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Buiding material
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| Term | Definition |
|---|---|
| What was used as binding material before cement. | Lime |
| Cement chief componenets. | 1. Calcareous (compounds of lime (calcium)). 2. Argillaceous. (clay). |
| Cement ingredients. | Lime(CaO)= 62-67%, Silica(SiO2)= 17-25%, Alumina(Al2O3)=3-8%, Calcium Sulphate(CaSO4)=3-4%, Iron Oxide(Fe2O3)=3-4%, Magnesia(MgO)=1-3%, Sulphur(S)=1-3%, Alkalies (K2O, N2O)=0.2-1%. |
| Functions of lime. | 62% Lime is generally used in OPC. When lime exceeds 67%, it expands and swell and disintegrates. Whne lime is less than 62%, it reduces the strength of cement and early setting of cement takes place. |
| Function of Silica. | This also imparts strength to the cement. But, when excess 25%, it increase the strength but also increases the setting time. |
| Functions of Alumina. | Alumina helps in quick setting of cement. Alumina also acts as flux in reducing the clinkering temperature i.e the the temperature at which clinkers of crment are formed. |
| Functions of calcium sulphate. | It is an anhydrous form of gypsum and helps in increasing the setting time of cement. |
| Functions of iron oxides. | It helps in providing strength, hardness and colour to the cement. |
| Functions of Magnesia. | It imparts yellow colour, hardness and soundness to the cement. |
| Functions of Sulphur. | It imparts soundness to the cement. |
| Functions of Alkalies. | These are available in naturaaly occuring clays from which cement is made. Alkalies have high affinity with water, when water evaporates, efflorescence i.e stains and white marks are left behind. |
| What are Bogues compounds. What are different compounds. | Was discovered by Bogues. These are complex compounds formed when different ingrediets of cement mixes/reacts with water. Tri-calcium aluminate (C3A), Tetra-Calcium Alumino-ferrite(C4AF), Tri-calcium Silicate(C3S), Di-calcium Silicate(C2S). |
| Explain Tri-Calcium Aluminate. | (4-14%)Tri-Calcium Aluminate is formed within 24 hours of mixing with water. This compound is responsibe for maximum evolution of heat during hydration process. Heat of hydration in cal/gm---after 3 days-210 cal-----after 90 days-310 cal. |
| Explain Tetra-Calcium Alumina Ferrite. | This compund is also formed within 24 hours of addition of water. (10-18%)Heat of hydration in cal/gm----After 3 days= 70 cal....After 90 days=100 Cal. |
| Explain Tri-Calcium Silicate. | (45-65%) This compound is aailabl in maximum percentage. It is formed within one week of mixiong with water. It is responsible for early development of strength.Heat of hydration in cal/gm...After 3 days= 60 cal......After 90 days=105 Cal. |
| Explain Di-Calcium Silicate. | (15-35%)It is responsible for progressive development of strength in cement. Its formation is completed after a long time i.e 1-2 years. Heat of hydration in cal/gm...After 3 days=12.........After 90 days=42 cal. |
| What is the purpose of curing. | Water is added to maintin temperature so that Bogues compounds can make. Water application is just the cheap method. By Electricity or steam or other methods are used for curing. |
| What is needed for early development of strength and why early strength is required. | C3S...Tri-Calcium Silicate is needed. It is needed for speedy constructions requirement or where strength of cement is needed immediately such as Rigid pavement, emergency construction works etc. |
| What compound is needed for late development of strength. | Dicalcium Silicate (C2S). For Dams, hydaulic structures late strength of cement is needed. |
| In mass concreting, what compouds are removed from cement. | C3A, C3S. |
| What is amount of percentage of water added to make C3S and C2S compounds. | C3S= 24% of amount of water by weight of cement. C2S= 21% of amount of water by weight of cement. |
| For complete hydration of cement, how much amount of water is added. | 38% = 40%. 23% amount of water is added for hydration purpose and 15% amount of water gets stored within voids of cement. |
| What is water cement ratio (W/C). | 0.40 |
| What are different processes for maunfacture of cement. | 1. Dry process (New method). 2. Wet process (Old method). |
| Explain Dry process). | Calcareous,arglaaceous compunds crushed to 25mm-fed in ball/tube mill for grinding-mixed ing. proportions-preheated upto 800 degree by exhaust gases of kiln-fed to rotatory kiln(1500)-clinkers formed-clinkers grinded in ball mill-stored in silos-transport |
| Explain wet process. | Calcareous crushed to 25 mm-Argillaceous added with water in wash mill-fine grinding of slurry in ball/tube mill-Blending of slurry i.e mixing of ingredients-fed to rotatory kiln-clinkers are formed-clinkers grinded in bal/tube mill-sored in sios-traaspt. |
| Field tests of cement. | Colour should be grey, should feel cool between hands, should be free from lumps, cement in water cup should settle suddenly, it should not float.A mould of 25*25*200 mm after 7 days should be able to carry load of 340 N. |
| Lab tests on cements. | 1. Soundness test-(i) Sieve test (ii) Air permeabilty test. (iii) Le-Chatlier test. (iv) Autoclave test. (2) Consistency test. (3) Initial setting time. (4) F.S.T. (5) Compression test. |
| Explain sieve soundness test. | The amount of cement is passed from 9th no. of sieve (90 micron). Is is shaken for 15 min and the weight retained is calculated. The weight retained should not be more than 10% in case of OPC. |
| Explain air permeability test. | This method is based upon finding the relationship between the air passing through the bed of cement and specific surface area of cement forming this bed. S.S.A is the surface area per unit gram of cement. (cm2/gm). |
| Explain Le-Chatlier test. Soundness of cement due to lime. | 30mm dia Cyl.with 0.5mm thkness and 165mm indicator arms.The soundness mainly by lime.500gm cement-gauge with 0.78P-put in cylndr-in water for 24 hrs(27-32deg)-taken out-x1 I.A-x1>0.5mm..in water again.tempt raise to b.p in 25-30min-put in 3 hrs-x2>x1>0.5 |
| What is soundness of O.P.C. | x2-x1 should not be greater than 10mm. |
| Explain autoclave method. | Test is sensitive to lime and magnesia. Mould of 25mm is taken in autoclave oven on whom steam pressure of 21 kg/cm2(guage pressure) is attained in 1 hr-continued for 3 hrs-change in any dimension should not be greater 0.8% i.e 0.2 mm. |
| What are tests done for soundness of lime, magnesia and sulphur. | 1. For lime, Le-chatlier test is done. 2. For lime and magnesia both, Autoclave test is done. 3. For sulphur, no test is available. |
| Explain consistency test. | Cons. test is the amount of water added in cement which permits the penetration of Vicat's plunger upto the depth of 30-33 mm from the top ofmould.500 gm cement taken with initial water content of 24%.Mould is 40 mm high and 80 mm wide.Temp-27+-2,R.H-90%. |
| Explain initial setting time test. Explain initial setting time also. | Consistency of 0.85 P is taken. The sqaure needle is used instead plunger in Vicat's apparatus. The time taken to reach 30-33 mm depth is known as I.S.T. I.S.T is the time from adding of water to the time when cement paste starts losing its plasticity. |
| Explain Final setting time. Explain final setting time test also. | The time of adding the water in cement to the time all plasticity is losen is F.S.T.In this,annular collar with needle is used. The time at which collar released on mould does not make impression but only needle does is F.S.T. |
| What is Final setting time of O.P.C. | 10 hours. |
| Explain compression test. | The cement mortar of 1:3 is made.The sand used is Ennore sand(South Indian sand). A mould of 75 mm is made and 0.4 W/C is used. Curing for 3 days, 7 and 28 days are done.Three samples for 3,7,28 days are tested in UTS for compression strength. |
| What are different mould size for different aggregate size for compression test. | 1. 20 mm= 150 mm mould. 2. 10 mm= 100 mm mould. |
| Lime origination. | CaCo3---Cao+Co2...CaCo3(limestone) is calcinated i.e heated in presence of air till material becomes red. CaO obtained from pure limestone calcination is Quick lime/caustic lime. |
| Hydrated lime origination and its other names. | CaO+H2O---Ca(OH)2---(in presence of H2Co3)--CaCo3...Ca(OH)2 is known as hydrated lime/slaked lime/milk of lime. |
| Explain slaking. | It is a process in which lime reacts with water and swells,cracks and falls out in form of powder form. |
| Lime composition. | Clay imparts hydraulicity.Excess, arrests the slaking,Deficiency, retards.Makes lime inslble in water.MgCo3-rspnsble for slaking and lime set slowly, less desired.Sulphur-retards slaking and lime to set quickly,more desired.Alkalies-results in staining. |
| Clay and Alkalies percentage in lime. Expalin hydraulicity. | Clay- (3-30%)...Alaklies-(0.1-2%). Hydraulicity is the property of lime which allows it to set in a damp area even without any circulation of free air. |
| Types of lime. | 1. Fat lime/white lime/pure lime. 2. Hydraulic lime/water lime. 3. Poor lime. |
| Explain Fat lime/white lime/pure lime. | In this lime, the slaking action vigorously takes place. The lime slakes upto 300% of its initial volume and falls out. Thus, it is not used for load bearing structures. Only used for finishing and sanitory construction. % of lime much much less than30%. |
| Explain Hydraulic lime/water lime. | This is known as water lime because it sets in the presence of water also. The % of clay is near to 30%. The hydraulic lime is used in load bearing structures. It resembles cement in colour i.e grey and thus not used for finishing purposes. |
| Explain Poor lime. | The clay % is much greater than 30%. It is used for structures of minor importance such as brickwall inside ground separating foundation and soil. |
| Explain mortar. | It consists of binding material such as cement, lime, gypsum...adulterant such as sand, anthracite, surkhi...and water. |
| What are the properties of sand desirable to be used as adulterant. | 1. Should be chemically inert. (should not react with cement).2). Should not contain any salt which absorb moisture from atmosphere. 3). Should be free from O.M.(oxidation of it release gases that make way and create cracks). 4). Fineness Modulous-2-3. |
| Explain functions of sand in mortar. | 1)Adds volume or bulkness.2)It helps in readjustment of strength with different sand content.3). It divides the mortar into different sublayers thereby increasing the S.A over which it can be applied.4). It reduces the shrinkage of mortar. |
| Types of mortar. | 1. Unit weight- light weight(less than 15KN/m2), Heavy weight-(More15KN/m2).2)Type of Binding material-cement, lime, gypsum, gauge.3). Type of use-brickwork, plastering.4).Sound proof,5) X-ray shielding.6). Thermal proof mortars. |
| What are gauged mortar. | Using the binding materials cement, lime, gypsum in different proportions is gauged mortars. |
| What Mortars content in different works. 1). Pointings. 2)DPC. 3).General construction activities. 4) Brickwork in foundation. | 1). 1:1 2). 1:2. 3)C.M-1:3. L.M-1:2. 4).C.M-1:6. L.M-1:3. |
| What is composition of bricks. | south africa india lene mein...1. Silica,SiO2 (40-60%). 2. Alumina,Al2O3 (20-30%).3.Iron Oxide,Fe2O3(5-6%).4. Lime, CaO(4-5%).5. Magnesia, MgO(<1%). |
| Explain functions of Silica in bricks. | 1). Silica helps in prevention of cracking, shrinkage and drying of the bricks. It helps in maintaining the uniform shape of the bricks. 2). If it is excess, it destroys the cohesion between particles forming the bricks. hence, results in disintegration. |
| Explain functions of Alumina in bricks. | 1. It imparts plasticity to the bricks which helps it during moulding process. 2. If it is in excess, it cause the shrinkage and warping during its drying process and bricks become hard during its burning process. |
| Explain functions of iron oxide in bricks. | It helps in fusion of lime with silica. It also imparts reddish brown colour to the bricks. |
| Explain functions of lime in bricks. | 1. It prevents the shrinkage of the bricks. 2. If it is in excess, the melting of the bricks takes place during burning process. Hence, shape of the brick is distorted.3.If it is in excess, the slaking also takes place which finally results in crackings. |
| Explain functions of magnesia in bricks. | It imparts yellow tinge to the bricks. |
| Explain harmful ingredients present in bricks. | 1. Lime. 2. Alkalies. 3. Iron pyrites. 4. Vegetative matter. 5. Pebbles. |
| Explain harmful effects of Lime. | It results in slaking which causes the cracks in bricks. |
| Explain harmful effects of Alkalies. | Alkalies acts as a flux in burning of the bricks and these bricks placed over each other fusion takes place and due to which desired shapes bricks are not obtained.2. It also results in staining and efflorescence of the bricks. |
| Explain harmful effects of Iron pyrites. | The iron pyrites in bricks causes crystallization and disintegration of bricks during its burning process because of oxidation. |
| Explain harmful effects of vegetative matters. | The vegetative matters in bricks when left unburnt which comes from clay when leads to oxidation produces gases which needs path to release into atmosphere and hence cracks in bricks are generated. |
| Explain harmful effects of pebbles. | The presence of these make bricks porous and reduces the load bearing capacity of bricks due to less surface area of bricks available. |
| Explain manufacture of bricks. | 1. Preparation of the brick earth(Clay).2. Moulding. 3. Drying. 4. Burning. |
| Explain preparation of the brick earth. | 1.Unsoiling. 2. Digging. 3. Cleaning. 4. Weathering. 5. Blending. 6. Tempering. |
| Explain unsoiling. | The soil is excavated upto 200 mm and is left unused as this contains maximum no. of impurities such as pebbles, vegetative matter etc. |
| Explain digging. | After 200 mm unsoiling, the clay is excavated upto the desired depth and is placed on the side. |
| Explain cleaning. | The clay excavated is cleaned i.e all impurities are taken out and removed. |
| Explain weathering. | The clay cleaned from impurities is kept as it is for the time so that weathering can remove left over organic matter by oxidation. |
| Explain blending. | The desired ingredients in clay are blended for manufature of bricks. |
| Explain tempering. | The clay is mixed with water in the pug mill so that moulding could be done. |
| Explain moulding of bricks. | Moulding of bricks are done by hand moulding or machine moulding. Hand moulding is done on ground i.e ground mouding or on table i.e table moulding. Machine moulding is done as plastic clay moulding or dry clay moulding. |
| What is the use of frog. | 1. For manufatures name. 2. It acts as a shear key when mortar connects the two bricks. |
| Explain drying. | The bricks are dried after moulding before heating as if heated immediately after moulding, it will lead to high shrinkage and this brick will disintegrate. The brick is dried till 2% moisture content. The bricks are dried naturally or artificially. |
| How bricks are stacked for drying. | They are kept on edges. |
| Explain burning. | Burning is done to induce strength and hardness to the bricks. If bricks are under burnt, they become soft and if overburnt, they become brittle and breakes easily. Burning is done in clamps or kilns. |
| what are properties of good bricks/tests on bricks Part I. | 1.Should not break in to pieces when drop>1m.(Toughness test).2.No impression when scratched with nail(hardness test).3.give ringing sound when struck(Soundness test).4.Min. comp.strgth=5.5 KN/m2.5.1st classbricks<20% water when for 24 hrs,II-22%,III-24%. |
| what are properties of good bricks/tests on bricks Part II. | 6.Alkali test-Not show staining when immersed in water for 24 hrs anddried.7.Shape/size-Std19*9*9. Nominal20*10*10.Trad23*11.4*7.6cm.weight of 1 m3 brick=1800 kg.wtof 1brick=3-3.5 kg.8.Free from impurities.9.Atleast table mounted bricks for construction. |
| Explain stretcher and header bricks. | Long side of the brick is called stretcher (19 cm) and short side is header (9 cm). Stretcher sides in a brick=4 sides. Header sides in a brick= 2 sides. |
| Explain Queen closer and king closer and bevelled closer. | Queen closer brick is brick cutting the head into two parts i.e h/2. King closer is brick cutted from h/2 to S/2. Bevelled closer is the brick cutted from h/2 to meeting the full S side of brick. |
| Explain Queen closer quarter, Quarter bat, Half bat, Three quarter bat. | Queen closer quarter is half h and half S. Quarter bat is quarter of stretcher. Half bat is half stretcher. Three quarter bat is 3/4 stretcher. |
| Explain English bond. | In English bond, alternate course of header and stretcher are used. In the header course, queen closer is followed by quinine header which breaks the alignment of vertical joints. Each stretcher course is terminated by three quarter bat. |
| Explain Flemish bond. | In Flemish bond, there is alternate header and stretcher used in each course. Queen closer is used after quinone header to remove alignment of vertical joints. Alternate course is terminated by three quarter bat.English bond-stronger, Flem bond-economical |
| Explain Stretcher bond. | This uses stretcher bonds. In alternate course, half bat is used at starting and end to remove alignment of vertical joints. |
| Explain Header bond. | This uses header bonds. The alternate course uses three quarter bat a start and ending. |
| What the shape of aggregates provides properties to concrete. | The shape and size of aggregate decides workability, plasticity, durability and strength of concrete produced from it. |
| What are different shapes of aggregates. | 1. Round. 2. Angular. 3. Flaky. |
| Why concrete made up of round aggregates are more workable. | 1. Offer less interlocking between round particles. 2. Surface area is minimum, hence less friction area is there which makes it more workable. 3. Round shape particles are usually smooth, hence offer less resistance. |
| Why concrete made of angular aggregates are more strengthier. | 1. Offer more interlocking between aggregates. 2. More friction resistance. 3. Angular aggregates are more rough and thus provides more resistance. |
| What kind of aggregate gives more strength and less workability. | Flaky aggregates. |
| What is angularity number. | To determine angularity of aggregate, this index is used. This is percentage of volume of voids present in it.If Vv=33%, Vs= 67%, Angulartiy no. is 0, if Vv=43%,Vs=57%, An=11.So,it lies 0-11. Less than 0-round aggregates, more than 11- flaky aggregates. |
| What are flaky aggregates. | One dimension is very big than the other two dimensions. |
| Explain flakiness index. Explain diagram also. | Flakiness index of an aggregate is the percentage by weight of particles whose least dimension is smaller than 0.6 time of its mean dimension. |
| Explain elongation index. Explain diagram also. | Elongation index is the percentage by weight of particles whose greatest dimension is greater than 1.8 times of its mean dimension. |
| Flakiness index and elongation index cant be done for aggregates sizes less than. | 6.3 mm. |
| What are different tests done for strength of aggregates. | 1. Aggregate crushing value test(ACV). 2. Aggregate impact value test (AIV). 3.Hardness test-Deval's attrition test, Dowry's abrasion test, Los angeles test. |
| Explain aggregate crushing value test.(ACV) | The aggregate is passed through 12.5 mm sieve and retained on 10 mm sievee and placed on container. Load of 40 tonne is subjected on it, the aggregate crush, passed through 2.36 mm sieve and weighed. Let x.Original weight=y. ACV=x/y*100. |
| Explain aggregate impact value test. (AIV) | The aggregate is placed in a container and a weight of 14 kg is fallen from a height of 38 cm 15 times. The aggregates after exceeding toughness value breaks. Passed 2.36 mm sieve. Similarly, AIV=x/y*100. |
| Explain hardness test. | The aggregates are placed inside a rotating drum with steel balls. The aggregates are then passed through 1.7 mm sieve, Hardness=x/y*100. |
| Explain Fineness modulous. Explain numerical process. | Fineness modulous is an index which decides the coarseness or fineness of the aggregates. FM value is obtained by dividing the cumulative percentage of aggregate retained on each sieve by a constant no. generally taken 100. |
| What is Fineness modulous of fine sand, medium sand, coarse sand. | Fine sand- 2.2 to 2.6. Medium sand- 2.6 to 2.9. Coarse sand-2.9 to 3.2. |
| What value of fineness modulous of sand cannot be used in construction of concrete. | 6.32. |
| Define admixtures. | Any other material other than water, sand, cement, coarse aggregates are known as admixtures. These are added to induce certain desirable properties in the concrete. |
| Name different admixtures. | 1. Plasticizers. 2. Superplasticizers. 3. Retarders. 4. Accelerators. 5. Mineral admixtures. 6. Air entraining admixtures. |
| Explain Plasticizers. | Added to increase workability at same w/c ratio or increases the strength at same workablity.0.1 to 0.4% is added which decreases 5-15% ofwater or increases 30-150 mm slump. Ex. lignosulphates,hydroxylated carboxylic acid, polyglycol esters,carbohydrates. |
| Explain superplasticizers. | It is just modification over plasticizers. It reduces upto 30% of water. Ex. SMF (sulphonated melamine formaldehyde), SNF (Sulphonated naphthamine formaldehyde), MLS(modified lignosulphates). |
| Explain retarders. | Added(0.05%to0.1%)to reduce the hydration process. It makes the concrete plastic upto long duration and workable. It can retard hydration process upto 72 hrs. Ex. Cellulose, starch, common sugar. Used in below earth construction where temperature is high. |
| Explain accelerators. | Accelerators are added to increase the rate of hydration process. It is used where speedy construction is needed.Ex. Cacl2, Fluorosilication, Triethanolamine. |
| Explain mineral admixtures. | All pozolanic material are mineral admixtures. |
| Explain Air entraining agents. | It helps in frost resistance. Increases the workability and plasticity.Ex.Hydrogen peroxide, wood resins, aluminium powder, plant and animal fat/oils. |
| Explain factors affecting workability. | 1. Water content.2. Aggregate/cement ratio. 3. Size of aggregate.4. Shape of aggregate.5. Surface texture of aggregate.6. Admixtures.7.Grading of concrete. |
| What is workability and what are different tests to find it. | The ease of placing of concrete is called workabilty. 1. Slump test.2. Compaction factor test.3. Flow table test. 4.Vee bee consistometer test. |
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