgent demand for better performance of HSLWC has stimulated active research on graphene oxide (GO) in strengthening mechanical properties and durability. This study was an effort to investigate the effect of different contents of GO on HSLWC manufactured from SC. For this purpose, six mixtures containing GO in the range of 0-0.08% (by weight of cement) were systematically designed to test the mechanical properties (compressive strength, flexural strength, and splitting tensile strength), durability (chloride penetration resistance, freezing-thawing resistance, and sulfate attack resistance), and microstructure. The experimental results showed that the optimum amount of 0.05% GO can maximize the compressive strength, flexural strength, and splitting tensile strength by 20.1%, 34.3%, and 24.2%, respectively, and exhibited excellent chloride penetration resistance, freezing-thawing resistance, and sulfate attack resistance. Note that when the addition of GO was relatively high, the performance improvement in HSLWC as attenuated instead. Therefore, based on the comprehensive analysis of microstructure, the optimal addition level of GO to achieve the best mechanical properties and durability of HSLWC is considered to be 0.05%. These findings can provide a new method for the use of SC in engineering.

Sustainable high-strength lightweight concrete with pumice stone and sugar molasses

AbstractThe building sector benefits from high-strength lightweight concrete (HSLWC) in various aspects, particularly in reducing the structure’s dead load. Incorporating waste materials into HSLWC encourages sustainable practices, reduces their environmental effect, and decreases product’s costs. This research focuses on producing sustainable HSLWC using a pumice stone and additive materials such as sugar molasses, silica fume, and high-range water reduction. The physical and mechanical properties and structural efficiency were investigated. The results demonstrate that the inclusion of additive material is the primary factor controlling the properties of the concrete. Also, using pumice stone instead of gravel in high-strength concrete significantly reduced weight and increased thermal insulation by 19.31 and 43.55%, respectively. Furthermore, the addition of steel fibers in HSLWC improved the compressive strength, tensile strength, ductility, and structural efficiency.