scholarly journals POZZOLANE AND CORROSION-INHIBITING PROPERTIES OF THE NATURAL ZEOLITE TUFF

2020 ◽  
Vol 5 (8) ◽  
pp. 78-86
Author(s):  
T. Smorodinova ◽  
M. Kotvanova
Keyword(s):  
Cement Paste ◽  
Natural Zeolite ◽  
Cement Stone ◽  
Leaching Kinetics ◽  
Reaction Products ◽  
Natural Pozzolan ◽  
Sulfate Ions ◽  
Hydrolysis Of ◽  
Zeolite Tuff ◽  
Anticorrosion Properties

In this article the activity of the zeolite tuff of the Lulinsky deposit of Khanty-Mansiysk autonomous okrug –Yugra to calcium and sulfate ions has been evaluated . The components of zeolite tuff bind these ions to sparingly soluble products. The experimental results obtained show that tuff can be used as a natural pozzolan. Concerning the reaction products, the dynamics of the phase composition of cement paste with the zeolite tuff additives during hardening is shown. Supplementation promotes hydrolysis of alite, while the content of calcium hydrosulfoaluminate increases. The dynamics of strength and the compression of cement paste without an additive and with the zeolite tuff additive are estimated. The possibility and efficiency of using of zeolite tuff as a reinforcing additive to Portland cement is shown. It was found that a 5 % zeolite tuff additive with a particle size of 5-10 μm at 7 days increases the compressive strength by 15 %, and at 28 days by 21 %. The study of the calcium hydroxide leaching kinetics from cement stone is showed that a 5 % zeolite tuff additive leads to suppression of the leaching process and indicates anticorrosion properties of additives.

scholarly journals POROSITY PARAMETERS OF CEMENT STONE CONTAINING CHEMICAL ADMIXTURES OF DIFFERENT PURPOSE / CEMENTINIO AKMENS SU SKIRTINGOS PASKIRTIES CHEMINIAIS PRIEDAIS PORINGUMO RODIKLIAI

2013 ◽  
Vol 5 (5) ◽  
pp. 530-535
Author(s):  
Lukas Venčkauskas ◽  
Mindaugas Daukšys
Keyword(s):  
Cement Paste ◽  
Cement Stone ◽  
Hardened Cement ◽  
Closed Porosity ◽  
Hardened Cement Paste ◽  
Chemical Admixtures ◽  
Average Size ◽  
The Impact ◽  
Plasticizing Admixture

The conducted research has established a complex influenceand the impact of separate chemical admixtures of differentpurpose on the parameters of the porosity of hardened cementpaste such as open and closed porosity, the average size of poresand the rates of pore inequality. According to the parametersof the porosity of hardened cement paste, on the basis of A. E.Sheikin’s methodology, the number of freezing-thawing cycleswas predicted. This research used plasticizing, viscosity modifyingand antifoaming admixtures. It has been found that, when theamount of plasticizing admixture in cement paste (W/C–0.45) isconstant and makes 1.1% of the cement mass, and the amountof viscosity modifying and antifoaming the admixture increasesfrom 0.1 to 0.6% and from 0.05 to 0.3% respectively, the openporosity of hardened cement paste varies between 30.21% and31.06%, while closed porosity varies between 5.39% and 6.22%.When the amount of the plasticizing admixture in cement paste(W/C–0.45) exceeds 1.1% of the cement mass, the open porosityof hardened cement paste increases by 1.4 times and closedporosity decreases by 2.5 times. While adding 0.1% of the viscositymodifying admixture to cement paste, the open porosityof hardened cement paste is increased by 1.5 times and closedporosity decreases by 2.4 times. The amount of 0.05% of thecement mass of the antifoaming admixture results in the increasedopen porosity of hardened cement paste by 1.5 times and reducedclosed porosity by 3.5 times. Santrauka Tyrimo metu nustatyta kompleksinė bei atskirų skirtingos paskirties cheminių priedų įtaka cementinio akmens poringumo rodikliams – atvirajam ir uždarajam poringumui, vidutinio porų dydžio ir porų vienodumo rodikliams. Tyrimuose naudoti cheminiai priedai: plastifikuojantis, klampą modifikuojantis ir mišinyje susiformavusias oro poras suardantis priedas. Nustatyta, kad cemento tešloje (V/C – 0,45) esant pastoviam plastifikuojančio priedo kiekiui – 1,0 % cemento masės, klampą modifikuojančio priedo kiekiui kintant nuo 0,1 iki 0,6 %, o mišinyje susiformavusias oro poras suardančio priedo kiekiui kintant nuo 0,05 iki 0,3 %, cementinio akmens atvirasis poringumas svyruoja nuo 30,21 iki 31,06 %, o uždarasis – nuo 5,39 iki 6,22 %. Cemento tešloje viršijus plastifikuojančio priedo 1,1 % cemento masės, cementinio akmens atvirasis poringumas padidėja apie 1,4 karto, o uždarasis poringumas sumažėja apie 2,5 karto. Pridėjus į tešlą 0,1 % cemento masės klampą modifikuojančio priedo, cementinio akmens atvirasis poringumas padidėja apie 1,5 karto, uždarasis poringumas sumažėja apie 2,4 karto. Oro poras suardančio priedo kiekis 0,05 % cemento masės cementinio akmens atvirąjį poringumą padidina apie 1,5 karto, uždarąjį poringumą sumažina apie 3,5 karto.

A Fluorescence Polarization Assay for Cyclic Nucleotide Phosphodiesterases

2002 ◽  
Vol 7 (3) ◽  
pp. 215-222 ◽  
Author(s):  
Wei Huang ◽  
Yan Zhang ◽  
J. Richard Sportsman
Keyword(s):  
Cyclic Nucleotide ◽  
Fluorescence Polarization ◽  
Drug Targets ◽  
Second Messengers ◽  
Reaction Products ◽  
Cyclic Nucleotide Phosphodiesterases ◽  
Extracellular Signals ◽  
Fluorescence Polarization Assay ◽  
Hydrolysis Of ◽  
Nucleotide Phosphodiesterases

Cyclic nucleotide phosphodiesterases (PDEs) catalyze the hydrolysis of the 3′-ester bond of cyclic AMP (cAMP) and cyclic GMP (cGMP), important second messengers in the transduction of a variety of extracellular signals. There is growing interest in the study of PDEs as drug targets for novel therapeutics. We describe the development of a homogeneous fluorescence polarization assay for PDEs based on the strong binding of PDE reaction products (i.e., AMP or GMP) onto modified nanoparticles through interactions with immobilized trivalent metal cations. This assay technology (IMAP) is applicable to both cAMP- and cGMP-specific PDEs. Results of the assay in 384- and 1536-well microplates are presented.

Study of the pozzolanic activity and hydration products of cement pastes with addition of natural zeolites

Clay Minerals ◽  
2011 ◽  
Vol 46 (2) ◽  
pp. 241-250 ◽  
Author(s):  
V. Lilkov ◽  
O. Petrov ◽  
V. Petkova ◽  
N. Petrova ◽  
Y. Tzvetanova
Keyword(s):  
Surface Area ◽  
Cement Paste ◽  
Chemical Reactions ◽  
Natural Zeolite ◽  
Early Stage ◽  
Pozzolanic Activity ◽  
Large Surface Area ◽  
Natural Zeolites ◽  
Hydration Products ◽  
Cement Pastes

AbstractThis paper presents results from comparative thermogravimetric, calorimetric and pozzolanic activity analyses of five natural zeolite samples from Bulgaria, Slovakia, Philippines, USA and North Korea. The zeolites actively participate in the hydration processes of cement. Their activity in the early stage of hydration is based mainly on the large surface area of the particles while, in the later stages of activation, chemical reactions occur between the products of the hydration of cement and the soluble SiO2 that is present in the bulk of the zeolites. It has been shown that in all cement pastes which contain zeolite additives, the quantity of portlandite is lower than that in pure cement paste or is even totally absent. The amounts of hydration products are greater when 30% zeolite is used than when 10% zeolite is added (excluding the sample with chabazite). The lowest pozzolanic activity is shown by chabazite, which possessed the lowest SiO2/Al2O2 ratio.

scholarly journals THE ESTIMATION METHODS OF MICROFILLERS INFLUENCE ON CEMENT STONE PROPERTIES/MIKROUŽPILDŲ ĮTAKOS CEMENTINIO AKMENS SAVYBĖMS ANALITINIO ĮVERTINIMO PRINCIPAI

1997 ◽  
Vol 3 (10) ◽  
pp. 69-75
Author(s):  
Juozas Deltuva ◽  
Žymantas Rudžionis
Keyword(s):  
Relative Density ◽  
Silica Fume ◽  
Cement Paste ◽  
Heterogeneous Material ◽  
Estimation Methods ◽  
Cement Stone ◽  
Structural Element ◽  
Regular Form ◽  
Amorphous Sio2 ◽  
Hardening Process

The concrete and cement microfillers are materials of different fineness, such as wastes of production or pulverized rocks. According to their influence on cement hardening process, they may be classified into inert microfillers or chemically active ones. The chemically active microfillers, such as silica fume, fly ashes and others, have more then 50% amorphous SiO2, that takes part in cement hardening process. Inert microfillers, such as granite, dolomite, sand dust and others, in most cases have no influence on the cement hydration. The usage of microfillers in concrete is common, but so far no clear dependence between the quantity of added microfillers and properties of concrete has been established. One of possible ways to estimate the microfillers influence on the products with cement binder is the structural element method. The structural element is the smallest cell, approximated to a spatial figure of regular form, that has all components with the same proportions, as in all the volume of heterogeneous material. The essence of this method is to divide the mix in to bigger particles, that are named “nuclei” of structural elements and take 50% of all mix volume, and smaller particles, that form cover layers of the nuclei and make up the rest of the volume of the mix. The dependence between the relative density of loose materials and relation (1) between the diameters of the bigger and smaller particles of the structural element has been estimated. This relation is changed when microfillers are added to the cement. There is a possibility to optimize relative density by (2), (3) and (4) relations, if the granulometric composition of the cement and microfillier is known. The experimental and calculated results of this optimization are shown in Table 1. The properties of pressed cement stone with inert microfillers admixture are presented in Table 2. Formulae for calculating the relative density (8) and compressive strength (11) of hardening cement have been estimated. The chemically active microfillers, such as silica fume, interact with Ca(OH)2 and form new CSH. The density and strength of cement stone increased after this interaction. The influence of chemically active microfillers on the relative density of the cement stone is given in (12). The density of cement stone increases to 4.5% and strength increases to 40.2%, if the quantity of inert microfillers in the cement paste reaches 10%. The density of cement stone increases to 7.4% and strength increases to 54.7%, if the quantity of chemically active microfillers in the cement paste reaches 10%.

Darstellung von o-Phenylen-bis(dibromphosphan) — Reaktionsprodukte von o-Phenylen-bis(dichlorphosphan) / Synthesis of o-Phenylene-bis(dibromophosphane) — Reaction Products of o-Phenylene-bis(dichlorophosphane)

1984 ◽  
Vol 39 (12) ◽  
pp. 1706-1710 ◽  
Author(s):  
H.-J. Wörz ◽  
E. Quien ◽  
H. P. Latscha
Keyword(s):  
Hydrogen Peroxide ◽  
Hydrogen Bromide ◽  
Equimolar Amount ◽  
Reaction Products ◽  
Large Excess ◽  
Cyclic Anhydride ◽  
Complete Hydrolysis ◽  
Hydrolysis Of

o-Phenylene-bis(dibromophosphane) (1) is prepared by reaction of P ,P,P′,P′-tetrakis(dim ethylamino)-o-phenylenediphosphane with hydrogen bromide in ether. The reaction of o-phenylene- bis(dichlorophosphane) (2) with CH3OH in ether yields o-phenylene-bis(phosphonousacid- dimethylester) (3). The Michaelis-Arbuzov conversion of 3, either by heat or by catalytic amounts of CH3I in toluene, yields ophenylene-bis(methylphosphinic-acid-methylester) (4). The reduction of 2 must be carried out with a large excess of LiAlH4 (1:4) in ether to give o-phenylenediphosphane (5). The cyclic anhydride (6) of P.P′-dichloro-o-phenylenediphosphonous acid is formed when 2 is hydrolyzed in ether with an equimolar amount of water. Complete hydrolysis of 2 with an excess of water gives o-phenylenediphosphonous acid (7). With hydrogen peroxide o-phenylenediphosphonic acid (8) can be isolated.

scholarly journals Multiple Reaction Products from the Hydrolysis of Chiral and Prochiral Organophosphate Substrates by the Phosphotriesterase from Sphingobium sp. TCM1

Biochemistry ◽  
2018 ◽  
Vol 57 (12) ◽  
pp. 1842-1846 ◽  
Author(s):  
Andrew N. Bigley ◽  
Tamari Narindoshvili ◽  
Dao Feng Xiang ◽  
Frank M. Raushel
Keyword(s):  
Reaction Products ◽  
Hydrolysis Of

The acid-catalysed hydrolysis of α-methylallyl acetate in aqueous solution

1968 ◽  
Vol 21 (7) ◽  
pp. 1727
Author(s):  
RA Fredlein ◽  
I Lauder
Keyword(s):  
Aqueous Solution ◽  
Reaction Products ◽  
Arrhenius Parameters ◽  
Crotyl Alcohol ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Tracer Experiments

The kinetics of the acid-catalysed hydrolysis of a-methylallyl acetate in aqueous solution have been studied over the range 30-100�. Oxygen-18 tracer experiments reveal the mechanism to be solely Aac2 and the Arrhenius parameters are consistent with this conclusion. Crotyl alcohol is observed in the reaction products. The formation of rearranged alcohol is explained by allylic isomerization of the α-methylallyl alcohol produced by the hydrolysis.

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