Investigation of properties of fresh and hardened self-compacting concrete with mineral additions based on industrial by-products

Beton, kao jedan od najčešće upotrebljavanih materijala u građevinskojindustriji evoluirao je sa razvojem građevinarstva, od početaka primene dodanašnjih dana. Konvencionalni beton se ugrađuje pomoću vibrirajućeopreme kako bi se u njemu redukovao sadržaj zaostalog vazduha,eliminisala mogućnost pojave kaverni i drugih šupljina na kontaktima saarmaturom i oplatom (takozvani normalno vibrirani beton, Normal VibratedConcrete – NVC). Na taj način beton postaje kompaktniji, gušći ihomogeniji, što je osnov za njegovo prihvatljivo ponašanje u konstrukciji.Tehnološka operacija kompaktiranja tradicionalno igra ključnu ulogu uproizvodnji kvalitetnog betona sa optimalnom čvrstoćom i trajnošću.Razvoj hemijskih dodataka tipa superplastifikatora omogućio je lakšeugrađivanje betona, pošto se malim doziranjem ovakvog hemijskog dodatkamogu smanjiti sile trenja između čvrstih čestica, što za rezultat dajepokretljivije i obradljivije betone (betone tečnijih konzistencija) koje jelakše ugraditi, uz zadržavanje iste količine vode. Ekstrapolacijom konceptaupotrebe superplastifikatora u pravcu dobijanja betona tečnijih konzistencijadošlo se do koncepta samozbijajućeg betona (Self-compacting Concrete -skraćeno SCC). Samozbijajući beton se može definisati kao beton, koji ćebez primene mehaničkih sredstava za ugrađivanje popunjavati sve ugloveoplate i uzane prostore između gusto raspoređenih šipki armature, samo poddejstvom sopstvene težine, tako da se u završnoj fazi dobije kompaktanbeton veće trajnosti.U sastav samozbijajućeg betona, po pravilu, ulaze veoma fini mineralnidodaci, od kojih su najčešće primenjivani krečnjačko i dolomitno brašno,kao i leteći pepeo. U okviru eksperimentalnog rada u ovoj disertaciji je,osim letećeg pepela (poreklom iz dve termoelektrane, TE "Kolubara" i TE"Kostolac") upotrebljen i sprašeni reciklirani beton (dobijen rušenjemdotrajalih armiranobetonskih konstrukcija, odnosno drobljenjem kontrolnihlaboratorijskih kocki) i sprašeni elementarni sumpor (koji se dobija kaonusprodukt u naftnoj industriji, u Rafineriji nafte Pančevo).U okviru eksperimentalnog rada spravljeno je i detaljno ispitivano 11mešavina SCC: dve referentne SCC mešavine sa krečnjačkim brašnom kaomineralnim dodatkom, pet mešavina sa letećim pepelom, tri mešavine sasprašenim recikliranim betonom i četiri mešavine sa sprašenim sumporom.Prethodno je prilikom definisanja recepture za SCC mešavine spravljeno iispitano 12 probnih (pilot) mešavina. Sve navedene mešavine, osim dveprobne (pilot) mešavine, imale su svojstva koja karakterišu samozbijajuće...Concrete, as one of the most commonly used materials in the constructionindustry, has evolved with the development of construction, from thebeginning to the present day. Placing of conventional concrete is usuallydone with the use of vibrating equipment to help in reduction of entrainedair content, eliminating the possibility of cavities occurrence in contact withreinforcement and formwork (the so-called Normal Vibrated Concrete,NVC). Concrete becomes more compact, denser and more homogeneous,which are the basic aspects for an acceptable behavior in the structure. Thisoperation, compaction, traditionally plays a key role in the production ofhigh quality concrete, with optimum strength and durability.Development of superplasticizers (chemical admixtures for concrete)allowed easier placing of concrete with stiffer consistency; a small dosageof this type of chemical admixtures can reduce the friction between theparticles, which results in more mobile and workable concrete (concretewith fluid consistency) that is easier to place in formwork, whilemaintaining the same amount of water. Extrapolation of the concept of thesuperplasticizers use towards obtaining concrete with fluid consistency ledto the concept of Self-compacting Concrete - SCC for short. Selfcompactingconcrete, is defined as a concrete mix that can be placed purelyby means of its own weight, with little or no vibration and is a highlyflowable concrete that spreads into place, fills formwork, and wraps eventhe most congested reinforcement, and showing no signs of segregation.Typically, SCC contains certain quantities of very fine mineral additions;the most commonly applied are limestone and dolomite powder and fly ash.Within the experimental work in this thesis, besides fly ash (originatingfrom two power plants, "Kolubara" and "Kostolac"), recycled pulverizedconcrete (obtained by demolition of old concrete structures) and powderedelemental sulfur (which is obtained as a by-product of the petrol industry, inPancevo Oil Refinery).Within this experimental work, 11 mixtures of SCC were prepared, tworeference SCC mixtures with limestone powder as mineral addition, fivemixtures with fly ash, three mixtures with ground recycled concrete andfour mixtures with ground elemental sulfur. Also, during the proces ofdefining the composition of SCC mixtures, 12 test (pilot) mixutures weremade and investigated. All mixtures, except two test mixtures, could becharacterized as self-compacting concrete, based on their fresh properties.The applied extensive testing of fresh and hardened SCC (with respect tothe designed properties of fresh SCC, the research findings of the recent..

The New Thermal Insulation Material Based on Miscanthus X Giganteus and Fly Ash

This investigations were carried out to study the fly ash utilization in manufacturing of thermal insulation based on Miscanthus x Giganteus fibres. This is a brand new cost-effective, ecological and energy-efficient material. In order to increase energy efficiency and resource saving, the lime and fly ash were used instead of cement binder. Two different mixtures were made, one with lime and one with lime and fly ash. The mixture with lime and fly ash showed the higher values of compressive and bending strength. It can be concluded that addition of fly ash contributes to mechanical properties of this new material

Investigation of properties of fresh and hardened self-compacting concrete with mineral additions based on industrial by-products

Beton, kao jedan od najčešće upotrebljavanih materijala u građevinskoj industriji evoluirao je sa razvojem građevinarstva, od početaka primene do današnjih dana. Konvencionalni beton se ugrađuje pomoću vibrirajuće opreme kako bi se u njemu redukovao sadržaj zaostalog vazduha, eliminisala mogućnost pojave kaverni i drugih šupljina na kontaktima sa armaturom i oplatom (takozvani normalno vibrirani beton, Normal Vibrated Concrete – NVC). Na taj način beton postaje kompaktniji, gušći i homogeniji, što je osnov za njegovo prihvatljivo ponašanje u konstrukciji. Tehnološka operacija kompaktiranja tradicionalno igra ključnu ulogu u proizvodnji kvalitetnog betona sa optimalnom čvrstoćom i trajnošću. Razvoj hemijskih dodataka tipa superplastifikatora omogućio je lakše ugrađivanje betona, pošto se malim doziranjem ovakvog hemijskog dodatka mogu smanjiti sile trenja između čvrstih čestica, što za rezultat daje pokretljivije i obradljivije betone (betone tečnijih konzistencija) koje je lakše ugraditi, uz zadržavanje iste količine vode. Ekstrapolacijom koncepta upotrebe superplastifikatora u pravcu dobijanja betona tečnijih konzistencija došlo se do koncepta samozbijajućeg betona (Self-compacting Concrete - skraćeno SCC). Samozbijajući beton se može definisati kao beton, koji će bez primene mehaničkih sredstava za ugrađivanje popunjavati sve uglove oplate i uzane prostore između gusto raspoređenih šipki armature, samo pod dejstvom sopstvene težine, tako da se u završnoj fazi dobije kompaktan beton veće trajnosti. U sastav samozbijajućeg betona, po pravilu, ulaze veoma fini mineralni dodaci, od kojih su najčešće primenjivani krečnjačko i dolomitno brašno, kao i leteći pepeo. U okviru eksperimentalnog rada u ovoj disertaciji je, osim letećeg pepela (poreklom iz dve termoelektrane, TE "Kolubara" i TE "Kostolac") upotrebljen i sprašeni reciklirani beton (dobijen rušenjem dotrajalih armiranobetonskih konstrukcija, odnosno drobljenjem kontrolnih laboratorijskih kocki) i sprašeni elementarni sumpor (koji se dobija kao nusprodukt u naftnoj industriji, u Rafineriji nafte Pančevo). U okviru eksperimentalnog rada spravljeno je i detaljno ispitivano 11 mešavina SCC: dve referentne SCC mešavine sa krečnjačkim brašnom kao mineralnim dodatkom, pet mešavina sa letećim pepelom, tri mešavine sa sprašenim recikliranim betonom i četiri mešavine sa sprašenim sumporom. Prethodno je prilikom definisanja recepture za SCC mešavine spravljeno i ispitano 12 probnih (pilot) mešavina. Sve navedene mešavine, osim dve probne (pilot) mešavine, imale su svojstva koja karakterišu samozbijajuće...Concrete, as one of the most commonly used materials in the construction industry, has evolved with the development of construction, from the beginning to the present day. Placing of conventional concrete is usually done with the use of vibrating equipment to help in reduction of entrained air content, eliminating the possibility of cavities occurrence in contact with reinforcement and formwork (the so-called Normal Vibrated Concrete, NVC). Concrete becomes more compact, denser and more homogeneous, which are the basic aspects for an acceptable behavior in the structure. This operation, compaction, traditionally plays a key role in the production of high quality concrete, with optimum strength and durability. Development of superplasticizers (chemical admixtures for concrete) allowed easier placing of concrete with stiffer consistency; a small dosage of this type of chemical admixtures can reduce the friction between the particles, which results in more mobile and workable concrete (concrete with fluid consistency) that is easier to place in formwork, while maintaining the same amount of water. Extrapolation of the concept of the superplasticizers use towards obtaining concrete with fluid consistency led to the concept of Self-compacting Concrete - SCC for short. Selfcompacting concrete, is defined as a concrete mix that can be placed purely by means of its own weight, with little or no vibration and is a highly flowable concrete that spreads into place, fills formwork, and wraps even the most congested reinforcement, and showing no signs of segregation. Typically, SCC contains certain quantities of very fine mineral additions; the most commonly applied are limestone and dolomite powder and fly ash. Within the experimental work in this thesis, besides fly ash (originating from two power plants, "Kolubara" and "Kostolac"), recycled pulverized concrete (obtained by demolition of old concrete structures) and powdered elemental sulfur (which is obtained as a by-product of the petrol industry, in Pancevo Oil Refinery). Within this experimental work, 11 mixtures of SCC were prepared, two reference SCC mixtures with limestone powder as mineral addition, five mixtures with fly ash, three mixtures with ground recycled concrete and four mixtures with ground elemental sulfur. Also, during the proces of defining the composition of SCC mixtures, 12 test (pilot) mixutures were made and investigated. All mixtures, except two test mixtures, could be characterized as self-compacting concrete, based on their fresh properties. The applied extensive testing of fresh and hardened SCC (with respect to the designed properties of fresh SCC, the research findings of the recent..

Investigation of properties of fresh and hardened self-compacting concrete with mineral additions based on industrial by-products

Beton, kao jedan od najčešće upotrebljavanih materijala u građevinskojindustriji evoluirao je sa razvojem građevinarstva, od početaka primene dodanašnjih dana. Konvencionalni beton se ugrađuje pomoću vibrirajućeopreme kako bi se u njemu redukovao sadržaj zaostalog vazduha,eliminisala mogućnost pojave kaverni i drugih šupljina na kontaktima saarmaturom i oplatom (takozvani normalno vibrirani beton, Normal VibratedConcrete – NVC). Na taj način beton postaje kompaktniji, gušći ihomogeniji, što je osnov za njegovo prihvatljivo ponašanje u konstrukciji.Tehnološka operacija kompaktiranja tradicionalno igra ključnu ulogu uproizvodnji kvalitetnog betona sa optimalnom čvrstoćom i trajnošću.Razvoj hemijskih dodataka tipa superplastifikatora omogućio je lakšeugrađivanje betona, pošto se malim doziranjem ovakvog hemijskog dodatkamogu smanjiti sile trenja između čvrstih čestica, što za rezultat dajepokretljivije i obradljivije betone (betone tečnijih konzistencija) koje jelakše ugraditi, uz zadržavanje iste količine vode. Ekstrapolacijom konceptaupotrebe superplastifikatora u pravcu dobijanja betona tečnijih konzistencijadošlo se do koncepta samozbijajućeg betona (Self-compacting Concrete -skraćeno SCC). Samozbijajući beton se može definisati kao beton, koji ćebez primene mehaničkih sredstava za ugrađivanje popunjavati sve ugloveoplate i uzane prostore između gusto raspoređenih šipki armature, samo poddejstvom sopstvene težine, tako da se u završnoj fazi dobije kompaktanbeton veće trajnosti.U sastav samozbijajućeg betona, po pravilu, ulaze veoma fini mineralnidodaci, od kojih su najčešće primenjivani krečnjačko i dolomitno brašno,kao i leteći pepeo. U okviru eksperimentalnog rada u ovoj disertaciji je,osim letećeg pepela (poreklom iz dve termoelektrane, TE "Kolubara" i TE"Kostolac") upotrebljen i sprašeni reciklirani beton (dobijen rušenjemdotrajalih armiranobetonskih konstrukcija, odnosno drobljenjem kontrolnihlaboratorijskih kocki) i sprašeni elementarni sumpor (koji se dobija kaonusprodukt u naftnoj industriji, u Rafineriji nafte Pančevo).U okviru eksperimentalnog rada spravljeno je i detaljno ispitivano 11mešavina SCC: dve referentne SCC mešavine sa krečnjačkim brašnom kaomineralnim dodatkom, pet mešavina sa letećim pepelom, tri mešavine sasprašenim recikliranim betonom i četiri mešavine sa sprašenim sumporom.Prethodno je prilikom definisanja recepture za SCC mešavine spravljeno iispitano 12 probnih (pilot) mešavina. Sve navedene mešavine, osim dveprobne (pilot) mešavine, imale su svojstva koja karakterišu samozbijajuće...Concrete, as one of the most commonly used materials in the constructionindustry, has evolved with the development of construction, from thebeginning to the present day. Placing of conventional concrete is usuallydone with the use of vibrating equipment to help in reduction of entrainedair content, eliminating the possibility of cavities occurrence in contact withreinforcement and formwork (the so-called Normal Vibrated Concrete,NVC). Concrete becomes more compact, denser and more homogeneous,which are the basic aspects for an acceptable behavior in the structure. Thisoperation, compaction, traditionally plays a key role in the production ofhigh quality concrete, with optimum strength and durability.Development of superplasticizers (chemical admixtures for concrete)allowed easier placing of concrete with stiffer consistency; a small dosageof this type of chemical admixtures can reduce the friction between theparticles, which results in more mobile and workable concrete (concretewith fluid consistency) that is easier to place in formwork, whilemaintaining the same amount of water. Extrapolation of the concept of thesuperplasticizers use towards obtaining concrete with fluid consistency ledto the concept of Self-compacting Concrete - SCC for short. Selfcompactingconcrete, is defined as a concrete mix that can be placed purelyby means of its own weight, with little or no vibration and is a highlyflowable concrete that spreads into place, fills formwork, and wraps eventhe most congested reinforcement, and showing no signs of segregation.Typically, SCC contains certain quantities of very fine mineral additions;the most commonly applied are limestone and dolomite powder and fly ash.Within the experimental work in this thesis, besides fly ash (originatingfrom two power plants, "Kolubara" and "Kostolac"), recycled pulverizedconcrete (obtained by demolition of old concrete structures) and powderedelemental sulfur (which is obtained as a by-product of the petrol industry, inPancevo Oil Refinery).Within this experimental work, 11 mixtures of SCC were prepared, tworeference SCC mixtures with limestone powder as mineral addition, fivemixtures with fly ash, three mixtures with ground recycled concrete andfour mixtures with ground elemental sulfur. Also, during the proces ofdefining the composition of SCC mixtures, 12 test (pilot) mixutures weremade and investigated. All mixtures, except two test mixtures, could becharacterized as self-compacting concrete, based on their fresh properties.The applied extensive testing of fresh and hardened SCC (with respect tothe designed properties of fresh SCC, the research findings of the recent..

The Laboratory Investigations of High-Density Polyethylene Drains for Application in Tailings

For the purposes of draining material deposited in the tailings pond under construction, there was a need to examine the properties of the high-density polyethylene drain tubes and the consisting materials in order to assess their adequacy in the specific conditions. The conducted laboratory investigations of the samples cut from the tubes included: determination of bulk density, tensile strength in the tangential direction, as well as the compressive strength in a radial direction. Representative samples of the tubes themselves were tested in two different loading dispositions, in order to record the load-deflection effects. The test results indicated the specific behavior of the tested material in service conditions

Correlation Between Dynamic Modulus of Elasticity and Compressive Strength for Self-Compacting Mortars

Application of non-destructive testing methods in defining the mechanical properties of mortar and concrete is continually developing. Self-compacting or self-leveling mortars are already widely applied in construction of new structures. As self-compacting mortars are finding their place in rehabilitation and repair of reinforced concrete structures, it is of high importance to design mixtures with compressive strength and modulus of elasticity compatible with existing concrete. Ten mortar series with variation of component materials (fly ash, recycled concrete aggregate, crushed brick aggregate and crushed brick filler) were the subject of following tests: resonant frequency, ultrasonic pulse velocity and compressive strength of mortar. Dynamic modulus of elasticity was calculated using the first two methods mentioned. Results from resonant frequency measurements were then used for calculating compressive strength of the mixtures through different models developed for ordinary concrete and available in the literature. It was shown that the model proposed by Gardner is closest to describing the behavior of mixtures with different component materials, but would need some corrections in order to be used for these purposes

Forming a correlation among the properties of fresh self-compacting concrete using fuzzy least squares model

The research presented in this paper was motivated by two problems regarding the properties of fresh self-compacting concrete (SCC). The first problem is that mixture properties can vary owing to different factors (composition, materials, ambient, etc.) and the second problem is that there is usually a restricted group of experimental results. Because of the importance of the properties of fresh SCC mixtures, different tests for determining its passing and filling ability, as well as segregation resistance, have been developed. In this paper, results from V-funnel and slump flow tests conducted on seven different concrete mixtures are presented. As a correlation between the measurements of V-funnel period t(v) and the slump flow period t(500) is usually strong, in this paper, it was expanded using approximate-distance fuzzy least squares method. The goal was to perceive the possible range of these properties and, when applicable, to reduce the number of tests necessary during the production of SCC

Upravljanje čvrstim otpadom u domenu armiranobetonskih elemenata ojačanih karbonskim tkaninama

U doba kada raspoloživost resursa postaje jedan od rastućih problema u svetu, javlja se potreba kako za reciklažom, tako i za upravljanjem čvrstim otpadom u koji, između ostalog, spada i građevinski otpad. Efektivno upravljanje građevinskim otpadom se smatra suštinskim za postizanje ciljeva kao što su očuvanje prostora za deponije, smanjenje uticaja na životnu sredinu, prilike za stvaranje novih radnih mesta i smanjenje troškova projekta. Rad se, iz perspektive armiranobetonskih elemenata ojačanih karbonskim tkaninama, bavi mogućnostima odlaganja i ponovne upotrebe komponentnih materijala, a sve u cilju smanjenja građevinskog otpada koji se odlaže na deponije. Na osnovu dobijenih rezultata prikazane su mere koje mogu biti primenjene kako bi došlo do poboljšanja trenutnog stanja u oblasti upravljanja građevinskim otpadom u Srbiji