Effect Of Layered Double Hydroxides Research Articles

Flexural Strength of Light-Weight Steel Fiber Reinforced Concrete Containing Biodegradable LDHs Microparticles: Experimental Study and Multiscale Finite Element Model

This study investigates the influence of LDHs (Layered Double Hydroxides) microparticles and steel fibers on the mechanical properties of lightweight concrete. Through a combination of experimental analysis and finite element modeling, the effects of LDHs and steel fibers on flexural strength and crack resistance were evaluated. The experimental results demonstrate a significant increase in flexural strength and toughness with the incorporation of LDHs microparticles and steel fibers. The finite element model corroborates these findings, highlighting the synergistic enhancement of mechanical properties due to LDHs and steel fibers. Additionally, the study discusses the frontier applications of LDHs in improving fracture characteristics and highlights the potential of hybrid reinforcement strategies in lightweight concrete. The findings reveal that both the quantity of microparticles and steel fibers significantly impact the concrete's residual strength. In scenarios without steel fibers, an optimal weight fraction of approximately 1 wt.% LDHs demonstrate a 39% increase in bearing capacity. Notably, under comparable conditions, the influence of LDHs microparticles on enhancing concrete mechanical characteristics appears to surpass the effects induced by steel fibers. However, at 2 wt.% LDHs usage, a decrease in load capacity by 3.3% is observed compared to the 1 wt.% LDHs configuration. This research provides valuable insights into optimizing concrete properties through novel material combinations and paves the way for future advancements in structural engineering.

Effect of Layered Double Hydroxide and Its Localization on the Structure and Properties of PBAT/PPC Composites

AbstractThe blends of poly(butylene adipate‐co‐terephthalate) (PBAT), poly(propylene carbonate) (PPC), chain extender (ADR) and layered double hydroxides (LDH) are prepared by different extrusion methods. Effects of LDH and its distribution on rheology, phase morphology, mechanical properties, water vapor barrier properties and food preservation properties are investigated. Results show that when PBAT, PPC, and LDH are mixed directly, LDH is preferentially distributed in the PBAT phase. When LDH are mixed with PPC firstly and then further with PBAT, LDH mostly migrates to the interface of PBAT and PPC. The epoxy groups of ADR react with the terminal groups of the polymers to improve the interfacial compatibility. Adding LDH, the mechanical properties and barrier properties of the materials are improved and by premixing of PPC and LDH, properties of composites are further improved. Compared with PBAT/PPC blends, the tensile strength and elongation at break of PBAT/PPC(LDH‐0.5)/ADR increased by 25.2% and 15.3%, respectively. The banana packaged in PBAT/PPC/LDH films maintains good freshness. It illustrates that PBAT/PPC(LDH)/ADR composites have a good application prospect in the field of barrier and food packaging based on their excellent mechanical, barrier, and preservation properties.

Synthesis of organic layered double hydroxide from waste bischofite and its application on ageing resistance of asphalt

For the utilization of waste bischofite from salt lakes, the waste bischofite was utilized to synthesize layered double hydroxide (LDH) by hydrothermal method, and the synthesized LDH was further organically intercalated with 3,5-Di-tert-butyl-4-hydroxyphenylpropionic acid (antioxidant, DPA) by anion exchange methods. Then, the synthesized LDH and DPA intercalated LDH (DPA-LDH) were applied to improve the ageing resistance of asphalt. X-ray diffraction and Fourier transform infrared spectroscopy manifested that LDH and DPA-LDH had been successfully synthesized. After DPA intercalation, the adhesive aggregation among LDH particles was obviously ameliorated, and the contact angle of LDH increased from 31.3° to 77.9°, the hydrophilicity of LDH was significantly decreased. The effect of LDH and DPA-LDH (3 % by weight of asphalt) on rheological properties, chemical constituents and molecular weight of asphalt before and after ageing were comprehensively studied. The high-temperature performance grade of asphalt increased from PG64 to PG70 with the addition of LDH and DPA-LDH, which indicated that LDH and DPA-LDH could enhance the high-temperature performance of asphalt. After ageing, the high and low- temperature performance of asphalt worsened, the colloidal stability index (CI) decreased from 3.548 to 1.844, the gel index (GI) was 48 %, the colloidal structure tended to gel structure, the molecular weight (Mw) enlarged from 3387 to 4101 (the Mw growth rate of 21 %). LDH could restrain the destruction of ageing on rheological properties, the colloidal structure gel of asphalt (the GI of 37.4 %) and molecular weight (the Mw growth rate of 13 %) of asphalt, and strengthen the ageing resistance of asphalt. Furthermore, the enhancement of DPA-LDH (the GI of 16.7 % and the Mw growth rate of 6 %) on the ageing resistance of asphalt was more superior than LDH. The result showed that the synthesized DPA-LDH exhibited outstanding performance in improving the ageing resistance of asphalt, which was beneficial to the long-life pavement and the utilization of abandoned bischofite from salt lakes.

Assessing the Adjuvant Effect of Layered Double Hydroxides (LDH) on BALB/c Mice.

The discovery and validation of new adjuvants are critical areas for vaccinology. Mineral materials (e.g., alum microparticles) have been used for a long time as adjuvants in human vaccine formulations. Nonetheless, the use of nanosized materials is a promising approach to diversify the properties of adjuvants. Nanoclays are potential adjuvants proposed by some research groups. However, their adjuvant mechanisms and safety have not been fully elucidated. Herein, we aimed at expanding the knowledge on the potential adjuvanticity of layered double hydroxide (LDH) nanoparticles by reporting a detailed method for the synthesis and characterization of LDHs and the adsorption of a model antigen (bovine serum albumin, BSA). LDHs varying in diameter (from 56 to 88 nm) were obtained, and an in vitro evaluation revealed that the LDHs are not inherently toxic. BSA was passively adsorbed onto the LDHs, and the immunogenicity in mice of the conjugates obtained was compared to that of free BSA and BSA co-administered with alum (Alum-BSA). The LDH-BSA conjugates induced a higher humoral response that lasted for a longer period compared with that of free BSA and Alum-BSA, confirming that LDH exerts adjuvant effects. The 56 nm LDH particles were deemed as the more efficient carrier since they induced a higher and more balanced Th1/Th2 response than the 88 nm particles. This study is a contribution toward expanding the characterization and use of nanoclays in vaccinology and justifies further studies with pathogen-specific antigens.

Fabrication of highly hydrophobic layered double hydroxide decorated with tannic acid cross-linked phosphazene as a novel flame retardant for polypropylene

Layered double hydroxide (LDH) is a promising flame-retardant nano-additive for polymers, however, its efficiency is highly based on its composition and dispersity. Based on this cognition, a core-shell LDH-based architecture (LDH@TA-HP) was designed using LDH sheet as core and tannic acid and phosphazene cross-linkd polymers network (TA-HP) as shell. In the flame retardant process, renewable tannic acid (TA) as a carbon source with phosphazene was combined to form an intumescent flame-retardant system, which synergizes with the “tortuous path” effect of LDH which greatly enhance the flame retardancy of PP and LDH@TA-HP composites (PP/LDH@TA-HP). With the addition of 20 wt% LDH@TA-HP, the peak heat release rate and total smoke production of the PP/LDH@TA-HP composites were decreased by 63.5% and 47.6%, respectively, in comparison with those of Neat PP. The flame retardant level reached UL-94 V-0 rating and the limiting oxygen index (LOI) value of PP/LDH@TA-HP composites reached 30.1%, which was related to the “tortuous path’’ effect of LDH and the formation of the intumescent char layer of TA-HP. This investigation provided a facile strategy for the design of multifunctional LDH-based hybrids, expanding LDH potential applications in polymer composites.

Dissolved Organic Matter and Lignin Modulate Aquatic Toxicity and Oxidative Stress Response Activated by Layered Double Hydroxides Nanomaterials.

Advanced nanomaterials can be released into the environment and can coexist with natural organic matter (NOM). However, evidence on the impacts of NOM on the environmental behavior and toxicity of advanced nanomaterials is still scarce. Here, we investigated the behavior and toxic effects of two layered double hydroxides (LDHs) nanomaterials with different metallic constituents (Mg-Al-LDH and Zn-Al-LDH) at relatively low exposure concentrations on a freshwater green alga (Chlorella pyrenoidosa) in the absence and presence of two types of NOM, namely dissolved organic matter (DOM) and dealkaline lignin (DL). The DOM or DL interaction with the LDHs at different mixture levels was shown to be an antagonistic effect on the growth inhibition toxicity to C. pyrenoidosa mainly. The estimation of the index of Integrated Biological Responses version 2 indicated that the joint interaction of the LDHs with DOM or DL occurred in the following order of frequency synergism > antagonism > additivity. Furthermore, the physicochemical characteristics of LDHs were crucial for illuminating the mechanism by which the DOM or DL modified the LDH-induced oxidative stress response. These findings highlighted the important role of NOM in the behavior and effect of LDHs as a representative of a new class of multifunctional nanomaterials in the freshwater environment.

Effect of Layered Double Hydroxides on the Deterioration Process of Cement Paste under Sulfate Attack

This study investigated the effect of layered double hydroxides (LDHs) on the deterioration process of cement paste in the sulfate environment. Cement pastes with the addition of original and calcined LDHs at 2.5 wt.% and 5.0 wt.% of cement were exposed to Na2SO4 solution for 360 days. The macroscopic performance of the cement paste was assessed based on mass variation, porosity, compressive strength, and content of sulfate ions. Furthermore, the microhardness, microstructures, and composition of the degraded pastes were examined using Vickers hardness (HV), mercury intrusion porosimetry (MIP), scanning electron microscope (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results indicate that cement paste incorporated with LDHs can mitigate the corrosion caused by sulfate effectively, especially in the case of calcined LDHs (C-LDHs), which primarily increase the adsorption of sulfate. Compared with the control specimen, the 180 d compressive strength loss ratio of specimens with 2.5 wt.% and 5.0 wt.% of C-LDHs decreased by 63.66% and 80.51%, respectively. Moreover, LDHs can reduce the amount of ettringite crystals, densify the microstructure, and refine the pore structure to mitigate the cement paste's sulfate corrosion significantly. Compared with the control specimen, the 180 d harmful pore volume fraction of specimens laced with 2.5 wt.% and 5.0 wt.% C-LDHs decreased by 43.77% and 54.51%, respectively. In terms of the content of C-LDHs, an optimal content of C-LDHs could ensure the dominant effect of adsorption, while excessive C-LDHs could refine pores. In addition, Vickers hardness has an excellent correlation with compressive strength, which could precisely predict the compressive strength. Moreover, by combining the Vickers hardness distribution and content distribution of sulfate ions, the cross-section of the paste could be classified into four regions to evaluate the deterioration process accurately: the degraded zone, the strengthened zone, the invaded zone, and the intact zone.

Combined Effect of Layered Double Hydroxides and Nano silver on Bacterial Inhibition and Gas Barrier Properties of Chitosan Grafted Polyacrylonitrile Nanocomposites

ABSTRACT Herein, chitosan-grafted-poly(acrylonitrile) (CS-g-PAN) nanocomposites are prepared by emulsifier-free emulsion polymerization technique with dispersion of layered double hydroxides(LDHs) and nano silver(AgNPs). The interactions of AgNPs and LDH with co-polymeric matrix are investigated by FTIR and XRD. It is noticed that LDH platelets are intercalated and partially exfoliated within the copolymeric matrices. Dispersion of fillers creates tortuous path which enhances the gas barrier properties up to seven folds. Antibacterial behavior of nanocomposites is achieved due to incorporation of silver nanoparticles and LDH. Thermal stability, chemical resistance and biodegradable properties of the synthesized material are also increased due to combined effect of LDH and AgNPs.

Ammonium Polyphosphate Intercalated Yttrium-Doped Layered Double Hydroxides to Enhance the Thermal Stability and Flame Retardancy of Poly(Lactic Acid)

The flammability of the biodegradable plastic PLA limits its application in industrial fields with high flame-retardant requirements. This paper provides a novel strategy for constructing refractory and thermostable PLA composites using layered double hydroxides (LDHs) chemically modified with ammonium polyphosphate (APP). XRD, FT-IR, SEM-EDS, and TEM confirm that the goal of LDHs has been successfully prepared. The thermal stability and combustion behavior of PLA composites were evaluated by the thermogravimetric analysis (TGA) and cone calorimetry tests (CCT). The crystallization behavior and tensile performances were also examined. The results showed that the incorporation of 15 wt% MgAlY-APP-LDHs practically makes the PLA composites reach the UL-94 V-0 grade. There were 43% and 20% reduction in the PHRR and THR of PLA/15APP-LDHs respectively due to the catalytic effect of Y elements and barrier effects of LDHs, which was a major performance against fire hazards. Furthermore, the increase in crystallinity and the decrease in mechanical strength of PLA composites are attributed to the nucleation of LDHs. In short, this research introduces the production of multifunctional PLA composites through APP intercalation of LDHs, which are deemed as prospective candidates for the next generation of sustainable plastics products.

Systematic Literature Review of the Effect of Layered Double Hydroxides on the Mechanical Properties of Rubber.

Layered double hydroxides (LDHs) have attracted interest as reinforcing fillers in elastomers due to their ease of synthesis and customisability. A systematic review was performed on the effect of LDHs on the mechanical properties of elastomers using the Scopus database. Of the 61 articles relevant to the search criteria, the majority were published on polyurethane (PU) and nitrile butadiene rubber (NBR). Mg-Al LDH was used in most of the studies and Zn-Al LDH was used second most common. LDH can act as a reinforcing filler, typically increasing tensile strength even at low concentrations, so it could be used as an alternative to traditional reinforcing fillers for elastomers. LDH can also be made a functional filler by selecting the right metals and interlayer anions. It was found that Mg-Al LDH and Zn-Al LDH can both participate in crosslinking reactions and can replace MgO and ZnO, respectively. Less Zn ions are required for crosslinking when LDH is used than when ZnO is used, making LDH more environmentally friendly. Organic modification is usually required to improve compatibility with the elastomer matrix, especially in non-polar elastomers. It enables exfoliation of the LDH and intercalation of polymer chains into the LDH interlayer to occur. Organic modifiers can also be used to functionalise the LDH. Stearic acid used in crosslinking systems can be replaced by stearate anions from stearate-modified LDH.

A Novel Mg-Al-Co LDH/ MAO Composite Films on LA103Z Magnesium-Lithium Alloy and Its Active Anti-corrosion Performance

In order to further improve the corrosion resistance of the micro-arc oxidization (MAO) film on LA103Z magnesium-lithium alloy, a Mg-Al-Co layered double hydroxide (LDH) film was fabricated on MAO film by an in-situ hydrothermal method. The results showed that with the extension of hydrothermal treatment time, the dense LDH film sealed the micro-pores and cracks in the MAO film successfully. In addition, LDH film treated with a hydrothermal treatment at 90°C for 24 h has the best electrical insulation. The hydrogen evolution rates (mL.cm–2.h−1) of the LDH/MAO composite films rank as LDH/MAO-24 h ≈ LDH/MAO-30 h (0.12) < LDH/MAO-18 h (0.15) < LDH/MAO-12 h (0.16) < MAO (0.25). Meanwhile, the results of potentiodynamic polarization curves showed that the corrosion potential of LDH/MAO-24 h film increased from –1.5349 to −1.388 V, and the corrosion current density decreased by three orders of magnitude. Therefore, the LDH/MAO film has better corrosion resistance than a single MAO film and adds long-term corrosion resistance to the magnesium alloy, which owes to the sealing effect of LDH on inherent defects and trapping effect on corrosion ions.

Experimental Investigation of MgAl‐NO2 and MgAl‐CO3 LDHs on Durability of Mortar and Concrete

Two kinds of layered double hydroxides (LDHs), MgAl‐NO2 (N‐LDH) and MgAl‐CO3 (C‐LDH), were incorporated to study the durability of mortar and concrete. The LDH contents of mortar were 1%, 2%, and 4% by mass and the LDH contents of concrete were 0.5%, 1%, 2%, 4%, respectively. The effect of LDHs on sulfate resistance of mortar was studied through dry‐wetting cycle test, compressive strength test, and flexural strength test. In addition, the effects of LDHs on pore structure, chloride resistance, carbonation resistance, shrinkage, and creep of concrete were investigated by SEM, mercury injection test, XRD, chloride ion diffusion coefficient test, chloride salt corrosion depth test, carbonation depth test, shrinkage test, and creep test. The results showed that LDHs can improve the ability of resisting ion corrosion, carbonization, shrinkage, and creep, reduce the pore content, and optimize the pore structure of mortar and concrete to some extent. Moreover, 4% LDHs had a better effect on improving the durability of mortar and concrete compared to 0.5%, 1%, and 2% LDHs, and the effect of C‐LDH was better than N‐LDH.

Effect of LDHs and Other Clays on Polymer Composite in Adsorptive Removal of Contaminants: A Review

Recently, the development of a unique class of layered silicate nanomaterials has attracted considerable interest for treatment of wastewater. Clean water is an essential commodity for healthier life, agriculture and a safe environment at large. Layered double hydroxides (LDHs) and other clay hybrids are emerging as potential nanostructured adsorbents for water purification. These LDH hybrids are referred to as hydrotalcite-based materials or anionic clays and promising multifunctional two-dimensional (2D) nanomaterials. They are used in many applications including photocatalysis, energy storage, nanocomposites, adsorption, diffusion and water purification. The adsorption and diffusion capacities of various toxic contaminants heavy metal ions and dyes on different unmodified and modified LDH-samples are discussed comparatively with other types of nanoclays acting as adsorbents. This review focuses on the preparation methods, comparison of adsorption and diffusion capacities of LDH-hybrids and other nanoclay materials for the treatment of various contaminants such as heavy metal ions and dyes.

Effect of layered double hydroxide, expanded graphite and ammonium polyphosphate additives on thermal stability and fire performance of polyisocyanurate insulation foam

This work examines the effect of Layered Double Hydroxides (LDHs), Expandable Graphite (EG) and Ammonium Polyphosphate (APP) on the thermal stability and behaviour under fire conditions of polyisocyanurate (PIR) insulation foams. Virgin materials’ and char residues’ morphologies were analyzed with a variety of experimental techniques including field emission scanning electron and optical microscopy along with Raman spectroscopy. Thermal stability and burning behaviour were examined using thermogravimetric (TGA) coupled with Fourier Transform Infrared (FTIR) spectrometer and cone calorimeter. TGA results suggested a decrease in degradation temperature upon introduction of fillers in PIR samples. FTIR spectra were used to determine the absorbance intensity of the different pyrolysis gases. Cone calorimeter data analysis established a limited effect on reducing the rate of heat release rate and smoke production with the inclusion of LDHs. However, EG or EG + APP addition, caused a considerable decrease in heat release rate, owing to the increased char strength and the release of non-combustible gases. The positive effect of EG or EG + APP in the fire behaviour of PIR foams was further supported by the morphological evaluation of their residual char samples.

Novel fluoride rechargeable dental composites containing MgAl and CaAl layered double hydroxide (LDH)

ObjectiveThis study aims to incorporate 2:1 MgAl and 2:1 CaAl layered double hydroxides (LDHs) in experimental dental-composites to render them fluoride rechargeable. The effect of LDH on fluoride absorption and release, and their physico-mechanical properties are investigated. Methods2:1 CaAl and 2:1 MgAl LDH-composite discs prepared with 0, 10 and 30wt% LDH were charged with fluoride (48h) and transferred to deionized water (DW)/artificial saliva (AS). Fluoride release/re-release was measured every 24h (ion-selective electrodes) with DW/AS replaced daily, and samples re-charged (5min) with fluoride every 2 days. Five absorption-release cycles were conducted over 10 days. CaAl and MgAl LDH rod-shaped specimens (dry and hydrated; 0, 10 and 30wt%) were studied for flexural strength and modulus. CaAl and MgAl LDH-composite discs (0, 10, 30 and 45wt% LDH) were prepared to study water uptake (over 7 weeks), water desorption (3 weeks), diffusion coefficients, solubility and cation release (ICP-OES). ResultsCaAl LDH and MgAl LDH-composites significantly increased the amount of fluoride released in both media (P<0.05). In AS, the mean release after every recharge was greater for MgAl LDH-composites compared to CaAl LDH-composites (P<0.05). After every recharge, the fluoride release was greater than the previous release cycle (P<0.05) for all LDH-composites. Physico-mechanical properties of the LDH-composites demonstrated similar values to those reported in literature. The solubility and cation release showed a linear increase with LDH loading. SignificanceLDH-composites repeatedly absorbed/released fluoride and maintained desired physico-mechanical properties. A sustained low-level fluoride release with LDH-composites could lead to a potential breakthrough in preventing early stage carious-lesions.

Fluoride removal by Ca-Al-CO3 layered double hydroxides at environmentally-relevant concentrations.

In this study, F- removal by Ca-Al-CO3 layered double hydroxides (LDHs) was investigated at environmentally-relevant concentration ranges (2-12 mg/L) to below the WHO guideline, with an emphasis on the effect of LDHs' modification, as well as the effects of initial F- concentration, adsorbent dose, pH, temperature and co-existing ions. Ca-Al-CO3 LDHs, either untreated, calcined or microwave treated, showed affinity for the removal of F- from synthetic groundwater with capacities of 6.7-8.4 mg F-/g LDHs at groundwater-relevant pH, with a higher F- removal capacity at lower pH (<8) and lower temperature (12 °C, as compared to 25 °C & 35 °C). Since calcination and microwave treatment resulted in only marginal defluorination improvements, using untreated LDHs appears the practically most feasible option. For the untreated LDHs, competition with Cl- and NO3- was not observed, whereas at higher HCO3- and SO42- concentrations (>250 mg/L) a slight reduction in F- removal was observed. This study indicates the potential of Ca-Al-CO3 LDHs as a cost-effective F- removal technology, particularly when locally sourced and in combination with low-cost pH correction.

Effect of layered double hydroxides addition on the ageing and self-healing properties of asphalt binder

In this paper, the effects of Layered Double Hydroxides (LDHs) incorporation on the ageing resistance and self-healing properties of asphalt binder were studied. Matrix asphalt (MA) and LDHs modified asphalt (LMA) binders were aged by short-term thermal oxidation and ultraviolet ageing and their ageing performance was characterized through the analysis of the SARA fractions and temperature sweep test. Frequency sweep test and capillary flow test were conducted to characterize the fluidity of the asphalts, and fatigue life recovery test was used to characterize the asphalt self-healing properties. The main results indicate that under the same ageing conditions, the light component contents of LDHs modified asphalt are higher than that of matrix asphalt and the complex modulus increment of LMA is lower than that of matrix asphalt. It means that LDHs modified asphalt has better anti-ageing performance. Besides, LDHs modified asphalt has higher fluidity and lower self-healing threshold temperature than matrix asphalt binder under the same ageing conditions, indicating that the incorporation of LDHs can effectively retard the reduction of asphalt flow capacity due to ageing. It was also found that asphalt binder containing LDHs had better self-healing potential due to the improvement of the ageing resistance. It was concluded that the addition of LDHs can effectively improve the ageing resistance and self-healing properties of asphalt binder.

Investigation of the effect of Mg-Al-LDH on pavement performance and aging resistance of styrene-butadiene-styrene modified asphalt

Layered double hydroxide (LDH) could improve the aging resistance of an asphalt binder. However, the previous work all arbitrarily selected only one dosage of LDH such as 3% or 5%, which could not be enough to know the effect of LDH and its dosage on the pavement performance and aging resistance of an asphalt binder accurately, it is important to investigate the LDH effect on the properties of asphalt from more widely ranges of dosages. Meanwhile, the LDH and asphalt binder interaction is still unclear. In this paper, six dosages (from 2% to 7%) of Mg-Al-CO32−-LDH were conducted to modify the styrene-butadienestyrene modified asphalt (SBS MA). The Fourier transform infrared spectroscopy (FTIR) and X ray diffraction (XRD) results indicate that there is no chemical reaction between LDH and SBS MA, the blending of LDH and SBS MA is a physical way. The rheological properties of SBS MA are studied by both dynamic shear rheometer (DSR) and bending beams rheometer (BBR), the results show that LDH can improve the high temperature performance of SBS MA, and does not significantly weaken other properties of SBS MA by controlling LDH dosage to be lower than 4%. The FTIR, complex modulus and VAI results show that LDH can significantly improve both the thermal oxide aging and UV aging resistances of SBS MA. LDH dosage of 4% is suggested to be the optimal dosage after considering the effect of LDH on the aging resistance and pavement performance of asphalt binder.

Effect of Layered Double Hydroxides with Different Particle Size on Properties of Bitumen

The crystal structure, microscopic morphology, particle size distribution and UV shielding properties of layered double hydroxides (LDHs) with different particle size were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), laser particle size analysis and ultraviolet and visible (UV-vis) spectrophotometer. The effects of LDHs with different particle size on the physical, rheological properties and UV aging resistance of bitumen were investigated by conventional physical properties and dynamic rheological characteristics. The results indicated that the particle size of LDHs had a little effect on the physical properties, and it had some influence on rheological properties of bitumen, but its influence on the UV aging resistance of bitumen was different significantly. When UV aging time was 9d, the viscosity aging indexes of bitumen modified by LDHs with different particle size (80nm, 115nm and 180nm) decreased by 48.2%, 58.1% and 63.8% compared with the pristine bitumen, respectively. LDHs with the particle size of 180 nm showed better improvement than other two kinds of LDHs on UV aging resistance of bitumen.

Effect of layered double hydroxides on ultraviolet aging properties of different bitumens

The objective of this paper was to investigate the effect of layered double hydroxides (LDHs) on physical and rheological properties of different bitumens (SK-90, TY-90 and GF-70) before and after ultraviolet (UV) aging. The results show that the physical properties of different bitumens are slightly influenced by LDHs. And the effect of LDHs on rheological properties of investigated bitumens largely depend on the bitumen nature, and LDHs show the least influence on rheological properties of SK-90 with highest phase angle and lowest complex modulus among the three bitumens. Due to the UV aging, LDHs modified bitumen shows the lower softening point increment, viscosity aging index and complex modulus aging index in comparison with the unmodified bitumens, indicating their good UV aging resistance. Compared with SK-90 and GF-70, LDHs show a better improvement in UV aging resistance of TY-90 which is more sensitive to UV aging.