Building industry
Concrete, Dry mixes, cement, asphalt - concrete, refractories, gypsum concrete
The unique zeolite properties, its high pozzolanic activity, specified its application possibility as active mineral additive in durable, frost- , moisture- , acid- , sulfate – resistant high strength concrete production. Such concretes are applied in hydraulic structure, as well as bridges, trestles, port installations building. It is known that 10-15% zeolite introduction allows to reduce cement consumption and use cementing of favorite ratio in building mortar and heavy concrete В15-В10 class.
With the introduction of activated zeolite into the concrete up to 200 μm in an amount of 10-20% of the cement mass (М400, М500), plasticizers need no application, as the zeolite gives high plasticity and concrete workability. If a plasticizer is used, its consumption should be 0,3 – 0,4 % of cement dry weight.
The zeolite introduction in concrete improves quality class up to 750-800 and water seeping up to W14-20.
LLC «Keramzit», Ulyanovsk uses activated zeolite, which has passed thermo mechanical treatment, in production of М300-М700 high tensile constructional keramzit concrete . Keramzit concretes of brand mentioned above with zeolite application have a number of advantages in comparison with concrete without use of zeolite – it is its freeze resistance, water resistance, crack resistance.
Moreover, they have higher resistance under fire conditions in comparison with concrete on heavyweight aggregate.
It is due to close values of thermal – expansion coefficient for the filler with zeolite and concrete matrix application.
As a result, higher heavy duty and durability is increased.
The zeolite use in solutions makes it hot which makes it possible to remove a thermal bridge when bonding. 10 % of activated zeolite introduction in to solution, reduces thermal conductivity of mortar mix in 5-10 times. The solution becomes elastic, has high water holding capacity, and not breaks down.
The zeolite use in concrete and concrete goods makes it possible to reduce time and temperature of steam operation. The zeolite is an internal agent in concrete curing, absorbing and keeping water inside for a certain time and then gradually giving it to the cement, promoting its full hydration.
Zeolite application in cement production
Activated zeolite is activity mineral additive, used in constructional materials production including cement. Natural zeolites are introduced in class-list of active mineral additives in accordance with OST 21-9-90, and its appliance in cement production is regulated by GOST 10178-85. Natural zeolites have high pozzolanic activity. (to 300 mg СаО per 1 gr) and can be introduced in 10-20 % doses from clinker mass. Moreover the natural zeolite can take a part of clinker grinding intensifier, increasing efficiency of a mill on 5-15 %.
Partial clinking substitution on 15-20% of zeolite makes it possible to get 400, 500 mark cement, 300 mark portland – pozzoland cement with decreased start time and final set.
The unique zeolite properties, its high pozzolanic activity specified its possibility of use as an active mineral additive in acid proof, sulfate resistant cements production.
The zeolites particularly well suited for hydraulic cement production, resistant to ambient chemical action, for example sea water.
When zeolites use in cement production, setting time decreases, start is 1,5 hours, finishes in 3 hours, specific surface is increased on 800-1900 m2/t., the cement brand is increased on 30-40 units.
Cement properties with natural zeolites addition
Efficiency of zeolite appliance in hardening systems, received by clinker mixed grinding, gypsum rock and 10-15 % of natural zeolites up to the residual of 15% on the sieve №008 have been studied.
It is found that these properties are different from non-additive. Thus, specific surface cement flours increases from 270-310 сm2/g to 420-550 сm2/g by Blaine. Water requirement grows up 24-26% tо 26-30%. Herewith test routine setting time, generally decreases to 15-60 min., however, cases of start and final set decelerating (to 1,5 hours) are detected.
Stone strength on cements with the addition of 10-15% zeolite powder in early periods of hardening (t=20±50С; age 3, 7, 14 days) is lower on 10-15 %, than non-additive . This is typical for all pozzolanic cements. In later terms (28, 90, 180 days), and also after thermal conditioning, stone strength on mixed cements is higher than the stone on ordinary Portland cement.
Zeolite desired content in cement is 10-15%. Herewith the strength of zeolite-containing blastfurnance cements is higher non-additive in all periods of hardening.
When slag sand partial constitution by the zeolite (10-15%), cement paste rheological characteristics are improved (yield value and dynamic viscosity), 10-15 % water gain is decreased. Increased stone sponginess and contraction value in early periods of hardening (up to 14 days) with hydration time increasing are decreased more intensively for zeolite – containing cementing.
Samples of such cement are characterized by better resistance against sulfate ion attack (Кс/с=0,93 — 1,04), in acid solution (Kd Ккисл.=0,81 in comparison with control 0,68 after 1-hour boiling in 40 % dipping acid), and also better freezing resistance (at cycles F=100 strength reduction is 3% in comparison with 10 % for non-additive concretes).
Zeolite application in dry mortars production
The zeolite is good filler at dry mortars production as on cement, and as on gypsum bases. It is a good plasticizer, makes dry mortars placeable, flexible, and increases its pot life, increases strength, water resistance, freeze resistance, decreases thermal conductivity. Zeolites containing dry mortars have high strength mixture adhesion with various bases (concrete, silicate brick, and ceramic, all kinds of foam mortar, gypsum plasterboard, and stone bed). It is no required previously ground the surface. The zeolite gives the mixtures humidity resistance, mixtures have high water holding capacity (99,64%) and crack resistance.
Biostability and fire resistance are significant for compo mortar. Mixtures have microbicidal properties.
The zeolite reduces heat conductivity factor that makes plaster, glue and floor mixes hot. Thus, when 10% of dry cement mass zeolite introduction, mixture thermal conductivity is decreased in 5-10 times.
Having high dispersive ability, the zeolite prevents from dry mortars solidifying and when mixing with water nubbles are not formed.
The best results are obtained when zeolite use in gypsum plaster mixtures both for manual application and machine.
The zeolite makes the mixture flexible, increases its pot life, allows to decrease gypsum binder consumption, makes mixture waterproof and reduces mixture thermal conductivity in 5-10 times. It is increases its strength. Gypsum adhesive compounds for tongue in groove partitions are obtained on basis of zeolite.
Universal adhesive based on zeolite is used for all kinds of foam mortar, foam concrete, gas silicate, and polystyrene concrete, concrete, for ceramic floor tile and facade tile, for ceramic brick etc.
High specification and low cost make the adhesive competitive on the market of dry mortars.
Repair mortars with zeolite have good adhesion, high strength, water resistant, (W10-W20), high freeze resistance F400 and low conductivity (0,2-0,3 W/m*К). Successfully applied on construction sites, equal foreign analogue and even exceed it in some specification.
When dry mortars production, as a rule a big amount of special additives is applied, which are responsible for various mixture specification, needed additives for air entrainment , adhesion arising, strength, moisture resistance, water retention increase, thermal conductivity reduce, plasticity rising, crack resistance increase. All additives are performed outside Russia, this is China, Germany, Turkey, Czechia, Italy.
The zeolite is able to change mixed in additives. That’s why dry mortars with activated zeolite are performed according to import phase-out program and by its quality equal to foreign analogue, and even exceed it in some specification, make mixtures of high quality and more cheaper.
Furthermore the zeolite being strong adsorbent is able to absorb and keep radioactive elements that make all mixtures pollution free.
The zeolite appliance in foam concrete production, gas silicate, polystyrene concrete
The zeolite, used as filler or as additive in foam concrete production, gas silicate, polystyrene concrete gives good results, that is: strengthen, allows to save cement consumption up to 20%, increases freeze resistance and water resistance of products and also reduces shrinkage and increases crack resistance. Introduction of 10% zeolite in these concretes, although slightly compress but at ones reduces thermal conductivity.
The appliance of zeolite in fire proof finish, mastic, and refractory production.
Zeolite applicability in fire safety security predetermines its physicochemical properties. Zeolites — water alumosilicates containing oxide of alkaline and alkaline – earth metals, characterized by a strictly regular pore structure, which is filled with water molecules in normal temperature conditions. The zeolites as well as have tallish heat capacity and thus can be a cooling agent.
Secondly, the zeolite can be is easily processed – grinding, sizing, pressing, forming, anhydration, baking that easily allows to create different technical forms.
It gives the possibility to use the zeolite as a component in the following means of fire safety of fabrication system attainment and building construction: in fire extinguishing powdered and combined compositions, as filler of expandable pain materials for which mechanical strength is extremely important, formed cooked cellular material layer under heating, in fire prevention device for its fire resistance rising.
Natural zeolite application field in fire safety devices of building constructions and fabrication system is very wide. The use of zeolite allows to get inorganic non-inflammable gas carbon on basis of silicon when heating, more flame resistant than organic gas carbon on basis of carbon.
The zeolite approved itself as perfect filler in refractory production (plates, blocks, panels) on the basis of high modulus liquid glass “Silinom”.
Zeolite appliance in asphalt - concrete production
One of the ways of road lifetime extension and at the same time cover upgrading is the use of new materials, such as zeolite activated.
The zeolite activated, received by thermo mechanical activation of natural zeolite, represents reactionary activated silica, having biogenicity. It is natural nanostructured material, molecule sieve with high ion exchange capacity, having high adsorptive capacity, perfect thermal – insulating properties.
The quality of ready asphalt covering, its life time directly depends on asphalt mix compression quality on-the-job. For standard asphalt covering density achievement is needed strictly respect a host of factors, that is: temperature control during mixture transportation, spreading and properly compression. Temperature spottiness of asphalt mix is revealed when mix transportation in asphalter.
The difference in temperature at laying place over the surface of customized covering can be very essential, resulting in separate under compacted zones formation, which breaks in time faster than all the rest covering, forming separate potholes.
As well as for asphalt mix preparation a big amount of ballast and sand from crashing the dense rocks is used that makes it very heavy and hardly to apply.
Characteristics of asphalt mix selection in the third climate zone is what that it is necessary to select asphalt concrete index both when operating at elevated temperatures and at negative temperatures, which is very difficult to achieve.
That’s why to escape expansion cracks formation is practically impossible.
Zeolite addition in 0,5-1% of mixture solid part makes it possible to achieve asphalt mix placeability without strength factor reduction at 50оС, 20оС.
Moreover, physical and mechanical performance of mixture at 0оС greatly improved , reducing from11 MPa to 9,5-7,4 МPa. Mixture more uniformly keeps the temperature and allows getting uniform sealing in covering.
Compressibility of mixture after zeolite addition improves by times, residual porosity is about 0,8% less. Zeolite appliance as additive in the manufacture of warm asphalt concrete is already used by German company MHI Naturstein&Baustoffservice GmbH.
The zeolite can be used as an ice- melter , containing calcium chloride or trietanolamine sodium.
Calcium chloride 22,5-45,0
Zeolite 50,0-77,0
Trietanolamine 0,5-5,0
In this case components not only mixed, as in case of getting frictional chemicals but zeolite soaking in calcium chloride happens with corrosion inhibitor input and getting of stable nubbles.
Zeolite and trietanolamine introduction makes it possible to increase compound efficiency, reduce degree of corrosion, strongly reduce calcium chloride consumption due to reagent action change. Such reagent can be used on bridges, where use of salt containing reagent is not permissible.
Salt as a component of a reagent dissolves ice and the zeolite quickly adsorbs received salt liquid, thus saving bridge covering and constructions.
Experimental works in this direction were carried out with the laboratory of highway department of the Ulyanovsk Region.
