Pozzolanic reactions of six principal clay minerals: Activation, reactivity assessments and technological effects

Six standard clays, before and after calcination at 3 or 4 temperatures and being mixed with Ca(OH)₂ [CH] in the presence of simulated cement pore solution, and with ordinary Portland cement, respectively, were studied in detail. Chemical compositions of most clays conform well to the requirement in ASTM C 618. Water demand of clay-containing mortar varies, depending on the crystal chemistry of raw clays, and on the specific surface area of calcined clays. Measurements of XRD background or alkali soluble Si are rapid methods in evaluation of the pozzolanic activity of clays. Compressive strength of mortars based on the raw clays is affected by structure of clays. Calcination increases the pozzolanic activity of clays and the compressive strength of the Portland cement — clay mortars. A close correlation exists between compressive strength of mortars and particle size distribution of the dehydroxylated clays. The most common reaction products of clay — CH mixtures are C-S-H² and C₄AH_x, while C₂ASH_j8 and C₃AH₆ were also detected with clays rich in Al.     

The origin of the pozzolanic activity of calcined clay minerals: A comparison between kaolinite, illite and montmorillonite

This paper investigates the decomposition of three clayey structures (kaolinite, illite and montmorillonite) when thermally treated at 600 °C and 800 °C and the effect of this treatment on their pozzolanic activity in cementitious materials. Raw and calcined clay minerals were characterized by the XRF, XRD, ²⁷Al NMR, DTG and BET techniques. Cement pastes and mortars were produced with a 30% substitution by calcined clay minerals. The pozzolanic activity and the degree of hydration of the clinker component were monitored on pastes using DTG and BSE-IA, respectively. Compressive strength and sorptivity properties were assessed on standard mortars. It was shown that kaolinite, due to the amount and location of OH groups in its structure, has a different decomposition process than illite or montmorillonite, which results in an important loss of crystallinity. This explains its enhanced pozzolanic activity compared to other calcined clay–cement blends.     

The production of smectite clay/graphene composites through delamination and co-stacking

Layers from delaminated colloidal dispersions of two structurally different layered solids-octylamine-intercalated graphite oxide and cetyltrimethylammonium-intercalated smectite - could be costacked to obtain smectite clay/graphite oxide composites. The layers of the two parent solids were randomly stacked together in these composites. On thermal decomposition the graphite oxide sheets in the composites are reduced to graphene sheets resulting in clay/graphene composites. The composition is not uniform in these composites, which have many smectite-rich and carbon-rich regions. The clay component of the clay/graphene composites could be leached out to obtain exfoliated graphite.     

Pozzolanic reactivity of fly ash - API method and K-value

The pozzolanic reaction of fly ash in mortar was primarily examined using a K-value from Ferét’s law. As a result, the pozzolanic reaction would be mainly controlled by the diffusion kinetic, and the diffusion constant would increase with water content in the mortar. The K-value is useful to estimate the degree of the pozzolanic reaction of mortar. Secondly, the relation between K-value and assessed pozzolanic activity index derived from accelerated chemical test (API method) was inspected. It is concluded that the API is one of the useful acceleration methods to evaluate the degree of the pozzolanic activity, because API has a good relation with K-value.     

Alkali-activated blends of calcined AlF3 production waste and clay

Recently, alkali-activated materials have shown great potential for use in the construction industry. The aim of this research was to study the properties of alkali-activated clay and the effect of incorporating AlF₃ production waste from a fertilizer production plant. The AlF₃ production waste, which was rich in alumina and silica, contributed to improved mechanical behaviour for all the mixtures investigated. This demonstrated the potential for use of this waste material. It was also noted that the dosage of Na₂O, Al₂O₃, and SiO₂ are significant factors that influence the binding mechanism and properties of alkali-activated clay samples. The raw materials, precursors, and alkali-activated samples were investigated by X-ray diffraction, fluorescence spectroscopy, and scanning electron microscopy. The highest compressive strength (17.50?MPa) was observed for alkali-activated clay samples containing 25% AlF₃ production waste, with an increase in compressive strength of up to 64% compared to the samples without the AlF₃ production waste. Deleterious natrite was shown to form in the samples without the production waste, which could be the reason for the lower observed mechanical properties of such samples.     

焦磷酸盐体系电镀Ni_(70)Cu_(30)合金工艺

为了得到Ni70Cu30合金镀层,研究了镀液中主盐浓度比、配位剂浓度、温度、pH、电流密度等工艺参数对合金镀层成分、外观等的影响,并考察了多种添加剂对镀层性能的影响.确定了最优镀液组成及工艺条件为:七水合硫酸镍70 g/L,五水合硫酸铜10 g/L,三水合焦磷酸钾242 g/L,硼砂38 g/L,二乙二醇3mL/L,,温度55℃,pH 8.7,电流密度4～9A/dm2.     

Determination of optimum compatibilizer (SMA) concentration for PBT/ABS (70/30) blend using tensile strength data

Poly(butylene terephthalate) (PBT), a thermoplastic polyester, was melt blended with acrylonitrile-butadiene-styrene (ABS) terpolymer using styrene-maleic anhydride (SMA) as the compatibilizer. The PBT : ABS ratio was fixed at 70 : 30 by weight and weight percent (wt %) of SMA was varied as 2.5, 5, and 7.5. The effect of variation of the SMA percent in the blend was studied by calculating and comparing the theoretical tensile strength values with the experimental ones. The adhesive strength (σ) and the interaction parameter (I) were also determined. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1485–1487, 1997     

Annealing effect on poly(vinylidene fluoride/trifluoroethylene) (70/30) copolymer thin films above the melting point

To further understand crystallization behaviors above the melting temperature (T_m), the morphologies and structure of ferroelectric poly(vinylidene fluoride/trifluoroethylene) [P(VDF–TrFE); 70/30] copolymer films at different temperatures were studied by atomic force microscopy, differential scanning calorimetry, and X‐ray diffraction (XRD). We found that there was a structural change in the P(VDF–TrFE) copolymer film above T_m, which corresponded to the transition from tightly arrayed grains to fiberlike crystals. For the samples annealed above T_m, heat treatment reduced the density of gauche defects and caused a better arrangement of the crystalline phase. So those samples were in the ferroelectric phase without gauche defects, with one sharp diffraction peak reflected in the XRD curves. It was helpful to further make clear the thermal behaviors from the melts of the P(VDF–TrFE) copolymers and discuss their application under higher temperatures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Characterization and use of acid‐activated montmorillonite‐illite type of clay for lead(II) removal

The natural local deposits of montmorillonite‐illite type of clay (MIC) were susceptible for acid activation. Raw clay was taken for experimentation, disintegrated on acid activation with sulfuric acid, which showed a particle size distribution. The montmorillonite and illite phases in the raw clay disappeared on acid activation and the activated clay, MIC(AA), showed with sodium‐aluminum‐silicate and beidellite phases apart from quartz (low) phase. The raw and acid‐activated clays were characterized using X‐ray powder diffractometry, X‐ray fluorescence, Fourier transform infrared spectrometry, and energy dispersive X‐ray, and their adsorption capacities were compared. When tested for adsorption of Pb(II) in aqueous solutions, the acid‐activated clay showed about 50% increased adsorption than raw clay. Sips adsorption isotherm and pseudo‐second‐order kinetic models were found to be best for the batch adsorption data. Kinetic studies showed the existence of film diffusion and intraparticle diffusion. A two‐stage batch adsorber was designed for the removal of Pb(II) from aqueous solutions. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Effect of pressure on electric generation of PZT(30/70) and PZT(52/48) ceramics near phase transition pressure

Impact experiment of Pb(Zr_0.3Ti_0.7)O₃ and Pb(Zr_0.52Ti_0.48)O₃ ceramics were conducted by empolying shock reverberation techniques within 3-7 GPa and X-ray diffraction patterns of these materials have been measured at pressure up to 32 GPa with a diamond anvil cell and synchrotron radiation. To refine the crystal structure, Rietveld analysis was performed and bulk moduli were calculated using Birch-Murnaghan equation of state. We found a tetragonal phase transforming to a cubic phase in Pb(Zr_0.3Ti_0.7)O₃ and Pb(Zr_0.52Ti_0.48)O₃ ceramics at ∼7.4 GPa and ∼4 GPa respectively. For dynamic pressure experiment, a metal flyer accelerated by a gas gun facility impacts into PZT ceramics to investigate electric energy. As pressure increased, output voltage of Pb(Zr_0.3Ti_0.7)O₃ and Pb(Zr_0.52Ti_0.48)O₃ ceramics slightly increased below ∼7 GPa and ∼4 GPa. But the voltage increased near ∼7 GPa and ∼4 GPa. From the result, we could confirm that the phase transition influenced the considerable effect on the electrical power generation.     

Preparation and properties of chitosan/clay (nano)composites: a silanol quaternary ammonium intercalated clay

Chitosan/clay (nano)composites were prepared by using a special quaternary ammonium intercalating agent coupled with a silanol group to facilitate the organic clay formation. Exfoliated clay in the chitosan matrix was attained at the higher intercalant dosages through X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses. Optical transmittance for the (nano)composites increased slightly with increasing the amount of intercalants in the clays. In light of the hydrophobic component on the intercalant and the effective clay content, the interfacial interaction between chitosan and modified clay may not be strong enough to render higher mechanical properties, even though the partially exfoliated clays were achieved to provide high interfacial area for the dispersed phase and the matrix. An optimum Young’s modulus was thus found for (nano)composites using modified clay at a medium dosage of intercalant, which resulted from the balance of the dispersion status and interfacial interaction. This outcome indicated high dispersion of modified clay may not guarantee high mechanical properties of (nano)composites. The antimicrobial property of chitosan against Escherichia coli (E. coli) increased further with the addition of modified clays, in which the intercalant exhibiting the antimicrobial function. The modified clay at an optimum dosage of modifier to balance the mechanical properties and antimicrobial property was attained.     

Development of a new rapid,relevant and reliable (R3) test method to evaluate the pozzolanic reactivity of calcined kaolinitic clays

The present paper introduces a new rapid, relevant and reliable (R³) test to predict the pozzolanic activity of calcined clays with kaolinite contents ranging from 0 to 95%. The test is based on the correlation between the chemical reactivity of calcined clays in a simplified system and the compressive strength of blends in standard mortar. The simplified system consists of calcined clay portlandite and limestone pastes with sulfate and alkali levels adjusted to reproduce the reaction environment of hydrating blended cements. The pastes were hydrated for 6 days at 20 °C or for 1 day at 40 °C. The chemical reactivity of the calcined clay can be obtained first by measurement of the heat release during reaction using isothermal calorimetry and second by bound water determination in a heating step between 110 °C and 400 °C.Very good correlations were found between the mortar compressive strength and both measures of chemical reactivity.     

Investigation of the Explosive Properties of HMX/Al 70/30

The production of HMX/Al 70/30 and the investigation of the characteristic properties are described and a comparison to RDX/Al 70/30 properties made. According to first test results, the possibility of an increased performance compared to RDX/Al 70/30 may not be ruled out.     

Crystallinity,ion conductivity,and thermal and mechanical properties of poly(ethylene oxide)–illite nanocomposites with exfoliated illite as a filler

Illite particles were exfoliated by the intercalation and subsequent deintercalation of dimethyl sulfoxide (DMSO) in the interlayer of illite, and the exfoliated illite particles were used to prepare a novel poly(ethylene oxide) (PEO)–illite nanocomposite. The resulting exfoliated illite and PEO–illite nanocomposites were characterized by X‐ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry, ion conductivity testing, thermogravimetry analysis, and mechanical testing. The XRD results showed that the acid treatment of illite to exchange K⁺ in the interlayer of illite with H⁺ was a necessary condition for the DMSO intercalation. SEM micrographs confirmed the exfoliation of the illite particles in the process of DMSO deintercalation from the interlayer of the illite–DMSO intercalation complex. A good dispersion of exfoliated illite in the PEO matrix was also confirmed. A gradual decrease in the PEO crystallinity in the PEO–illite nanocomposites was observed with increasing exfoliated illite concentration. The ion conductivity of the nanocomposites gradually increased with the filler content and reached 3.21 × 10⁻⁵ S/cm at an illite concentration of 20 wt %. The formation of an amorphous region around the exfoliated illite was beneficial for Li⁺‐ion conduction. The ion conductivity significantly increased when the amorphous regions were connected to each other to form a conducting path for Li⁺ ions with a high filler concentration of greater than 10 wt %. Meanwhile, the thermooxidative stability and mechanical properties of the PEO–illite nanocomposites were also enhanced when exfoliated illite was introduced into the polymer matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44226.     

Investigations on electrical characteristics of (PbO)30(CuO)x(As2O3)(70-x) glass ceramics

This study is mainly focused on dielectric properties of lead arsenate glasses crystallized with different concentrations of CuO over continuous ranges of frequency (3 Hz −100 kHz) and temperature (300–633 K). The glasses were prepared by melt quenching technique and were heat treated for prolonged time for ceramization. Prepared samples were characterized by XRD, SEM and DSC techniques. SEM studies indicated that the samples are composed of small crystal grains of the size varying from 0.2 to 1.0 µm cemented with the residual glass phase. XRD studies indicated CuAs₂O₄, Pb₂Cu₇(AsO₄)₆ and Cu₂O are the main crystal phases developed during the crystallization. Optical absorption studies confirmed the presence of copper ions in Cu⁺ valence state in addition to Cu²⁺ state and the fraction of Cu⁺ ions is found to increase with the content of CuO. The optical band gap exhibited increasing trend with CuO content. IR spectral studies indicated an increase of degree of polymerization of the glass network with the CuO content. The observed variations of dielectric parameters with frequency, temperature and CuO content are discussed using different polarization mechanisms. The dielectric relaxation effects exhibited by the loss tangent and the electric moduli are analyzed using graphical method and observed relaxation effects are attributed to the complexes of divalent copper ions with oxygens. The impedance diagrams indicated increase of bulk resistance of the samples with increase of CuO content. The ac conductivity exhibited a decreasing trend with increase of CuO content. The conduction phenomenon is explained using polaron hopping between Cu⁺ and Cu²⁺ ions. The temperature independent part of the conductivity is explained using quantum mechanical tunneling (QMT) model. Finally, it is concluded that the insulating strength of the material increased with CuO content and such materials may be useful as electrical insulators in the low temperature region     

Aqueous dispersion of novel silylated (polyurethane-acrylic hybrid/clay) nanocomposite

Organofunctional silane-modified clay was synthesized using an ion exchange technique. The evolution of the ion exchanged or grafted amount and of the yield were monitored as a function of the initial silane concentration by thermogravimetric analysis. Qualitative evidence of the presence of chemically attached silane molecules on clay was proved by Fourier transform infrared spectroscopy. The grafted amount determined by thermogravimetric analysis was in good agreement with the cation exchange capacity of pristine clay, as determined by confirming that the silanes, which replaced the sodium ions, are grafted onto the clay edges. Using the silane-modified clay, novel aqueous silylated (polyurethane-acrylic/clay) nanocomposite dispersions (SPUA - silylated polyurethane-acrylic) were prepared and studied. X-ray diffraction and transmission electron microscopy examinations indicate that the clay platelets are mostly intercalated or partially exfoliated in the SPUA matrix with a d-spacing of ∼2-2.50 nm. SPUA/clay dispersion with higher clay content exhibits a marginal increase in the average particle size, however, silane-modified clay has a pronounced effect. In addition, the incorporation of clay can also enhance the thermal resistance and mechanical properties of SPUAs dramatically through the reinforcing effect of organophilic clay. Clay does not influence the location and peak broadness of the glass transition temperature (T_g) of the soft segment as well as hard segment domains in the SPUA/clay films. However, the T_g of hard segment domains of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS)-clay nanocomposites were higher than those of commercial clay-based nanocomposites. Better water and xylene resistance of the silane-modified clay nanocomposites proved that trifunctional organosilane can be used as effective modifiers for clays. This method provides an efficient way to incorporate silane-modified clay in the SPUA matrix.     

Effects of amorphous nylon on the properties of poly(butylene terephthalate) and 70/30 poly(butylene terephthalate)/nylon 6 blends

In this work, the effects of adding small amounts of amorphous nylon (a-nylon) on the properties of poly(butylene terephthalate)(PBT) have been studied. Miscibility and properties of PBT/a-nylon blends were compared with those of PBT/nylon 6 blends. Blends were prepared in a twin-screw extruder. The compositions of a-nylon or nylon 6 were varied from 0 to 20 phr. Rheological, thermal, mechanical, and dynamic mechanical properties of the blends were examined using a capillary rheometer, a differential scanning calorimeter (DSC), a universal testing machine (UTM), and a Rheometrics Mechanical Spectrometer(RMS), respectively. The PBT showed a single endotherm around 225.4°C on the DSC thermogram at the first heating scan but exhibited a second endotherm at a temperature below that of the original endotherm at the second heating scan. When a-nylon was added, the original endotherm was remarkably affected, but the second endotherm was not appreciably changed; i.e., the heat of fusion at the original endotherm decreased linearly with increasing a-nylon content, meaning that the addition of a-nylon affects significantly only the higher-melting crystals of PBT. The impact strength of PBT was decreased with nylon 6 content but was increased with increasing content of a-nylon. With an increase in the a-nylon content, the tensile modulus and the flexural modulus of PBT were decreased. Of interest is, however, that the tensile strength was significantly increased with a-nylon up to 15 phr. The melt viscosity of PBT was decreased with increasing a-nylon content, whereas it was not significantly changed with nylon 6 addition; i.e. the addition of a-nylon acted as a lubricant or a processing aid for PBT. The dynamic mechanical and the morphological studies showed that PBT was more miscible with a-nylon than with nylon 6. It was also found that a-nylon exhibited a compatibilizing effect for the PBT/nylon 6 blend of 70/30 wt% composition.     

Biocomposites based on date palm flour reinforced (70/30) polypropylene/thermoplastic starch blend: Effects of flour treatment and selective dispersion

In this work, biocomposites have been prepared from a matrix consisting of polypropylene (PP) and thermoplastic starch (TPS) compatibilized using maleic anhydride (MA) grafted PP (PP-g-MA) and flour obtained from local date palm trees (DPF). To mediate the high hydrophilic character of the filler and attain an optimal dispersion, MA treated DPF (MA-DPF) was prepared via DPF esterification. Pretreated and MA treated DPF composites have been prepared by incorporating 10, 20 and 30% of the flour. MA-DPF has also been dispersed according to a second method consisting of dispersing the flour into starch/glycerol mixture before plasticizing to obtain MA-DPF modified TPS batches that were incorporated into PP to get the same matrix composition and flour loadings as for the first composites. The study of the composites properties proved the MA-DPF efficiency in increasing their impact resilience and diminishing their aptitude to water absorption. This was possible due to the association of the MA-DPF/TPS existing interactions to the better affinity of the esterified flour for the PP phase through its reduced hydrophilic nature. Also, SEM analysis confirmed that the interesting impact and water resistances of MA-DPF modified TPS filled PP composites derive from the DPF reinforced TPS phase consisting the materials.     

30kt／a粒状饲料级磷酸盐的生产装置设计

叙述30 kt/a粒状饲料级磷酸盐(MDCP)的生产工艺流程、主要设备、产品规格、质量.较详细介绍磷酸的净化技术.