Naslov (srp)

Hidratacija novosintetizovanog belitnog cementa sa mineralnim dodacima

Autor

Nešković, Jasmina, 1976-

Doprinosi

Trumić, Milan, 1966-
Vučetić, Snežana, 1981-
Miljević, Bojan
Trumić, Maja, 1977-
Jovanović, Ivana

Opis (eng)

The experimental research carried out as part of this doctoral dissertation entitled"Hydration of newly synthesized belite cement with mineral additives" aimed to preparenew types of alite and belite mortars that contain fly ash and blast furnace slag as industrialwaste mineral additives. After artificially induced cracks, they were treated in three ways:1) prolonged hydration in the conditions of tap water and Danube water,2) by immersion in a suspension of the healing agent (10 mass% suspension of newlysynthesized belite in distilled water) and3) bio-induced healing by application of external healing agent, a suspension of the bacteriaSporosarcina pasteurii DSM 33 in controlled conditions of sterile demineralized and Danubewater.By analyzing the results of general experiments, the following conclusions were drawnaccording to the phases of the experimental work:Mineral additives, fly ash and blast furnace slag, which were used in the experiments,can be successfully applied as an additive to cement after previous micronization, becauseaccording to all the physical and chemical properties tested, they meet the conditionsprescribed by the standards in this field.By analyzing the compressive strength of alite mortars, it was determined that theamount of 10 mass% of mineral additives (ash/slag) was optimal for subsequent tests,because the obtained values were close to the values for CEM I, which in these tests was59.33 MPa after 28 of the day. More precisely, with the addition of ash in the amount of 10%by mass, the compressive strength value was 62.5 MPa, and with the addition of slag in thesame mass fraction, the compressive strength was 58.61 MPa.With the addition of belite (1, 5 and 10 mass%) to the selected alite mortar systems(with 10 mass% mineral additive), the compressive strength values were lower, and theyshowed an increasing trend with the increase in the mass fraction of belite for all systemswith mineral additives. Thus, the system with ash and belite (both 10 mass%) had thehighest compressive strength value of 61.62 MPa, and the system with slag and belite (both10 mass%) had a strength value of 53.72 MPa. The exception to the trend was the CEM Isystem with belite without mineral addition, where the value decreased with increasingmass fraction of belite. On the basis of these conclusions, a mass participation of 10 mass%of white was adopted for further research on bio-induced healing.With extended hydration after 240 days in conditions of curing in tap water andDanube water, this research has proven that it is possible to activate the mechanism ofautogenous healing. After a period of prolonged hydration of 240 days, the healing in theCEM I system (alite system) was complete for the initial crack widths of 0.315 mm treatedin Danube water, and 0.21 mm for the initial crack widths of the samples treated in tapwater. For alite systems with mineral additives, the healing of samples treated in tap watershowed lower efficiency compared to the healing of samples treated in Danube water. Thealite system with 10 mass% ash showed a healing of 42.98% under conditions of treatmentin Danube water for initial crack widths of 0.235 mm. The alite system with the addition ofslag of 15 mass% and the initial crack width of 0.621 mm healed 37.84 % also in theconditions of treatment in Danube water.After a period of prolonged hydration of 240 days, belite systems with 1 mass% belitewithout mineral addition could fully heal under conditions of curing in Danube water forinitial crack widths of 0.479 mm. In the case of belite systems (5 mass% and 10 mass%) withslag, the healing efficiency was the same under conditions of maintenance in tap andDanube water. Crack widths of 0.456 mm healed up to 37.92% at a mass fraction of belite of5 mass%. The system with ash and belite of 10 mass% under conditions of curing in tapwater healed up to 75.66% for initial crack widths of 0.229 mm, while initial crack widths ofsmaller dimensions of 0.09 mm were completely healed.The experiment of immersion in belite suspension (10 mass% belite in distilled water)as a healing agent also proved that the healing process was possible for the observed periodof 28 and 150 days. In contrast to autogenous healing by prolonged hydration, and bio-induced healing by bacterial culture, healing by immersion in a healing agent suspensiongave better efficacy for all selected systems. This method proved to be the most effective inthese studies.In the case of the CEM I system and belite without mineral addition, the suspensionachieved the best performance with a mass percentage of belite of 1 mass%, where thehealing of a crack with a width of 0.445 mm was 52.81% after 28 days of the observed period.In the CEM I system and belite with added ash, the best performance was also in the systemwith 1 mass% of belite, where an efficiency of 48.1% was achieved with an initial crack widthof 0.21 mm already after 14 days of suspension action. The CEM I system and belite withslag (5 mass% belite) healed in the belite suspension by 55.36% at an initial crack width of0.168 mm, but for a slightly longer suspension period of 150 days.In contrast to the standard dimensions of the samples, in laboratory samples wherethe cracks were superficial and did not exceed 0.5 mm in depth, healing was complete in allsystems already after 7 days of suspension action.In bio-induced healing by external application of the S. pasteurii DSM 33 suspension,the best efficiency was achieved by the alite system with 10 mass% slag and the belite systemof pure belite after 7 days in controlled conditions with bacterial culture in a steriledemineralized and Danube water. The efficiency achieved in the system with CEM I and 10mass% slag was 28.12% for initial crack widths of 0.504 mm, while the efficiency of thesystem of pure belite was 36.98% for initial crack widths of 0.789 mm.After the bio-induced healing research was completed, a classification was made ofall the recorded images of the CEM I system with 10 mass% slag, which, next to the purebelite system, is the system with the most successful results. The final classification accuracyusing the MATLAB 2023A and the ResNet 50 as a deep learning model was 91.55%, whichwas also confirmed by calculation.Taking into account all of the obtained results within the doctoral dissertation, it is possibleto state several significant scientific achievements in relation to existing publications both atthe national and international level. This novelty is primarily reflected in the fact that theself-healing process was monitored in the presence of bacterial culture on standard cementmortars with mineral additives as well as on belite mortars that also have mineral additivesin their composition. Namely, in the available scientific literature, researchers mainly dealtwith either the influence of mineral additives on the self-healing process, or the influence ofbacterial cultures on standard cement mortars and concretes. Also, a significant novelty isthe curing of mortar in a suspension of newly synthesized belite, and especially the curingof mortar during the process of bio-induced self-healing in Danube water, which is asignificant step in the transfer of scientific results from the laboratory level to real systems.In the end, the results have a distinct multidisciplinary character because although artificialneural networks are widely used in many areas of social and technical sciences, they are stillin the development phase in the field of application of monitoring the effectiveness of bio-induced healing of cement mortars.

Opis (srp)

Eksperimentalna istraživanja koja su izvedena u okviru ove doktorske disertacije podnazivom „Hidratacija novosintetizovanog belitnog cementa sa mineralnim dodacima”imala su za cilj pripremu novih vrsta alitnih i belitnih maltera koji u svom sastavu sadržepepeo i zguru kao industrijske otpadne mineralne dodatke. Nakon veštački izazvanihpukotina na njima, sprovedena su lečenja na tri načina:1) produženom hidratacijom u uslovima česmenske i Dunavske vode2) potapanjem u suspenziju lekovitog agensa (10 mas% suspenzije novosintetizovanogbelita u destilovanoj vodi)3) bio-indukovanim zaceljenjem spoljašnjom aplikacijom lekovitog agensa (suspenzijabakterije Sporosarcina pasteurii DSM 33) u kontrolisanim uslovima sterilne demineralizovanei Dunavske vodeAnalizom dobijenih rezultata opšežnih eksperimenata izvedeni su sledeći zaključci pofazama eksperimentalnog rada:Mineralni dodaci, pepeo i zgura, koji su korišćeni u ispitivanjima mogu uspešno da seprimenjuju kao dodatak cementu nakon prethodne mikronizacije, jer po svim ispitanimfizičko-hemijskim osobinama ispunjavaju uslove koje propisuju standardi iz ove oblasti.Analizom čvrstoća na pritisak alitnih maltera, utvrđeno je da je količina od 10 mas%mineralnih dodataka (pepela/zgure) optimalna za naredna ispitivanja, jer su dobijenevrednosti bile bliske vrednostima za CEM I koja je u ovim ispitivanjima iznosila 59,33 MPanakon 28 dana. Tačnije, dodatkom pepela u količini od 10 mas% vrednost čvrstoće napritisak iznosila je 62,5 MPa, a dodatkom zgure u istom masenom udelu čvrstoća na pritisakje iznosila 58,61 MPa.Dodatkom belita (1, 5 i 10 mas%) u odabrane sisteme alitnih maltera (sa 10 mas%mineralnog dodatka) vrednosti čvrstoća na pritisak su bile niže, a pokazale su trend porastasa povećanjem masenog udela belita za sve sisteme sa mineralnim dodacima. Tako je sistemsa pepelom i belitom (oba po 10 mas%) imao najveću vrednost čvrstoće na pritisak od 61,62MPa, a sistem sa zgurom i belitom (oba po 10 mas%) imao vrednost čvrstoće od 53,72 MPa.Izuzetak trenda je imao sistem CEM I sa belitom bez mineralnog dodatka gde je vrednostopadala sa povećanjem masenog udela belita. Na osnovu ovih zaključaka za daljaistraživanja bio-indukovanog zaceljenja je usvojeno maseno učešće belita od 10 mas%.Produženom hidratacijom nakon 240 dana u uslovima negovanja u česmenskoj iDunavskoj vodi ovim istraživanjem je dokazano da je moguće aktivirati mehanizamautogenog zaceljenja. Nakon perioda produžene hidratacije od 240 dana zaceljenje usistemu CEM I (alitni sistem) je bilo potpuno za početne širine pukotine od 0,315 mmnegovanih u Dunavskoj vodi, a 0,21 mm za početne širine pukotine uzoraka negovanih učesmenskoj vodi. Za alitne sisteme sa mineralnim dodacima, zaceljenja uzoraka negovanihu česmenskoj vodi su pokazala manju efikasnost u odnosu na zaceljenja na uzorcimanegovanih u Dunavskoj vodi. Alitni sistem sa 10 mas% pepela je pokazao zaceljenje od 42,98% u uslovima negovanja u Dunavskoj vodi za početnu širinu pukotine od 0,235 mm. Alitnisistem sa dodatkom zgure od 15 mas% i početnom širinom pukotine od 0,621 mm zacelio je37,84 % takođe u uslovima negovanja u Dunavskoj vodi.Nakon perioda produžene hidratacije od 240 dana belitni sistemi sa 1 mas% belita bezmineralnog dodatka mogli su u potpunosti da zacele u uslovima negovanja u Dunavskojvodi za početnu širinu pukotine od 0,479 mm. Kod belitnih sistema (5 mas% i 10 mas%) sazgurom efikasnost zaceljenja je bila ista i u uslovima negovanja u česmenskoj i u Dunavskojvodi. Širine pukotina od 0,456 mm zacelile su do 37,92 % pri masenom udelu belita od 5mas%. Sistem sa pepelom i belitom od 10 mas% u uslovima negovanja u česmenskoj vodi jezacelio i do 75,66 % za početne širine pukotina od 0,229 mm, dok su početne širine pukotinamanjih dimenzija od 0,09 mm potpuno zacelile.Eksperimentom potapanja u suspenziju belita (10 mas% belita u destilovanoj vodi)kao lekovitog agensa je takođe dokazano da je proces zaceljenja moguć za posmatraniperiod od 28 i 150 dana. Za razliku od autogenog zaceljenja produženom hidratacijom, i bio-indukovanog zaceljenja bakterijskom kulturom, zaceljenje potapanjem u suspenzijulekovitog agensa je dalo bolju efikasnost za sve odabrane sisteme. Ova metoda se u ovimistraživanjima pokazala kao najdelotvornija.Kod sistema CEM I sa belitom bez mineralnog dodatka, suspenzija je najbolji učinakostvarila pri masenom učešću belita od 1 mas% gde je zaceljenje pukotine širine od 0,445mm bilo 52,81 % nakon 28 dana posmatranog perioda. Kod sistema CEM I sa belitom idodatkom pepela najbolji učinak je takođe bio u sistemu sa 1 mas% belita, gde je ostvarenaefikasnost od 48,1 % sa početnom širinom pukotine od 0,21 mm već nakon 14 danadelovanja suspenzije. Sistem CEM I i belit sa zgurom (5 mas% belita) je zacelio u suspenzijibelita za 55,36% pri početnoj širini pukotine od 0,168 mm ali za nešto duži period delovanjasuspenzije od 150 dana.Za razliku od standardnih dimenzija uzoraka, kod laboratorijskih uzoraka gde su pukotinebile površinske i nisu prelaze 0,5 mm dubine, zaceljenje je bilo potpuno kod svih sistemaveć nakon 7 dana delovanja suspenzije.Kod bio-indukovanog zaceljenja spoljašnjom aplikacijom suspenzije bakterije S.pasteurii DSM 33 najbolju efikasnost su ostvarili alitni sistem sa 10 mas% zgure i belitnisistem čistog belita nakon 7 dana negovanja u kontrolisanim uslovima sa bakterijskomkulturom u sterilnoj demineralizovanoj i Dunavskoj vodi. Efikasnost koja je ostvarena usistemu CEM I sa 10 mas% zgure je iznosila 28,12 % za početne širine pukotina od 0,504 mmdok je efikasnost kod sistema čistog belita iznosila 36,98 % za početne širine pukotina od0,789 mm.Nakon završenih istraživanja bio-indukovanog zaceljenja izvršena je klasifikacijasvih snimljenih slika sistema CEM I sa 10 mas% zgure koji je pored sistema čistog belita,sistem sa najuspešnijim rezultatima. Konačna tačnost klasifikacije korišćenjemprogramskog jezika MATLAB 2023A i podprograma ResNet 50, kao modela dubokogučenja je iznosila 91,55% što je potvrđeno i računskim putem.Uzimajući u obzir sve dobijene rezultate u okviru doktorske disertacije moguće jekonstatovati nekoliko značajnih naučnih dostignuća u odnosu na postojeće publikacije,kako na nacionalnom tako i na međunarodnom nivou. Ove novine se pre svega ogledaju učinjenici da je proces samozaceljena praćen u prisustvu bakterijske kulture na standardnimcementinim malterima sa mineralnim dodacima, kao i na belitnim malterima koji u svomsastavu takođe imaju mineralne dodatke. Naime, u dostupnoj naučnoj literaturi istraživačisu se uglavnom bavili ili uticajem mineralnih dodataka na proces samozaceljenja, iliuticajem bakterijskih kultura na standardnim cementnim malterima i betonima. Takođe,značajnu novinu predstavlja i negovanje maltera u suspenziji novosintetizovanog belita, anaročito negovanje maltera tokom procesa bio-indukovanog samozaceljenja u Dunavskojvodi, što je značajan korak u prelasku naučnih rezultata sa laboratorijskog nivoa na realnesisteme. Na kraju, rezultati imaju izraziti multidisciplinarni karakter jer iako veštačkeneuronske mreže imaju široku primenu u mnogim oblastima društvenih i tehničkih naukajoš uvek su u fazi razvoja u oblasti primene praćenja efikasnosti bio-indukovanog zaceljenjacementnih maltera.

Opis (srp)

Rudarsko inženjerstvo - Mineralne i reciklažne tehnologije, Inženjerstvo materijala / Mining engineering - Mineral and recycling technologies, Materials engineering Datum odbrane: 29.02.2024.

Jezik

srpski

Datum

2024

Licenca

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