Analiza aprofundata privind implicatiile structurale rezultate din utilizarea combustibiulilor alternativi la fabricarea cimentului – IARIS CEEX Modul I, PC-D04-PT2-538

Numar contract: 121/2005
Director proiect: dr. ing. Daniela Nastac
E-mail: daniela.nastac@ceprocim.ro
Telefon: 021 3188884/interior 191

1.1 Beneficiar: Agentia Manageriala pentru Cercetare Stiintifica, Inovare si Transfer Tehnologic

Agentia Manageriala pentru Cercetare Stiintifica, Inovare si Transfer Tehnologic AMCSIT
Splaiul independentei, nr. 313, Sector 6, 060042 Bucuresti, ROMANIA
Phone: +(4021) 402 93 43
Fax: +(4021) 402 97 50
Web: http://www.amcsit.ro

1.2. Coordonatorul proiectului: CEPROCIM SA Bucuresti

clinker 1

ROMANIA, 6 Bucharest, # 6 blvd. Preciziei, code 062203
Phone: +(4021) 318 88 84; 318 88 90; 318 88 93
Fax: +(4021) 318 88 76; 318 88 94.
E-mail: office@ceprocim.ro; res@ceprocim.ro
Web: www.ceprocim.ro

1.3 Parteneri : Partener 1 :

Universitatea „Politehnica” Bucuresti, Centrul de Biomateriale BIOMAT
Splaiul independentei, nr. 313, Corp J, Sala JK, 214, Sector 6, 060042, Bucuresti, ROMANIA
Phone/Fax: +(4021) 316 95 63
Web: http://www.biomat.ro

Partener 2:

Institutul de Chimie-Fizica I.G. Murgulescu al Academiei Romane Splaiul independentei, nr. 202, P.O.Box 194, Sector 6, 060021, Bucuresti, ROMANIA
Phone: +(4021) 316 79 12
Fax: +(4021) 312 11 47
Web: http://www.icf.ro

Partener 3:

Universitatea Dunarea de Jos Galati Strada Domneasca, nr. 47, 800008, Galati, ROMANIA
Phone: +(40236) 46 03 28
Fax: +(40236) 46 13 53
Web: http://www.ugal.ro

Partener 4:

Universitatea Tehnica de Constructii Bucuresti B-dul Lacul Tei, nr. 124, Sector 2, 020396, Bucuresti, ROMANIA
Phone: +(4021) 242 12 08
Fax: +(4021) 242 07 81
Web: http://www.utcb.ro

1.4.Perioada de executie: 10.10.2005 – 30.06.2008

1.5.Descrierea proiectului:

1.5.1 Scopul proiectului:

Principalul scop al proiectului IARIS este de a obtine controlul asupra procesului de clincherizare ceea ce implica control asupra proprietatilor cimentului obtinut, deci asupra calitatii produsului finit. Atingerea acestui scop s-a desfasurat gradual prin urmatorii pasi: acumulare informatie de baza crearea de ipoteze de lucru elaborare concept extindere concept evaluare concept control. Proiectul IARIS a urmarit prin aceasta abordare racordarea la prioritatile, obiectivele si activitatile specifice ariei europene de cercetare in domeniul tehnologiilor de constructii.

1.5.2 Rezumat:

Scopul final al proiectului IARIS a fost acela de a gasi un nivel optim de substitutie a combustibilului traditional cu cel alternativ la fabricarea clincherului de ciment Portland. Necesitatea acestei cercetari rezida din doi factori importanti cu care se confrunta, in acest moment, fabricile producatoare de ciment: reducerea emisiilor de CO2 si conservarea resurselor de materii prime naturale.
Desi, utilizarea deseurilor in industria cimentului este o tema supusa unor vii controverse intre experti si societate, prezentul proiect si-a propus sa aduca cunostinte noi privind influenta elementelor straine (elemente prezente in cantitati minore si in urme) asupra calitatii cimentului si a modalitatii de utilizare a deseurilor combustibile si materiilor prime secundare la obtinerea clincherului de ciment Portland.
Atingerea obiectivului final al proiectului s-a efectuat prin tratarea intr-o prima etapa a problematicii legate de interdependenta dintre structura principalelor faze mineralogice, pure, prezente in clincherul de ciment Portland si comportarea lor la hidratare sub influenta elementelor minore. Studiul s-a focalizat asupra a patru elemente: fosfor, staniu, zinc si cadmiu. Aceasta maniera de conducere a experimentului s-a considerat utila datorita eliminarii influentei efectelor complexe, datorate unui spectru larg de elemente prezente in materiile prime din industria cimentului.Cea de a doua etapa a avut drept scop extrapolarea datelor obtinute in prima etapa prin urmarirea procesului de clincherizare si hidratare in conditiile utilizarii materiilor prime industriale.
Compararea, in final, a clincherelor de laborator cu clincherele industriale obtinute in conditiile utilizarii deseurilor necombustibile (folosite ca materii prime secundare) si combustibile (folosite drept combustibili alternativi) a avut drept scop demonstrarea aplicabilitatii practice a cercetarilor din cadrul proiectului.

1.5.3. Obiectivele proiectului:

Proiectul IARIS urmareste desfasurarea in comun de catre consortiu a activitatilor de cercetare si dezvoltare tehnologica de mare complexitate, activitati ce includ cercetarea fundamentala si aplicativa. Realizarea in comun a activitatilor propuse va conduce implicit la dezvoltarea parteneriatului pe lunga durata intre institutiile participante, urmarindu-se dezvoltarea pe plan intern a unor baze materiale de cercetare puternice. Obiectivele anuale ale proiectului sunt urmatoarele:

  • Studiu documentar privind utilizarea combustibililor alternativi in industria cimentului si influenta lor asupra formarii si proprietatilor clincherului de ciment Portland
  • Stabilirea dependentei dintre polimorfismul alitului si belitului si continutul de elemente straine cu evaluarea comportarii la hidratare a fazelor sintetizate
  • Cercetari experimentale privind influenta elementelor straine asupra proprietatilor si structurii topiturii
  • Evaluarea efectelor utilizarii combustibililor alternativi la obtinerea clincherului de ciment Portland prin simularea procesului de clincherizare in laborator
  • Evaluarea activitatii hidraulice a clincherelor de laborator obtinute prin utilizarea materiilor prime naturale si combustibililor alternativi ca reflexie macroscopica a particularitatilor structurale
  • Aplicari practice ale rezultatelor cercetarii

1.5.3. Rezultate finale

Principalele rezultate ale cercetarii sunt enumerate in continuare:

  • Baza date din literatura de specialitate privind tipuri si nivele de substitutie a combustibililor traditionali, modalitati de sinteza si actiune a elementelor minore asupra principalelor faze ale clincherului, prezenta elementelor minore in compusii de hidratare ai cimentului
  • 33 de solutii solide de alit si belit sintetizate in laborator
  • rezultate experimentale ce evidentiaza modificarile polimorfice ale alitului si belitului datorate introducerii P, Zn, Cd si Sn in structura cristalina
  • rezultate experimentale ce evidentiaza parametrii structurali ai solutiilor solide de alit si belit
  • retete de obtinere a fazei interstitiale cu considerarea prezentei P, Zn, Cd si Sn
  • aprox. 20 de clinchere de laborator obtinute cu cenusa a 2 combustibili alternativi si materii prime naturale
  • algoritm metode pentru evidentierea variatiilor compozitionale si polimorfice a fazelor individuale ale clincherului
  • evaluarea comportarii la hidratare la diferite termene a aprox. 20 de clinchere de laborator
  • analiza comparativa a clincherelor de laborator cu clincherele industriale
  • caracterizare betoane obtinute din cimenturi cu combustibili alternativi

1.6.Specialisti participanti la proiect:

Specialisti
Coordonator proiect – CEPROCIM S.A.
P1- UPB-BIOMAT
P2 – ICF I.G.Murgulescu
P3 – Universitatea Dunarea de Jos Galati
P4 – UTCB
TOTAL
Director proiect /Responsabil proiect Drd. ing. Daniela Nastac Dr. ing. Florin Miculescu Dr. ing. Victor Oprisan Fruth Prof dr. Viorica Musat Prof. dr. Maria Gheorghe 5 persoane
CS I / Profesori 2 persoane 2 persoane 1 persoana 2 persoane 1 persoana 8 persoane
CS II 3 persoane 2 persoane 5 persoane
CS III 1 persoana 2 persoane 2 persoane 5 persoane
CS 5 persoane 3 persoane 3 persoane 2 persoane 13 persoane
Doctori 2 persoane 3 persoane 2 persoane 3 persoane 3 persoane 13 persoane
Ingineri 4 persoane 4 persoane 2 persoane 2 persoane 12 persoane
Tehnicieni 3 persoane 2 persoane 5 persoane
Laboranti 1 persoana 1 persoana

2.1. Etapa I: Studiu documentar privind utilizarea combustibililor alternativi in industria cimentului si influenta lor asupra formarii si proprietatilor clincherului de ciment Portland

2.1.1. Activitatea EI.1: Studiu aprofundat al literaturii de specialitate privind tipurile de combustibili alternativi utilizati in momentul actual pe plan european si national si identificarea surselor de metale grele si alte elemente straine prezente in clincher si ciment

2.1.2. Activitatea EI.2: Studiu documentar privind modalitatile de sinteza a fazelor mineralogice principale prezente in clincher si influenta elementelor minore asupra microstructurii si fazelor polimorfe formate

2.1.3. Activitatea EI.3: Studiu documentar privind elementele minore prezente in compusii de hidratare si comportarea acestor elemente in pasta de ciment intarita

2.2. Etapa II: Stabilirea dependentei dintre polimorfismul alitului si belitului si continutul de elemente straine cu evaluarea comportarii la hidratare a fazelor sintetizate

2.2.1. Activitatea EII.1: Stabilirea nivelelor de substitutie a Si cu P, Zn, Cd si Sn si obtinerea solutiilor solide de alit si belit

2.2.2. Activitatea EII.2: Evidentierea modificarilor structurale si polimorfe datorate prezentei ionilor straini in structura alitului si belitului cu stabilirea dependentei dintre polimorfism si continutul de P2O5, ZnO, SnO2 si CdO

2.2.3. Activitatea EII.3: Evaluarea comportarii la hidratare a fazelor silicatice cu continut variabil de P, Zn, Cd si Sn

2.3. Etapa III: Cercetari experimentale privind influenta elementelor straine asupra proprietatilor si structurii topiturii in scopul evaluarii cineticii procesului de clincherizare

2.3.1. Activitatea EIII.1: Stabilirea compozitiei oxidice a fazei interstitiale in vederea urmaririi influentei P, Zn, Cd si Sn asupra structurii si proprietatilor fizico-chimice ale topiturii

2.3.2. Activitatea EIII.2: Urmarirea influentei P, Zn, Cd si Sn asupra proprietatilor topiturii cu implicatii directe asupra cineticii procesului de clincherizare

2.3.3. Activitatea EIII.3: Diseminare informatii prin participarea la congrese, conferinte, manifestari stiintifice, simpozioane nationale si internationale

2.4. Etapa IV: Evaluarea efectelor utilizarii combustibililor alternativi la obtinerea clincherului de ciment Portland prin simularea procesului de clincherizare in laborator

2.4.1. Activitatea EIV.1: Stabilirea intervalelor de substitutie a combustibilului traditional cu cel alternativ si observarea efectelor utilizarii sale in procesul de clincherizare prin utilizarea materiilor prime naturale

2.4.2. Activitatea EIV.2: Determinarea variatiilor compozitionale si microstructurale a principalelor faze ale clincherelor obtinute din amestecuri de materii prime naturale si cenusa combustibil alternativ

2.5. Etapa V: Evaluarea activitatii hidraulice a clincherelor de laborator obtinute prin utilizarea materiilor prime naturale si combustibililor alternativi ca reflexie macroscopica a particularitatilor structurale

2.5.1. Activitatea EV.1: Examinarea procesului de hidratare la diferite termene in scopul evaluarii efectelor datorate modificarilor microstructurale prin utilizarea combustibililor alternativi

2.5.2. Activitatea EV.2: Urmarirea particularitatilor structurale ale fazelor individuale formate in urma procesului de hidratare

2.5.3. Activitatea EV.3: Diseminare informatii prin participarea la congrese, conferinte, manifestari stiintifice, simpozioane nationale si internationale

2.6. Etapa VI: Aplicari practice ale rezultatelor cercetarii in vederea transferului tehnologic pentru utilizarea deseurilor combustibile si largirea bazei de materii prime la fabricarea cimentului in Romania

2.6.1. Activitatea EVI.1: Analiza comparativa a clincherelor industriale cu cele de laborator obtinute prin utilizarea combustibililor alternativi

2.6.2. Activitatea EVI.2: Obtinerea si caracterizarea unor betoane pe baza de cimenturi rezultate din clinchere industriale fabricate prin utilizarea combustibililor alternativi

2.6.3. Activitatea EVI.3: Masa rotunda in scopul diseminarii cunostintelor acumulate si a identificarii posibilitatilor de continuare a activitatilor in programul PC7

3.1 Etapa I:Scopul acestei etape a proiectului IARIS a fost acela de a prezenta nivelul actual al cunostintelor pe plan mondial privind impactul utilizarii combustibililor alternativi asupra formarii si proprietatilor clincherului de ciment Portland. S-a efectuat si un studiu asupra conditiilor in care elementele minore, ce includ si metalele grele, periculoase, incorporate in pasta de ciment intarita pot fi eliberate in mediul inconjurator.

3.2 Etapa II:S-a analizat formarea solutiilor solide de alit si belit. Astfel, ionii constituenti ai retelei cristaline de baza, Ca si Si, au fost substituiti cu procente diferite de P, Zn, Cd si Sn. Alegerea acestor elemente substituente a avut la baza procentul ridicat al acestora in combustibilii alternativi, faina de oase, cauciucuri uzate si namol canalizare.
S-a observat o imbunatatire a procesului de ardere in cazul alitului dopat cu Zn si Sn. O scadere nesemnificativa a gradului de legare a CaO s-a constatat la compozitiile de alit dopat cu P si Cd, dar fara influente negative asupra procesului de ardere.
Determinarile de difractie de raze X au evidentiat stabilizarea a doua forme polimorfe ale alitului (monoclinic si triclinic) si a formelor polimorfe de temperatura inalta ale belitului.

3.3 Etapa III: Scopul acestei etape experimentale a proiectului IARIS a fost acela de a investiga influenta P, Zn, Cd si Sn asupra structurii topiturii formate la obtinerea clincherului. Acest aspect prezinta o importanta deosebita deoarece topitura reprezinta „calea” prin care se formeaza alitul in clincherul industrial. S-a observat stabilizarea alitului monoclinic pentru faza interstitiala cu adaos de P si Cd. Din punct de vedere structural s-a constatat o deplasare a distantelor interplanare d, atat pentru C4AF cat si pentru C3A, catre valori mai mici comparativ cu referinta, sugerand o scadere a dimensiunii cristalitelor, fapt ce este confirmat si de latirea profilelor picurilor considerate si/sau introducerea de dislocatii in cristale. Deplasari marcante ale benzilor vibratiei de alungire nesimetrica 3 (evidentiate prin spectrometria IR), triplu degenerata, indica o trecere de la structura tetraedrica la cea octaedrica. Acest lucru are o semnificatie majora asupra comportarii topiturii, intrucat structurile octaedrice sunt mai putin mobile in topitura ceea ce are ca rezultat scaderea vitezei de formare a alitului.

3.4 Etapa IV: Scopul acestei etape a proiectului a fost acela de a analiza efectul utilizarii atat a materiilor prime alternative (zgura cristalina, cenusa zburatoare) cat si a deseurilor combustibile asupra formarii clincherului. Interactia elementelor minore ce au ca sursa de provenienta caile amintite anterior influenteaza procesul de clincherizare prin accelerarea, in cazurile favorabile, a reactiilor de sinterizare, modificarea proprietatilor topiturii cu influente asupra proceselor de difuzie sau a reactiilor la interfata solid-lichid, modificarea reactivitatii amestecului de materii prime etc. S-au utilizat trei tipuri de amestecuri de materii prime (faini) industriale obtinute cu materiale alternative. Un element de noutate il reprezinta caracterizarea fainilor prin aplicarea metodelor chimice de dizolvare a carbonatilor pe doua fractiuni granulometrice. Aceasta a permis calculul cantitativ al cuartului, cenusii, oxizilor de fier si dolomitului prezenti in faina prin combinarea metodelor chimice cu microscopia optica. A fost analizata de asemenea aptitudinea la clincherizare a celor trei faini prin arderea acestora la patru temperaturi si trei perioade de timp diferite de mentinere la palier. De asemenea, urmarindu-se si influenta deseurilor combustibile, doua namoluri din industria petroliera si faina de oase au fost amestecate in diverse proportii cu cele trei tipuri de faina. In final au fost obtinute sase clinchere de laborator ce au fost caracterizate. Un element de noutate in caracterizarea clincherelor obtinute cu faina de oase il reprezinta determinarea nivelelor de substitutie ionica in fazele silicatice.

3.5 Etapa V: A fost studiata comportarea la hidratare a alitului dopat cu P, Zn, Cd si Sn si a clincherelor obtinute prin utilizarea combustibilului alternativ sub forma de namol din industria de prelucrare a petrolului si faina de oase. Procesul de hidratare a fost examinat pentru un numar de 97 de probe ce au constat din diverse solutii solide ale alitului si clinchere, hidratate la un raport apa/solid diferit functie de tipul de material, timp de trei perioade distincte 7, 28 si 90 zile. S-a observat o comportare imbunatatita la hidratare a probelor de alit dopate cu Sn. Experimental, s-a evidentiat formarea unui compus nou, burtite, acest mineral fiind cauza consumarii portlanditului din seria A(Sn)0.05-A(Sn)0.5. S-a observat o scadere a cantitatii de portlandit si apa legata in compusii de hidratare formati la 28 si 90 zile, granita pentru aceasta comportare diferita fiind proba A(Sn)0.05. Microscopia electronica a evidentiat o pasta hidratata mult mai compacta (pori capilari sub 5 ?m) in cazul seriei A(Sn)0.01-A(Sn)0.05 comparativ cu etalonul.

Prin cresterea timpului de hidratare s-a remarcat umplerea porilor capilari cu hidrosilicati de calciu. S-a observat o slaba crestere a lixivierii calciului la 90 zile pentru probele A(Sn)0.025 si A(Sn)0.25. Cresterea continutului de P2O5 favorizeaza formarea hidroxiapatitei, fapt evidentiat prin difractia de raze X si continutul de apa legata chimic. Se observa o mentinere constanta a nivelului portanditului si a apei legate chimic pentru intreaga serie A(P)0.01-A(P)0.05 la termen de 90 zile.

Atat hidroxiapatita cat si hidrosilicatii de calciu au tendinta sa se formeze langa suprafata particulelor de alit anhidre ceea ce influenteaza hidratarea la termene mai mari de 28 zile. In cazul probelor de alit dopate cu Cd s-a remarcat comportarea foarte buna la hidratare a probei A(Cd)0.10. Cresterea termenului de hidratare de la 28 la 90 zile nu contribuie semnificativ la cresterea continutului de portlandit si apa legata chimic. In schimb, s-a remarcat o lixiviere accentuata a calciului la 90 zile. Cadmiul nu prezinta modificari ale concentratiei sale in solutia de lixiviere la 90 zile comparativ cu 28 zile. In cazul clincherelor sintetizate in laborator s-a remarcat o comportare superioara a celor sintetizate cu namol petrolier trifazic si faina de oase. In cazul clincherelor sintetizate cu faina de oase si SnO2 (oxidul de staniu a fost adaugat in vederea cresterii aptitudinii la clincherizare din aportul combustibilului alternativ) hidratate 7 si 28 zile s-a remarcat obtinerea aceluiasi mineral burtite ce apare si in cazul seriei de alit dopat cu Sn.

Nu s-a remarcat formarea hidroxiapatitei prin hidratarea clincherelor obtinute din materii prime naturale, datorita aportului mai mic de P2O5 comparativ cu alitul dopat cu P.

3.6. Etapa VI: A fos studiata influenta combustibililor alternativi si a materiilor prime alternative asupra fabricarii la nivel industrial a cimentului si asupra stabilizarii elementelor grele in pasta de ciment intarita si beton. Utilizarea combustibililor alternativi cu o valoare ridicata a puterii calorifice determina diminuarea consumului de energie. O valoare mica a puterii calorifice conduce, in schimb, la scaderea temperaturii de combustie ceea implica cresterea debitului gazelor de ardere pentru compensarea acestui neajuns.

Controlul concentratiei metalelor grele este important intrucat emisia lor este nociva pentru om si mediul inconjurator (Hg, Cd, Pb, As, Cr, Tl), iar altele provoaca coroziunea, cum este cazul V, Zn. In functie de volatilitatea fiecarui element, prin arderea combustibilului alternativ, metalele grele se concentreaza in cenusa rezultata , aceasta fiind in cele din urma inglobata in clincher. Utilizarea materiilor prime secundare (zgura de furnal, cenusa zburatoare) si a combustibililor alternativi conduce la cresterea continutului de elemente minore in clincher.

Desi materiile prime secundare reprezinta o cale importanta de introducere a elementelor straine in clincher, totusi, nu pot fi considerate singura sursa relevanta. Pe langa combustibilii alternativi, materiile prime secundare, in special cele din industria otelului sunt caracterizate de o puternica heterogenitate si un interval larg al concentratiei elementelor minore. Contributia fiecarui tip de combustibil alternativ la totalul elementelor minore din clincher difera de la un tip de deseu la altul. Deseurile municipale solide reprezinta principalul mijloc de introducere a Cd, Cu, Sn, Ni, Cr, si Pb in clincher. Anvelopele uzate reprezinta o sursa principala de introducere a Zn. Prezenta zgurii de furnal în amestecul de materii prime influenteaza favorabil aptitudinea la clincherizare. Deseurile din industria de prelucrare a petrolului si faina de oase pot fi utlizate drept combustibili alternativi, fara a afecta proprietatile clincherului.

Particulele de zgura cu o dimensiune maxima de 45 µm alaturi de minerale argiloase precum illit si clorit îmbunatatesc aptitudinea la clincherizare a fainii. Clincherul obtinut cu faina de oase prezinta o comportare la hidratare mai buna pentru proportii mici de adaos de faina de oase si anume maxim 2%. Deseurile petroliere prin puterea calorifica ridicata reprezinta combustibili alternativi cu potential ridicat, dar continutul acestora in metale grele, limiteaza proportia lor la 5% Eliminarea elementelor periculoase din produsele de constructii, în apa de suprafata si pânza freatica – conform conditiilor de expunere a aplicatiei în constructii, este o certitudine. Apa /solutia apoasa din porii betonului , cu un caracter puternic bazic (pH 12,5 – 13) are rol decisiv în procesul de transfer de masa la interfata solid / matrice / lichid/solutie. Contaminantii trec mai întai din matrice în solutia bazica din porii betonului. Solutia apoasa din pori se modifica, din punct de vedere calitativ, dar cu urmari nesemnificative asupra pH-ului. Acesta se conserva la valori 12,5-13 ca efect al predominantei calcitului ca factor esential de influenta asupra lixivierii metalelor grele.
Transferul acestora din porii betonului in mediul apos extern depinde de factori chimici (gradienti de concentratie, solubilitate, tipul de specii chimice dizolvate) precum si de geometria si marimea porilor, inchisi sau deschisi. A fost studiat transferul metalelor grele din matricea lianta a betonului, în mediul apos, în functie de parametrii specifici testelor de lixiviere. Astfel, lixivierea Mn, Ni, Co si Cu, este favorizata de valori mai scazute de pH, sub 7, pentru Hg si Pb se remarca caracterul amfoter, iar lixivierea Sb, V si Cr creste cu bazicitatea solutiei, in limitele testate pana la pH 10. Pentru compararea comportarii la lixiviere a betonului cu ciment fabricat prin utilizarea combustibililor alternativi s-au efectuat incercari pe betoane si paste cu deseuri galvanice, relevante prin continutul de metale grele, in special Cr, Cu si Zn. Abilitatea de precipitare a metalelor grele are caracter selectiv. Astfel, concentratia Cr(VI) a fost mai mica in extractul de la betonul cu CEM III/A decat la betonul cu CEM I. A rezultat si s-a confirmat ca zgura de furnal favorizeaza precipitarea Cr(III), prin reducerea Cr(VI) solubil datorita mediului reducator (cu anioni sulfura care se oxideaza la sulfat pe seama Cr(VI).

Publicatii ISI:

1. D. Nastac, U. Kääntee, J. Liimatainen, M. Hupa, M. Muntean, „Influence of P(V) on characteristics of calcium silicates and hydration of clinkers”, Advances in Cement Research, 19 (2007) 3, pg 93-100, ISSN 0951-7197 2. D. Nastac, V. Fruth, M. Muntean, „Modificari ale parametrilor structurali in solutiile solide de alit cu adaos de fosfor”, Revista Romana de Materiale, 38 (2008) 3, pg 193-202, ISSN 1583-3186

Conferinte internationale:

1. D. Nastac, M. Hupa, M. Muntean, „Influence of using meat and bone meal as an alternative fuel on formation and properties of Portland cement clinker”, Proc. 12th International Congress on the Chemistry of Cement, 2007, Montreal, ST3, T3-05.6, pg. 1-8, published by the National Research Council of Canada; Montreal Canada; July 2007, Catalog NR15-77/2007E-MRC, ISBN 978-0-660-19695-4

2. D. Nastac, U. Kääntee, J. Liimatainen, M. Hupa, M. Muntean, „Phosphorus substituted calcium silicates phases of Portland clinker”, Proc. 16th International Conference on Building Materials, 2006, Weimar, vol 1, pg. 0139-0146

3. N. Vlad, D. Nastac, N. Cazangiu, G. Guslicov, M. Ioan, „Influence of using alternative fuels on cement manufacture”, Proc. 16th International Conference on Building Materials, 2006, Weimar, vol. 1, pg. 0109-0116

4. V. Musat, E. Fortunato, S. Petrescu, A.M. Rego, „Effect of thermal treatment on the electrical properties of sol-gel N: ZnO thin films”, I-1a 43, E-MRS, iunie 2007, Strasbourg, Franta

5. V. Musat, E. Fortunato, S. Petrescu, A.M. Rego, „ZnO/SiO2 nanocomposite thin films by sol-gel method”, I-3a 38, E-MRS, iunie 2007, Strasbourg, Franta

6. K. Uzuneanu, P. Tanase, M. Ripa, „Theoretical and experimental analysis on use of alternative fuels for internal combustion engines”, Int. Workshop Advanced Machining Technology in Automotive Production, 2007, University of Technology Cracovia, Poland

7. P. Tanase, K. Uzuneanu, E. Stratulat, „Gasification of biomass for energetic use”, Int. Workshop Advanced Machining Technology in Automotive Production, 2007, University of Technology Cracovia, Poland

8. M. Ripa, L. Deleanu, K. Uzuneanu, „Three test methods for conformity assesment of fluids”, Int. Workshop Advanced Machining Technology in Automotive Production, 2007, University of Technology Cracovia, Poland

9. D. Nastac, V. Fruth, M. Muntean, N. Vlad, T. Chendrean, „Polymorphic forms of alite stabilized by phosphorus” Proc. Conferinta Cercetarea de excelenta – premiza favorabila pentru dezvoltarea spatiului romanesc de cercetare, Brasov, 2008, în curs de publicare

10. D. Nastac, M. Muntean, N.Vlad, „Meat and bone meal as an alternative fuel in Portland cement clinker manufacture” Conferinta Cercetarea de excelenta – premiza favorabila pentru dezvoltarea spatiului romanesc de cercetare, Brasov, 2007

11. D. Nastac, M. Muntean, „Comportarea elementelor minore in pasta de ciment intarita” Proc. Conferinta Cercetarea de excelenta – premiza favorabila pentru dezvoltarea spatiului romanesc de cercetare, Brasov, 2006, vol. 1, pg. L1-17/1-9

12. G. Guslicov, M. Coarna, A. Pop, C. Vlad, „An overview on interlaboratory tests for cement organized by the testing laboratory of CEPROCIM S.A. in the last 11 yers” Proc. 1st International Proficiency Testing Conference, Sinaia, 2007, 125-134

13. M. Ioan, L. Radu, C. Mandoiu, „Software enhanced method for rapid determination of the early heat of hydration of cement CEM II/A and B-S to predict the 28 day compressive strength” Proc. 1st International Proficiency Testing Conference, Sinaia, 2007, 355-362

14. A. Pop, M. Toader, T. Paraschiv, „Heavy metal determinations for the emissions from the incineration plants by atomic absorbtion spectrometry with graphite furnace” Proc. 1st International Proficiency Testing Conference, Sinaia, 2007, 386-392

Alte publicatii:

1. D. Nastac, N. Vlad, M. Muntean, „Sinteza documentara privind comportarea elementelor minore in pasta de ciment intarita” Buletin Tehnic Informativ CEPROCIM, 4/2006, pg. 41-49

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