Exzmple Exam question for K0002B 2024.pdf

Example questions for K0002B 2024 1. Atom is a. the smallest particle of an element b. the same as molecule c. the nucleus of a molecule 2. Most atoms are a. Nonmetals b. Metals c. Polymers 3. Electron octet is: a. is the tenden...

Example questions for K0002B 2024 1. Atom is a. the smallest particle of an element b. the same as molecule c. the nucleus of a molecule 2. Most atoms are a. Nonmetals b. Metals c. Polymers 3. Electron octet is: a. is the tendency of atoms to contain eight electrons in the valence shell b. Is a tendency of atoms to remove 8 electrons from the valence shell during ionization c. When an atom contains 8 electrons in total on all shells 4. Ionic bonds are formed: a. Between two ions with opposite charges b. Between two ions with the same charges c. The charge is not aLecting the ionic bonding 5. Concrete and other brittle materials are mostly based on: a. Ionic bonds b. Covalent bonds c. Metallic bonds 6. The concept of the “sea of electrons” is valid for: a. Ionic bonding b. Covalent bonding c. Metallic bonding 7. In solids the molecules: a. Can vibrate but cannot move b. Can move freely c. Do not move and do not vibrate 8. Elastic deformation can be defined as: a. When the shape change is reversible and it will return to its original form once the load is removed  b. The shape will only partially return to its original shape after the load is remove c. The material with elastic deformation will return to its original shape only after heating to 100oC. 9. On a molecular level: a. The pure compression can not cause a total failure as greater compression results in greater repulsion forces between atoms b. The pure compression will lead to a failure when atoms are fractured c. There is no pure compression 10. Hooks law states that: a. When subjecting an element to small deformations the displacement (deformation) is proportional to the applied load b. When subjecting an element to small deformations the displacement (deformation) is not proportional to the applied load c. When subjecting an element to small deformations the displacement (deformation) is not aLected by the applied load 11. Which cement phase would cause flash set after mixing with water if gypsum would not be added to the cement clinker? (Vilken cement mineral skulle orsaka flashhärdning efter blandning med vatten om gips inte skulle tillsättas cementklinkern?) Aluminat är mycket reaktivt med a) Alite (Alit) vatten och orsakar "flash set" vilket b) Belite (Belit) när när cement stelnar mycket snabbt. c) Tricalcium aluminate (Aluminat) 12. Which Portland cement phase is responsible for the long-term strength gain a. Alite (Alit) Belit står för den långvariga hållfastheten i Portland Cement. b. Belite (Belit) Reagerar långsammare med vatten. c. Tricalcium aluminate (Aluminat) 13. Plastic shrinkage is a. A process that causes shrinking of concrete that is at least 14 days old b. A process that causes shrinking and clay-like cracking of freshly cast concrete Orsakas av förlust av fukt, oftast inom de första timmarna efter gjutning c. It is a process that is associated with the formation of Ettringite 14. Lowering the water-to-cement ratio will generally: a. Increase the compressive strength Leder till mer hållfast och tät betong, dock medför det en b. Decrease the compressive strength mer svårt arbetad blandning som kan behöva plastmedel eller andra tillsatser.  c. Have no eLect 15. Lowering the water-to-cement ratio will generally a. Lower penetration of chlorides into concrete microstructure b. Enhance penetration of de-icing salts due to the formation of better interconnected capillary pores Minskar mängden vatten som kan skapa porer vilket leder c. Have no eLect till en mer tät mikrostruktur som gör det svårare för skadliga ämnen att ta sig in i betongen. Detta ökar hållbarheten. 16. The typical mixing duration of concrete in industrial pan mixes is a. 15-30 seconds b. Between 1-3 minutes c. 20 minutes or longer 17. The maximum temperature of concrete during hydration is: a. 55oC För höga temperaturer kan leda till: b. 90 C o - ökad risk för termiska sprickor - accelerated setting times c. There is no limit - reduced strength development 18. Concrete used for casting in hot weather (>25oC) can contain secondary cementitious materials that replace part of the Portland cement to lower the hydration heat. Which of the following materials is the most recommended? a. Silica fume GGBFS är en biprodukt från stålframställning. Reagerar långsammare b. Natural clay med portland cement vilket genererar mindre värme under härdningen c. Ground Granulated Blast furnace slag OBS! Silica fume förbättrar hållbarheten och hållfastheten men kan faktiskt HÖJA temp. 19. Silica fume is under härdningen d. Industrial by-product which has strong pozzolanic reactivity and is commonly used in ultra-high strength concrete (compressive strength >150 MPa after 28 days of curing) e. Industrial byproduct that can be added to concrete to lower its hydration heat by >50% f. Industrial byproduct which is recommended especially for concrete used in massive structures and up to 95% of Portland cement can be replaced with that material 20. White cement is a. Portland cement that has a white color after production and after hardening b. A special type of alkali-activated binder produced from ingredients not containing alumina or ferrite  c. Portland cement which is gray when packed but once mixed with water forms white concrete 21. Cement hydration is a. A chemical process is when several chemical phases are formed. Including 80% of Portlandite, 10% of CSH and 10% of Calcite b. A chemical process that is based on a chemical reaction between tricalcium aluminate (from Portland cement) and sodium hydroxide solution producing CSH, Portlandite, and AFm phases c. A chemical reaction of Portland cement after the addition of water Skapar: CSH, portlandite 22. Ettringite is a. The main hydration product when the curing temperature exceeds 90oC b. Phase forming due to the reaction of dicalcium silicate and gypsum c. Phase forming due to reaction between gypsum and tricalcium aluminate Avgörande för att kontrollera stelningstiden för cement och hjälper 23. Portlandite is till att stabilisera de tidiga hydrationsprodukterna av cement a. Phase forming in the reaction between dicalcium silicate and water b. Phase forming in the reaction between pozzolanic material and CSH c. Phase forming in the reaction between tricalcium aluminate and water Bidrar till alkaliniteten av cementen som hjälper till förhindra rostning av... 24. Pozzolanic reaction is a. The reaction between pozzolanic material and Portlandite forming CSH b. The reaction between tricalcium aluminate and pozzolanic material forming CSH c. The reaction between silica fume and gypsum forming CSH 25. Pozzolanic materials are a. Gypsum, white cement b. Quartz filler, fine aggregates c. Fly ash, blast furnace slag 26. Air entraining agent is a. Chemical enabling production of lightweight concrete b. Chemical enabling formation of small air voids enhancing frost durability of concrete c. Chemical enabling formation of big air voids enhancing fire resistance of concrete Tillsätts i betong för att skapa små jämt fördelare luftbubblor som förbättrar betongens motståndskraft mot frysspänningar vilket ökar dess hållbarhet i kalla klimat 27. Plasticizer is  Tillätts för att minska mängden vatten som behövs utan att kompromissa arbetbarheten av blandningen eller hållfastheten och hållbarheten hos den härdade betongen. a. Chemical admixture enables the production of concrete which after hardening has increased flexibility b. Chemical admixtures enable the reduction of water amount but sustain the same workability c. Chemical admixture enables the production of concrete which after hardening is suitable for absorption of impacts without cracking 28. What is the minimum temperature that is assumed to be safe and not cause permanent damage to concrete in winter conditions a. 5 oC b. 0 oC c. -5 d oC 29. The compressive strength of concrete can develop only due to the forming of ice in winter conditions and its value can reach a. 0 MPa b. 20 MPa c. 80MPa 30. Concrete casting is planned to begin in the early morning of January. All was prepared the day before, formwork, and reinforcement were checked, and heating systems were test-run. After arrival at the construction site, the site engineer saw that there was a snow accumulation in the formwork and some ice formation on reinforcement. The concrete truck with heated concrete is waiting for the sign to place the concrete. What should be done? a. Casting should be canceled b. Casting can start as concrete is hot and will melt snow and ice c. Casting can be performed but steam must be used to remove all snow and ice 31. Shortly after casting and still before the initial setting a. Water should be sprayed on the surface to prevent cracking b. The surface should be covered with plastic foil or special sprayed membranes to prevent the evaporation of water c. A layer of wet sand should be spread on the surface to provide additional water and enhance the hydration process 32. Delayed ettringite formation can occur after 100 years if: a. The concrete temperature during hydration reached 70oC, and water with sulfates could penetrate the concrete binder matrix through cracks and capillaries.  b. The concrete was partially frozen during hydration c. The concrete was exposed to liquids containing micro ettringite crystals during the hardening process. 33. Alkali aggregate reaction includes: a. Formation of silica-rich gel around reactive aggregates b. The formation of an alkali-activated binder matrix around reactive aggregates which tends to crack under loads Cement och mineraler i aggregaten bildar c. Dissolving of aggregates in the presence of alkalis en gel som absorberar vatten och expanderar som kan orsaka sprickbildning och försämring av strukturen 34. Which zone imposed the biggest tread to the concrete durability when compared to the seawater: a. The splash zone b. The permanently immersed zone c. The zone that is only exposed to air and seawater droplets carried by wind 35. Carbonation of concrete involves: a. A buildup of carbon due to the exposure to fire b. The reaction of CO2 with Portlandite and the formation of Calcium Carbonate and lower of pH in concrete pH-sänkningen kan leda till minskat c. Reaction of CO2 with CSA and formation of Portlandite skydd för armeringsstålet, vilket gör det mer mottaglig för korrosion. 36. The corrosion of steel occurs in the area which is: a. Anode b. Cathode c. In both areas 37. The cathodic protection system used in concrete structures can: a. Reverse corrosion b. Prevent and stop corrosion c. It does not aLect the steel corrosion but densifies the concrete microstructure and limit ingress of water Gör armeringsstålet i betongen till en anod i en elektrokemisk cell vilket motverkar korrosions- processen. Tar inte bort befintlig rost men hjälper 38. Frost damage to concrete occurs due to: till att stoppa ytterligare korrosion från att uppstå a. Only expansion of water during freezing b. Expansion of water during freezing and building up of internal tensional stresses due to the movement of water to and from the freezing spots c. Only due to the movement of water