Compressive Strength Results Research Articles

GRADING DESIGN AND PERFORMANCE STUDY OF STABILIZED GANGUE OF SKELETON-DENSE CEMENT

Gangue is a kind of waste rock produced in coal mining. Gangue in different regions has considerably different physicochemical properties. As a road material, gangue has an uneven particle size distribution and breaks easily, so its application in road projects is limited. To increase gangue utilization, a grading range that is applicable to cement-stabilized gangue was established in this study in consideration of the uneven particle size distribution and easy breakage of gangue. The aim was to explore the feasibility of using gangue as a road base. The appropriate mixing ratio of coarse and fine aggregates was optimized based on the grade filling method and the K method in accordance with the results of 7d unconfined compressive strength (UCS). Moreover, the reasonable grading scope of the stable gangue aggregate of skeleton-dense cement was determined. On this basis, experiments were conducted on splitting strength, compressive resilience modulus, and freeze–thaw performance, and the shrinkage characteristics were analyzed. The stable gangue aggregate of skeleton-dense cement was compared with that of the grading-median (GF) mixture recommended by standards. Results demonstrated that the stable gangues of cement formed a skeleton-dense structure when the content ratio between coarse and fine gangue aggregates was 40%–50%. When the cement dosage was 5%, the 7d, 28d, and 90d UCS of the designed grading mid-value (TJ2) increased by 38.03%, 40.13%, and 34.93%, respectively, compared with that of GF. Specifically, the 7d UCS was higher than 3.0 MPa. The 28d TJ2 was 30.13% higher than the GF anti-freezing coefficient, and TJ2 decreased by 35.85% relative to the GF shrinkage coefficient. The cement-stabilized gangue of the designed grading showed better pavement performance than that of the standard recommending grading. These findings provide a theoretical reference for the practical engineering application of cement-stabilized gangue. Keywords: grading, skeleton dense, gangue, mechanical properties, durability

Study on Engineering Properties of Concrete Containing Marble Powder as Admixture

The construction industry relies heavily on concrete for its operations in the development of houses and other infrastructural facilities due to its structural stability and strength. To fulfil the requirement of concrete materials, this study focuses on investigating the use of marble powder as admixture in concrete production and its effect on the fresh and hardened properties of concrete. About 72 samples of concrete were prepared using marble powder admixture in four separate mixes by adding marble dust with the range from 0% to 6% at an incremental rate of 2wt.% of cement. The workability of the concrete mix with marble waste admixture was found to be higher than that of the control mix. The maximum compressive strength increases with the 4% marble powder admixture after 28 days and it equal to 24.50%, as compared with control mix and the flexural strength also shows a maximum increment in strength with 4% of marble powder after 28 days, which is 5.59% as compared with control mix. The density of concrete increases from 2.14 to 2.82 gm. /cm3 with the increase in admixture from 0% to 4%, on other hand with 6% marble waste the density slightly decreases when compared with the result obtained from 4% marble waste admixture. Therefore, using marble powder as an admixture up to 4% in concrete production gives excellent results in compressive strength, flexural strength, and density compared to the control mixes of concrete.

Pemanfaatkan Subtitusi Fly Ash dan Bahan Kapur Alam untuk Peningkatan Mutu Paving Block

Utilization of waste materials as building materials is a solution to reduce waste materials that exist in nature.Fly ash as a waste product from coal combustion contains silica which can be used to increase the compressivestrength of concrete/mortar. Paving Block as a building material made of mortar composition can be increasedits compressive strength by substituting some cement material with fly ash. Fine aggregate material in the formof sand can also be substituted with natural limestone waste material. In this study, paving blocks were madeusing limestone as a substitute for fine aggregate and fly ash as a cement substitute. The ratio of materials formaking paving blocks is 1: 4. For variations of substitution materials, fly ash is used as a cement substitution.The variation of fly ash is 20% and while the limestone waste is used variations of 0%, 10%, 20%, 30% and 40%.The compressive strength test was carried out at the age of 7 days, 14 days, and 28 days. The results of the studyof compressive strength at the age of 7 days obtained a value of 12.24 MPa at a natural limestone substitutionconcentration of 20.7%. For the age of 14 days the compressive strength value is 15.27 MPa with an optimumconcentration of 20.1% at the concentration of natural limestone, while at the age of 28 days the compressivestrength value is 17.11 MPa, with the optimum concentration of natural limestone material being 20. .15%. Theincrease in compressive strength from the optimum mixture to the normal mixture was 28.93%. Based on SNI 03-0691-1996 the paving blocks produced in this study include Quality B.

ANALISIS KUAT TEKAN BETON MENGGUNAKAN LIMBAH BOTOL KACA SEBAGAI PENGGANTI SENAGIAN AGREGAT HALUS DAN GULA MERAH SEBAGAI BAHAN TAMBAH / ADITIF BETON

Various studies in the field of concrete were carried out in an effort to improve the quality of concrete, thetechnology of the research and experiment materials intended to answer the increasingly high demands on the useof concrete.One way to reduce excessive mining of natural materials is by utilizing waste glass bottles and brown sugar,especially glass bottles which area lot of waste and accumulate in the environment around the house.This study aims to analyze the compressive strength of concrete using wasteglass bottles and brown sugar as a substitute for fine aggregate and water. Mix Design in glass bottles and brownsugar as a substitute for fine aggregate and water. Mix Design in This study uses the SNI 2000 method. Thecomposition of glass bottle waste is 5% and 10% to fine aggregate while brown sugar is 0.25% and 0.50% againstwater. The specimens were cylindrical in shape with a diameter of 15 cm and a height of 30 cm as many as 24specimens aged 7, 14 and 28 days. The results of the average compressive strength using glass bottle waste and brown sugar with a composition of 5% and 10% for fine aggregate and 0.25% and 0.50% for water, namely for variation 1 of 8.98Mpa, 11.74 Mpa , 16.06 Mpa while for variation 2 it is 7.45 Mpa, 9.87 Mpa, 14.99 Mpa. then the percentagereduction of concrete variations 1 and 2 against normal concrete is 4.02%, 5.86%, 3.94% and 5.55%, 7.73%,5.01%.

Hydration products, pore structure, and compressive strength of extrusion-based 3D printed cement pastes containing nano calcium carbonate

While interest in extrusion-based 3D concrete printing technology has been growing in recent years, only limited literature investigates the hydration products and pore structure of 3D printed cementitious materials (3DPC). The microstructure and compressive strength results of 3D printed cement paste with and without nano calcium carbonate (NC) were investigated and compared to conventionally cast cement pastes. Herein, all mixes possess approximately the same static yield stress, which was adjusted by an additional polycarboxylate superplasticizer (SP). The compressive strength test was employed to quantify the mechanical anisotropy of samples. The hydration products and microstructure of samples were evaluated at 7 days using X-ray diffraction (XRD), scanning electron microscopy (SEM), and backscattered electron image (BSE) analysis. The results demonstrate that 3D printed cement paste showed a lower compressive strength than cast cement pastes in all directions. The intense and sharp calcium hydroxide (CH) peaks were seen in the XRD analysis of the 3D printed sample, which suggested its high crystallinity. The large size of plate CH can be observed in SEM images. These results indicate that CH grains in 3D printed samples have enough space to grow due to the relatively loose microstructure. This observation was confirmed by the porosity of the 3D printed sample analyzed by BSE images. The BSE imaging analysis also showed that the pore size distribution of the 3D printed sample was different from that of the cast sample. Additionally, the interfacial transition zone (ITZ) in the 3D printed sample presented a looser microstructure than the cast sample. Therefore, the reduced compressive strength of 3D printed cement pastes is the relatively loose microstructure, high porosity, and weak ITZ between unhydrated clinkers and hydration products.

Absorption capacity and porosity percentage of geopolymer concrete with varying percentage of source material and alkalinity ratio

The main objective of this study is to determine the absorption capacity and porosity characteristics of geopolymer concrete with the variation in percentage of source material such as fly ash of 350 kg/m3, 450 kg/m3 and 550 kg/m3 respectively. Twelve mixes with different alkaline liquid (NaOH/Na2SiO3) ratio from 2 to 3.5 with increment of 0.5 was considered for evaluation. The quantity and effect of sodium hydroxide and sodium silicate in these twelve mixes were considered for evaluating the characteristics of concrete. M - Sand was used as fine aggregate and recycled coarse aggregates were taken for this study. Cube specimens of 150 mm × 150 mm × 150 mm were cast and cured at 60°C temperature with oven curing for 24 hours. It was found that absorption percentage of concrete increases by increase in porosity. And compressive strength of concrete gets increases by increase in percentage of porosity up to alkaline ratio 2.5 beyond that more increase in porosity reduces the strength of concrete. It was found that absorption and porosity percentage of mixes increase with increase in source material. Thus compared to 350 kg/m3 of flyash, 550 kg/m3 of flyash shows enhanced compressive strength results. More compressive strength was achieved with mixes of alkaline liquid ratio (NaOH/Na2SiO3) and source material 550 kg/m3. Since more amount of NaOH and water were added to these mixes compared to other mixes and more amount of alumina and silica present in source material helps to enhance the polymerization process. Increase in more percentage of alkaline liquid (NaOH/Na2SiO3) ratios reduces the strength of concrete due to more liberation of heat.

A systematic review study on different kinds of interlocking concrete blocks designs and properties

Interlocking concrete blocks (ICBs) have been recently used worldwide to be alternative conventional blocks. ICBs are more sustainable, low involve low production cost, and environment-friendly as they emit less carbon dioxide than normal ones. ICBs have been used particularly in war zones and places affected by natural disasters where the need for quick, sustainable, low-cost buildings and earthquake-resistant buildings is indispensable. This paper provides a comprehensive literature review about different types of ICBs. It aims to demonstrate different configurations of ICBs incorporated with recycled concrete aggregate (RCA) and other additive materials used for construction. To achieve this, the compares different related studies which analyse the compressive strength results of RCA mixtures with different RCA replacements, w/c ratio, and mix proportions. Additionally, the paper discusses several techniques and methods to improve the behaviour of ICBs.

Influence of Sintering on Thermal, Mechanical and Technological Properties of Glass Foams Produced from Agro-Industrial Residues.

This study investigates the technological, thermal, mechanical, and technological properties of glass foams produced with soda-lime glass residues and rice husk ash sintered at 850–950 °C. The results for apparent density (0.28–0.30 g/cm3), porosity (82–87 ± 4%), compressive strength (1.18 ± 0.03–1.25 ± 0.03 MPa), and thermal conductivity (0.283–0.326 W/mK) are within the limits for commercial foams. The volumetric expansion potential and low thermal conductivity of the glass foams produced favor their use as thermal insulating materials in coat walls, thus improving thermal comfort in the construction sector. The results of X-ray fluorescence show that the foam glass is of the soda-lime type (SiO2, Na2O, and CaO), the rice husk ash is rich in SiO2, CaO, Na2O, Al2O3, K2O and Fe2O3, and the calcium carbonate is rich in CaO. The glass foams produced in this study are promising because they present more economical and efficient manufacturing, resulting in lightweight materials with thermal insulating properties that can be used in the construction sector. These glass foams also reduce the consumption of natural and synthetic raw materials, adding value to the waste used in this study by transforming them into co-products, thus favoring the economic circulation of the region.

Experimental Study of Concrete Making Using Recycled Coarse Aggregate

Concrete is a form of construction in the form of a composite material consisting of a mixture of fine aggregate, coarse aggregate, cement, and water. However, in certain cases, the concrete application is often a problem, especially the lack of a minimal amount of coarse aggregate material, increasing material prices. Recycled concrete aggregate (RCA) is an embodiment of concrete composed of recycled materials. Recycled material is obtained from fragments or remnants of the demolition of unused concrete. The method used to make concrete from the constituent materials using concrete waste as coarse aggregate per the rules of science is experimental. The tests are the aggregate moisture content test, the mud content test, the coarse aggregate abrasion test, the slump test, and the concrete compressive strength test at 28 days of treatment. The compressive strength results showed that the normal concrete sample could reach FC 18.53 MPa. The concrete sample using recycled coarse aggregate reached FC 23.79 MPa, so using recycled materials for manufacturing concrete can achieve the planned target

Molecular simulation and experimental investigation on enhancement of microbe cement in municipal solid waste incineration fly ash

The enhancing effects of microbe cement on municipal solid waste incineration (MSWI) fly ash have been modeled by molecular dynamics and investigated experimentally. Molecular dynamics is utilized to explore the adsorption mechanism of heavy metal (Pb ions) in cementitious materials in four aspects: intensity distribution, mean square displacement (MSD), radial distribution function (RDF) and time correlation functions (TCF), revealing that the stable formation of chemical adsorption with C-S-H is the main reason. So the leaching of heavy metals can be reduced with cement hydration such as microbe cement with MSWI fly ash. Furthermore, the strengthening effects of microbe cement are inspected experimentally with a compression test, X-ray diffraction, scanning electron microscopy and atomic absorption spectrometer with a content range from 0 to 60%. The results of compressive strength, microstructure inspection and heavy metals’ leaching concentration show that the optimum content of microbe cement for solidifying and enhancing MSWI fly ash is 30% above range.

Experimental Investigation on the Mechanical Characteristics of Cement-Based Mortar Containing Nano-Silica, Micro-Silica, and PVA Fiber

This paper investigates bending and compressive strengths as mechanical characteristics of cement-based repair mortar containing nano-silica (NS) and micro-silica (SF) as cement replacements particles and polyvinyl alcohol (PVA) fibers. The mentioned materials were added to the mortar in three different conditions, including single (just one material), binary (mixture of two admixtures), and ternary (mixture of all three admixtures) modes. The use of PVA fibers, nano-silica and micro-silica in the triple combination of a cement-based mortar is the primary objective of the current research. In total, 28 mix designs with various percentages of particles and fiber were employed in the current study, and 112 different specimens were prepared to conduct the experimental research. The compressive and flexural strength results have been selected as the criteria for obtaining the optimum mix design for each condition. In order to specify the mechanical characteristics of specimens, a compressive test was carried out according to ACI 318, and the three-point bending test was utilized according to BS EN 1015-11. The results obtained from this study show that the mixture containing 10% silica fume (SF10) can be considered the optimum mix design for the single-mode condition. For such a mix design, a flexural strength increase of 27% and a compressive strength improvement of 48% were determined in comparison to the reference mixture design. The mixture containing nano-silica at 2% and silica fume at 8% (NS2SF8) was the optimum mix design in the binary mode condition. With the current mix design, a flexural strength improvement of 24% and a compressive strength increase of 49% in a 28-day specimen were recorded. Finally, under the ternary mode condition, a flexural strength enhancement of 3.5% and a compressive strength improvement of 4.6% were obtained. Additionally, the mixture design containing a PVA content of 0.75% and an SF content of 10% (PVA0.75SF10) was considered optimum.

Green clinker-free binders: Simultaneous immobilization and carbonation of ferrous metallurgical residues activated by sulfur wastes

In this work, green clinker-free binders (GCFBs), an alternative cement, were fabricated by recycling sulfur wastes to activate ferrous metallurgical residues for immobilization of solid wastes and carbonation of carbon dioxide synchronously. The results of compressive strength revealed that GCFB-2 activated by thenardite has the highest strength (36.74 MPa) in 3–28 days, and the GCFB-3 activated by ardealite retains a positive growth rate, as well reaches the maximum strength (38.51 MPa) in 120 days. The mineral compositions of GCFBs hardened paste disclosed that ettringite, CSH gels, and portlandite are the main hydrates, which are the strength source of immobilized solid wastes. After the carbonation of carbon dioxide, the compressive strength declines, calcite was the main mineral product, and the net carbonation capacity of carbon dioxide is 2.86–4.75 g/Kg for GCFBs. GCFBs have offered the double benefits of CO2 emission reduction and waste management, and the hardened pastes are a well better alternative aggregate due to the extremely high compressive strength. This study could provide a new perspective on the full resource utilization of industrial solid wastes, while GCFBs are an excellent alternative to cement in the field of environmental immobilization, with outstanding carbon capture and storage capacity in terms of CO2 carbonation.

Influence of metakaolin on the hydration and microstructure evolution of cement paste during the early stage

The incorporation of metakaolin into cementitious materials could improve the compressive strength and durability of cement paste, which are correlated well with the hydration behavior of cement-metakaolin blended mixture. The aim of this work is to reveal the coupled effects between the cement hydration and the pozzolanic reaction of metakaolin during the early stage, the methodologies including fluidity, setting time, compressive strength were employed to measure the properties of cement paste, while another methodologies, such as conductivity, Mercury Intrusion Porosimetry (MIP), Thermogravimetric (TG), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were adopted to investigate the hydration behavior and microstructure characterization. The results indicated that the fluidity of fresh cement paste decreased sharply with the increase of metakaolin, and the addition of superplasticizer could improve the fluidity of fresh cement paste effectively. The setting times of fresh cement paste were delayed slightly with the incorporation of metakaolin. The conductivity of cement suspension dropped gradually with the increase of metakaolin during the early stage, meaning the hindrance to the ion dissolution from cement-metakaolin blended mixture. The compressive strength increased slightly with the addition of metakaolin at 1 d, while it increased remarkably at 3 d. The results of MIP presented that the pore structure was refined with the increase of metakaolin at 3 d. The TG results showed that the incorporation of metakaolin promoted the formation of hydration products at 3 d. The XRD results presented that calcium hydroxide (CH) decreased with the addition of metakaolin, which may be consumed by the pozzolanic reaction of metakaolin. SEM observation confirmed that the microstructure of cement paste became much denser with the increase of metakaolin, which was in good agreement with the results of compressive strength and MIP measurement.

Fresh and hardened properties of alkali-activated slag concrete: The effect of fly ash as a supplementary precursor

The present study explores the possibility of replacing blast furnace slag (BFS) with coal fly ash (FA) to produce alkali-activated material (AAM) concrete with hybrid precursors. With an increased FA replacement ratio, the reaction kinetics, fresh and hardened properties of AAM mixtures have been investigated. The retardation effect on the reaction kinetics with an increased FA content has been observed, which not only extended the induction period along with the heat flow evolution but also reduced the cumulative heat release up to 24 h. Spherical FA particles can provide a ball-bearing effect to improve the workability of the hybrid AAM mixtures, while FA also slows down the deterioration of fresh properties since they are less reactive compared to BFS particles. Regarding the strength development, FA results in the reduction at all curing ages in the mixtures with a low silicate modulus (Ms0.25). Similarly, reduction in 1-day compressive strength has been detected in high silicate modulus mixtures (Ms0.5) with FA replacement, while the mixture with 10% FA exhibits the highest compressive strength among Ms0.5 concretes at later curing ages. Bigger capillary pores have been detected in AAM mixtures with an increase in FA content. However, AAM with 10% FA shows the lowest porosity in Ms0.5 mixtures, which is in agreement with the compressive strength results.

Characteristics of Foamed Concrete Containing Ultra-fine Drift Sand of the Yangtze River

The primary goal of this study was to evaluate the use of Ultra-fine Drift Sand from the Yangtze River (China) in place of natural sand in the production of foamed concrete. The experimental design included factors with varying levels: the proportion of Ultra-fine Drift Sand at four levels (0 percent, 30%, 60%, and 100%). Ultra-fine Drift Sand was substituted in proportion to the mass of material. Each factor's effect on compressive strength, density (dry and saturated), air voids, and water absorption was assessed. According to the results, all factors had significant findings. The compressive strength of concrete increased due to an increase in curing time; fly ash content up to 30%; increasing the percent of Yangzi river sand; and decreasing slag. The mixture of 10% SF (Silica Fume), 24% FA (Fly Ash) and 100% YS (Yangzi soil) gives the enhanced results in concrete strength, by which it reaches about 7 MPa compared with other findings. The remaining percentages of mixing benefit compression strength results. This method of treatment provides an economical way through providing a cheap material that enhances the mechanical properties of concrete, provides a light weight concrete, and a good isolator material to improve the building's thermal insulation to reduce ecological problems and save energy. Doi: 10.28991/CEJ-2022-08-08-013 Full Text: PDF

Assessment of Destructive and Nondestructive Analysis for GGBS Based Geopolymer Concrete and Its Statistical Analysis.

Geopolymer is the alternative to current construction material trends. In this paper, an attempt is made to produce a sustainable construction composite material using geopolymer. Ground granulated blast furnace slag (GGBS)-based geopolymer concrete was prepared and tested for different alkaline to binder ratios (A/B). The effect of various temperatures on compressive strength properties was assessed. The cubes were exposed to temperature ranging from 50 to 70 °C for a duration ranging from 2 to 10 h, and the compressive strength of the specimens was analyzed for destructive and non-destructive analysis and tested for 7, 28, and 90 days. The obtained compressive strength (CS) results were analyzed employing the probability plot (PP) curve, distribution overview curve (DOC), probability density function (PDF), Weibull, survival, and hazard function curve. Maximum compressive strength was achieved for the temperature of 70 °C and an A/B of 0.45 for destructive tests and non-destructive tests with 44.6 MPa and 43.56 MPa, respectively, on 90 days of testing. The survival and hazard function curves showed incremental distribution characteristics for 28 and 90 days of testing results with a probability factor ranging from 0.8 to 1.0.

Pengaruh Penggunaan Serbuk Arang Batok Kelapa Terhadap Kuat Tekan Beton

Processing of coconut shells into charcoal powder as a concrete mixture. The use of coconut shell charcoal powder on the compressive strength of concrete aims to be a substitute for cement for normal concrete compressive strength and to determine the optimum concrete compressive strength after substitution of cement using coconut shell charcoal powder. In this study the use of coconut shell charcoal powder as a cement substitution with variations of 0%, 2.5%, 5% and 7.5%. Concrete testing was carried out at the age of 28 days after treatment by being immersed in water. The results of the analysis showed that the average compressive strength value of the addition of coconut shell charcoal powder at variations of 5% and 7.5% decreased by 11% and 12.57% because with the increasing number of calcium hydroxide formed, the cement adhesion will decrease so that the structure inside will be weak and cause the compressive strength to be low, while the variation of adding coconut shell charcoal powder 2.5% has an increase of 2.07% against normal concrete compressive strength. From the results of the characteristic concrete compressive strength obtained with substitution variations of 2.5%, 5%, and 7.5% respectively of 278.74 kg/cm2, 243.43 kg/cm2 and 238.96 kg/cm2, the concrete These include class II K 275 concrete (middle class concrete) structural concrete.

A novel methodology to research the residual compressive mechanical properties of composite stiffened panel after low velocity impact based on quantification damage simulation

AbstractComposite stiffened panels have become one of the most usual components in the design process of the aircraft's structure due to their splendid mechanical properties in the last decades. The main purpose of this work is investigating and presenting a more precise method to forecast the residual compressive mechanical behavior of the composite stiffened panel. First of all, an axial compression after impact (CAI) test is performed to understand the failure mechanism of different type of L‐shaped stiffened carbon fiber reinforced polymer panels with barely visible impact damage, which is introduced by the low velocity impact test. Subsequently, a finite element model, which contains a quantification damage model, is established in ABAQUS software based on the CAI test results to predict the mechanical behavior of these composite stiffened panels during the CAI test process. Both of the experimental and predicted results demonstrate that the propagation of the delamination caused by LVI is going to exert a destructive influence on the total failure of the composite stiffened panel, and the prediction results of the residual compressive strength of these composite stiffened panels are well consistent to that measured in the CAI test.

Evaluation of the Technological Properties of Soil–Cement Bricks with Incorporation of Coconut Fiber Powder

The objective of this work was to evaluate the effect of partial replacement of soil by different percentages of coconut fiber powder in the manufacture of soil–cement bricks. The reference mix ratio of 10:1 (soil:cement) in volume was used for the manufacture of bricks, in addition to the partial replacement of soil mass by 5, 10, and 15% of coconut fiber. The characterization of the raw materials was performed with the analysis of the granulometry, together with technological tests, such as mechanical compressive strength and water absorption. As a result, it was observed that the soil has 34.30% clay and 62.80% sand, characterizing a sandy-clay soil type and the coconut fiber powder was characterized as a fine aggregate. The mechanical compressive strength tests showed a decrease in their average values according to the increase in the incorporation of coconut fiber into the bricks. It was concluded that the results of the mechanical compressive strength and some of the water absorption are in disagreement with the Brazilian technical standard. This conclusion corroborates other studies that show the difficulty in standardizing reference mixtures and working with soil, which is a highly heterogeneous material.

The Effect of Chromium on the Chemical and Physical Properties of Industrial Sludge Based Geopolymer

This paper investigates the immobilization of chromium in the industrial sludge-based geopolymer. Mechanical, physical and microstructure properties were used to characterize different samples. The results show that lower heavy metals addition has less effect on the compressive strength. However, excessive addition of Cr(VI) (1.5 and 3%) causes a deterioration of geopolymer matrix with a significant drop of the compressive strength. The compressive strength shows that the use of sodium hydroxide as an alkaline activator is not suitable for chromium immobilization. The use of 1.5 and 3% amount of chromium increases the conductivity of leachates, which explains a change in the microstructure of materials. This is in agreement with the results of compressive strength. XRD patterns of all samples show an amorphous structure with less effect of chromium on the crystalline phases. SEM of the reference sample demonstrates a dense structure of binder. However, the porosity of the matrix increases with the addition of 3% Cr(VI).