Addition Of Superabsorbent Polymer Research Articles

Influence of Super-Absorbent Polymer on Growth and Productivity of Green Bean under Drought Conditions

The water-retaining and yield-increasing capacity of super-absorbent polymer (SAP) are essential for soil remediation in arid and semi-arid areas. Water availability is an increasing challenge to plant development and crop yield. During the growing seasons in 2021 and 2022, the present study was conducted to evaluate the effect of the addition of different amounts of SAP on the development and yield of green beans (Phaseolus vulgaris L. cv Bronco) under varying water deficit stresses, compared with the control treatment without SAP and water deficit stress. The results demonstrated that a 50% reduction in water requirement (WR) resulted in significant decreases in leaf fresh weight, specific leaf area, leaf total chlorophyll content, pod number, leaf free water content, pod fresh weight per plant, and yield. Decreases were also found in pod total chlorophyll content, carotenoids, dry matter and total protein, leaf proline content, and crude fiber content. Additionally, leaf water saturation deficit was significantly increased under the stress compared with the full irrigation at 100% WR. However, irrigation at 75% WR increased pod contents of ascorbic acid, total sugars, and leaf bound water. The current study also indicated that addition of SAP significantly enhanced the above-mentioned growth characteristics under irrigation at 50% and 75% WR. Treatment with SAP at 3 g/plant was the most effective in mitigating the adverse effects of water deficiency, especially at the irrigation rate of 75% WR. Pearson’s correlation analysis showed significantly positive correlations between the growth parameters, as well as pod yield, under water stress and SAP. This study provides a promising strategy for green bean cultivation by adding SAP to soil to alleviate water shortage stress.

Mitigating autogenous shrinkage of cement with carbon nanotube sponge

Autogenous shrinkage can be mitigated by the addition of superabsorbent polymer (SAP), however, typically at the cost of a significant strength loss. To overcome such dilemma, hydrophilic carbon nanotube sponge (H-CNTSP) was proposed in this study as a novel internal curing agent. Due to the high porosity and enriched hydrophilic functional groups, H-CNTSP can absorb pore solution at 72 g/g driven by the capillary force, which is 176%–620 % higher than the commercial SAPs. The autogenous shrinkage of cement can be reduced or mitigated with the addition of 0.05–0.2 wt% H-CNTSP due to the continuous water release after final setting. Interestingly, the compressive strength loss resulting from the addition of H-CNTSP can be greatly diminished and even be overcompensated by the formation of CNT/hydrate nanocomposite shell with a higher modulus. This study illustrates the great potential to optimize concrete performance through proper design of assembly structures with chemically functionalized nanomaterials.

A multiscale micromechanical progressive elastic-damage model for cementitious composites featuring superabsorbent polymer (SAP)

A multiscale micromechanics-based progressive damage model is developed to investigate the overall mechanical behavior and the interfacial microcrack evolutions of the cementitious composites featuring superabsorbent polymer (SAP) under uniaxial tension. Elastic properties, progressive damage process, and homogenization procedure of cementitious composites are systematically integrated in this model. The effective elastic moduli of the composites are determined based on a multiscale micromechanical framework. According to the small strain assumption, the total strain tensor and the elastic-damage compliance tensor are additively decomposed into elastic and damage-induced components. The damage-induced strains and compliances are then deduced from micromechanics. To characterize the progressive elastic-damage induced by microcracks, stages of microcrack propagation are identified from the interface contact stress and the matrix cleavage stress. The complex potentials and stress intensity factors for kinked interface cracks are derived from the distributed dislocations method. By implementing the homogenization process, the macroscopic mechanical behavior is obtained from the micro/mesoscale. The results indicate that the material parameters have clear mechanical significance. Different parameters, such as the SAP addition ratio, aggregate content, initial interfacial crack size, and initial interfacial crack location, are revealed to be influential in the overall mechanical behavior of the composites. The proposed model can be generalized to other particle-reinforced composites with different constituent properties, which can potentially contribute to the design and optimization of durable composites.

THE INFLUENCE OF TOTAL WATER-TO-CEMENT RATIO ON THE MECHANICAL PROPERTIES OF CEMENTITIOUS COMPOSITES INTERNALLY CURED WITH POLYACRYLIC SUPERABSORBENT POLYMERS (SAP)

Superabsorbent polymers (SAP) allow for the introduction of changes to the pore network characteristics in cementitious composites and the course of binder hydration. Therefore, SAP addition contributes to significant changes in multiple properties of concrete. The effect of internal curing differs depending on its design process – the initial content of curing water in the concrete mix, polymer characteristics and water absorption properties, the state in which it’s added (nonsaturated/hydrogel), and the design method regarding curing water content in the entire water content. The authors investigated those variables’ influence on selected concrete properties – compressive strength, water absorption, and shrinkage. All independent variables significantly influenced the studied properties of concrete. The increase in the total water-to-cement ratio led to a significant decrease in the mechanical properties of cementitious composites. Modification with the use of SAP added in the form of hydrogel had the most positive influence on the properties of concrete.

Rheology of Superabsorbent Polymer-Modified and Basalt Fiber-Reinforced Cement Paste with Silica Fume: Response Surface Methodology

A composite's rheology can be changed by adding superabsorbent polymer (SAP) and basalt fibers and using silica fume. This study aimed to investigate the effects of these components on the viscosity and shear stress parameters of the paste. The proportions of the components were varied, with SAP content ranging from 0.01% to 0.03%, basalt fiber from 0% to 0.50%, silica fume (micro silica) at 15%, and water content from 0.40 to 0.50. Response surface methodology was used to optimize the mixture proportions, and the rheological properties of the resulting pastes were characterized using a rheometer. Results showed that the addition of SAP and basalt fiber had a significant impact on the rheological properties of the paste, with increasing amounts of both resulting in increased viscosity and shear stress. Overall, this study highlights the potential of SAP and basalt fiber in advances of the rheology of cement paste and provides insight into the optimal proportions of these components for achieving desired rheological properties. The findings of this study could be useful in developing high-performance concrete with enhanced rheological properties, which could have a wide range of applications in the construction industry. In addition, 0.50% BF, 0.01% SAP, and 0.445 water-to-cement were found as optimum proportions regarding the rheology of the cement paste.

Using superabsorbent polymer to mitigate the fast setting and high autogenous shrinkage of carbide slag and sodium silicate activated ultrafine GGBS based composites

Alkali-activated GGBS based composite is a low carbon engineering material, but limited by some unavoidable disadvantages, such as fast setting and high autogenous shrinkage. In present work, superabsorbent polymer (SAP), which was synthesized by copolymerizing acrylic acid and acrylamide, was used to control the setting time and autogenous shrinkage of carbide slag and sodium silicate activated ultrafine GGBS based composites (CSGC). Results indicated that the fast setting of CSGC was effectively controlled by the addition of SAP. The initial and final setting time were delayed by more than 30 min and 60 min respectively, which provides the possibility to ensure the on-site construction operation. Although SAP mitigated the fast setting of CSGC, it had a negligible effect on the heat release during hydration. Autogenous shrinkage was reduced by 27% when only 0.1% SAP was added, and the compensation of autogenous shrinkage became more pronounced with the increased SAP dosage. The amount of large capillary pores above 100 nm was significantly increased in CSGC incorporating high SAP dosage, which leads to a decline in compressive strength. However, the compressive strength of CSGC with low SAP dosage can match that of reference group at 28 d, due to the internal curing effect of released water from SAP.

A novel gel dry water: Preparation and application in methane-air explosion

To weaken the adverse effects of methane-air explosions on industrial processes and the environment, the development of highly effective explosion inhibitors is imperative. In this study, a novel ammonium polyphosphate gel dry water (AGDW) powder was synthesized by incorporating superabsorbent polymer (SAP) and ammonium polyphosphate (APP) as additives. The addition of SAP significantly enhanced the physical properties such as stability and water retention of AGDW powder, while APP improved its suppression effects. The suppression effect of AGDW powder on methane-air explosions was investigated in a square explosion pipeline. Experimental results revealed that 4 g AGDW powder with 15 wt% APP completely hindered the propagation of the explosion flame, resulting in a 91.2% reduction in peak temperature and completed elimination of the pressure reflection wave. Increasing the spraying pressure from 0.2 MPa to 0.4 MPa, 2 g AGDW powder with 5 wt% APP was sufficient to suppress the explosion completely. The suppression mechanism of AGDW powder on methane-air explosions was comprehensively elucidated from the cooling effect, diluting effect, and interrupting the chain reaction. This work sheds light on the preparation and application of novel dry water powders and provides a feasible solution for ensuring process safety and controlling gas explosions.

Effects of Superabsorbent Polymer Addition on the Thermal Properties of Eutectic Phase Change Material

In this study, the influence of a super absorbent polymer (SAP) addition on the thermal properties of phase change material (PCM) was investigated. It was found that adding SAP reduced the melting temperature of PCM and improved phase separation properties. While the addition of 1.0 wt% of SAP to PCMs decreased latent heat by 3 J/g to 24.4 J/g, the addition was determined to be necessary to prevent leaks from a functional duct unit (FDU) and assure product stability. The results obtained from a series of brine refrigeration tests indicate that the supercooling temperature decreased by 0.3 °C to 1.7 °C when 1.0 wt% of SAP was added to PCM. The addition of SAP to PCM appears to promote supercooling by encouraging condensation during phase change. As a result of applying SAP-added PCM to the FDU, the isothermal operation performance was improved compared to existing refrigerators.

Effect of Superabsorbent Polymer (SAP) Size on Microstructure and Compressive Strength of Concrete.

Superabsorbent polymers (SAPs) are hydrophilic, polymeric network materials renowned for their ability to enhance various properties of cementitious materials. This investigation examines the impact of SAP size on the hydration degree, porosity, and compressive strength of cement pastes and concrete under diverse curing conditions and ageing periods. The findings reveal that SAP addition stimulates the hydration of the C2S phase, particularly during the early curing stages, thereby favouring early strength development. However, the effect of SAPs on hydration promotion diminishes as their size increases. Conversely, the size of SAPs affects the hydration range of their action, and the 400 µm SAP demonstrates the most extensive range of hydration enhancement, reaching up to 105 µm. Additionally, SAPs effectively reduce porosity in small pores (4 nm-10 μm), with 200 μm and 400 μm SAPs exhibiting the highest efficacy. While analysing the effects of SAPs on larger pores (>10 μm), the results show that although larger SAPs result in larger average porosity, the total porosity is effectively reduced, particularly in samples incorporating 400 μm SAP. The compressive strength of cement paste, even after 28 days, is slightly reduced following the introduction of SAPs. However, the strength of concrete, due to the naturally occurring pores eliminating the negative effects of the pores produced by SAPs, is significantly increased following the introduction of SAPs, especially 400 µm SAP.

Investigation on the compressive strength and durability properties of alkali-activated slag mortar: Effect of superabsorbent polymer dosage and water content

This paper presents the properties of alkali-activated slag (AAS) mortar additivated with a superabsorbent polymer (SAP) to improve its mechanical and durability properties. The effect of different dosages of SAP (0.0–0.3% with respect to the blast furnace slag weight) and different extra water additions on setting time, autogenous shrinkage, compressive strength, water permeability, frost resistance, heat of hydration, and porosity is presented and discussed. The results highlight the beneficial effect of adding SAP on the mechanical and durability properties of the proposed mixtures. Only at higher percentages of SAP and additional water occur performance drops due to excessive macro-porosity of the system. It is interesting to point out that, in contrast, shrinkage always decreases as the percentages of SAP addition and additional water increase, although it cannot be completely eliminated. Experimental evidence also highlights that significant benefits can be gained from using this material in harsh environments.

Feasibility study on superabsorbent polymer (SAP) as internal curing agent for cement-based grouting material

The closed working condition of grouting materials leads to insufficient curing water supply during their strength development. In this work, the superabsorbent polymer (SAP) was used as the internal curing agent for grouting material. The effects of SAP content on the rheological and mechanical properties of grouting material were studied under various water-cement ratios (w/c) and curing environments. The time-dependent variation of fresh slurry's viscosity was measured by Brinell viscometer. The pore structure and micromorphology characteristics were analyzed by Mercury Intrusion Porosimetry (MIP) and Scanning Electron Microscope (SEM). The results indicate that the addition of SAP increases the viscosity of fresh slurry and decreases its fluidity, thereby improving the slurry's internal uniformity at a higher w/c. And in its actual working condition, grouting material's strength can be boosted with less than 0.3% SAP dosage. Although SAP will introduce some irregular mesoscopic pores (0.2 − 0.3 mm), the MIP data analysis proves SAP refines the microscopic pore structure of grouting materials. SEM data analysis proves SAP optimizes the microstructure of grouting material, which cured in dry environment. In general, SAP improves the internal uniformity of grouting material by absorbing excess mixing water and gradually releasing it to promote cement hydration, which improves the strength of grouting material. Hence, SAP is a practicable internal curing agent for grouting material and 0.2% is the recommended dosage.

Study on neutron shielding performance of high strength mortar modified by saturated super absorbent polymer

In order to meet the requirements of nuclear safety, it is important to prepare mortars that simultaneously mortar with high compressive strength and neutron shielding properties. In this study, acrylamide-saturated super absorbent polymer (0.1, 0.2, 0.3%) was added to high-strength mortar to investigate its effect on neutron shielding performance. The influence mechanism of compressive strength, phase composition, and microstructure was analyzed, and the neutron radiation shielding performance of mortar was evaluated by Monte Carlo N Particle Transport Code (MCNP) simulation software. The results showed that the fluidity and hydration degree increased with the addition of super absorbent polymer (SAP), which increased by at least 10% and 27% compared with the control group. Proper addition of SAP can refine the pore structure of the matrix in the mortar. The highest compressive strength of mortar (113 MPa) was achieved when adding 0.1 %SAP of the total mass of the mixture. In addition, the addition of saturated super absorbent polymer significantly improved the fast neutron shielding effect of mortar, with a shielding rate 55% higher than that of normal mortar. For the same moisture content, SAP water-augmented mortar has the same shielding capacity as direct water-augmented mortar, but the compressive strength was improved by 19%.

Synergetic effect of superabsorbent polymer and shrinkage reducing admixture on the properties of alkali-activated slag binders

This research is to investigate the synergistic effects of superabsorbent polymer (SAP) and shrinkage-reducing admixture (SRA) on autogenous shrinkage, hydration and microstructure of alkali-activated slag system (AAS). Results revealed that the addition of SRA reduced the absorption capacity of SAP, resulting in a smaller size distribution of macrovoids throughout the AAS matrix. Nevertheless, the presence of SAP affected the ability of SRA to effectively reduce the surface tension of the pore solution of AAS. Instead, the addition of SAP resulted in an increase in surface tension by up to 14%. This phenomenon can be explained by the hydrophobic interactions between SAP networks and SRA molecules. The combination of SAP and SRA in AAS exhibited greater effectiveness in controlling autogenous shrinkage compared to using SRA alone, resulting in a reduction of around 53% compared to 46%. On the other hand, incorporating only SAP proved to be more effective, leading to a higher reduction of 90%. However, this combined effect is reported to be counteractive and dependent on the content of each component. Moreover, the hybrid system of SAP and SRA demonstrates a pronounced retardation effect on AAS hydration. The XRD patterns showed no new reaction products were formed. As revealed by SEM analysis, the microstructure of AAS containing SAP and SRA exhibited a distribution of microvoids ranging from 5 to 50 μm. This can explain the reduction of the compressive strength by incorporation a high content of SAP combined with SRA. However, incorporating a lower dosage of SAP is advantageous when combined with SRA in AAS systems. Finally, the integration of SAP and SRA had a positive influence on the properties of AAS mortars, thus compensating for the limitations of each constituent.

Microstructure and Water Retention Kinetics in Autogenous Cured Self-Compacting Concrete Blends Using Super Absorbent Polymer.

This research aimed to determine how a super absorbent polymer affects the microstructural characteristics and water retention kinetics of a new composite made by substituting granite pulver (GP) and fly ash (FA) for cement. Understanding the mechanics of water movement is crucial for comprehending the effectiveness of autogenous curing. Several experiments were conducted to analyze the water mitigation kinetics of super absorbent polymer (SAP) in the hydrating cement paste of autogenous cured self-compacting concrete (GP-ACSSC) mixtures. In the first hours following casting, water sorptivity, water retention, and hydration tests were carried out. The effects of various concentrations of SAP and GP, which was utilized as an alternative cement for the production of sustainable concrete that leads to reduction in carbon footprint, on the autogenous cured self-compacting concrete with reference to the abovementioned properties were explored. The investigation showed that releasing the curing water at a young age, even around the beginning of hydration, allowed homogenous and almost immediate distribution of water across the full cured paste volume, which improved the water retention kinetics. Compared to the control mixtures, the addition of SAP up to 0.6% and the substitution of cement with GP up to 15% had favorable impacts on all water kinetics parameters.

Effect of γ-PGA and γ-PGA SAP on soil microenvironment and the yield of winter wheat.

Agricultural poly-γ-glutamic acid (γ-PGA) and γ-PGA super absorbent polymer (SAP) are two forms of γ-PGA applied in agriculture. Different quantities of γ-PGA and γ-PGA SAP (40 kg/hm2, 80 kg/hm2, 120 kg/hm2 and 160 kg/hm2) were applied to the soil in order to investigate their effects on the microenvironment of soil root zone and the yield of winter wheat. The soil water content increased with increasing amounts of γ-PGA SAP. The content of nitrate nitrogen and ammonium nitrogen increased with the increasing amounts of γ-PGA, while γ-PGA SAP significantly increased the content of ammonium nitrogen. The number of soil microorganisms and soil enzyme activities in the root zone increased with the addition of γ-PGA and γ-PGA SAP. The yield of winter wheat increased with the addition of γ-PGA or γ-PGA SAP, but the increasing rate decreased when the amount of γ-PGA and γ-PGA SAP exceeded 80 kg/hm2, with increases of 5.95% and 6.77% compared to the control group, respectively. The addition of γ-PGA significantly increased the protein content of wheat grains, and the WUE increased with increasing amounts of γ-PGA and γ-PGA SAP.

Experimental study on the properties of internal cured concrete reinforced with steel fibre

Internal cured concrete modified with superabsorbent polymer (SAP) has received extensive attention due to its excellent crack resistance and durability, but the decrease of mechanical property caused by the macro pores left after SAP water release has limited its application to a certain extent. In this study, steel fibre was used for improving the strength and toughness of internal cured concrete modified with SAP (IC) to satisfy the development trend towards high strength concrete nowadays. Four steel fibre volume fraction dosages (0.5%, 1%, 1.5% and 2%) were adopted. Water absorption test, freeze–thaw test and dynamic compressive test were conducted to investigate the influences of steel fibre on dense degree, frost resistant, and mechanical property of IC respectively. The results showed that, 1) under standard curing conditions (20 °C and 95% RH), with the addition of SAP, the dense degree of concrete was weakened, but the frost resistant was strengthened; 2) the dense degree, frost resistant, and dynamic compressive properties of IC were considerably improved by adding steel fibre; 3) the optimal volume fraction dosage of steel fibre is 1.5%. Furthermore, a dynamic compressive constitutive model was developed, which can reflect the effects of steel fibre dosage and strain rate simultaneously.

The Effect of Superabsorbent Polymer on Fair-Faced Concrete Performance Based on White Cement

Introducing superabsorbent polymer (SAP) into white fair-faced concrete can achieve the purpose of internal curing, which is beneficial to the popularization and application of white fair-faced concrete. The effects of the SAP mixture and internal curing water content on the properties of white fair-faced concrete were investigated macroscopically through the indexes, including slump, electric flux, standard cube compressive strength, and tensile splitting strength. The mechanism of these influence laws was further analyzed by scanning electron microscope (SEM). The results show that the slump increases with the increase of SAP content and internal curing water; the incorporation of SAP can significantly reduce the electric flux of white fair-faced concrete and improve its durability; with the increase of SAP admixture and internal curing water content, the compressive strength of white fair-faced concrete decreases, which has a significant impact on the early compressive strength; the addition of SAP is beneficial to the improvement of the tensile properties and tensile-compression ratio of white fair-faced concrete. When the SAP content is 0.2%, and the internal curing water is ten times the mass of SAP, the optimal performance of white fair-faced concrete can be achieved; the water released by the SAP promotes the secondary hydration reaction, which can refine the internal structure of white fair-faced concrete.

Investigation on Performances and Functions of Asphalt Mixtures Modified with Super Absorbent Polymer (SAP).

The super absorbent polymer (SAP) has been attracting extensive concerns due to its strong capacity in water absorption and retention. The amorphous hydrogels formed by the post-absorbent SAP have the potential of clogging the micro-cracks in asphalt materials and refraining the rainwater from infiltrating. This provides the possibility of applying SAP in asphalt pavements to seal or fill the cracks and relieve the distresses caused by rainwater infiltration in the underlying layers. Before exploring the cracking sealing mechanism of SAPs in asphalt pavements, a series of experiments were performed to evaluate the feasibility and influences of SAPs in asphalt mastics and asphalt mixtures on their mechanical performances and functionalities. Firstly, the basic properties of SAPs were analyzed, and then the rheological properties of the asphalt mastics using SAP replacing mineral powder (10%, 20%, 30%, and 40% by volume) were explored. The water stability and infiltration reduction effect of the asphalt mixtures incorporated with SAP were evaluated by the Marshall stability test, immersion Marshall stability test, freeze-thaw splitting strength test, Cantabro test, and permeability test. The test results indicated that SAPs could be used in the asphalt mixtures to partially substitute mineral powder with desirable mechanical performances. When less than 10% of the mineral powder was replaced by the SAP, the high-temperature performance and fatigue life of the asphalt mastics could be improved to some extent, but both declined after the content of the SAP was larger than 10%. Due to the hydrogels formed by SAPs after water absorption, the water stability of the asphalt mixtures deteriorated with the increased content of SAPs. Moreover, the results from the permeability tests implied that the SAP hydrogels could fill the seepage channels in the material, thus improving the migration and infiltration resistances of the asphalt mixtures. With the increased contents of SAPs, the permeability coefficients of the asphalt mixtures could be reduced up to 55%. Based on the research findings in this study, when an appropriate amount of SAP was added in the asphalt materials, desirable temperature stability, water stability, and fatigue resistance could be achieved regarding actual requirements from applications. At the same time, the addition of SAPs could effectively refrain the infiltration and migration of rainwater in asphalt pavements, thus potentially mitigating the effect of water erosion on the underlying layers.

Research on Performance Deterioration of Internally Cured Pavement Concrete under the Coupling Effect of Salt Freeze-Thaw.

This paper aims at solving the material durability problem caused by spraying deicing salt on pavement concrete in the northern winter. Super absorbent polymer (SAP) was adopted as an internal curing agent to enhance the durability of pavement concrete. Curing parameters including particle size and dosage of SAP and curing condition were optimized based on mortar tests by means of the grey target decision method. The deterioration rule of durability and mechanical properties of pavement concrete internally cured by different SAP dosages after salt freeze-thaw cycles were explored through rapid freeze-thaw test. Combined with the characteristics of pore structure, hydration and microstructure, the influence mechanism of SAP on the salt freeze-thaw resistance of pavement concrete was revealed. The experimental results showed that: (i) The reduction in mass loss rate and relative dynamic modulus was significantly improved by SAP internal curing with moderate dosage; (ii) The more freeze-thaw cycles the specimen underwent, the greater the increase in strength; (iii) After 75 cycles, the chloride ion erosion depth could be decreased by approximately 23.18%. Moreover, the addition of SAP could refine the pore size, inhibit the generation of shrinkage microcracks, and promote the degree of cement hydration in the late stage, which improved the internal density of the cement concrete structure. Therefore, the deterioration of pavement under the coupling effect of salt freeze-thaw was reduced.

Mechanical properties of loess subgrade treated by superabsorbent polymer

Moisture variation is one of the crucial factors affecting the strength and deformation of loess. In this study, superabsorbent polymer (SAP) was introduced as moisture regulator to enhance the ability of accommodating moisture variations of loess and then to improve the stability of loess subgrade. Water migration test was first performed to evaluate the variation law of the effect of SAP on the moisture content of loess in a closed system. Then mechanical tests were carried out to investigate the influence of SAP on the mechanical properties of loess. Besides, microscopic tests were conducted to find out chemical and physical behavior of SAP on the loess. Test results demonstrated that SAP can significantly reduce the water content of loess by 8.26–26.42 %. The unconfined compressive strength (UCS) of loess increased by 37 % after 14 days curing with an optimum SAP content of 1 %, reaching 100 kPa. The dynamic resilient modulus (MR) gradually decreased as a result of SAP addition. The dissipated energy and damping ratio of loess reached the maximum values (100 mJ and 5 %, respectively) at 1.0 % SAP content, which were 10 times and 5 times higher than that of pure loess, respectively. The treatment of loess by SAP was mainly caused by the coupling of physical and chemical water absorption of SAP in the water environment. The incorporation of SAP had no effect on chemical functional groups and mineral composition of loess, but caused water redistribution, thereby changing the mechanical properties.