High Strength Lightweight Aggregate Research Articles

Resource recovery of sludge incineration residue in lightweight aggregate: Performance mechanism, and environmental safety analysis

In response to escalating global environmental concerns and the need for sustainable waste management, this study explores the transformative potential of high-temperature sintering in converting sludge incineration residues (SIR) into lightweight aggregates. The research investigates the influence of sintering temperature and time on the physical, mechanical, and environmental characteristics of the resulting aggregates. High-strength lightweight aggregates with optimal properties are achieved at 1085 ℃ and 10 minutes, exhibiting favorable freeze-thaw resistance. Microscopic analyses reveal the presence of glassy substances in the aggregates, with higher sintering temperatures leading to increased glassy content but also more substantial pores. Importantly, high-temperature sintering significantly reduces the leaching rate of heavy metal ions. This study contributes valuable insights into the micro-characteristics and environmental safety of SIR-sintered lightweight aggregates, providing a sustainable solution for waste utilization in the development of high-performance construction materials.

A novel foaming-sintering technique for developing eco-friendly lightweight aggregates for high strength lightweight aggregate concrete

To address the scarcity of natural aggregates and reduce energy consumption in the concrete industry, a sustainable lightweight aggregate (LWA) was prepared with a self-foaming and sintering method by utilizing waste glass powder as the primary precursor and incineration bottom ash as a foaming agent. The effect of NaOH content (0 M, 2 M, and 8 M) on the physical properties of LWA was investigated. Replacing manufactured sand with sintered LWA (0 M-LWA and 2 M-LWA) by 50 vol% and 100 vol% to investigate their impact on the physical properties, mechanical properties, shrinkage, and alkali-silica reaction of high strength LWA concrete. The high strength LWA concrete prepared with 0 M-LWA possessed a density of 2127 kg/m3 and compressive strength of 108.7 MPa, which were slightly lower than that with manufactured sand. Due to the porous and lightweight nature of 2 M-LWA, the density and compressive strength of LWA concrete significantly decreased with the increased 2 M-LWA volume. Nevertheless, 100%-2M showed satisfying density of 1835 kg/m3 and compressive strength of 50 MPa. The internal curing effect of 2 M-LWA effectively mitigated the autogenous shrinkage of LWA concrete. The alkali-silica reaction expansion of all LWA was innocuous.

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.

Killing two birds with one stone: Preparation of ceramsite high-strength lightweight aggregate via co-sintering of dredged sediment and municipal solid waste incinerated fly ash

The disposal of dredged sediment (DS) and municipal solid waste incineration fly ash (MSWIFA) has become a notable concern. In this study, a novel ceramsite high-strength lightweight aggregate (HLWA) was developed by the co-sintering of DS and MSWIFA. The optimal HLWA (DS-10FA-1160) was synthesized using a mixture of 90 % DS and 10 % MSWIFA at 1160 °C. DS-10FA-1160 exhibited a high cylinder compressive strength (42.82 MPa) and negligible leaching concentrations of heavy metals (HMs). The “killing two birds with one stone” mechanism was adopted as follows: MSWIFA promoted the generation of strength enhancing phases (e.g., rankinite and amorphous phases) while phillipsite-K and the disconnected pore structure of DS-10FA-1160 steadily encapsulated HMs.

Shrinkage prediction model of high strength lightweight aggregate concrete based on relative humidity

Concrete shrinkage affects the overall stability and long-term service performance of the structures. Lightweight aggregates (LWAs) with a porous structure are an ideal internal curing material to mitigate concrete shrinkage. Nevertheless, the low elastic modulus of LWAs has a negative impact on concrete shrinkage. In order to clarify the influences of LWAs in the high strength lightweight aggregate concrete (HSLC) on its shrinkage performance, the compressive strength, internal relative humidity (IRH), elastic modulus, and autogenous shrinkage (AS) of HSLC were analyzed experimentally in this study. The correlation of these parameters was investigated. As indicated by the results, compressive strength and elastic modulus were negatively related to the content of LWAs. The 28-day AS and IRH of HSLC and the critical moment of IRH increased by 3.9%, 20.2% and 36 h, respectively, when the content of LWAs increased from 0% to 100%. A linear relationship between AS and compressive strength and an exponential relationship between AS and IRH were established. Additionally, a shrinkage prediction model considering IRH of concrete and water absorption by LWAs was proposed for HSLC.

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.

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.

Flexural fatigue behavior of hybrid steel-polypropylene fiber reinforced high-strength lightweight aggregate concrete

Compared with ordinary concrete, high-strength lightweight aggregate concrete (HSLC) can remarkably attenuate self-weight in engineering structures. However, the fatigue performance of ordinary concrete is better than that of HSLC. Herein, the flexural fatigue behavior, including fatigue life and crack propagation process, of hybrid fiber (HF) reinforced HSLC under different stress levels (S = 0.85, 0.80 and 0.75) was investigated. A further analysis on the fatigue life and crack propagation rate of HF reinforced HSLC was also conducted by two-parameter Weibull distribution (2PWD) and Paris law, respectively. The results indicated that the fatigue life of all specimens followed the 2PWD under various stress levels. Compared to the single fiber reinforced HSLC, the HF reinforced HSLC exhibited minimum crack propagation rates, the longest duration of stable development stage and fatigue life. The fatigue life equation was established with double logarithmic fatigue equation by considering failure probability. Furthermore, the expression of crack propagation rate with respect to crack length of each group of specimens was proposed under various stress levels.

Preparation and properties of high-strength lightweight aggregate ceramsite from nepheline tailings

Nepheline tailings (NTs) were made into pellets and then transformed to lightweight aggregate ceramsites by sintering approach, the effects of mix composition and sintering process on air-void structure and performance were studied. The results show that introducing mineralizer, rising sintering temperature and extending holding time increased air-void size, decreased density, reduced cylinder compressive strength and rose water absorption of NT-based ceramsite. Acceleration of heating rate led to the increase of density, resulting in strength enhancement, but heating rate of 20 ℃/min caused uneven air-voids, weakening strength. Dense enamel layer on surface, suitable air-void structure and well-crystallized nepheline of ceramsite contributed to preparation of high-strength lightweight ceramsite with a NT content of 93 % to 97 %, bulk density of 577 kg/m3 to 823 kg/m3, cylinder compressive strength of 4.3 MPa to 9.3 MPa and a low water absorption of 0.3 % to 0.8%

Shrinkage Prediction Model of High Strength Lightweight Aggregate Concrete Based on Relative Humidity

Shrinkage Prediction Model of High Strength Lightweight Aggregate Concrete Based on Relative Humidity

Preparing high-strength ceramsite from ferronickel slag and municipal solid waste incineration fly ash

This study investigated the feasibility of preparing ceramsites from ferronickel slag and municipal solid waste incineration (MSWI) fly ash by evaluating the effect of adding MSWI fly ash on the phase and microstructure transformations and properties of ceramsites. The theoretical calculations indicated that when the addition of MSWI fly ash ranges from 10 wt% to 60 wt%, the main phases in the system are diopside, feldspar, forsterite and merwinite, all of which contribute to the improvement of ceramsites properties. The TG-DSC, XRD and SEM analyses revealed that the initial phase of ferronickel slag and MSWI fly ash can be transformed into ceramsite phases during the roasting process. Specifically, forsterite and enstatite produced by the decomposition of olivine in ferronickel slag will react with calcium oxide produced by the decomposition of fly ash to form diopside and merwinite. Additionally, the reaction product will gradually change from diopside to merwinite as the MSWI fly ash addition increases. An excellent ceramsite with the cylindrical compressive strength significantly exceeding the requirements of high strength lightweight aggregates could be obtained by roasting the ferronickel slag with addition of 20 wt% MSWI fly ash at 800 °C for pre-roasting 15 min and 1275 °C for roasting 20 min, demonstrating its remarkable application prospects in concrete.

Compressive strength prediction of high-strength oil palm shell lightweight aggregate concrete using machine learning methods.

Promoting the use of agricultural wastes/byproducts in concrete production can significantly reduce environmental effects and contribute to sustainable development. Several experimental investigations on such concrete's compressive strength ([Formula: see text]) and behavior have been done. The results of 229 concrete samples made by oil palm shell ([Formula: see text]) as a lightweight aggregate ([Formula: see text]) were used to develop models for predicting the [Formula: see text] of the high-strength lightweight aggregate concrete ([Formula: see text]). To this end, gene expression programming ([Formula: see text]), adaptive neuro-fuzzy inference system ([Formula: see text]), artificial neural network ([Formula: see text]), and multiple linear regression ([Formula: see text]) are employed as machine learning ([Formula: see text]) and regression methods. The water-to-binder ([Formula: see text]) ratio, ordinary Portland cement ([Formula: see text]), fly ash ([Formula: see text]), silica fume ([Formula: see text]), fine aggregate ([Formula: see text]), natural coarse aggregate ([Formula: see text]), [Formula: see text], superplasticizer ([Formula: see text]) contents, and specimen age are among the nine input parameters used in the developed models. The results show that all [Formula: see text]-based models efficiently predict the [Formula: see text]'s [Formula: see text], which comprised [Formula: see text] agricultural wastes. According to the results, the [Formula: see text] model outperformed the [Formula: see text] and [Formula: see text] models. Moreover, an uncertainty analysis through the Monte Carlo simulation (MCS) method was applied to the prediction results. The growing demand for sustainable development and the crucial role of eco-friendly concrete in the construction industry can pave the way for further application of the developed models due to their superior robustness and high accuracy in future codes of practice.

Experimental study on axial compression for composite hollow column of steel fiber, high-strength lightweight aggregate concrete and angle steel

In order to study the axial compression performance for composite hollow column of steel fiber, high-strength lightweight aggregate concrete and angle steel, the axial compression tests were carried out on five composite hollow columns of steel fiber, high-strength lightweight aggregate concrete and angle steel with the variation parameters of hollow ratio (0%, 15%, 16%, 32% and 36%) and the form of opening (round hole and square hole). The failure phenomena and failure forms of the specimens were observed, and their stress–strain curves were measured, and the axial bearing capacity formula suitable for composite hollow column of steel fiber, high-strength lightweight aggregate concrete and angle steel was established. The following conclusions may be obtained from the test results: the axial compression performance for the composite hollow columns of angle steel is influenced by the hollow ratio and opening form greatly. The axial compression performance for composite hollow columns of steel fiber, high-strength lightweight aggregate concrete and angle steel is almost close to that of composite solid columns when the hollow ratio is low; The higher the void ratio, the more the cracks at the surface of the concrete, some transverse cracks appear, the peak load decreases by about 5–38%, and the deformation ductility coefficient increases gradually; The deformation ductility coefficient of round-hole hollow column is lower than that of square-hole hollow column. Based on the test, the finite element software ABAQUS is used to simulate the SCAH column. The correctness of the model is verified via the comparison between the numerical simulation results and the test results. At the same time, the stress nephogram of concrete and steel at different stages and the stress nephogram at concrete restraint state are simulated. According to the finite element simulation results, Mander model is used to calculate the axial compression bearing capacity of composite hollow column of angle steel. The high calculation accuracy and suitable for popularization can be obtained.

Bond-slip behaviors of composite steel-reinforced high strength lightweight aggregate concrete columns with innovative X-shaped steel sections

This paper provides an insight into the bond-slip performance of the new type of steel-reinforced high strength lightweight aggregate concrete (SRLWAC) column with innovative X-shaped steel sections through experimental and theoretical studies. Three SRLWAC specimens were tested under push-out force; the variables are the confinement by stirrups (ρsv) and shear connectors (SCs). Force-slip curves, force axial and horizontal deformations, failure modes, and crack patterns of the specimens were investigated; the force transfer, bond-stress, bond shear transmission length, and strains were studied. Comparisons between the bond strength of the studied specimens and ordinary types column specimens from 13 previous studies showed a superior bond capacity for the new type specimens. Five related models of bond capacity were discussed, and the utility of the models was put forward. A simplified load-slip model was proposed and verified. The most feasible model and the simplified model were used in the parametric study. The results showed that the material strengths and geometric configurations parameters affect the bond strength capacity. The confinement and SCs have effects on the bond and failure mode. The natural bond-stress combined with SCs produced smaller bond strength than that from both natural bonds and using higher ρsv. Recommendations for future works are developed.

Resourceful utilization of quarry tailings in the preparation of non-sintered high-strength lightweight aggregates

Quarry tailings are usually stockpiled due to stable crystalline structures below 100 °C and abundant sources, which lead to a serious environmental impacts and high ecological risks. This paper presents a study of transforming the fly ash and quarry tailings as the main raw materials into lightweight aggregates (LWAs) for using in civil engineering. A novel curing regime (autoclave technology) has been proposed to obtain higher compressive strength of LWAs. The effects of curing parameters (including temperature and steam pressure) on the properties (compressive strength, water absorption, loose bulk density, phase composition, pore structure and microstructure) of LWAs were systematically evaluated. On the other hand, this research also studies the effect of cement content on the basic properties of LWAs, which was decreased from 30 to 10 wt% for declining the CO2 emission. Results show that the strength sharply increases from 2.48 to 11.95 MPa and the water absorption decreases from 11.2 to 2.09% with increasing the elevated curing temperature from 25 to 190 °C. The LWA prepared with 70 wt% solid wastes (fly ash and quarry tailings) at 190 °C achieved the highest strength (11.95 MPa) and the lower loose bulk density (1160 kg/m3), which could meet the requirement of Chinese LWAs standard (GB/T 17431.1-2010). The water absorption of LWAs is below 5% except sample T25. The total porosity of LWAs decreases from 39.65% to 26.32% at 150 °C and from 42.54% to 27.24% at 190 °C while the cement content increases form 10 wt% to 30 wt%. At the same time, the percentage of pores (>50 nm) also gradually decreases. While the curing temperature, pressure and cement usage are above 150 °C, 1.00 MPa and 10 wt% respectively, will promote the formation of new phase composition (analcime). That also further increases the strength and percentage of harmless pores and few harmful pores. Therefore, this research offers a new curing method for producing LWAs from 70 to 90 wt% solid waste and is a rapid and sustainable solution for the large-scale recycling of quarry tailings.

Confinement in bending of high-strength lightweight aggregate concrete beams

The use of lightweight aggregate concrete (LWAC) is limited as a mainstream construction material in structural applications due to more brittle post-peak material behavior and uncontrolled crack propagation compared to normal density concrete (NWC). To improve the ductility of LWAC structures, the confinement effect from the transverse reinforcement in conjunction with longitudinal reinforcement was considered. In addition, it was tested the influence of concrete cover. The ultimate compressive strain at peak load was approximately 3.5‰ for all beams, which is like the level expected for NWC. It is possible to increase the ductility of LWAC structures by appropriate reinforcement detailing.

Effect of Spent Garnet Waste as Partial Fine Aggregate Replacement on Properties of High Strength Lightweight Aggregate Concrete

As time goes on, the usage of natural resources for concrete production affects the environment. Both the quarrying activities for granite aggregate harvesting and sand mining destroys the environment. At the same time, industrial by-products namely palm oil clinker (POC) and spent garnet waste which thrown as waste, also cause pollution. The inclusion of spent garnet waste as fine aggregate replacement in POC lightweight aggregate concrete production would reduce the consumption of river sand. This research investigates the effect of using spent garnet waste as a fine aggregate replacement on workability, dry density, and compressive strength of POC lightweight aggregate concrete. Five concrete mixes were prepared by varying the percentage of spent garnet waste as a fine aggregate replacement up to 40% by the weight of fine aggregate. All concrete specimens underwent water curing until the testing age of 7 and 28 days. The specimens were tested to determine dry density and compressive strength. Overall, the use of spent garnet as partial fine aggregate replacement influences the concrete properties. Inclusion of 20% spent garnet in concrete resulted in formation of semi-lightweight concrete with density of 2240 kg/m3. On top of that, the concrete with spent garnet exhibit higher compressive strength of about 60MPa which is about 14% higher than control specimen. Conclusively, the utilization of spent garnet as a partial fine aggregate replacement would save river sand consumption and reduce the dumping of spent garnet.

Probabilistic flexural fatigue strength of ultra-lightweight cement concrete and high strength lightweight aggregate concrete

Recently, more attention has been paid to the development of lightweight aggregate concrete due to its many advantages, such as low density, good thermal insulation, and fire resistance. The fatigue performance of ultra-lightweight cement composite (ULCC) and lightweight aggregate concrete (LWAC) with comparable compressive and flexural strength was investigated and compared in this paper. The data of three-point flexural fatigue loading experiments were collected from the literature for 108 specimens sized as 100 mm × 76 mm × 406 mm. The least-squares regression (LR) and the orthogonal regression (OR) methods were adopted and compared to fit the experimental coefficients of the Wöhler equations. Two- and three-parameter Weibull distribution models were used and compared when evaluating the probabilistic fatigue life of ULCC and LWAC at given stress levels. Analysis results show that the coefficients of the Wohler equations fitted by LR and OR methods in this study are similar. For stress levels in the middle ranges, namely, approximate 0.65–0.8, the differences of the S-N curves by two and three-parameter models are slight. When stress levels are larger than 0.8 or smaller than 0.65, significant differences exist between curves fitted by the two models. The nonlinear curves obtained from the three-parameter model are deemed more consistent with the actual situation than the linear curves by the two-parameter model.

Численный анализ поведения изгибаемых железобетонных балок, изготовленных из легкого высокопрочного бетона, с разным коэффициентом армирования

Lightweight high-strength concrete structures are currently spreading, primarily in civil engineering and bridge construction. High-strength lightweight aggregate concrete has advantages over heavyweight concrete when used in structures that must have high strength and buoyancy due to lower density and high enough strength. In this regard, it seems appropriate to use lightweight high-strength concrete in hydraulic engineering construction in offshore oil platforms and dry dock gate. In the presented work, computational studies of the stress-strain state of reinforced concrete beam structures made of light high-strength concrete have been carried out. To model the behavior of reinforced concrete beams made of lightweight high-strength concrete, spatial finite-element models have been developed. Researches were performed in the software «ANSYS». The developed models are verified by data of full-scale tests of beams with two reinforcement coefficients: 0.036 and 0.015. The performed studies allowed making a conclusion about the difference in behavior and destruction of beams at two reinforcement coefficients.

Preparation and Properties of High-Strength Lightweight Aggregate Ceramsite from Nepheline Tailings

Preparation and Properties of High-Strength Lightweight Aggregate Ceramsite from Nepheline Tailings