Clay Aggregates Research Articles

Characteristics of Lightweight Concrete Fabricated with Different Types of Strengthened Lightweight Aggregates

The vast majority of different waste building units have negative environmental impacts around the world. Crushed building units can be recycled and utilized in the concrete industry to solve these problems and maintain natural resources. This study investigated the feasibility of employing crushed autoclaved aerated concrete (CAAC) and crushed clay brick (CCB) as a lightweight aggregate (LWA) to fabricate environmentally friendly recycled lightweight concrete (LWC). In addition, a lightweight expanded clay aggregate (LECA) was also used as an LWA, namely to study how the high porosity of an LWA can adversely affect the properties of LWC. Through the experimental program, all types of LWAs were pre-treated and strengthened with two cementitious grouts, and then the performance of the produced LWC was assessed by determining the slump of fresh concrete, the dry density, the unconfined compressive strength, and the splitting tensile strength at ages of 3, 7, 28, and 56 days. The laboratory results revealed that both CCB and CAAC can be reused as full substitutions for normal-weight coarse aggregate to manufacture LWC with appropriate properties. The obtained data show that the properties of an LECA, CCB, and CAAC were improved, and the porous structure can be strengthened by pre-treatment and coating with grouts. In the same way, the mechanical performance of produced LWC is also enhanced.

Production of lightweight expanded aggregates from smectite clay, palygorskite-rich sediment and phosphate sludge

Abstract Lightweight expanded clay aggregates (LWAs) are porous materials with low density and high strength (EN-13055-1), and they are important in sustainable construction through their lightweight nature and ability to provide thermal or acoustic insulation. The objective of this work was therefore to evaluate the preparation of LWAs using a smectite clay (M1 formulation), whose application in common ceramic production is difficult. An alternative approach was proposed for the valorization of phosphate sludge and a palygorskite-rich sediment by mixing them with expanded clay (M2 formulation) for LWA production. This could result in economically cost-effective products with significant environmental benefits. Pellets were prepared and fired at various temperatures (1100°C, 1125°C and 1150°C), and relevant properties such as bloating index, density, water absorption and compressive strength were determined. Additionally, the microstructure, mineralogical transformations and phase compositions under various sintering temperatures were investigated. Increasing the temperature from 1000°C to 1150°C significantly improved the expansion properties of LWAs, and 1150°C seemed to be the optimal firing temperature at which the best expansion properties were achieved. In addition, the incorporation of the selected waste improved the properties of the final products, leading to lower density, greater strength and greater bloating with the development of the internal pore structure as compared to the LWAs without this addition. Because of their low density (0.6 g cm–3) and sufficient compressive strength (0.86 MPa), the manufactured LWAs can be used in construction (as insulating panels or in lightweight concrete) and in green roofs.

Analysis of the Influence of Shell Sand Content on the Performance of Ceramisite Lightweight Aggregate Concrete

This study investigates the impact of varying shell sand replacement rates (0%, 5%, 10%, 15%, 20%, 25%) on the properties of clay ceramsite lightweight aggregate concrete (CLC) through six experimental groups. Results indicate that a 5% replacement rate of shell sand yields optimal mechanical properties and working performance in CLC. Examination of specimen failure diagrams, electron microscopy and theoretical analysis reveals that shell sand predominantly influences CLC’s overall performance by influencing internal pore development and the formation of a “bonding defect zone” between shell sand and cementitious material. This also elucidates why specimen failure predominantly arises from internal ceramic particle fracture.

EXPERIMENTAL STUDY ON LIGHTWEIGHT CONCRETE USING LECA MATERIALS

This study investigates the feasibility of incorporating Lightweight Expanded Clay Aggregate (LECA) materials into concrete to produce lightweight concrete with improved mechanical properties. The experimental approach involves varying proportions of LECA aggregate in concrete mixes and assessing their compressive strength, density, workability, and durability. Additionally, the study examines the effect of LECA aggregate on the thermal and acoustic properties of lightweight concrete. Results from the experiments demonstrate the potential of LECA as a viable lightweight aggregate in concrete production, offering insights into optimizing mix designs for enhanced performance and sustainability in construction applications.

Improving the mechanical properties and durability of steam-cured concrete by incorporating recycled clay bricks aggregates from C&D waste

The output of C&D waste is increasing year by year, among which low-quality recycled brick aggregates (RBAs) have not been well utilized and brought environmental burden. The durability of steam-cured concrete (HCC) is often compromised due to the detrimental effects of this curing regime on the long-term performance and microstructure development of the concrete material. To address this issue, this study investigates the potential of incorporating RBAs to improve the long-term durability of HCC. The results demonstrate that the incorporation of a small amount of RBA (10–20%) not only enhances the 28-d strength of HCC by 2.5–11.3%, but also improves its impermeability by mitigating heat damage effects. The combined application of fine and coarse RBA was found to effectively balance the negative effects of coarse RBA on the performance of HCC. Furthermore, the utilization of RBA in HCC was shown to have economic and environmental benefits. The results of this study demonstrate a simple and effective approach to improve the long-term durability of HCC while promoting the high-value utilization of solid waste.

Experimental and numerical investigation of the tensile strength of lightweight concrete including expanded clay aggregate with emphasis on the double punch test

Experimental and numerical investigation of the tensile strength of lightweight concrete including expanded clay aggregate with emphasis on the double punch test

Effect of sand fineness modulus on SCC and SCLC properties

Due to the advantageous characteristics of self-compacting concrete (SCC) and self-compacting lightweight concrete (SCLC), the advancement of the SCC is considered a remarkable engineering feat. Fine aggregate is one of the main parameters of SCC; however, its effect on SCC and SCLC properties is somewhat restricted due to the limited extent of in-depth research conducted in this field. To investigate the effect of changes in sand fineness modulus (FM) on the fresh and hardened properties of SCC and SCLC, an experimental investigation with twelve mixtures was designed. Two series of mixtures were used, each with two coarse aggregate types: Light Expanded Clay Aggregate (LECA) and natural gravel. Each series included different sand FM (2.3, 2.7, and 3.1), with the incorporation of 7% micro-silica (MS) as a cement substitute in some designs. The fresh properties of the concrete were evaluated through tests such as Slump Flow, V-Funnel, U-box, L-Box, and J-Ring, in addition to the Static Segregation Column test. For evaluating the hardened properties, 192 specimens were tested, including compressive, tensile, and flexural specimens. Moreover, fracture energy was also investigated. As the sand FM increased, it was expected that the fresh properties of concrete might decrease due to coarser aggregate volume, and the hardened properties would improve under these conditions. However, the results showed that increasing the sand FM improved the fresh and hardened properties of SCC and SCLC. By increasing the sand FM, the flowability, filling ability, and passing ability of both concrete improved, but on the other hand, elevating the sand FM reduced the segregation resistance of the mixes. In contrast, the hardened properties exhibited contrasting outcomes with increasing the sand FM. Increasing the sand FM improved the compressive strength by about 20% in both concrete types.

Investigation of the Mechanical and Physical Properties of Structural Lightweight Concrete Produced with Expanded Clay Aggregate from Söğüt Region

The use of mild materials shows an increasing tendency in industrial areas. These materials are also preferred to reduce the unit weight of the building elements in the construction sector. Various light aggregates are used to produce light concrete with a lower density than normal concrete, and the properties of these light aggregates significantly affect the properties of the concrete. In this study, the use of expanded clay aggregate (ECA) produced in the Söğüt region in structural lightweight concrete was examined. Expanded clay, sand, and crushed stone aggregate were used as aggregates in concrete mixtures. The mixture granulometry was kept the same for each group. For this purpose, 60 samples were prepared for a total of 4 mixtures with different contents. Slump and unit volume weight tests were carried out on fresh concrete samples, and compressive, flexural, and splitting tensile strength tests were carried out on 7- and 28-day-hardened concrete samples. Some of the concrete mixture samples were subjected to tests after being kept in the curing pool for 7 days, and some for 28 days. As a result of the experiments, the unit weight and compressive strength values obtained from the samples produced with ECA as coarse and fine aggregate in order to achieve the highest strength target are 1413 kg/m³ and 30 MPa, respectively. The same values were found to be 1652 kg/m³ and 39 MPa in the samples produced with river sand as fine aggregate and ECA as coarse aggregate. In the samples produced using ECA as fine aggregate and crushed stone aggregate as coarse aggregate, these values were also found to be 1689 kg/m³ and 50 MPa.

Feasibility Study of Expanded Clay Aggregate Lightweight Concrete for Nonstructural Applications

In nonstructural infill panels, common materials like expanded polystyrene panels face fire susceptibility, autoclaved aerated concrete (AAC) incurs high production costs, and traditional bricks come with a significant carbon footprint and weight. So, there is a requirement for infill panels that are not just resilient and lightweight but sustainable as well. This study seeks to address these issues by introducing sustainable and lightweight expanded clay aggregate (ECA) in concrete. Firstly, eight ECA mix designs were prepared by integrating fly ash and kerosene with clay, and ECA with a bulk density of 0.59 g/cm³ and compressive strength of up to 1.73 MPa were prepared. The lightest ECA mix was then chosen to explore their use in lightweight aggregate concrete (LWAC) along with fly ash as a secondary cementitious material. The resulting LWAC had a minimum density of 1,050 kg/m³ and a compressive strength of 6.8 MPa, fulfilling the standard requirements of a minimum of 3.5 MPa for nonstructural concrete.

Mineralogical, Petrographical and Geochemical Properties of the Late Oligocene Coal Seam (Seam-VI): Insights into Elemental Enrichments and Palaeodepositional Environment (İbrice field, Thrace Basin)

The Thrace Basin hosts several mineable coal seams (upwards numbered I to VII) within the coal-bearing Late Oligocene-age Danişmen Formation. For the first time, the properties of the Seam-VI in the İbrice (Malkara) area have been investigated in order to evaluate elemental enrichments and palaeoenvironmental conditions. The xylite-rich and mineral-rich lithotypes were identified from the studied coal samples representing the whole-coal thickness. The coal samples, on a dry basis, display variable ash yields (13.2–63.0%), total C (21.2–57.8%), and total S (0.9–4.1%) contents. The minerals identified using XRD-whole rock analysis include clay minerals, quartz, pyrite, calcite, dolomite, and feldspars. Siderite is only identified in a single sample. Aragonite is detected in two samples, which contain fossil shell remains. The SEM observations agree with XRD data, and apatite, barite, biotite, pentlandite, sphalerite, Ti-oxide, and zircon were also identified as accessory phases. Huminite is the predominant maceral group in the studied samples, while liptinite and inertinite group macerals display variable proportions. The mean %Rr values of ulminite macerals are around 0.40-0.41±0.01-0.02%, indicating relatively low-rank coal. This study implies that the precursor peat-mires of the Seam-VI were mainly developed under forested mire conditions, where woody peat-forming plants were abundant, and occasionally the contributions of herbaceous plants were important. The coexistence of syngenetic pyrite and carbonate minerals (e.g., siderite and carbonate mineral bands) could be related to the development of weakly acidic to neutral conditions within palaeomires. Furthermore, the predominance of clay minerals and the presence of detrital accessory minerals (e.g., apatite, pentlandite, and Ti-oxides) can also be indicators of clastic influx into palaeomires. Although aluminosilicate minerals (e.g., clay minerals) are abundant in dominant phases, SEM-EDX data shows that accessory minerals mainly control the elemental enrichments in the Seam-VI. The Mn enrichments in the samples seem to be controlled by Mn-bearing siderite micronodules. Considering the presence of sulphide mineralization and metallic ore deposits in the Strandja and Rhodope massifs, enrichments of Cr, Co, Ni, Ge, and Mo are related to As-bearing pyrite grains and accessory sphalerite and pentlandite grains within clay mineral aggregates in the samples. In addition, the Sr-bearing barite overgrowths around feldspar grains and syngenetic carbonate mineral bands could also cause Sr enrichments. Overall, clastic influx ratios into palaeomires and pH conditions during peat accumulation controlled the elemental enrichments in the Seam-VI.

Influence of Expanded Clay Aggregate on the Engineering Properties of Lightweight Concrete

In seismically active locations, civil infrastructures, such as buildings, bridges, and dams, are frequently subjected to earthquakes. Using lightweight construction materials is one method for enhancing the seismic resistance of infrastructure. This study examined the engineering properties of lightweight concrete manufactured using expanded clay aggregate, with the purpose of developing sustainable and environmentally friendly building materials. Laboratory tests focused on the effects of the aggregate shape and the supplementary superplasticizer, as well as on the influence of the concrete age. Experimental studies were conducted to measure fresh (slump) and hardened properties (compressive strength, splitting tensile strength, and density). The expanded clay aggregate was produced by burning at a temperature of 800 to 1 200 °C. Cubic, oval, and round aggregate shapes with a maximum size of 20 mm were evaluated. This study also examined the effect of superplasticizers on the engineering properties of lightweight concrete. The composition of the superplasticizer varied from 0 to 2,5%. According to the experimental results, the engineering properties of lightweight concrete made with oval aggregates are advantageous in comparison with those using cubic and round shapes. It is also demonstrated that optimal amounts of superplasticizer are necessary to develop materials with adequate properties. It can be concluded that expanded clay aggregate can be used as an alternative material to produce lightweight concrete.

Study on the shear properties of masonry pagoda mortar and its influencing factors

Mortar stands as one of the fundamental components in masonry construction, significantly enriching the global cultural heritage, particularly evident in ancient masonry structures. In this paper, the improvements of shear strength of mortar were studied, based on the original formulation material of sticky-rice lime mortar. The study considered the effect of different aggregates and additives on the shear strength of mortar, the shear tests and scanning electron microscopy were employed to analyze the shear strength index and microscopic shear basis of the mortar. The results showed that 2 wt% Na-SiO2 significantly enhanced the shear strength of the mortar. Furthermore, the adhesion and frictional resistance between fiber and lime played a crucial role in enhancing the mortar's shear resistance. Incorporating a 0.5 wt% fiber additive not only effectively improved the mortar's brittleness but also acted as a deterrent to crack formation. Compared to pure lime mortar, the mixture of sand and clay aggregate exhibited a larger capacity at the same volume. This mortar also showcased better plasticity and ductility, making it more suitable for structures with significant shear deformation. These analytical findings provide valuable insights for modifying mortars in the restoration of historical buildings.

Thermal and mechanical properties of a sustainable bio-flax fibre-based lightweight aggregate concrete

A novel lightweight aggregate concrete (LWAC) or lightweight concrete (LWC) is developed using expanded perlite powder and lightweight expanded clay aggregate as a replacement for conventional fine and coarse aggregates, respectively. Furthermore, the natural plant-based flax fibre in treated form was added to the LWC mix at three different volume fractions. The mechanical and thermal characterisation of LWC was carried out using the compressive strength test, split tensile test, modulus of rupture, thermal conductivity and thermal resistance test. Moreover, the microstructural and durability properties were obtained using scanning electron microscopy/energy dispersive X-ray spectrum analysis, rapid chloride penetration test, sorptivity test and water absorption test. Test results reveal that the addition of 2.0% flax fibre resulted in improved mechanical, thermal and durability properties when compared to LWC with no fibres. Moreover, the microstructural analysis using SEM revealed the formation of ettringite which is responsible for the strength development in the LWAC mix.

An Innovative Sunlight‐Driven Device for Photocatalytic Drugs Degradation: from laboratory‐ to real‐Scale Application. A First Step Toward Vulnerable Communities

AbstractFreshwater represents one of the most precious resources on the planet, so it is fundamental to preserve it. In this work, an innovative sunlight‐driven device composed of bismuth oxybromide (BiOBr) grown on a material derived from natural sources, i.e., Lightweight Expanded Clay Aggregates (LECA), is developed to clean surface waters under natural solar light irradiation. For this purpose, the photodegradation of two non‐steroidal anti‐inflammatory drugs, ibuprofen, and diclofenac, is investigated under varying operative conditions. Laboratory‐ and real‐scale experiments reveal that the fabricated floating BiOBr/LECA photocatalyst fully degrades diclofenac, whereas limited abatement of ibuprofen is observed. Based on the identification of specific transformation products (TPs) during the degradation, this behavior seems to be strongly related to the different structures of the two drugs. In fact, the main TP produced during diclofenac degradation derives from dechlorination and ring condensation: this type of photocatalytic degradation pathway is generally favored over the C─C bonds's cleavage, which is a unique possibility for IBU abatement. Moreover, the potential partial adsorption of these species on the photocatalyst's active sites can cause their deactivation. Finally, reusability tests demonstrate the high stability of the floating composite.

Structure feature and compressive crushing behavior of lightweight clay aggregate particle: experiments and numerical simulations

Structure feature and compressive crushing behavior of lightweight clay aggregate particle: experiments and numerical simulations

Spatial cross-correlation of surface soil physicochemical properties with soil erosion estimated by fallout radionuclides in croplands in a semi-humid region of Iran

Most attempts to correlate soil erosion rates with soil physiochemical properties have not fully succeeded. We employed 137Cs and 210Pbex tracers to understand the interactive impacts of medium- to long-term soil erosion rates on soil texture, structure, and composition in different cropping management systems and slope gradients. To do so, cultivated areas of a sub-watershed were subdivided into three iso-sectors based on slope gradient and typical cropping systems in the region: dry farming with slopes of 10–30 and < 10 % and irrigated farming with a slope of < 10 %. Some soil physiochemical properties were assessed, including particle size distribution, organic carbon (OC), aggregate percolation stability (PS), sealing index (SI), and semi-quantitative XRD of clays. The weighted average net erosion rates in cultivated lands estimated by 137Cs and 210Pbex methods were 26.3 and 31.4 Mg ha−1 yr−1, respectively. Among studied iso-sectors, the dry farming site with a slope of < 10 % had the highest net soil erosion rates and the lowest values for PS and SI, highlighting that land management is a more influential factor on soil erosion than the slope gradient. Both Pearson coefficient and spatial cross-correlation index (SCI) showed a negative correlation between clay content, aggregate stability and soil erosion due to the abundance of expandable clays in the region. However, unlike the Pearson coefficient, SCI showed that the soil loss rates had the strongest association with PS in space, but very weak ones with OC and SI, highlighting PS as a promising indicator of soil quality. SCI proved a superior analysis, which provides the spatial causality between the two variables in space. Findings suggest that to ensure food security in the face of future climate change, careful management practices should be implemented in dry farming lands with high amounts of expandable clays, making them prone to aggregate breakdown and soil erosion.

Utilization aspects of extruded polystyrene and expanded clay aggregate in road frost protection structures

Utilization aspects of extruded polystyrene and expanded clay aggregate in road frost protection structures

Deionization-induced colorless transparency in physical gels formed by clay aqueous dispersions

Physical gels formed by aqueous clay dispersion are typically turbid and have a milky appearance. The colorless and transparent nature of gels expands the potential for novel applications. In this study, we successfully produced a transparent gel by deionizing the gel as much as possible while maintaining its dynamic elastic modulus, akin to water. The aqueous clay suspensions exhibited specific sol-gel regions corresponding to the type of clay. According to images obtained through cryo-SEM, the three-dimensional network formed by clay became finer when deionization was carried out, and the aqueous dispersion exhibited Rayleigh scattering. The reduction in the extent of Mie scattering due to the suppression of clay aggregation through deionization results in its colorless transparency. This transparent gel will open up various potential applications, including 3D printing support structures, 3D cell culture, 3D art and displays with dispersed materials, educational materials with visual effects, enhancing traditional products, and innovative engineering applications.

Thermomechanical Properties of a Concrete Composed of Cherry Tree Resin and Expanded Clay (Exclay) Aggregate

Expanded clay (exclay) aggregate and cherry tree resin are used in this study to produce a lightweight construction material. Based on the grain diameter, exclays are classified as d = 2–4 mm and d = 4–6 mm. Cement is added to each group as the binder material. The exclay ratios vary as 10%, 20%, 30%, 40% and 50% of the total volume in the samples. The cherry tree resin is poured into the concrete mixture with a ratio of 1% and 1.5% of cement + exclay mixture in order to form artificial pores in each sample group. The produced samples are subjected to some tests, such as thermal conductivity, water absorption and compressive strength. It is determined that due to the increase in exclay ratios and particle diameter, there is an increase in porosity along with water absorption, but there is a decrease in density, thermal conductivity and compressive strength. Hence, these newly produced concretes are recommended for panel walls, brick, concrete briquettes, inner and outer plaster and concrete partition elements.

Quality analysis of self curing concrete incorporated with lime coated light weight expanded clay aggregate (LECA)

Quality analysis of self curing concrete incorporated with lime coated light weight expanded clay aggregate (LECA)