NO123563B

NO123563B -

Info

Publication number: NO123563B
Application number: NO495568A
Authority: NO
Inventors: U Sundelin; E Eriksson
Original assignee: Intong Ab
Priority date: 1967-12-13
Filing date: 1968-12-11
Publication date: 1971-12-06
Also published as: GB1203893A; BE725479A; DE1813881A1; SE311856B

Description

Fremgangsmåte for fremstilling av porøse lettballastkorn. Process for the production of porous light ballast grains.

Den foreliggende oppfinnelse vedrbrer en fremgangsmåte for fremstilling av porbse lettballastkorn beregnet på stbping av lettballastbetong, idet legemer av gass- eller skumbetong knuses til korn som forsynes med skall av et hydraulisk bindemiddel, f.eks. Portlandsement, hvorefter de således behandlede korn herdes. The present invention relates to a method for the production of porous lightweight aggregate grains intended for the filling of lightweight aggregate concrete, in that bodies of aerated or foamed concrete are crushed into grains which are provided with a shell of a hydraulic binder, e.g. Portland cement, after which the thus treated grains are hardened.

Fra svensk patent nr. 60 172 er det kjent å fremstille porbse betongmasser, i hvilke de i konvensjonell tungbetong anvendte ballastmaterialer, som sand og grus, er erstattet med gass- eller skumbetong som er knust til korn. Fordelene med slike betongmasser er at ved samme varmeisoleringsevne oppnås bnsket vann-tetthet og at legemer med god varmeisoleringsevne kan fremstilles uten æsing eller luftinnblanding ved stbpingsprosessen. Dette byr på den fordel at stbpingen kan utfores av ikke-spesialut-dannede folk samtidig som massen kan stbpes i vilkårlig store enheter uten at homogeniteten reduseres. From Swedish patent no. 60 172, it is known to produce porous concrete masses, in which the ballast materials used in conventional heavy concrete, such as sand and gravel, are replaced with gas or foam concrete that is crushed into grains. The advantages of such concrete masses are that, with the same thermal insulation capacity, the desired watertightness is achieved and that bodies with good thermal insulation properties can be produced without aeration or air mixing during the sealing process. This offers the advantage that the stacking can be carried out by non-specially trained people at the same time that the mass can be stacked in arbitrarily large units without the homogeneity being reduced.

I praksis har det imidlertid vist seg vanskelig å fremstille slike betongmasser ved samtidig opprettholdelse av god varmeisoleringsevne for betongen, således er det ved anvendelse av gass- eller skumbetong som ballastmateriale umulig å tilberede massene uten at de porbse ballastkornene knuses i de for bland-ingen anvendte redskaper. Når ballastmaterialet knuses til korn, vil kornstbrrelsen i en fraksjon bli så liten at varmeisolerings-evnen nedsettes i vesentlig grad. En annen ulempe ved betong-massene er at kornene har så lav egenfasthet at også den ferdige betongens fasthet blir lav. In practice, however, it has proven difficult to produce such concrete masses while simultaneously maintaining good thermal insulation properties for the concrete, so when using gas or foam concrete as ballast material, it is impossible to prepare the masses without the porous aggregate grains being crushed in the ones used for the mixture implements. When the ballast material is crushed into grains, the grain size in a fraction will be so small that the thermal insulation ability is reduced to a significant extent. Another disadvantage of the concrete masses is that the grains have such a low intrinsic strength that the strength of the finished concrete is also low.

Et formål med den foreliggende oppfinnelse er å eliminere de ovenfor nevnte ulemper samt dessuten å oppnå hittil ukjente for-deler ved betongmasser av den innledningsvis nevnte type. Dette skjer ifblge oppfinnelsen ved at for påfbring av bindemiddelskallene lagres kornene i vann så lang tid at de mettes med vann, at det hydrauliske bindemiddel i torr tilstand påfbres de våte korn og at de med bindemiddel belagte korn herdes ved hjelp av damp under bket trykk og bket temperatur. Derved oppnås det lettballastkorn med god egenfasthet, hvilket medfbrer at den ferdige betong får en god fasthet. An aim of the present invention is to eliminate the above-mentioned disadvantages and also to achieve hitherto unknown advantages with concrete masses of the type mentioned at the outset. According to the invention, this happens by applying the binder shells to the grains stored in water for such a long time that they are saturated with water, the hydraulic binder in a dry state is applied to the wet grains and the binder-coated grains are hardened with the help of steam under low pressure and baked temperature. This results in light aggregate grains with good intrinsic strength, which means that the finished concrete has good strength.

Den ifblge oppfinnelsen nevnte gass- eller skumbetong kan utgjbres av i handelen vanlige gass- eller skumbetongarter med en tetthet på o 0.4, 0.5 eller 0.65 kg/dm 3. Den for formålet anvendte gass- eller skumbetong knuses til kornstbrrelse på ned til 4 mm. Herved er det vesentlig at knusingen ikke drives altfor langt, for ellers ville kornene bli så små at deres porbsitet går tapt. Efter knusingen forsynes kornene med et skall av et hydraulisk bindemiddel, f.eks. av Portlandsement eller blanding av Portlandsement med kalk. Påfbringen av skall kan skje på den måte at kornene fuktes og rulles over et skikt av torr sement, hvorved kornene på grunn av sin fuktighetsgehalt adsorberer sementen og tilforer denne den for avbinding nbdvendige mengde vann, hvorved det dannes et tynt sementskall som tillates å herde noe. Her-efter foretas en herding som med fordel kan skje i en dampautoklav. Efter avsluttet herding er lettballastkornene ferdige og kan innstbpes som ballast i betong. The aerated or foamed concrete mentioned according to the invention can be produced from commercial aerated or foamed concrete types with a density of o 0.4, 0.5 or 0.65 kg/dm 3. The aerated or foamed concrete used for the purpose is crushed to a grain size of down to 4 mm. Here it is essential that the crushing is not carried out too far, because otherwise the grains would become so small that their porosity is lost. After crushing, the grains are provided with a shell of a hydraulic binder, e.g. of Portland cement or a mixture of Portland cement with lime. The shell can be applied in such a way that the grains are moistened and rolled over a layer of dry cement, whereby the grains, due to their moisture content, adsorb the cement and add to it the amount of water required for setting, whereby a thin cement shell is formed which is allowed to harden somewhat . After this, curing is carried out, which can advantageously take place in a steam autoclave. After completion of curing, the light ballast grains are ready and can be incorporated as ballast in concrete.

Ved stbping av betong er det viktig at betongmassen i lbpet av karbonatiseringstiden tilfores store mengder vann. Dette skjer vanligvis på den måte at vann ved hjelp av vannslanger eller lignende sprbytes på det ferdige stbpte betonglegemet. When placing concrete, it is important that large quantities of water are added to the concrete during the carbonation period. This usually happens in such a way that water is sprayed onto the finished concrete body with the help of water hoses or the like.

Ifblge den foreliggende oppfinnelse har det vist seg å være mulig å tilfore betongens karbonatiseringsvann på en betydelig enklere måte. Man har nemlig funnet at gass- eller skumbetong-korn som lagres i vann for påfbring av det fasthetsbkende skall, •efter påfbring har evnen til å avgi innesluttet fuktighet. Dette skjer på grunn av at skallet, hvis dette utgjbres av et hydraulisk bindemiddel, oppviser mikroskopiske porer som gir kapilar-virkning, hvorved vann kan diffundere ut fra kornenes kjerne. For fremstilling av slike vannavgivende korn har det vist seg tilstrekkelig å lagre kornene i vann i ca. to dbgn. According to the present invention, it has been shown to be possible to add carbonation water to the concrete in a significantly simpler way. Namely, it has been found that gas or foam concrete grains which are stored in water for application of the strength-enhancing shell, •after application, have the ability to release trapped moisture. This happens because the shell, if this is expanded by a hydraulic binder, exhibits microscopic pores that produce a capillary effect, whereby water can diffuse out from the grain's core. For the production of such water-releasing grains, it has proven sufficient to store the grains in water for approx. two dbgn.

Nedenfor folger et eksempel på en foretrukken utfbrelsesform Below follows an example of a preferred embodiment

av oppfinnelsen. of the invention.

Eksempel Example

Lettbetong med tetthet 0.65 kg/dm 3ble knust i en kjefttygger til korn som eftér fjerning av de fineste partikler, viste fblgende kornstbrrelsesfordeling: Lightweight concrete with a density of 0.65 kg/dm 3 was crushed in a jaw crusher into grains which, after removal of the finest particles, showed the following grain size distribution:

Kornene ble lagret i vann i to dbgn, hvorefter de gjennomfuktede korn ble utlagt på et rystebord, på hvilket det var lagt et skikt av torr Portlandsement. Herved avga kornene den for sementav-bindingen nbdvendige mengde vann, slik at det på kornene ble dannet et tynt skall av ikke avbundet sement. Derefter lot man sementskallene herde noe, hvorefter kornene ble innfort i en dampautoklav med temperatur og trykk på 183°c resp. 10 kp/cm^. Behandlingen i autoklaven varte i seks timer. The grains were stored in water for two days, after which the thoroughly moistened grains were laid out on a shaking table, on which a layer of dry Portland cement had been laid. In this way, the grains gave off the amount of water necessary for cement debonding, so that a thin shell of unbound cement was formed on the grains. The cement shells were then allowed to harden somewhat, after which the grains were placed in a steam autoclave with a temperature and pressure of 183°c or 10 kp/cm^. The treatment in the autoclave lasted six hours.

De ifblge denne fremgangsmåte fremstilte lettballastkornene ble anvendt for stbping av betonglegemer som ble testet vedrbrende tetthet og fasthet. For dette formål ble det tilberedt et bindemiddel bestående av 25 vektdeler Portlandsement og 75 vektdeler sand, hvilket bindemiddel ble blandet med lettballastkornene i vektforholdet 1:5, hvorefter vann ble tilsatt. Betongmassen ble stbpt i kubusformenheter på 10 x 10 x 10 cm. Efter 28 dbgns lagring oppviste prbveenhetene en tetthet = 1.72 kg/dm 3 og en trykkfasthet opptil 206 kp/cm <2>. The light ballast grains produced in accordance with this method were used for filling concrete bodies which were tested for density and firmness. For this purpose, a binder was prepared consisting of 25 parts by weight of Portland cement and 75 parts by weight of sand, which binder was mixed with the light ballast grains in a weight ratio of 1:5, after which water was added. The concrete mass was stbpt in cube-shaped units of 10 x 10 x 10 cm. After 28 days of storage, the test units showed a density = 1.72 kg/dm 3 and a compressive strength of up to 206 kp/cm <2>.

Claims

Method for the production of porous lightweight aggregate grains intended for stpping of lightweight aggregate concrete, in that bodies of aerated or foamed concrete are crushed into grains that are provided with a shell of a hydraulic binder, e.g. Portland cement, after which the thus treated grains are hardened, characterized in that for the application of the binder shells, the grains are stored in water for such a long time that they are saturated with water, that the hydraulic binder in a dry state is applied to the wet grains and that the binder-coated grains are hardened by using steam under reduced pressure and reduced temperature.