Clay Mixtures Research Articles

Synergizing date palm seeds-derived oxidized activated carbon: Sustainable innovation for enhanced water retention, efficient wastewater treatment, and synthetic dye removal

Herein, this study explores the efficacy of oxidized activated carbon from date palm seeds (OACDS) as a multifaceted solution for sustainable wastewater treatment and water retention improvement. Through oxidation synthesis, OACDS demonstrates exceptional capability in adsorbing contaminants from water sources, offering a promising eco-friendly option for environmental remediation. Batch adsorption experiments highlight the rapid and efficient removal of Rh-6 G dyes, achieving an impressive 88.06% adsorption rate under optimized conditions of pH 6 and a 70-minute contact time. Moreover, OACDS exhibits remarkable adsorption capacities, reaching 91.3% at a 60 mg adsorbent dose and 94.23% at 55°C. Kinetic and adsorption analyses align with PSO and Langmuir models, indicating chemisorption and mono-layered adsorption of Rh-6 G on OACDS. Thermodynamic evaluation suggests the process's spontaneity and endothermic nature. The regeneration experiment revealed a notable 10.9% decrease in the adsorption capacity of OACDS towards Rh-6 G after five cycles. These findings substantiate the reusability and cost-effectiveness of OACDS, underscoring its potential economic advantages. Beyond wastewater treatment, OACDS showcases notable water retention properties, promising for agricultural applications. Its integration into clay and sandy soil enhances water retention capacities, with the clay soil-OACDS mixture displaying a peak of 16.8 mL. The material's rough and porous surface positively impacts water retention in crops, benefiting agricultural yields. Comprehensive characterization analyses using SEM, FTIR, and XRD support OACDS's effectiveness in adsorption, highlighting its amorphous structure and suitability for environmental applications. This study positions OACDS as a comprehensive solution addressing wastewater treatment and water conservation challenges, encouraging further exploration of agricultural byproducts for sustainable environmental solutions.

Prefab Light Clay-Timber Elements for Net Zero Whole-Life Carbon Buildings

"Net zero whole life carbon" is an ambitious climate target that refers to neutralizing and offsetting the entire LCA-based carbon footprint of a building, including both operational and embodied greenhouse gas emissions. Especially in the Northern climate, viable building envelope structures must, therefore, provide good thermal insulation and low embodied emissions. Carbon offset is typically based on excess on-site renewable energy or purchased carbon offsets disconnected from the building and the site. Viable strategies for carbon neutrality start by minimizing material-related and energy-related CO2e emissions. As a result, new kinds of building envelope structures have been recently introduced in the academic literature and experimental building projects. Traditional construction materials, such as timber and clay, have been sourced locally and processed manually, providing good results for the embodied emissions in life cycle assessment. Recent studies on clay-based construction materials have concluded that more research on clay as a construction material is needed, in particular considering its environmental performance. One specific concern in the Northern climate is that the weather conditions limit clay construction outdoors and prevent industrial-scale application of these solutions. The methods of prefabrication can address these issues. This study introduces the critical technical and environmental properties of a new prefabricated wall element based on a combination of light timber frame and light clay. In a hybrid light clay-timber structure, a mixture of clay and hemp shives is cast between the timber studs. On the one hand, the novelty of this wall structure is the prefabrication that enables industrial applications and upscaling without the limitations of weather conditions. On the other hand, the study assesses the climate impact of a light clay-timber wall element : cradle-to-gate emissions, thermal insulation, and the climate benefits outside the system boundary (carbon handprint) reported in the D-module of the LCA framework. The study also shows that natural materials require a different approach than synthetic materials from industrial processes. There may be variations in the properties of hemp and clay, especially when local sourcing is prioritized for better environmental performance. Moreover, the mixing and installation processes have a significant impact on the final properties and the performance. We show that constructing a light clay wall is a knowledge-intensive process that may result in very different technical properties.

Determining The Depth of Hard Soil Layers Using Geoelectric Resistivity and Cone Penetration Test Methods (Case Study: Kelurahan Bontoramba Kecamatan Somba Opu Kabupaten Gowa)

Hard soil layers can impact the loading, stability, and behavior of structures in the geotechnical field. Comprehensive understanding of the depth and properties of hard soil layers can aid in designing suitable structures. Therefore, this study employed the resistivity geoelectric and Cone Penetration Test (CPT) methods to map the features of hard soil layers. Resistivity data were acquired through measurements utilizing the geoelectric method, while data on cone resistance, shear resistance, and friction ratio were gathered through field measurements using the CPT tool. The collected data was analyzed comprehensively to obtain a complete understanding of soil conditions. Based on resistivity values, the results indicated the research site comprises alluvium, very dry clay, and dry sandy soil. Based on the CPT test, it is determined that the layers contain mixtures of fine-grained soils, clay, silt, and sand. Therefore, it can be inferred that the dense sand lithology constitutes the hard soil layer geologically. The employment of both approaches delivers supplementary details on soil features and depth.

Factors Influencing the Dynamic Shear Modulus and Damping Ratio of Granulated Rubber–Clay Mixtures in Xiong’an New Area

Factors Influencing the Dynamic Shear Modulus and Damping Ratio of Granulated Rubber–Clay Mixtures in Xiong’an New Area

Molding properties of clay mixtures in the soft mud brick manufacture

The article reveals physical and mechanical characteristics of clay mixtures in the soft mud brick manifacture. Considering that currently Russia has no advisory or regulatory documents on the selection of raw materials for soft mud bricks and requirements for their physical and mechanical properties, this issue is quite relevant. The authors, based on their extensive practical experience, present data on acceptable ranges of clay mixtures deformation and critical compressive stress in the soft mud brick manufacture, as well as the results of studies on the influence of electrolyte additives on these indicators. The findings of how the mineral composition of clay raw materials and moisture con-tent influence the critical compressive stress and stickiness of clay mixtures are also presented. Thus, it has been experimentally established that the critical compressive stress of clay mixtures for soft mud bricks should be in the range of 0.2 – 0.8 kg/cm2, and the deformation degree of raw bricks should be in the range of 3 – 5 units. Moreover, even within such narrow limits, depending on their variation as well as on the method of molding and the composition of clay mixtures, it is possible to obtain differ-ent structures of the brick front surface: granular, tuberculate, grooved, wavy, corrugated, spotted, scaly, and their combinations. The moisture content of clay mixtures, depending on the type of clay raw material, can vary within very wide limits: from 20 to 38 per cent. The data obtained will make it possible to develop methods for selecting raw materials for soft mud bricks, which in turn will con-tribute to the organization of its wide production in various regions.

Comparative Soil Analysis from Different Crime Prone Areas of Kottayam and Kollam Districts of Kerala for Forensic Characterization

Soil is the loose surface material that covers land on which plants grow. It consists of a mixture of organic remains, clay, and rock particles, which gives it its uniqueness from place to place. Because of the uniqueness of soil, it has a high evidential value in the field of forensic science. In the present study, research has been conducted to check the range of variations in the soil collected from different crime-prone areas of Kottayam and Kollam districts of Kerala by physical, chemical, microscopic, and instrumental examination. In physical examination, soil colour, texture, consistency, and density were measured, and in chemical examination, pH and total soluble sulphate of the soil were measured. In instrumental examination, Heavy metal analysis was done by using Atomic Absorption Spectrometry (AAS), which helps to measure the amount of trace elements present in the soil. The study found that each soil has some significant variations that make it unique. In the field of forensic science, this can be highly helpful in determining the origin of soil by examining its colour, texture, structure, content, etc.

Utilization of Earthquake Demolition Wastes and Afşin–Elbistan Fly Ash for Soil Improvement after the Kahramanmaraş Earthquake (6 February 2023)

Türkiye is surrounded by active faults that have the potential to produce big earthquakes. Recently, one of these faults has become active. Two earthquakes of magnitude 7.7 and 7.6 occurred 9 h apart on 6 February 2023 in Kahramanmaraş. It is reported that 150 million tons of earthquake demolition waste (EDW) is estimated to be produced as a result of those natural hazards. This waste poses a serious risk to both the environment and human health. Its use in geotechnical applications will provide serious environmental benefits. In this study, Afşin–Elbistan fly ash (AEFA) and EDW were used to stabilize weak clayey soils in different proportions. Samples were prepared by separately adding 5, 10, 15, and 20% AEFA and EDW to high-plasticity clay. The AEFA used in this study was used because the production of AEFA is too high, and it is not used in concrete production because it does not comply with the standards and causes serious environmental problems for the region. The Atterberg limit, standard compaction, unconfined compression strength (UCS), triaxial, and California bearing ratio (CBR) tests were performed on soil samples, and samples were prepared from soil mixtures with various proportions of AEFA and EDW added. In addition, clay mixtures were prepared with EDW by keeping the AEFA ratio constant at 15% and their effects were also investigated. According to Atterberg test results, the natural soil class was determined as high-plasticity clay, the soil class of the mixtures created by adding EDW and AEFA was determined as low-plasticity clay, and all ternary mixtures were determined as low-plasticity silt. In addition, the maximum dry density increased for all mixtures, while the optimum water content decreased. A significant increase was observed in UCS test results, especially in ternary mixtures. While cohesion increased in AEFA mixtures, it decreased in ternary mixtures as the EDW ratio increased. It was observed that the internal friction angle increased in all mixtures. According to CBR test results, it was determined that the binary AEFA mixture ratio was 20%, the binary EDW mixture ratio was 10% and above, and all ratios of the ternary AEFA + EDW mixtures could be used as road sub-base material. After the major earthquake disaster, the use of EDW is of great importance for the environment. As a result, AEFA and EDW were found to enhance the geotechnical properties of clay.

Desiccation and crack behavior of modified waste materials–clay mixture as landfill liner: a systematic review

Desiccation and crack behavior of modified waste materials–clay mixture as landfill liner: a systematic review

Porcelain Stoneware Tiles Based on Clays Mixture and Recycled Waste Glass Powder: Effect of Soaking Time

The effect of soaking time on the properties of porcelain stoneware tiles based on clay mixture and recycled waste glass powder was studied. Mixture was prepared and fired at 1150°C. During firing, raw mixture was subjected to various soaking times: 30, 60, 90 and 120 min. The by-products were characterized by their linear shrinkage, water absorption, bulk density, flexural strength, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results were modelled by using different mathematical expressions. The results demonstrated that physico-mechanical properties of ceramic probe are significantly affected by soaking time. After 30 min, products satisfied the ISO 13006 standard condition for porcelain stoneware wall and floor tiles: water absorption value was lowest (0.07%) and mechanical strength value was 44.4 MPa. Prolonged soaking time was undesirable due to its negative effect (bloating) on the products’ physical and mechanical performance. The XRD patterns indicated the presence of mullite, cristobalite, enstatite, anorthite, hematite and quartz as the main crystalline phases. SEM images of the tiles fired at 1150°C for 30 min display a very close texture and dense microstructure.

Geoarchaeology of open-air sites of the Foz do Chapecó area in the upper Uruguay river, southern Brazil

This paper presents the results of the investigations that defined the formation of the sedimentary deposits and the chronological sequence of the Foz do Chapecó archaeological area in the Volta Grande of the Upper Uruguay River, Southern Brazil. This research was undertaken to contribute to the definition of the diachronic, sedimentary and stratigraphic context of the archaeological occupations. To achieve these goals a geoarchaeological prospection by land and water was conducted, focusing on the valley bottoms, in the whole Volta Grande area. It comprehended the characterization of surface sedimentary deposits, the exposure and analysis of stratigraphic profiles, and sedimentological analysis. Four superficially exposed deposits were identified: i.e., fluvial conglomerates, fine sediments with sandy texture, clay colluviums and current and recent alluvial deposits. Six interesting points for the opening of stratigraphic profiles were identified, and subsequently resulted in the identification of sedimentary facies associated with river-bed, colluvial and colluvial-alluvial deposits. Three of these points presented a clear sequence of archaeological levels in the stratigraphic context. The results indicated that the local sediments are predominantly composed of a variable mixture of silt and clay, with sands occurring predominantly in an interdigitated form. The stratigraphic structure of the identified layers led to the establishment of 7 sedimentary facies, associated with colluvium (Cm), colluvium-alluvium (Sm) and alluvium and fluvial channels (Sm, Fl, Gms, Gt, Gp, Gh). The radiocarbon dating gives an age between 12.0 and 0.3 cal kBP, indicating that the filling of the local valley occurred during the end of the Pleistocene and throughout the Holocene by means of both fluvial and colluvial systems. Nine distinct archaeological levels, with a clear stratigraphic, chronological, and technological characterization were identified. The pre-ceramic archaeological sequence shows the following chronology: the oldest occupation occurred between 12.0 and 11.0 cal kBP (Cm facies); this was followed by an occupation between 10.5 and 9.5 cal kBP (Cm, Gt, Gp and Gh facies in three archaeological sites with eleven 14C data), then an occupation between 8.7 and 8.5 cal kBP (Cm facies), another between 5.7 and 5.5 cal kBP, one more between 4.8 and 4.6 cal kBP (Cm facies), and the last between 3.4 and 3.3 cal kBP (Cm and Sm facies). The ceramic phase seems to form a single dense component with the anthropogenic soil formation, and was dated between 0.5 and 0.3 cal kBP (Sm facies). These data present a previously unpublished chronostratigraphic sequence that is unique for the context of open-air sites in inner southern Brazil.

Geotechnical, microscopic and mineralogical characterization of surficial sediments nearshore the southern coast of Brazil

ABSTRACT Many important maritime projects depend on the correct characterization of surficial sediments (e.g. gas and water pipelines; dredging works; transport of sediments, and water-soil-structure interaction). However, the sampling and characterization of such sediments are very challenging due to the environmental conditions. Furthermore, the investigation often consists only of a basic granulometric analysis. In this context, this paper presents a geotechnical, mineralogical, and microscopy characterization of an offshore area on the southern coast of Brazil. Surficial samples were collected from the seabed, in water depths between 13.0 and 91.0 metres. Then, they were submitted to basic geotechnical characterization tests (size distribution by sieving and sedimentation, Atterberg limits, and basic physical properties), mineralogical analysis by X-ray diffraction tests (XRD), microscopy investigation by scanning electronic microscopy (SEM) and shear vane tests. Based on the state and index parameters of the sediments, as well as the undrained shear resistance, three main sets of sediments have been identified: group I (sands), group II (clayey sands), and group III (mixtures of sand, silt, and clay). The spatial distribution of sediments was also inferred, reflecting different deposition environments and bottom dynamics. The clay mineral quantification through XRD revealed that the predominance of 2:1 clay minerals is related to the higher plasticity found in some samples. Moreover, the presence of diatoms could explain the difference in porosity in the samples, resulting in a higher plasticity and lower shear strength.

Projected traditions? Tracing an East German-Cuban Collaboration in Loam and Soil Cement Construction in Havana-Cocosolo

This article unveils the history of constructing the "Cocosolo Experimental House" in Havana, a collaborative endeavor involving East German and Cuban participants. This singular project was designed around 1989-90, in parallel with the end of the GDR, to serve as a prototype for “self-construction technology” making use of local soil. A crucial step in the development process of this project was the search for the most suitable construction material, ultimately leading to a choice between loam (a mixture of clay, silt, sand, and aggregates such as gravel, which does not require an additional binder) and soil cement (a mixture of local soil and cement, while cement works as binder). Although several obstacles prevented the project from being completed as planned, it was finished after the East German group from Weimar left within the framework of Cuba’s specific local self-construction system. The history of the Cocosolo project unfolds as a tapestry of experimentation, adaptation, and unintended consequences. It addresses both the socialist discourse regarding material scarcity—and the actual lack of construction materials in the Cuban context. In our article, based on archival research in Cuba and Germany as well as site surveys, we unpack the expectations of the German partners experimenting with loam abroad, as well as those of the Cuban actors, focusing on the local uses of soil cement technology. Finally, to nuance the understanding of how a Cuban loam-building tradition was imposed, we analyze the clash of expectations at the construction site.

Multilayer immobilizing of denitrifying Bacillus sp. and TiO2-AgNPs on floating expanded clay carrier for co-treatment of nitrite and pathogens in aquaculture.

Nitrite contamination and the spread of pathogens can seriously degrade water quality. To simultaneously control these factors, an innovative approach of fabricating a remediation agent that contained denitrifying bacteria and TiO2-AgNPs co-immobilized on floating expanded clay (EC) was proposed in this study. The EC was fabricated from a mixture of clay and rice husk through pyrolysis at a high temperature of 1200 °C, followed by a rapid cooling step to create a porous structure for the material. TiO2NPs were modified with Ag to shift the absorbance threshold of TiO2-AgNPs into the visible region of 700-800 nm. The experimental results showed that the stirring speed of 250 rpm was suitable for immobilizing TiO2-AgNPs on EC and achieved the highest Ti and Ag content of 639.38 ± 3.04 and 200.51 ± 3.71 ppm, respectively. Coating TiO2-Ag/EC with chitosan (0.5%) significantly reduced the detachment level of immobilized TiO2-AgNPs compared to that of the material with no coating. In particular, this functionalized material inhibited 99.93 ± 0.1% of Vibrio parahaemolyticus pathogen but did not adversely affect the denitrifying bacteria after 2 h of visible light irradiation. Based on the electrostatic bond between oppositely charged polymers, the denitrifying bacteria, Bacillus sp., in alginate solution was successfully immobilized on the chitosan-coated TiO2-Ag/EC with a bacteria density of (76.67 ± 9.43) × 107 CFU g-1, retaining its nitrite removal efficiency at 99.0 ± 0.27% through six treatment cycles. These findings provide solid evidence for further investigating the combination of biodegradation and photodegradation in wastewater treatment.

A review of mix design terminologies for cement admixed sandy clay

In densely populated countries, underground construction and land reclamation could be possible options to solve the demand for land space, thus securing sustainable long-term development of the nation. For example, in Singapore, land reclamation has been widely conducted using excavated materials from underground development. The excavated materials are commonly marine clays that contain sandy soils. To improve the mechanical properties of these soft soils, cement-treated soil stabilization is popularly adopted. In fact, many researchers have investigated the properties of pure cemented clay or pure cemented sand using conventional design parameters such as water content (water/solids) and cement content (cement/dry soil). However, can these terminologies be still used to accurately examine the role of sand in cemented sandy clay mixtures? Through unconfined compression testing, it is herein shown that the use of existing mix design approaches in the literature cannot properly explain the variation of strength with sand content for cemented sandy clay mixtures. A new mix design approach is thus proposed in this study, which ensures that the role of sand in a cemented clay matrix can be quantified.

Laboratory Investigation of the Unsaturated Shear Strength Characteristics of Sand–Clay Mixtures

Sandy‐clay mixtures are commonly used in civil engineering projects, such as transportation and water resources, due to their unique construction properties. While the macromechanical characteristics of these mixtures under saturated conditions are well understood, their behavior in unsaturated states is still not fully elucidated. This study aims to investigate the mechanical behavior of sand–clay mixtures under unsaturated conditions by examining the influence of varying sand content and matric suction on their shear strength. The research includes unsaturated shear strength tests and nuclear magnetic resonance (NMR) experiments to analyze the pore characteristics within the mixtures at different sand content levels. The correlation between changes in pore structure and shear strength is systematically analyzed. The unsaturated shear strength of the mixtures is predicted using the Fredlund shear strength formula and compared with the measured values. The results indicate that the unsaturated shear strength of the mixture decreases as the sand content increases but stabilizes once the sand content reaches 20%. Below 20% sand content, the changes in micropore distribution are not significant with increasing sand content. However, beyond 20% sand content, there is a noticeable increase in the ratio of large pores and a decrease in the proportion of small pores. The sand content of 20% represents a critical threshold for the strength and porosity variations in the mixture. Under constant matric suction, the unsaturated shear strength of the mixture improves with the increase in sand content. However, the predictive accuracy of the Fredlund shear strength formula gradually diminishes as the sand content increases.

Synthesis of chitosan based new material for recovery of Pt (IV)

In this study a new type of adsorbent bead precursor was reached using chitosan and pretreated clay. The pretreated clay was produced from the clay of the "Tsogt-Ovoo" deposit in the Umnugovi province of Mongolia. It was produced by acid and heat treatment to remove its mechanical impurities. The mixtures of chitosan and pretreated clay were taken with various ratios (8:1, 8:2, and 8:3) for chemical processing to obtain a chitosan-based adsorbent bead for recovery of (Pt(IV)) from aqueous solution. It was examined that the adsorption capacity of the adsorbent bead when the chitosan and pretreated clay mass ratio 8:2 was the highest for platinum ion (Pt (IV)). The adsorption properties of Pt (IV) were studied depending on the solution pH, contacting time, temperature, initial concentration of platinum ion solution, and amount of adsorbent material. The adsorption efficiency was the highest (93.29%) when the initial concentration of the platinum ion was 50 mg/l at the following condition; pH=3, temperature 250C, time 3 hours, and the amount of the adsorbent material 0.1 g. It represents that the chitosan clay bead can be applied for the recovery of platinum (Pt (IV)) from aqueous solution.

Effect of application of urban sewage sludge as organic amendment on germination and growth of Retama monospermain Oran region of Algeria

Appropriate disposal of huge amount of sewage sludge generated in urban areas pose a serious threat to the environment. The urban wastewater treatment sludge has the potential as mineral organic amendment strategy in th fight against wind erosion through planting of Retama monosperma in Algeria. In the present study, the sewage sludge was sampled at the Bousfer –Oran wastewater treatment plant, and amended with different cultivation substrates. Further, its influence on the growth of young R. monosperma, plants, with an aim to replant them at sandy littoral deposits. The preliminary results of our work showed that the replanting of young Retamaplants in the substrate formed by a mixture of mud and limestone showed improved growth compared to the fourteen other substrates tested, from the point of view of structure, texture and fertilizing abilities.The sample of a mixture of clay and mud had a compact structure for the seeds to germinate. However, the growth of young plants transplanted into the latter was found to be improved giving an acceptable result considering the contributions of this organic amendment.

Potential application of sludge pond ash as a novel additive for clay stabilization

Clays often have unfavorable geotechnical properties that limit construction applications on them. There is a need for sustainable soil improvement techniques to enhance the strength and stiffness of clays. While previous studies have explored clay stabilization with common supplements like cement, lime and fly ash, the utilization of sludge pond ash (SPA) as a sustainable additive has been limited and there is a lack of understanding of the interactive effects of SPA proportion, moisture content, and curing time on the mechanical behavior of clay. The objective of this study is to examine the mechanical properties of clay enhanced with SPA under different curing conditions. To achieve this, different proportions of SPA were mixed with the clay to obtain accurate findings on the efficacy of SPA addition on compaction and unconfined compressive strength (UCS) of the clay to determine mechanical properties. Scanning electron microscopy (SEM) provided imaging of clay improved with SPA to evaluate the microstructural changes in soil texture. Firstly, the sludge from a pond burned at 1000 °C (the optimal temperature determined by microstructural X-ray diffraction (XRD) analysis) was added to the mixture as 0, 2, 4, 6, 8 and 10% of the soil's dry weight, respectively. The studied samples were prepared with the same energy (equivalent to the standard Proctor test) at different moisture contents and were tested in a uniaxial device at 7, 28 and 56 days of curing. It was found that adding SPA to the base soil decreased the maximum dry unit weight (MDUW). On the other hand, it increased the optimum moisture content (OMC) of the compacted mixture. The study examined the combined effects of moisture content and curing time on the compounds, revealing that these factors induced a decrease and an increase in the UCS, respectively. The addition of SPA as an additive material to the clay mixture was found to exert a significant effect on the strength properties of the clay, with an optimal percentage of around 10%. Empirical correlations were also developed to predict the UCS of the SPA-improved clay with high precision. Furthermore, SEM analyses show that SPA acts as a glue gel between aggregate in the mixture and coat clay particles that changes the blend texture and alters weak bonding to aggregate-like particles. The results of both macro- and micro-scale analyses collectively confirm the superior efficacy of the optimal SPA replacement in enhancing various strength and stiffness properties of the clay.

EFFECTS OF COMBINATIONS OF LIMESTONE POWDER AND METAKAOLIN ON MORTAR COMPRESSIVE STRENGTH DEVELOPMENT

Cement production is a major contributor to carbon dioxide (CO2) emissions, and concrete is one of the most widely used building materials in the world. To reduce CO2 emissions from cement, supplementary cementing materials have been widely introduced in mortar and concrete mixtures. This research will explore the mechanism that determines the development of compressive strength in mortar made with partly substituted cement and a mixture of limestone powder and laboratory-quenching heat-treated kaolinite clay (also called metakaolin). Metakaolin is rich in Southeast Asian countries and needs further investigation to adopt in cement systems. Limestone powder and metakaolin constitute 45% of the binding cement ingredient by weight (dry). The strength was evaluated using mortar, and the microstructure was determined using paste. The results show that at 28 days, the compressive strength of mortar containing 45% cement substitution by 15% limestone powder and 30% metakaolin with 1% PCE (per B45S 1:2) was 97% relative to the reference mortar. However, due to the impurities in metakaolin, its synergistic interaction is limited, which results in the compressive strength being lower than anticipated.

Changing law of permeability coefficient during compression for reconstituted sandy clays

Sandy clay is defined as a sand–clay mixture with the mechanical behavior dominated by fine clay but affected by coarse sand. Twenty sets of one-dimensional incremental load consolidation and falling head permeability coefficient tests were performed on sandy clays. The samples of sandy clays were prepared by mixing two hosted clays with different sand fractions from 0% to 60%. The interrelation between the change of permeability coefficient with void ratio and the compression curves is established. The results indicate that the effect of sand fractions on permeability coefficient can be attributed to the variation of void ratio at liquid limit induced by sand fractions. The initial void ratio affects permeability coefficient by changing the void ratio under the same effective vertical stress. These two findings highlight that the permeability coefficient-void ratio relationship of sandy clays is a function of void ratio at liquid limit and void ratio. An empirical method of estimating permeability coefficient is also proposed using two physical indices of void ratio and void ratio at liquid limit for sandy clays having void ratio at liquid limits ranging from 0.63 to 1.73 and initial void ratios varying from 0.72 to 2.67.