Compacted Specimens Research Articles

Influence of Compaction Methods on the Optimum Moisture Content and Performance of Roller Compacted Concrete Pavements

Despite numerous advantages, there are a few challenges associated with the designing and fabrication of roller compacted concrete pavement (RCCP) specimens—compaction mechanisms employed in the RCCP mix proportioning, specimen fabrication, and actual pavement construction are different in principle, leading to significant disparity between the field and laboratory performance. To reconcile this discrepancy, an effort has been made to study the effect of compaction on the performance of RCCP. Initially, the effect of different compaction types, namely vibrating table, vibrating hammer, modified Proctor, and gyratory compactor (GY) on the optimum moisture content of RCCP was investigated, then the roles of moisture content and compaction type on dry density, mechanical aspects (compressive strength, indirect tensile strength, and flexural strength), rideability, and transport properties (porosity and absorption) of RCCP were elucidated. Also, alternative methods for quantifying the workability and compactability of GY compacted specimens are proposed. The findings from this study suggest employing a particular compaction mechanism both for the mix proportioning as well as specimen fabrication to avoid the under- or overestimation of RCCP performance.

Effect of Static and Dynamic Methods of Compaction on Mechanical Properties of Silt

Engineered fills, such as roads, earthen dams, embankments, and earthen sites, are enhanced by compaction to increase strength and decrease compressibility. Static and dynamic compaction are the most popular and important methods in geotechnical engineering practice with different compaction mechanisms. However, the significant differences in the physical and mechanical properties between both compaction methods that have been reported in the literature were limited to clay or sand. Limited attempts have been made to quantify the variations in silt’s mechanical attributes that were caused by the sample preparation method. A series of consolidated drained triaxial shear tests and some mercury intrusion porosimetry (MIP) tests were constructed to interpret this. The results showed that static and dynamic compaction had a significant influence on the mechanical properties of the silt coupled with the molding water content. The shear strength of the dynamically compacted samples was higher than those of the statically compacted samples, as was cohesion (c), and the sample preparation method had little effect on the internal friction angle (φ). Furthermore, samples that were compacted at optimum water content (wot) had greater strength than those compacted on the dry or wet side of the optimum. Compared with the static compaction sample, the pore size distribution curve of the dynamic compaction sample shifted to the left with the peak pore size, distribution density, and the interaggregate pores proportion decreased. The strength discrepancy could be traced to differences in the silt structure features, for example, pore size distribution and particle orientation between statically or dynamically compacted specimens.

Impact of iron corrosion on swell pressure of compacted barmer bentonite induced with thermal history

The bentonite is compacted around the steel canister containing high-level waste to ensure the sealing of the canister by blocking the entry of harmful radiations emitted due to the reactions of active radionuclides. However, the canister continuously exhibits a high temperature (150 °C–200 °C) due to radioactive waste decay over a long time, which creates a thermal history on the surrounded compacted bentonite. Corrosion can generate changes in the bentonite buffer, which comes in direct contact with the canister and may lead to a change in its swelling ability. This study investigates the influence of corrosion products on the swell pressure of compacted bentonite specimens subjected to thermal history. Two Bentonite samples (B1 and B2) from the Barmer district of Rajasthan, India, were mixed with corrosion products and compacted at dry densities 1.5 Mg/m3, 1.75 Mg/m3 and 2.0 Mg/m3. These specimens were subjected to thermal histories at 110 °C and 200 °C and saturated with distilled water. The decrease in the swell pressure values was observed with the corrosion product and the increase in temperature of induced thermal history—comparatively, more time required for saturation in the presence of corrosion products than in its absence. The alteration in montmorillonite minerals might have occurred under the induced thermal history and corrosion reaction.

Effects of Support Friction on Mixed-Mode I/II Fracture Behavior of Compacted Clay Using Notched Deep Beam Specimens under Symmetric Fixed Support

This paper investigates the effects of support friction on mixed-mode I/II fracture behavior of compacted clay using notched deep beam (NDB) specimens under symmetric fixed support. Numerical models of 330 NDB specimens were established considering the crack inclination angle, crack length, support span, and support friction coefficient, and the normalized fracture parameters (YI, YII, and T*) of NDB specimens were calibrated. The numerical results showed that the values of YI, YII, and T* decreased at different degrees after considering the support friction. Notably, the support friction coefficient could significantly change the loading pattern at the crack tip. To verify this phenomenon, 12 compacted clay NDB specimens were prepared, and a mixed-mode I/II fracture test was performed under fixed support conditions; the phenomenon of asymmetric crack propagation was studied. The test data were processed using the numerical calibration results of YI, YII, and T* with and without consideration of friction. Afterward, the test data were compared and analyzed by combining the generalized maximum tangential stress (GMTS) and the maximum tangential stress (MTS) criteria. The analysis indicated that the real fracture characteristics of compacted clay NDB specimens could not be reflected when conducting mixed-mode I/II fracture tests under symmetric fixed support conditions if the test results were analyzed by YI, YII, and T* without considering support friction, as in previous studies.

A clay-coal fly ash based dual hydraulic-reactive liner for controlling acid mine drainage.

Hydraulic liners are used to restrict hazardous leachates such as acid mine drainage (AMD) from entering the hydrogeological system. In this study, we hypothesized that: (1) a compacted mix ratio of natural clay and coal fly ash with a hydraulic conductivity of at most 1 × 10- 8 ms- 1 can be achieved, and (2) mixing clay and coal fly ash in the right proportion can result in increased contaminant removal efficiency of a liner system. The effects of adding coal fly ash to clay on the mechanical behavior, contaminant removal efficiency, and saturated hydraulic conductivity of the liner were investigated. All clay:coal fly ash specimen liners with less than 30% coal fly ash had significantly (p < 0.05) lower cohesion stress values, and were discarded without further tests. Saturated hydraulic conductivity values showed no significant effect (p > 0.05) on the results of clay:coal fly ash (7:3) specimen liners and compacted clay liner. The clay:coal fly ash mix ratios of 8:2 and 7:3 significantly (p < 0.05) reduced the leachate concentration of Cu, Ni, and Mn. The pH of AMD increased from an average of 2.14 to 6.80 after permeating through a compacted specimen of mix ratio 7:3. Overall, the 7:3 clay to coal fly ash liner showed superior pollutant removal capacity and its mechanical and hydraulic properties were comparable to compacted clay liners. This laboratory scale investigation emphasizes potential limitations with column scale evaluation of liners and provides new information on the application of dual hydraulic reactive liners for engineered hazardous waste disposal systems.

Effect of compaction water on strength and hydraulic properties of bentonite-based liner

The abundance of pond ash and its resemblance to natural sand encourages its use as a substitute for sand in sand–bentonite (SB) liner material. Compaction water content influences the geoengineering properties of cohesive soil to a great extent. Accordingly, the compaction, strength, permeability and shrinkage characteristics of both pond ash–bentonite (PAB) and SB mixes are investigated at standard and modified Proctor compaction energies at various water contents to support the recommendation of the PAB mixture as an alternative landfill liner. At similar compaction conditions, the PAB mix exhibits higher unconfined compressive strength (UCS) and hydraulic conductivity than the SB mix. The UCS values of mixes compacted on the dry side of optimum are higher than those of mixes compacted on the wet side. Dry-side compacted mixes exhibit a reduction in hydraulic conductivity with permeation time, whereas no substantial reduction in hydraulic conductivity is noticed for wet-side compacted mixes. Furthermore, the volumetric shrinkage of both PAB and SB mixes is within the permissible value of 4%, for a wide range of water variation from the dry to the wet side of optimum. The observed mechanical properties are correlated to the shape of coarse fraction particles and the corresponding microstructural arrangements of the compacted specimens.

Rainfall erosion of natural fibers cement treated mud

This study evaluated the possible application of inexpensive mud stabilization treatments for the purpose of reducing soil erosion. The soil erosion was investigated by measuring soil loss over the surface of compacted specimens made by natural fibers cement treated mud exposed to a rainfall test sequence. The compacted specimens were made by adding 5 kg/m3 to 50 kg/m3 cement and 0 kg/m3 to 20 kg/m3 natural fibers to 40% to 60% water content mud. The results showed that the increasing of either cement content or natural fibers content reduced the soil erosion from 50% to 80%. Furthermore, a numerical function was developed to predict the value of soil loss of the treated mud based on the ratio of cement content, natural fibers content and initial water content.

Improvement in geotechnical properties of soft filter cake stabilized with autoclaved aerated concrete powder: Experimental evidence and micro-mechanism

Filter cake is a type of engineering waste soil composed of fine-grained particles, typically characterized by its high initial saturation and poor engineering performance. In this study, autoclaved aerated concrete powder (AACP) was used as an admixture to improve the mechanical properties of filter cake. The effects of AACP content and curing time on the unconfined compressive strength (UCS) and volume change behavior of compacted specimens were investigated. The test results showed that the UCS of compacted AACP/filter cake mixtures initially increased with increasing AACP content, reaching a peak value at 40 % AACP content, and subsequently decreased. The sample containing 40 % AACP (cured for 28 days) exhibited a constrained modulus comparable to that of conventional embankment filling materials, but with the added advantage of a lower dry density. Expansion of the parent soil, when exposed to water, occurred through interparticle expansion. The addition of AACP resulted in a reduction in the thickness of the diffuse double layer (DDL) of clay particles, as well as a decrease in the interparticle repulsive force. This allowed soil particles to approach each other more closely and facilitated the formation of aggregated soil particles. AACP incorporation further altered the particle size distribution and soil structure, thereby contributing to the improvement in mechanical properties of the filter cake. The physicochemical and microstructural observations, such as SEM, XRD, and MIP analyses, and zeta potential tests, were in good agreement with the changes in the geotechnical properties of the samples. These experimental results provide technical references for the utilization of AACP and filter cake in embankment engineering.

Shear strength behavior of organic soils treated with fly ash and fly ash-based geopolymer

Abstract Organic soil is a problematic soil that needs to be treated before construction because of the low shear strength and high compressibility. Using by-product materials, such as fly ash (FA), to improve soils is a cost-effective and sustainable procedure. Because treatment with FA may lead to reduce shear strength, a FA-based geopolymer was used with a cohesive organic soil to substitute the reduction in strength. A series of unconfined compressive strength tests (UCS) were conducted on compacted specimens treated with FA and geopolymer. The geopolymer was produced by adding sodium hydroxide to activate the FA. Different levels of FA content, curing period, and temperature were applied to the specimens. The results indicate that for the FA treated specimens, the UCS decreased as the FA increased. For the geopolymer-treated specimens, as FA percentage in the geopolymer increased, the UCS increased and the axial strain at failure decreased. The optimum content of FA, in the geopolymer, was 20%, and the highest UCS was achieved at a curing period of 28 days at a temperature level of 65°C. Based on the obtained results, FA-based geopolymer can effectively be used to improve the strength of organic soils.

Geotechnical-Electrical Evaluation of Soil Compaction Parameters, South of Baqubah City

Soil compaction is fundamental for improving the geotechnical properties of a wide range of engineering structures. Evaluation of compaction parameters is crucial for maintaining the long-term performance of these structures. In this study, geotechnical-electrical relationships were adopted to evaluate the compaction parameters of soil south of Baqubah City. Forty-seven soil specimens, collected from eight locations, were prepared and compacted at various conditions that can be found in the geotechnical practice. First, laboratory tests such as sieve analysis, liquid limit, and plastic limit were carried out to characterize and classify the soil based on USCS classification. Second, the specimens were prepared in the lab using different moisture content, dry density, and compaction efforts. Electrical resistivity measurements were then conducted on compacted specimens using Kangda KD2571B2 instrument. All laboratory tests were performed based on ASTM standards. The results revealed that the soil at the site is fine-grained type CL of medium plasticity clay with sand. Optimum Moisture Content OMC and Maximum Dry Density MDD were, respectively, 14.72% and 1.83 g/cm3 for the Standard Proctor compaction test; and 11.08% and 1.90 g/cm3 for the Modified Proctor compaction test. Geotechnical-electrical relationships achieved showed that soil resistivity is strongly influenced by the main compaction parameters; moisture content, dry density, and compaction energy, particularly at low moisture content. A high correlation coefficient (R2 &gt; 0.98) was achieved for the resistivity-degree of saturation and resistivity-volumetric moisture content relationships. These correlations were validated with R2 (0.896-0.934) between the measured and predicted data, which indicates the advantages of adopting the resistivity method as a complementary tool for the preliminary site investigation.

Investigation of unaged and long-term aged bio-based asphalt mixtures containing lignin according to the VECD theory

In the near future, the world of civil and building engineering will be dominated by the advent of bio-materials. Even the road paving sector is involved in the transition towards more sustainable solutions, promoting at the same time environmental benefits and economic savings. Currently, one of the main goals is to ensure that bio-binders offer good performance, at least comparable with that offered by conventional materials. In the last decades, the exponential increase in traffic volumes has led to various types of asphalt pavement distresses, among which fatigue cracking is one of the most common. Within this context, this study presents the characterization of a bio-based asphalt mixture obtained by replacing 30% of bitumen with lignin, which was compared with a reference asphalt mixture containing a plain bitumen characterised by the same penetration grade. Laboratory produced and compacted specimens were subjected to complex modulus and cyclic fatigue tests with the Asphalt Mixture Performance Tester (AMPT). Both unaged and long-term aging conditions were investigated. The tests and the subsequent analyses were based on the simplified viscoelastic continuum damage (S-VECD) approach. Overall, the results showed that the presence of lignin led to a lower aging susceptibility, but also caused a slight reduction in fatigue life due to an increase in the material stiffness. Furthermore, the obtained results confirmed previous findings deriving from the study of the two binders and from the conventional characterization of the same asphalt mixtures as well.

Impact of Rumble Strips on Longitudinal Joint Pavement Performance

Milled centerline rumble strips are commonly used to reduce lane departure crashes. Safety benefits of installing rumble strips are viewed as a higher priority than the potential impacts to longitudinal joint performance, often leading to a reduced pavement life. There are several different approaches to minimize the impact that rumble strips may have on joint performance, such as careful selection of pavement candidates for installation of rumble strips, using a sealant on top of the rumble strip (top-down) or using a joint sealer (bottom-up). The objective of this study was to assess the impact of using a void reducing asphalt membrane (VRAM) as a joint sealer on longitudinal joint performance with and without the addition of rumble strips. Laboratory testing was completed on plant mix lab compacted specimens and field cores sampled along the centerline joint of two different roadways. Testing consisted of low and intermediate temperature cracking tests and permeability testing. Results from this study showed that VRAM was effective in mitigating increased permeability concerns with the addition of rumble strips into the pavement surface. In relation to laboratory cracking results, there was no significant difference observed between cracking tolerance index (CT-Index) values with and without rumble strips for cores sampled from one project location, while the second project location showed that CT-Index increased with the presence of the VRAM. Continued monitoring of field sections included in this study and future trial sections will be beneficial in understanding the link between laboratory testing, field performance, and variability associated with centerline joint performance.

Developing an advanced ANN-based approach to estimate compaction characteristics of highway subgrade

The current methodology of assessing the compaction characteristic of subgrade fillers is time-consuming. The spot-sampling method and the following laboratory tests bring bias to engineering practice. This study proposes an advanced approach to determine the maximum dry density, optimum moisture content, and compactness of subgrade based on ANN algorithms. A large number of compaction tests are performed to assess the compaction quality of various types of subgrade fillers. The particle gradation is specifically considered. Wave propagations of the compacted specimen are assessed based on the ultrasonic test, and the anisotropic feature is demonstrated. The dynamic elastic parameters are derived to further reveal the interaction mechanism. A dataset is proposed by combining these laboratory data and the literature data. The PSO-BP-NN model is developed to automatically predict the compaction parameters of different filling materials. A positive correlation is demonstrated between the elastic modulus and the total density, and Poisson’s ratio illustrates an inverse trend. The compaction energy is influential to the maximum dry density while the moisture content has the greatest impact on the compactness. This study aims to develop an accurate model to replace the extensive Proctor test and efficiently evaluate the compaction quality of subgrade for highway constructions.

Enzymatic-Induced Calcite Precipitation (EICP) Method for Improving Hydraulic Erosion Resistance of Surface Sand Layer: A Laboratory Investigation

As a bio-inspired calcite precipitation method, bio-grouting via enzymatic-induced calcite precipitation (EICP) uses free urease enzyme to catalyze the urea hydrolysis reaction. This soil stabilization approach is relatively new and insufficiently investigated, especially for applications involving surface layer stabilization of sandy soil deposits for increasing hydraulic erosion resistance. This paper presents a laboratory investigation on the surface erosion resistance improvements for compacted medium-gradation quartz sand specimens mediated using 10 different EICP treatment protocols. They involved single- and two-cycle injections of the urease enzyme (activity of 2400 U/L) and 0.5, 0.75, or 1.0-M urea–CaCl2 cementation solution reagents. The urease enzyme was extracted from watermelon seeds. Erosion rates were determined for various hydraulic shear stresses applied using the erosion function apparatus. The spatial distribution and morphology of precipitated calcite within the pore-void spaces of the crustal sand layer were investigated with a scanning electron microscope. Compared to untreated sand, all 10 investigated EICP treatment protocols produced substantially improved erosion resistance, especially for the higher cementation solution concentration (1.0 M). Of these 10 EICP protocols, a single cycle of enzyme–1.0-M-cementation solutions injections was identified as the more pragmatic option for achieving near-optimum erosion resistance improvements. Highest and lowest amounts (18.8 and 5.0 wt%) of precipitated calcite corresponded to the best and worst performing EICP-treated specimens, although the calcite’s spatial distribution in treated specimens is another important factor.

Coupled analysis of soil shear strength and retention curves with different interstitial fluids

Soil shear strength is a fundamental property in analyzing the stability of soil masses in many geotechnical applications, such as slope stability, foundations, and retaining structures. Routinely application considers water as the interstitial fluid composing the soil, however, in some instance other liquids than water can infiltrate the ground due to accidental leakages of fuel and chemical substances. This paper evaluates the influence of fluids of different nature (water, ethanol, and diesel) on the shear strength of compacted specimens of clayey soil, both under saturated and unsaturated conditions. Test results show that the shear strength increases with suction and decreases with the dielectric constant for all the tested liquids. Based on simplified experimental procedures, two coupled models are proposed to reproduce the influence of soil suction and fluid dielectric constant on the soil shear strength and soil liquid retention curve, fairly reproducing experimental results, thus contributing to push unsaturated soil mechanics to geotechnical practice.

%100 Geri Dönüştürülmüş Asfalt Kaplamanın Türkiye'de Soğuk Karışım Bakım Malzemesi Olarak Kullanılabilirliğinin Deneysel Olarak İncelenmesi

In this study, the usability of 100% RAP as a cold patching material (CPM) was experimentally investigated. As part of this study, first, the RAP material has been characterized to determine its binder content and particle size distribution of the extracted aggregate. Then, three sets of RAP specimens (each set has three specimens) were prepared. These specimens were conditioned at 22°C, 40°C and 45°C for three hours. Then, the specimens were compacted with 75 Marshall hammer blows. The compacted specimens were then tested for their Marshall stability, and flow at 22°C. Air contents of the test specimens were also determined . It was observed that as conditioning temperatures of the compacted test specimens increased, their Marshall stability test results increased but their flow and air content test results mostly decreased. Marshall stability test results of all three sets of specimens were well above the specification limits. Moreover, all test specimens except for only one specimen conditioned at 22°C met the flow and air content criteria. It could be concluded that 100% RAP could be used as a CPM especially above 22°C. If it is needed to be used at around 22°C, it must be ensured that it is well compacted so that its air content is below 8% for a durable and comparably long-lasting cold patching application.

Effect of Specimens’ Height to Diameter Ratio on Unconfined Compressive Strength of Cohesive Soil

Abstract The undrained shear strength (Su) and cohesion (Cu) of cohesive soils are frequently determined using an unconfined compression test. However, the test results are heavily dependent on specimen size. This causes uncertainty in geotechnical analyses, constitutive models, and designs by overestimating or underestimating the shear strength of cohesive soils. Therefore, the study aims to assess the effect of the height-to-diameter ratio on the unconfined compressive strength (UCS) of cohesive soil. The soil specimen was tested on a compacted cylindrical specimen at the maximum dry density and optimum moisture content with a height to diameter (H/D) ratio of 1–3 for 38, 50, and 100 mm specimen diameters. Disturbed sample specimens were considered for the laboratory program. Accordingly, the standard Proctor compaction test determines soil classification and compaction characteristics. The unconfined compression test was performed for undisturbed and compacted remolded states of various diameters of cohesive soil specimens to investigate the strength variation with the specimen variation in H/D ratio. The laboratory test results revealed that cohesive soil's unconfined compression strength value drops rapidly with height-to-diameter ratios and the soil specimens’ diameter increases. However, the UCS value was stable at H/D ratio from 1.75 to 2.25. As the specimens’ diameter and H/D ratio increased, the peak UCS value axial strain decreased. Similarly, the gap between the axial strains of peak UCS value for the smallest and the most significant H/D ratio decreased with increase in the specimens’ diameter.

Retention Behaviour of Heavy Metals from Industrial Sludge Amended with Admixtures to Use Them as Liners for Landfill Facilities

The solidification of contaminants within the soil/waste has proved to be a versatile technique to de-contaminate them and make them usable for several applications. In this method, the development of binder provisions leads to the conversion of the environmentally unstable condition of waste materials into a nearly stable material. Further, these materials pose a minimum threat that can be absorbed into the environment. Normally lime/cement and other pozzolanic materials are used as binder materials. In this work, it is proposed to use the efficiency of binding fly ash to improve the unconfined compressive strength (UCC) of soils, particularly during the curing period. This is because improvement in strength is a reflection of the improvement of bonding soil particles. Fly ash as the main source material, in addition to a minor proportion of cement and lime, is used to determine the strength. UCC test results revealed that as the percentage of fly ash increases there is an increase in compressive strength. It is also observed that with an increase in lime content and an increase in cement content, the UCC strength also increases. The strength in cement-stabilized compacted specimens is more compared to lime-stabilized mixtures. To confirm that the improvement in strength is related to the solidification of contaminated metals, particularly for soils containing copper and chromium, the stabilized mixture is tested for the leaching of these metals. Leaching tests were conducted on various stabilized mixtures at different curing periods. The leachate was examined for metal ion concentration using Atomic Absorption Spectrophotometer. The leaching behavior of heavy metals from different proportions of soil matrix revealed that with an increase in lime or cement percentage, a decrease in leachability is observed. It is found that the leaching of heavy metals from cement-stabilized soils was lower than in lime mixture combinations. However, minimum strength improves the solidification and retention of heavy metals effectively.

Effects of Freeze-Thaw Cycles on Permeability Behavior and Desiccation Cracking of Dalian Red Clay in China Considering Saline Intrusion

Red clay with features of high liquid (plastic) limit, low permeability, medium-low compressibility and high strength is widely used in anti-seepage projects including roadbed, earth dam, tailings and landfill cover. This study investigates the hydraulic conductivity and propagation of desiccation cracks of compacted red clay in Dalian, China, considering the effect of freeze-thaw (F-T) cycles and saline intrusion. A series of compacted specimens were subjected to different F-T cycles at various controlled salt concentration of 0.2% and 4%. The surface cracking initiation and propagation process of compacted specimens under wetting-drying (W-D) cycles were monitored by Digital Image Correlation technique. The results indicated that permeability coefficient of compacted specimens increased significantly after the first F-T cycle regardless of specimens with variable dry density and salt concentration. The relationship between the number of F-D cycles and permeability coefficient can be expressed as the exponential function for Dalin red clay. Dry density and Saline inhibits the desiccation cracks of compacted specimens under W-D cycles. However, the F-T cycles have a modest promoting effect on crack propagation on the surface of saturated red clay. This study analyzes the underlying formation mechanisms of desiccation cracking-inducing geohazards and provides some guidance for the long-term performance of infrastructures upon saline intrusion and F-T cycles for red clay.

A novel powder-metallurgical eco-friendly recycling process for tool steel grinding sludge

This work comprehensively investigates the reuse of AISI D2 tool steel grinding sludge as secondary raw material into a powder metallurgical process route. The tool steel grinding sludge initially contains about 15 mass% of silicon carbide and aluminium oxide abrasive particles as well as residual cooling lubricant emulsion consisting of water and oil leading to an increased carbon content of 2.56 mass%. A three-stage decontamination procedure of the grinding sludge is performed, including drying, removing non-metallic abrasive particles via magnetic separation, and recovering the cooling lubricant oil by supercritical carbon dioxide extraction. Subsequently, the prepared grinding metal chips are densified by a novel energy efficient short-time sintering technique called electric discharge sintering. The carbon content of the sludge could be reduced to 1.71 mass%. However, it was found that remaining contaminations lead to a change in the alloying composition of the recycled material, which influences the tempering behavior. Increased carbon and silicon levels promoted a high retained austenite fraction after quenching of more than 67 vol%. By adopting the heat treatment, the hardness of the recycled samples could be adjusted to a level similar to that of the cast reference material in quenched and tempered condition. Reducing the retained austenite content to 2.3% by tempering led to a hardness of roughly 700 HV1.However, the recycled material showed less than 40% of the compressive strength of the cast reference material. On the one hand, the lower compressive strength can be attributed to the inadequate removal of oxidic abrasive particles during the recycling process and their poor integration into the metal matrix of the compacted specimens. In addition, oxidized layers on the chip surfaces counteract metallurgical bonding between the chips during electric discharge sintering.