Flocculation Structure Research Articles

Research on Municipal Sludge Dewatering and Modified Catalytic Combustion Technology

Aiming at the problem that high moisture content of municipal sludge with flocculation structure and high water retention capacity, which makes dewatering and drying difficult, this paper carries out research on dewatering, drying and modified combustion technology of municipal sludge with the goal of resource and energy utilization. The sludge dewatering agent ZC-2T and catalytic oxidation nitrification agent ZC-4R were preferably selected as the main components of modified adjusting agent ZC-1W for industrial application of sludge energy disposal. The compounded modified adjusting agent ZC-1W has a positive contribution to improve the combustion performance of sludge mixed with raw coal, which providing important theoretical support and practical data for the large-scale industrial development and application of municipal sludge. The study will generate significant economic and social significance.

Rheological Properties and Structural Build-Up of Cement Based Materials with Addition of Nanoparticles: A Review

Nanoparticles improve the mechanical properties and durability of cement-based materials. However, owing to the high surface energy and specific surface areas of nanoparticles, the packing characteristic of cementitious particles will be affected. With the action of the electrostatic attraction and Van der Waals force, the cementitious particles are agglomerated into flocculation structures, and the free water is entrapped. Furthermore, as the water consumption of cement-based materials increases, the flowability gets worse, which is thought to be one of the reasons limiting its application in practical engineering. In addition, nanoparticles increase the viscosity and thixotropy of fresh cement-based materials and provide more nucleation sites in cement paste, accelerating the cement hydration process in early hydration. In this paper, the research progress on the rheological properties and structural build-up of cement-based materials with the addition of nanoparticles was reviewed. The applicability of rheological test methods and rheological models was summarized. The variation of rheological parameters of fresh cement-based materials affected by nanoparticles species, contents, dispersion method, superplasticizer, etc., were discussed. Based on the packing density, water film thickness, and flocculation structures, the action mechanism of nanoparticles on the rheological properties of cement-based materials was analyzed. Further research topics on the rheology and structural build-up of nano-modified cement-based materials are suggested as well.

Physical properties and tensile strength evolution of gypsum materials under different water content conditions

To investigate the physical properties and tensile strength evolution of gypsum materials under different water content conditions, three groups of gypsum standard samples were prepared, including natural, saturated and dehydrated gypsum samples. Electron microscopy, composition analysis, Brazilian splitting tests and numerical simulation analysis were carried out. The results are as follows. The larger the water content of the samples is, the higher the content of CaSO4·2H2O, the more flocculation structures on the surface, and the higher the longitudinal wave propagation speed. Saturation and dehydration change the composition of the sample and cause a change in its tensile strength and failure mode. The fitting effect of the modified Hoek-Brown criterion is obviously better than that of the modified Mohr-Coulomb criterion because it considers the influence of uniaxial compressive strength. The Balmer criterion introduces the index b and greatly improves its regression accuracy. The vertical compressive stress exhibits a concentrated distribution. At x = 0, the peak value of the vertical load appears at the two ends of contact between the specimen and the indenter and gradually decreases from both ends to the centre. The horizontal stress is mainly tensile stress, and the value at x = 0 is the theoretical tensile strength. It is uniformly distributed on the line directly affected by the vertical load and decreases to both ends of the specimen along the line. It is reduced to 0 at the left and right ends. The horizontal deformation arises from both sides of the disk tip and then spreads downwards in an arc during loading. The horizontal strain in the upper part of the disk is always larger than that in the lower part. The upper part reaches its tensile strength and then fails due to the continuous loading.

Effect of nano-metakaolin on the thixotropy of fresh cement paste

• Nano-metakaolin increases the thixotropy of fresh cement paste. • The maximum thixotropy of cement pastes occurs in the temperature range of 25–30 °C. • The thixotropy of NMK cement pastes shows an increasing trend with the hydration time. • The thixotropy of NMK cement pastes increases linearly with the yield stress. Nano-metakaolin (NMK) was used to increase the viscosity of fresh cement pastes and the mechanical properties and durability of hardened cement-based materials. However, the effect of NMK on the thixotropy of fresh cement pastes was not systematically investigated. The paper investigates the thixotropy of NMK cement pastes, the effects of superplasticizer, NMK content, hydration time, and environmental temperature were considered. The size of the flocculation structures (flocs) of the NMK cement pastes was measured, and the hysteresis loop area of the NMK cement pastes was identified. The relationships between the hysteresis loops area and yield stress, packing density, and particles spacing of the NMK cement pastes were established. The results showed that the incorporation of NMK increased the thixotropy of fresh cement pastes with and without superplasticizer addition. NMK significantly increased the thixotropy of the cement pastes with superplasticizers addition. The thixotropy of NMK cement pastes firstly increased and then decreased within 10 – 45 °C, the maximum thixotropy appeared at around 25–30 °C. The thixotropy of the NMK cement pastes exhibited an increasing trend with the hydration time. The thixotropy of the NMK cement pastes linearly increased with the yield stress. The hysteresis loop area decreased with the increase of the packing density and particles spacing.

Effects of an Isobutylene-Maleic Anhydride Copolymer on the Rheological Behavior and Early Hydration of Natural Hydraulic Lime.

Natural hydraulic lime (NHL) is a cementitious material widely used in the restoration of stone cultural relics and maintenance of historic buildings, the practical use of which is mainly hindered by its poor fluidity. Due to the multilayer (double-layer) adsorption that isobutylene–maleic anhydride (IBMA) has on the surface of NHL, the effects that IBMA copolymer have on the fluidity and hydration of NHL were thus investigated. Moreover, the yield stress and plastic viscosity of NHL pastes were found to be reduced significantly by the incorporation of IBMA. Combined with the effects of electrostatic repulsion and steric hindrance, the flocculated structures in NHL pastes were gradually dismantled, releasing the trapped water and leading to a significant enhancement in the fluidity of NHL. IBMA was found to postpone the early hydration of NHL. In particular, it showed that adding specific content of IBMA can significantly improve the early strength of NHL.

Investigating saturated hydraulic conductivity of remolded loess subjected to CaCl2 solution of varying concentrations

• The K sat characteristics of remolded loess under CaCl 2 solutions are presented. • The response of EDL effect to CaCl 2 concentrations is evaluated. • Microstructure evolution of loess induced by CaCl 2 solutions is revealed. • The mechanism of K sat change in seepage process is disclosed. • The findings in this study have broad application value to other soils. Loess has been widely used in site remediation engineering projects in the Chinese Loess Plateau. With the interaction between CaCl 2 solution and cutoff wall, how does its permeability change, is the response pattern consistent for different concentrations, and what is the mechanism? To address this series of problems, the effects of CaCl 2 solutions of varying concentrations on the permeability of remolded loess were investigated by saturated permeability test, and the mechanisms underlying these effects were explored through free swelling ratio, zeta potential, thermogravimetric analysis (TGA), grain-size tests, as well as SEM and MIP tests. The results indicate that K sat values of the samples permeated with both deionized water (DW) and 0.001 mol/L CaCl 2 solution increase with time, with a greater increase observed in the latter. This is mainly due to that the electrical double layer (EDL) effect induced by Ca 2+ , as the dominant factor, controls particle flocculation and pore structure development. Under seepage of a 0.010 mol/L CaCl 2 solution, the EDL effect plays a dominant role during the initial stage. However, chemical weathering causes the disintegration of loess particles, and the dissolution of carbonates is inhibited by Ca 2+ . These are not conducive to pore development; thus, K sat first increases and then decreases significantly. The K sat of samples permeated with a 0.005 mol/L CaCl 2 solution first increases and then stabilizes, which represents the transitional stage of the two aforementioned change trends. This is mainly because the effective pores are increased by leaching and cation exchange, and then the porosity is in dynamic equilibrium under the combined action of the EDL effect, geochemical action, and microstructural evolution. Thus, the saturated hydraulic conductivity ( K sat ) of remolded loess is sensitive to the concentrations of CaCl 2 solutions, with different response modes.

Preliminarily evaluation of poly (AA-co-AMPS) on the properties of sulphoaluminate cement

• Comparing the effect of structural parameters on the rheology and hydration of SAC. • Stronger effect of degree of polymerization on its properties. • Long-term strength reduction of SAC caused by poly (AA- co -AMPS). • Changes in hydration rates leading the paste shrinkage and strength reduction. The previous article reported the effect of poly (AA- co -AMPS) on the rheology of sulphoaluminate cement (SAC), but the effect of structural parameters of the copolymer on the properties, especially the mechanical properties, would decide the value for SAC as a superplasticizer. To further evaluate their effect on SAC, a series of copolymers were synthesized, and their effects on the rheology, hydration, and mechanical properties were tested. Copolymers could control the fluidity and the setting as reported, but the degree of polymerization would be a stronger factor than the ratio of carboxyl to sulfonyl groups. Meanwhile, flocculation structure destruction and particle dispersion are the main reasons for rheology properties changing, while inhibiting the formation of AFt would significantly retard the hydration. However, the polycarboxylic acid segments in this copolymer might cause or enhance the inherent shrinkage of SAC leading to the compressive strength of 28 d decreasing.

Unconfined compressive strength and pore structure evolution law of structural clay after disturbance

The clay in the Zhanjiang Formation has thixotropic properties, which has greatly influenced the foundation engineering in the Zhanjiang area. The evolution law of macroscopic strength and clay microstructure during thixotropy can be used to explain the practical engineering problems caused by thixotropy. For undisturbed and reconstituted soil curing for a different period, unconfined compressive strength test, scanning electron microscopy, and mercury injection porosimetry test were carried out to obtain the unconfined compressive strength and pore structure evolution law in the thixotropic process. The results indicate that the Zhanjiang Formation structural clay is very sensitive to disturbance and its unconfined compressive strength decreases from 180.29 to 11.73 kPa after the natural structure is completely destructed. After 300 d of curing, the unconfined compressive strength of clay increased from 11.73 to 53.43 kPa because of thixotropy, which increased by 3.55 times. The stacking flaky flocculation structure of the undisturbed soil is destructed by reconstituting, turning to flaky flocculation structure, and the large pores are homogenized, the small pores develop into medium pores, and there is a decrease in soil strength. In the process of thixotropy, the soil particles gradually coagulate and form an aggregates flocculation structure, and the strength of clay increases with the increase in the degree of cementation. Based on the results, the thixotropic pattern of clay was established and its thixotropic mechanism was explained.

Application of Rheo-optic In Situ Measurement Technology to Study Waxy Crude Oil Rheology

The micromechanism of waxy crude oil gelling is the interaction between wax crystals to form a certain intensity flocculation structure, which significantly increases the cost of production and transmission. In this paper, rheo-optic in situ measurement technology is applied to the rheological study of waxy crude oil for the first time and also to the rheological response of typical waxy crude oil to thermal history, the micromechanism of shear-thinning, and the dynamic behavior of wax crystal. Through the new experimental technique and analysis method, it is found that two types of wax crystals can be formed under certain thermal historical conditions, which have opposite performances in microscopic morphology, mechanic properties, and flocculation tendency, and the change of its proportion in crude oil is the root cause of the initial cooling temperature affecting the fluency of waxed crude oil. It was found that the microscopic behavior of waxy crude oil with the increase of shear rate went through the following whole process: the waxy crude oil system changes from static to dynamic, the wax crystal flocculation network undergoes deformation, cracks, and ruptures, and wax crystal aggregates break, small aggregates orient along the flow field, and small aggregates continues to deform and break. When the shear rate is below 5 s–1, the crack of the flocculation structure plays a leading role. It is only after the shear rate exceeds 5 s–1 that the deformation of the wax crystal and its flocs begins to function. Furthermore, according to the microscopic images of the wax crystals motion sequence, the micromorphology of different types of flocs and the dynamic behaviors under shearing are systematically analyzed by dynamic micro-object capture technology.

Effects of Nonaqueous Phase Liquids Pollution on the Permeability and Microstructure of In-Filed and Laboratory Soaked Contaminated Clay Soils

The fact that the permeability and microstructure properties of clay will be changed by NAPL (Nonaqueous Phase Liquids) pollution draws high attention in the study of the interaction between NAPL and contaminated soil. Through in-field contaminated clay soils from vinyl chloride and 1, 1, 2-trichloroethane-contaminated site in Shanghai, the variation of the content of vinyl chloride and 1, 1, 2-trichloroethane pollutants in clay with depth was obtained. The change of plasticity, permeability, and microstructure properties of the clay samples contaminated by vinyl chloride and 1, 1, 2-trichloroethane were investigated in detail. The measured test results were compared with the uncontaminated clay and indoor soaked contaminated clay samples by TCE (Trichloroethylene). The test results showed that the microstructure characteristics of clay were changed under the influence of the content of TCE, vinyl chloride, and 1, 1, 2-trichloroethane. The total porosity, accumulative pore volume, and the content of the macroporosity percentage of clay soils showed an increasing trend. The flocculation structure of contaminated clay samples was observed, but there were no overhead pores and connected cracks. Volatile organic pollutants were detected in both field and indoor contaminated clay samples. The plastic limit and liquid limit of each layer of contaminated samples decreased slightly, the plastic index did not change significantly, and the pore ratio and permeability coefficient increased gently. At the same time, the clay shrinkage was aggravated by TCE pollution, and cracks appeared on the surface of soil samples. However, no connected cracks were formed. Test results indicated that the self-developed improved permeability test device can be used to test the permeability coefficient of clay samples with shrinkage and to crack by NAPL pollution. The permeability coefficient showed an increasing trend, though the increase was not at the level of magnitude.

A conceptual model focusing on internal flocculation structures and water film thickness for analyzing fresh properties of cement paste containing attapulgite

A multiple sieve method for characterizing different flocculation structure sizes within cement paste was proposed. The effects of flocculation structures of different sizes on the fresh properties of cement paste containing attapulgite were investigated through grey theory. The bonding strength coefficient was proposed as a representative index to characterize the sizes and strengths of the flocculation structures. The water film thickness (WFT) and bonding strength coefficient were combined to establish a model for analyzing the fresh properties of cement paste. The results indicated that the flocculation structures in the interval of 0–425 µm primarily affected the flow parameters and bleeding rate, while the flocculation structures>425 µm primarily affected the rheological parameters, thixotropy, and adhesiveness. BGA and GBA affected the fresh properties by changing the WFT and bonding strength coefficient. The WFT and the bonding strength coefficient together determined the fresh properties of the cement paste.

Rheological evaluation of nano-metakaolin cement pastes based on the water film thickness

The aim of this study was to evaluate the rheology of nano-metakaolin (NMK) cement pastes based on the water film thickness (WFT). The effects of the NMK content, water-to-binder (w/b) ratio, superplasticizer (SP), environmental temperature, and hydration time were considered in the rheological test. The fluidity, apparent viscosity, yield stress, plastic viscosity, packing density, and WFT of the investigated NMK cement pastes were determined. The flocculation structures (flocs) of the NMK cement pastes were examined. A mathematical model and a BP neural network model were established to predict rheological parameters. The results showed that the NMK increased the apparent viscosity, yield stress, and plastic viscosity of fresh cement pastes. NMK weakened the effects of environmental temperature and hydration time on the rheology of fresh cement pastes. The NMK addition increased the number of flocs in fresh cement pastes and yielded a lower packing density and WFT. A mathematical model and a BP neural network model based on WFT were available to accurately predict the rheological parameters.

Elucidating how particle flocculating controls fresh properties of cementitious system containing attapulgite powder (AP) and polycarboxylate ether superplasticizer (PCE)

The flow spread, flow rate, yield stress, apparent viscosity and adhesiveness of cementitious systems containing newly processed attapulgite powder (AP) and polycarboxylate ether superplasticizer (PCE) at different w/c ratio were investigated. The bonding strength coefficient was proposed to quantify the size and strength of the flocculation structure within the paste, and its relationships with fresh properties were explored. The results showed AP and PCE with appropriate mixing ratios can improve the fresh properties of paste. The flocculation structure transformation model was established to explain the influence of AP and PCE on the size of the flocculation structures with the change of w/c ratio, which can be divided into three stages. The bonding strength coefficient increased with increasing AP substitution and decreasing PCE addition. PCE and AP affected fresh properties by changing the bonding strength coefficient.

Influence of the flocculation effect on the rheological properties of cement slurry

The rheological properties have an important impact on the migration and diffusion of cement slurry in grouting reinforcement applications. The microscopic interaction between particles affects the macroscopic rheological behaviors of cement slurry. However, the detailed influence mechanisms still remain unclear. In this work, five different fineness cements were selected to investigate the rheological properties. The focused beam reflectance measurement (FBRM) system was used to detect the in-situ flocculation characteristics under different water-to-cement ratios, cement fineness, and shear rates. In addition, the initial and time-dependent rheological properties under various conditions were measured by a rotary viscometer. The results reveal that these three factors influence the number and particle size distribution of flocculent particles, and the degree of flocculation increases linearly with time. Cement slurry with a water-to-cement ratio ranging from 0.6:1 to 1.6:1 follows the Bingham model. The yield strength and plastic viscosity decrease with increasing water-to-cement ratio, and increase with increasing cement fineness. The apparent viscosity is reversible with the change of shear rate. The influence of water-to-cement ratio, cement fineness, and shear rate on the flocculation effect is consistent with the influence on rheological parameters. Three factors and time affect the rheological properties by influencing the formation and destruction of the flocculation structure, and then changing the content of free water and intergranular force in cement slurry. Our study has revealed the evolution of rheological properties from a microscopic point of view, which can provide theoretical guidance for the design and application of cement slurry.

Macroscopic Behavior and Microscopic Structure Evolution of Marine Clay in One-Dimensional Compression Revealed by Discrete Element Simulation

Marine clay has been attracting in-depth research on its mechanical behavior and internal structure evolution, which are crucial to marine infrastructure safety. In the formation process of marine clay, including the sedimentation and consolidation stages, the compression behavior and internal structure evolution are highly dependent on the pore water salinity. Discrete element method (DEM) simulation is a powerful tool to study the microscopic mechanics behind the complicated macroscopic mechanical behavior of marine clay. In this study, a DEM simulation scheme is systematically proposed to numerically study the macroscopic beahvior and microscopic structure evolution of marine clay in one-dimensional compression that mimics the marine clay formation process. First, the proposed calculation scheme for double layer repulsive interaction and van der Waals interaction is introduced. Then, the developed DEM simulation scheme is validated by satisfactorily reproducing the experimentally observed one-dimensional compression curves and internal structure transition from an edge-to-edge/edge-to-face flocculated structure to a face-to-face dispersed structure. Finally, evolutions of coordinate number and fabric anisotropy are quantitatively evaluated in the microscopic view. The noticeable effects of ion concentration on the internal structure evlotion and mechanical behavior of marine clay have been examined and discussed.

Experimental investigation in the permeability of methane hydrate-bearing fine quartz sands

The permeability is one of the intrinsic parameters that determines the fluid flow in the porous media. The permeability in hydrate-bearing sediments affects the gas recovery and production of hydrate reservoirs significantly. The irregular permeability characteristics are challenging for fine-grained hydrate-bearing sediments. In this study, a series of experiments was conducted using an one-dimensional pressure vessel to investigate the hydrate formation characteristics and the permeability in hydrate-bearing fine quartz sands (volume weighted mean diameter was 36.695 μm). Hydrate saturations (0–26% in volume) were controlled and calculated precisely based on the amount of injected water and gas, the system pressure and temperature. The results indicated that the hydrate nucleation induction period was completed during gas injection, and the average time of hydrate formation was within 500 min. The permeability of methane hydrate-bearing fine quartz sands was investigated by steady gas volume flow. For hydrate saturation lower than 13.94%, the hydrate mostly formed in grain-coating, the permeability reduction exponent calculated by Parallel Capillary, Kozeny Grain Coats and Simple Cubic Filling models were 2.00, 2.10 and 1.74 respectively, and Simple Cubic Filling model was in accordance with the experimental data best. However, for hydrate saturation ranged from 13.94% to 25.91%, the permeability increased due to the flocculation structure formation of fine quartz sands and hydrate, which caused the increase of effective porosity. A new relationship among hydrate saturations, effective porosity, the ratio of permeability in the presence and the absence of hydrate was developed. This study developed the mathematical models for predicting the permeability with hydrate saturation in fine quartz sands, which could be valuable for understanding the characteristics of hydrate-bearing fine-grained sediments.

Study on Microstructure Characteristics of Fresh Cement Paste

In this paper, RST rheometer is used to test the rheological characteristics of fresh cement paste under different water-cement ratio and different shear rate, and quantitatively calculate the area of hysteresis loop and the destruction energy of flocculation structure.The microstructure of cement paste with different water-cement ratio was observed by Ultra depth of field optical microscope, and the microstructure pictures were processed by Image-J software,then quantify the quantity and size of cement congeries.It is found that the destruction energy of flocculation structure can quantitatively characterize the destruction degree of flocculation structure.Under the condition of the same shear rate, the larger the water-cement ratio, the smaller the hysteresis loop area, the smaller the destruction energy of flocculation structure, the increase of the number of aggregates in cement paste, the enhancement of dispersion and the reduction of aggregate size.The attachment strength of aggregates in cement paste is weakened, and the flocculation structure is more easily damaged. Under the same water-cement ratio, the smaller the shear rate, the smaller the destruction energy and the lower the destruction degree of flocculation structure.With the increase of shear rate, the destruction energy of flocculation structure increases.

Improved dewaterability of drilling waste sludge by ultrasonic and potassium permanganate co-treatment

The drilling waste sludge, as a colloidal suspension, would cause secondary pollution to environment if it’s inappropriately disposed. Dewatering pretreatment could reduce the volume and costs before final disposal. In this study, ultrasonic and potassium permanganate (KMnO4) co-treatment was investigated in drilling waste sludge dewatering pretreatment. The results showed that the water content (WC) was significantly reduced to 27.09%, and the dewatering time and SRF decreased by 46.67% and 17.68% after pretreating by 60 W of US and 12 mg/g DS (dry solid) of KMnO4 in 5 min. The volatile suspended solid (VSS) solubilization revealed that KMnO4 could easily disintegrated organic matters and further elevated VSS solubilization to 41.05% with the assistance of US. The mechanistic investigation illustrated that ultrasonic helped decompose sludge flocs and KMnO4 further oxidized recalcitrant organic matters, consequently enhancing sludge dewatering performance. In addition, the electrostatic repulsion was reduced and Zeta potential was elevated, which prompted particle size, flocculation and viscosity of drilling waste sludge. After US+KMnO4 pretreatment, the electronegativity, flocculation, hydrophobicity, and porous structure were strengthened, which enhanced the dewaterability of drilling waste sludge. The result in this study illustrates that ultrasonic and KMnO4 co-treatment is efficacious in drilling waste sludge dewatering pretreating.

Strength and Microstructure of Clay Geopolymer Non-Load-Bearing Masonry Units Using Fine-Clay Brick Waste and Palm Oil Fuel Ash

This research studies the applicability of alkali-activated cement with a mixture of fine-clay brick waste (FCBW) and palm oil fuel ash (POFA) to manufacture environmentally friendly masonry units. FCBW and POFA were used as a precursor, while a dredged soft clay (SC) was used as aggregate. Sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solutions were used as the liquid alkaline activator. Effects of NaOH concentration, initial SiO2/Al2O3 mole ratio, Na2SiO3/NaOH ratio, and curing conditions on the strength and microstructure of the FCBW-POFA-SC geopolymers were evaluated. The FCBW-POFA-SC geopolymers had a lower total unit weight than compacted SC because NaOH in the geopolymer binder caused a flocculated soil structure. It was found that Na2SiO3/NaOH=70/30, 10 M NaOH, and FCBW/POFA=70/30 were the best ingredients providing the rigid network of the geopolymer structures. The suitable heat duration of 48 h at 80°C accelerated the dissolution rate of the Si and Al and polycondensation in the geopolymer structure, resulting in denser geopolymer gels and early strength gain. With this optimum ingredient and suitable heat condition, 7-day unconfined compressive strength (UCS) of the FCBW-POFA-SC geopolymers achieved the requirement of the Thailand industrial standard for non-load-bearing masonry units (UCS>2.5 MPa). The geopolymer products were found to be sodium aluminum silicate hydrate (N─ A─ S─ H) and calcium aluminum silicate hydrate (C─ A─ S─ H). The research outcome will promote the usage of waste materials for manufacturing environmentally friendly infrastructure in Thailand and other countries.

Utilization of Lime Sludge Activated by Salt in Egyptian Expansive Soil Improvement

Expansive soils are active clays which cause engineering problems all over the world. This research deals with the impact of lime sludge (LS) as industrial solid waste from sugar-cane factory and sodium chloride salt (NaCl) on engineering properties of expansive soil. In this research, an analytical study of chemical and physical properties of Egyptian expansive soil in Sixth of October City was made as a case study. The laboratory results showed improvement of chemical, microstructural properties and thus the engineering properties of this soil. The results of chemical analysis showed the ability of soil to improve pH; soil alkalinity raise to the required level of stabilization. After soil treatment, Microstructure scanning electron with energy dispersive spectroscopy (SEM-EDX) analyses showed that new cementitious compounds are formed and soil was changed from a weak dispersed structure to strong flocculated structure. It was also observed by increasing LS and NaCl concentrations the plastic limit increased and the liquid limit decreased, hence decreased plasticity index; the rate of soil free swelling is decreased due to change of expansive soil texture. Therefore, lime sludge activated by NaCl has positive effects on engineering properties of soil. By this way we protect the environment from industrial solid wastes.