SEM-EDS Tests Research Articles

Effect of Grain Size and Porosity/Binder Index on the Unconfined Compressive Strength, Stiffness and Microstructure of Cemented Colombian Sands.

Artificial cementation of granular soils results in improved stabilization, increased stiffness, and greater mechanical strength. The porosity index and volumetric cement content η/Civa is presented as a key measure to study the evolution of different soil stabilization types. However, this index had not been previously studied or adjusted for sands in Colombia. Therefore, this study evaluates the applicability of the η/Civa index on unconfined compressive strength (qu) and stiffness (Go), complemented by microstructural analysis, in four sandy soils from Luruaco (Atlántico), Lorica (Córdoba), Medellín (Antioquia), and Bogotá D.C. The soils were stabilized with Type III Portland cement in dosages of 3%, 5%, 7%, and 9%, and subjected to UCS, ultrasound, and SEM-EDS tests after a curing period of 7 days. It was found that increasing cement content results in higher qu values for the samples, and higher molding density also leads to higher qu values. Additionally, the grain size distribution influenced the adjustment of parameter "a". In the sands from Bogotá and Lorica, with high uniformity, the value of "a" was 1.00. In contrast, mineralogy and particle shape played a predominant role in the sands from Medellín and Luruaco, where the coefficient of uniformity is higher, suggesting a possible inverse relationship between particle angularity and the value of "a".

Recovery of Low-Concentration Tungsten from Acidic Solution Using D318 Macroporous Resin.

Tungsten is a crucial strategic metal that plays a significant role in various fields, such as the defense industry, fine chemicals, and the preparation of new materials. During the practice of numerous tungsten smelting processes, a large amount of acidic wastewater containing low concentrations of WO3 is generated. The adsorption method, known for its simplicity, effectiveness, and ease of operation, represents the most promising approach for tungsten recovery and is vital for the sustainable development of the tungsten industry. In this study, D318 macroporous resin was used as an adsorbent to investigate its effectiveness in adsorbing WO3 from acidic solutions. Static adsorption experiments revealed that the adsorption capacity of D318 resin for WO3 was 683 mg·g-1. Kinetic analysis indicated that the controlling step for the adsorption of WO3 from acidic solutions by D318 resin was intraparticle diffusion. Thermodynamic analysis demonstrated that the adsorption process was endothermic and could occur spontaneously. By fitting the isothermal adsorption equation, it was found that the Langmuir model was more suitable for describing the adsorption process of WO3 on D318 resin in acidic solutions. The results of dynamic adsorption experiments showed that under optimized conditions, the dynamic adsorption capacity for WO3 was 529 mg·g-1; when using NaOH as the desorbent for cyclic desorption, the desorption rate for WO3 was 98.21%. XPS and SEM-EDS testing and analysis confirmed that D318 macroporous resin exhibited excellent adsorption performance for tungsten in acidic solutions.

Mechanical properties and microscopic mechanism of solid waste based binder solidified stone waste

The stone waste generated by stone industry occupy land resources, cause safety hazards and need to be efficiently resourcefully utilized. In this study, the CGF solid waste based binder (abbreviated as CGF) with calcium carbide residue (CCR), ground granulated blast furnace slag (GGBS), and fly ash (FA) as components was developed to solidify the stone waste. Through “treating waste with waste”, the resource utilization of solid waste was realized. The mechanical properties and reaction mechanism of CGF solidified stone waste were investigated through unconfined compressive strength (UCS), XRD, and SEM–EDS tests. The results show that CGF has the better solidify effect on stone waste, and its strength meets the requirements of the road base material standards. Compared to cement, the CGF solidified stone waste existed higher UCS at both 7 and 28 d of curing. The UCS of CGF solidified stone waste reaches 2.93 and 4.42 MPa under curing of 7 and 28 d at 5% binder content, which is 1.61 and 1.37 times higher that of P.O. 42.5 cement. Furthermore, the primary mineral-based stone wastes will not react with the binder, and the CGF generates gelling products such as C-S–H C-A-H, and C-A-S–H through alkali-activated reactions between the components of CGF. These gelling products enhance the UCS of solidified stone wastes through cementing and filling effects. The findings provide a feasible approach with low-carbon emission and low-cost for resourceful utilization of stone wastes.

Preparation and characterisation of NH3 gas sensor based on PANI/Fe-doped CeO2 nanocomposite

PANI/Fe-doped CeO2nanocomposite was synthesised by the in-situ process. The produced powders were characterised by XRD, XPS, FT-IR, Raman, HRTEM and SEM-EDS tests. The sensors' function was based on PANI/Fe-doped CeO2nanocomposite with thin film deposited on top of interdigitated electrodes (IDT). NH3 detection with PANI/Fe-doped CeO2 nanocomposite sensor could be successfully performed even at room temperature (RT) and relative humidity of 45 %. Results demonstrated that PANI/Fe-doped CeO2 might be promising sensing materials for detecting the low NH3 concentration (ppm). In addition, the sensor is selective to the interfering gases, including CO, CO2 and NO2. This sensor displays acceptable repeatability and stability over time.

Strength, toughness and interface modification of graphene oxide grafted carbon fiber modified concrete

Graphene oxide grafted carbon fiber (CF-GO) is prepared by "grafting to" chemical graft method. The elements and chemical bonds on the surface of CF-GO are characterized by XPS test, which confirms the successful preparation of CF-GO, and the monofilament tensile strength of CF-GO is tested. The dispersion effect of CF-GO under different dispersion methods is compared, and CF-GO modified concrete (CF-GOMC) is prepared. The strength and toughness of CF-GOMC are tested and compared with those of carbon fiber modified concrete. In addition, the modification mechanism of CF-GO on fiber/concrete matrix interface is analyzed by SEM-EDS test. The results show that the monofilament tensile strength of CF-GO increases by 22.22% compared with that of carbon fiber. When dispersing with high-efficiency water reducer combined with ultrasonic wave, the dispersion effect of CF-GO is the best, the resistivity of CF-GOMC is the minimum, and the strength is the maximum. CF-GO can improve the strength and toughness of concrete, and its improvement effect is better than carbon fiber. The optimal contents of CF-GO and carbon fiber are 0.3% and 0.2% respectively. Graphene oxide on the surface of CF-GO enhances the fiber/concrete matrix interface physically and chemically by improving the mechanical interlocking force between CF-GO and concrete matrix and promoting the formation of hydration products on the surface of CF-GO. Moreover, the content of C-S-H crystal at the CF-GO/concrete matrix interface increases.

Chloride binding of barium-containing zeolite corrosion inhibitor in Portland cement mortar

The use of sea sand is limited in reinforced concrete due to the presence of corrosive free chloride ions. In this study, a barium-containing zeolite corrosion inhibitor was designed and added into mortar to improve the chloride binding ability by avoiding the interference of SO42− in forming chloroaluminate salts under the condition of ensuring the necessary setting time of the mortar. Ion dissolution tests showed that the amount of Ba2+ released by the corrosion inhibitor in the first 3 h was only 29.6 mg/L, which avoided the problem of rapid setting of the mortar. The ability of the mortar to bind free chloride ions was assessed by leaching titration, and the sample with 16 wt% corrosion inhibitors showed a 32% increase in the bound chloride ratio compared to the control sample at 28 d. The results of XRD, TG-DTG, 27Al MAS NMR and SEM-EDS tests indicated that the slow-release Ba2+ from the corrosion inhibitor promoted the formation of chloroaluminate by precipitating SO42− in the late hydration stage in the mortar. Electrochemical impedance spectroscopy results further confirmed the effectiveness of the corrosion inhibitor in inhibiting the rusting of the steel bars. This study provides guidance for the use of sea sand resources and the long-term corrosion prevention of reinforced concrete.

Corrosion of Pure Magnesium and Binary Magnesium Alloy in Ringer's Solution

The work presents monitoring of the corrosion rate for pure magnesium and the binary magnesium alloy Mg72Zn28. Alloying elements with a purity of 99.9% were used. The melting was performed under the protection of inert gas - argon in an induction furnace. The liquid alloy was poured into a copper mold. In order to make amorphous ribbons, the obtained samples in the form of rods were re-melted on a melt spinner machine. The next step was to perform corrosion tests in Ringer's solution. Corrosion tests were carried out at a temperature of 37°C and pH 7.2. The purpose of using Ringer's solution was to recreate the conditions for the body fluids of the human body. The use of the following research methods, such as: OCP (open circuit potential), LSV (linear sweep voltammetry) and EIS (electrochemical impedance spectroscopy), was aimed at determining the corrosion resistance of the tested materials. Tests carried out in Ringer's solution showed that pure magnesium has significantly worse corrosion resistance than the binary Mg72Zn28 alloy. The conducted research also confirmed that the cathodic reaction takes place faster on the surface of amorphous ribbons. It was also confirmed that for both crystalline materials there is diffusion of chloride ions through the corrosion product layer. SEM-EDS tests were performed on the surface of an amorphous ribbon of the Mg72Zn28 alloy after corrosion in Ringer's solution.

KARAKTERISASI BIODEGRADASI PADA KOMPOSIT POLYMER POLYLACTID ACID (PLA) DENGAN PENAMBAHAN CHITOSAN DAN HYDROXYAPATITE

Polylactid Acid (PLA) is a biodegradable polymer made from natural ingredients so it is safe to use for biomaterials. The purpose of this study was to determine the biodegradation characteristics of the addition of chitosan powder and Hydroxyapatite to PLA. There were 4 variations in this study, namely PLA 100 (pure PLA), PLA-chitosan-Hydroxyapatite 94-3-3 (Composite 1), PLA-chitosan-Hydroxyapatite 94-0-6 (Composite 2), PLA-chitosan-Hydroxyapatite 94-6-0 (Composite 3). Samples were prepared using the extrusion method to form filaments, then the filaments were injected with a temperature of 170-190°C and an injection pressure of 5-6 bar. Characterization was carried out using the Immerse Test, FTIR Test, and SEM-EDS Test. The results of the Immerse Test showed an increase in sample mass of 1.04%, 1.1%, 1.05% and 1.14% respectively. FTIR test results did not show any new functional groups in the composite. The results of the SEM test indicated the presence of Na and Cl deposits on the sample surface as evidenced by the results of the EDS test that all samples contained Na and Cl elements. So that the weight gain occurs because the three materials are not chemically mixed which easily separate and cause cavities, these cavities are filled with HBSS liquid.

Stabilization of Expansive Soil Using Marble Powder and Phosphoric Acid against Physical Properties and SEM-EDS Tests

The Gedebage region faces a myriad of challenges, including road deformations, swelling of roads and bridges, and cracks in drainage foundations, buildings, and asphalt concrete. To address these issues, a comprehensive analysis of soil physical properties was conducted at the POLBAN soil mechanics laboratory, along with chemical tests at the POLMAN laboratory. The primary objective was to understand the physical properties and mineral composition of Gedebage soil and develop effective soil management strategies. Soil stabilization was employed as a method to enhance infrastructure resilience in Gedebage. Marble powder waste (MPW) was utilized in varying concentrations (2.5%, 4%, 5.5%, and 7%) along with 4% phosphoric acid (PA) to optimize the solution. MPW filled soil pores and improved cohesion, while PA reduced moisture content, enhanced particle bonding, increased load-bearing capacity, and minimized soil volume changes. Initial soil tests revealed a high plasticity index (PI) of 54.20%, indicating Gedebage, expansive clay soil nature with significant potential for expansion and plasticity. The AASHTO classified it as "A-7-6", and the USCS classified it as "CH." Stabilization experiments demonstrated that the most effective combination was the original soil + 7% MPW + 4% PA, resulting in a PI of 16.03% and an activity level (Ac) of 0.48. AASHTO classified this combination as "A-2-6," and the USCS as "CL." Furthermore, MPW oxygen, silica, and aluminum content exhibited potential for pozzolanic reactions, while PA reacted with soil mineral cations likes: Ca, Fe, Al dan Phosphor, forming a water-resistant layer. MPW and PA effectively improved the expansive clay soil's ability to withstand moisture-induced changes. This study serves as a foundation for further investigations into the mechanical properties of Gedebage soil, focusing on bearing capacity and stability, using MPW and PA in civil and infrastructure foundation applications.

Experimental study on municipal solid waste incineration fly ash as a component of coal gangue geopolymer and the feasibility of making geopolymer mortar

In this study, municipal solid waste incineration fly ash (MSWI FA) was used as a component to supplement the missing element of Ca in the coal gangue (CG) to synthesize CG-MSWI FA geopolymer (CG-MFG). The mixed NaOH and Na2SiO3 solution is adopted as alkali activator. The influence of MSWI FA content, NaOH/ Na2SiO3 ratio, liquid–solid ratio and NaON concentration on the strength and reaction on the CG-MFG is studied by unconfined compressive strength (UCS), XRD, FTIR, TGA and SEM-EDS tests. The heavy metal leaching concentration of the CG-MFG is investigated by ICP-OES test. The test results show that MSWI FA acted as a supplementary calcium source for CG is capable of effectively improving the UCS of the CG-MFG. The optimal dosage of MSWI FA is 15 %. The NaOH/ Na2SiO3 ratio significantly affects the strength of the CG-MFG and its optimal proportion is 25:75. The CG-MFG with 15 % MSWI FA content, 25:75 NaOH/ Na2SiO3, 0.45 liquid–solid ratio and 8 mol/L NaON concentration acquires the highest UCS of 30.28Mpa. The immobilization efficiency of heavy metals from MSWI FA in the CG-MFG is larger than 84.66 %. The energy consumption and carbon dioxide emission of preparing the CG-MFG is much lower than those of Ordinary Portland Cement (OPC) with reduction of 71.9 % ∼ 78.0 % and 70.1 % ∼ 82.9 %, respectively. The amorphous geopolymeric gels are observed as the main geopolymerization product of the CG-MFG. The UCS of the CG-MFG mortar reaches 4 MPa, showing possibilities of replacing cement by the CG-MFG in construction industry and shedding light on recycling of hazardous and solid wastes of MSWI FA and coal gangue.

Polymer shape effect on damage evolution, internal defects and crack propagation of 3D-printed polymer-based cementitious backfill

The strength property and damage mode of cementitious tailings backfill (CTB) are governed by its structural characteristics in the presence of the microstructure/internal defect effects. However, this correlation is still unclear for 3D-printed polymer (3D-PPL) based CTB materials. Hence, the mechanical properties of microscopic damage and fracture evolution of 3D-PPL reinforced CTB were studied in this study. The fracture of CTBs with three shapes of polymer (cross, quarter, and EEP) were visualized and digitally characterized by the Brazilian splitting test, scanning electron microscopy (SEM) and industrial computed tomography. Experimental results indicate that CTB’s failure mode mainly starts from the low-density pore area, gradually evolves to a crack, and finally expands to the main crack by the center of the specimen. 3D-PPL has a certain interface bonding and supporting effect on CTB specimens, and the 3D-PPL specimen’s porosity is significantly below that of ordinary backfill. Incorporating 3D-PPL into CTBs effectively decrease the penetrated pore number, while enhancing the density of CTB’s microstructure, which dominates the strength and integrity of specimens. 3D-PPL-based backfill specimens also indicate a complex and diverse damage pattern, with a negative link between crack volume and tensile strength. The 3D fractal dimension of cracks in 3D-PPL-based fills is greater than that of ordinary fills. Combined with SEM-EDS tests, CTB’s hydration materials were mostly CSH gels, which interleaved as nucleating agents to inhibit crack growth. The findings of the present work will be beneficial for manufacturing and operational usage of 3P-PPL-based backfills.

MECHANOSYNTHESIS OF MMC Cu-C DOPED WITH Ti FOR APPLICATION OF PANTOGRAPH CONTACT STRIP (PCS)

This research was conducted to determine the effect of the addition of Titanium (Ti) and the sintering temperature variation on MMC CuC alloys as reinforcing elements. The process of this research uses powder metallurgical method with an alloying technique in Mechanical Alloying using a Planetary Ball Mill (PBM) machine with a speed of 600 rpm for 2 hours, the ratio of powder to the ball mill is 10:1. The compacting process is carried out using dies 11 mm in diameter and compacting pressure of 90 Kg/cm2. The sintering process is carried out three times, with variations in sintering of 800oC, 900oC, and 1000oC with sintering time for 1 hour in the tube furnace in the argon gas vacuum environment. The number of samples used in this study amounted to 9 samples with variations in alloy and temperature sintering, consist of MMC CuC alloy with addition of Ti 0%, 0.5%, 1.5% (T=800 oC), MMC CuC with addition of Ti 0%, 0.5%, 1.5% (T=900 oC), and MMC CuC with addition of Ti 0%, 0.5%, 1.5% (T=1000 oC). The tests included Vickers hardness testing, metallography testing, XRD testing, and SEM-EDS testing. The addition of Ti elements and varying sintering temperature had an effect on the hardness value of MMC CuC material with the highest hardness value in samples with 1.5% Ti alloy (800oC) which is 87.25 HV, and the lowest porosity value is 2.491% in the sample of 1.5% Ti (1000oC).

Investigating the synergistic effect of graphene nanoplatelets and fly ash on the mechanical properties and microstructure of calcium aluminate cement composites

Nanomaterials like graphene nanoplatelets (GNP) have been extensively applied in various fields as reinforcing materials offering excellent mechanical properties. However, for calcium aluminate cement (CAC) composites, the investigation of the GNP reinforcing effect is lacking. The synergistic effects of GNP and fly ash (FA) in CAC composites were evaluated in this study. The GNP was initially dispersed in mixing water using a dispersant combined with ultrasonication. The CAC composites with different GNP contents were prepared and their mechanical performance was investigated. In addition, partial replacement of CAC with FA was investigated for increasing sustainability and material cost of GNP-CAC composites. Their fresh properties, mechanical properties, and microstructural performance were analyzed using different techniques involving flowability, bulk density, volume of permeable void, water absorption, compressive strength, splitting tensile strength, flexural strength, nitrogen adsorption, TGA, and SEM-EDS tests. Using FA and GNP in CAC composites offers a positive impact by significantly increasing their strengths. Optimized mix was achieved by replacing 20% of FA and adding 0.3% of GNP in CAC composites. Results revealed that the 20% FA replacement of cement with 0.3% GNP addition remarkably increased the compressive, splitting tensile and flexural strengths at 28 days by about 57.2%, 35.5%, and 21.7%, respectively. The results suggest that using FA and GNP contributes to synergistic effects to promote the formation of silica tetrahedron in calcium aluminate silicate hydrate (CASH) gel, to refine pore characteristics, and to reduce conversion effects of metastable phases of CAC such that it can ultimately produce a green rapid-set high-performance concrete system.

Assessing the viability of a high performance one-part geopolymer made from fly ash and GGBS at ambient temperature

This study aims to investigate the feasibility of preparing a one-part geopolymer using fly ash (FA) and ground granulated blast furnace slag (GGBS) as the main raw materials and solid sodium hydroxide and sodium silicate as activation conditions under ambient conditions. Orthogonal tests were conducted to study effects of FA on the GGBS mass ratio (F:G), solid alkali content, sodium hydroxide–to–sodium silicate mass ratio (SH:SS), and water-to-solid ratio on the unconfined compressive strength (UCS), setting time, and fluidity of the one-part geopolymers. The microstructure, composition, and pore distribution characteristics of the geopolymers were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), and mercury intrusion porosimetry (MIP). The findings revealed that (1) the mechanical characteristics of the geopolymer were most severely influenced by F:G, and the compressive strength of the geopolymer considerably decreased with an increase in F:G. (2) The influences of the alkali content and water-to-solid ratio on the setting time of the geopolymer were essentially the same and significantly larger than those of the F:G and SH:SS variables. (3) The most important element affecting the fluidity of the geopolymer was the water-to-solid ratio. Microscopic analysis verified the results of the macroscopic experiments. The XRD and SEM-EDS tests indicated that the reaction system produced a mixed gel by activating some of the Ca in the GGBS was activated with FA, which filled the pores of the geopolymer and increased its strength. The MIP test also revealed that specimen S7 exhibited the smallest pore space among the selected specimens. The microscopic experiments revealed that the reaction system produced a mixture of calcium silicate hydrate (C-S-H) gels and hydrated sodium silicate N(C)-A-S-H gels.

Hydration kinetics and microstructure development of Ultra-High Performance Concrete (UHPC) by high volume of phosphorus slag powder

In this paper, the effect of phosphorus slag(PS)hydration kinetics and microstructural development of UHPC with different degree of substitute (20%, 40% and 60% by mass) were explored. Up to 60% substitution of cement by PS which still shown excellent mechanical property compared to without PS at the age of 60-days. The phase development is a qualitative discussion by thermal gravimetric analysis combined with XRD with Rietveld method, the pore structure is evaluated to MIP. The hydration products are characterized by SEM (scanning electron microscopy) with EDS (Energy-dispersive X-ray) analyses. The results shown that the utilization rate of cement has been significantly improved, for instance, the hydration rate of the cement is enhanced from 54.3% for PS0 to 87.0% for the UHPC with PS60; the Ca/Si ratio decreased with the enhance of PS content and the microstructure is become denser by SEM-EDS tests. The pozzolanic-reaction of PS cloud produce more hydrated products by thermodynamic calculation, which can optimize the pore structure of paste. And the growth trend of C–S–H gel is consistent with the compressive strength growth trend.

New insights into the combination of Fe(III) and xanthan gum in dewatering of coal slurry: Molecular self-assembly

Aggregation is an economical and widely existing method to in fine coal particles dewatering, but the effect of cations on the flocculation activity of different bio-flocculant was inconformity. In this work, the aggregation behavior of coal slurry using XG combination Fe3+ was investigated. The adsorption of FeCl3·6H2O and XG was investigated via wetting heats, water contact angle, Zeta potential and SEM-EDS testing. The results show that the combination of FeCl3·6H2O and XG could build up layer-by-layer self-assembly multilayers on coal particles surface. Further, solution chemistry, FTIR and XPS analyses were performed to detect the adsorption mechanism. The results indicate that Fe(OH)3(s) covering and coordination reaction of the Fe active sites with the polar groups of XG are the main driving force for the self-assembly. The obtained settling tests results show a great potential of the combination of XG combination Fe3+ in the dewatering of coal slurry. The flocculation dewatering model of coal with FeCl3·6H2O and XG was drawn.

Surface characterization of Fe–10Al–25Mn alloy for biomaterial applications

The austenitic stainless-steel biomaterial, AISI 316L stainless steel, is one of the most widely used for orthopedic or prosthetic implant devices because it is easy to manufacture at a relatively low cost. However, corrosion is a challenging issue related to major alloying compounds with body fluids and wear. Therefore, this study aimed to develop a biomaterial of Fe–Al–Mn alloys by minimizing chromium (Cr) and nickel (Ni) contents. In the research, an attempt has been made to increase the corrosion resistance of Fe–10Al–25Mn alloy using plasma nitriding, which was considered one of the most cost-effective surface treatments. The processes were carried out at various treatment temperatures between 350 and 550 °C, with a pressure of 1.8 mbar in 3 h. Several tests were performed, such as chemical compositions, scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDS), hardness, and corrosion. The results indicated that the treatment of plasma nitriding at temperatures up to 500 °C significantly enhances the corrosion resistance and increases the hardness of the alloy. At 500 °C, the percentage of nitrogen atoms reaches a peak and then decreases. It means that the nitride formation process on the alloy surface occurs more massively. The amount of nitrogen deposited on the surface of the Fe–10Al–25Mn alloy, as well as a thin layer of iron nitride, is noticeable in the SEM-EDS test. Furthermore, the formation of phases due to the nitriding temperature significantly impacts the alloy properties.

Improvement of Organic Soil Shear Strength through Calcite Precipitation Method Using Soybeans as Bio-Catalyst

Organic soil has a high content of water and compressibility. Besides that, it has a low specific gravity, density, and shear strength. This study evaluates the applicability of the soybean crude urease for calcite precipitation (SCU-CP) method and its effectiveness in organic soil as a soil-amelioration technique. Various soybean concentrations were mixed with a reagent composed of urea and calcium chloride to produce the treatment solution. Its effect on the hydrolysis rate, pH, and amount of precipitated calcite was evaluated through test-tube experiments. SEM-EDS tests were performed to observe the mineralogy and morphology of the untreated and treated samples. The treatment solution composed of the reagent and various concentrations of soybeans was applied to organic soil. The increasing strength of the organic soil was evaluated using direct shear (DS) and unconfined compression (UCS) tests. The test-tube results show that a hydrolysis rate of 1600 u/g was obtained when using 50 g/L of soybeans with a precipitation ratio of 100%. The mechanical tests show a significant enhancement in the parameters of the organic soil’s shear strength. A shear strength improvement of 50% was achieved in this study. A UCS of 148 kPa and cohesion of 50 kPa was obtained in the treated samples of organic soil. This research elucidates that the SCU-CP is an effective technique for improving organic soil’s shear strength.

CHARACTERIZATION OF IRON PRODUCTION WITH MILLSCALE BY PRODUCT REDUCTION

Millscale is a large by product of metal factory. Many methods to recycled it to many applications. The aim of this research is recycled millscale to produce the iron by reduction method with graphite as reductant agent. The reduction process was deed by milled millscale and graphite powder with 4:1 weight ratio was by used High Energy Milling with 4, 6, 12 hours milling time variations. The powder then was characterized by X-Ray Diffraction (XRD), Vibrating Sample Magnetometer (VSM) and SEM-EDS test. The XRD test result is Fe3C as a main phase then carbon, magnetite, wustite and Iron as a minor phase. The percentage of iron composition is increase during milling times amount to 6; 10.9; 13 %. The remanence for the 4, 6, and 12 hours of milling time variation, is 2.89, 3.39, and 4.98 emu/g, for the coercivity (Hc) is 209.58, 188.47, and 223.65 Oe and the magnetic saturation number is 22.59, 30.7, 39.15 emu/g, from Hc value it is concluded that the powder has superparamagnetic behavior. From SEM-EDS is knowed that the distribution of Fe is more uniform on the surface samples with the increase of milling time.

Microscopic Tests on Evaluation of Self-Healing Efficiency in Cementitious Materials with a Novel Self-Healing System

In this study, Na2CO3 solution as a self-healing agent was impregnated in LWA for autonomic self-healing on cracked cementitious material. The results showed that under the joint action of expansive agent, crystalline additive, phosphate and carbonate, the crack area showed a high self-healing efficiency (close to 70%) after curing in the still water 28d. SEM-EDS test results showed that in addition to ettringite and C-S-H/C-A-S-H, there was also a large amount of CaCO3 crystal in the depths of the crack.