Description : The use of air-entraining agents in concretes (a) Increases workability of concrete (b) Decreases bleeding (c) Decreases strength (d) All of these
Last Answer : (d) All of these
Description : The factor which affects workability, is (A) Water content and its temperature (B) Shape and size of the aggregates (C) Air entraining agents (D) All the above
Last Answer : (D) All the above
Description : State two disadvantages of air entraining admixtures.
Last Answer : Disadvantages of air entraining admixtures: 1.Porosity of the concrete mass increases the chances of honeycombing. 2.The density of concrete i.e. unit weight decreases. 3.Workability of concrete increases but strength of concrete decreases up to certain extent.
Description : Workability improved by adding (A) Air-entraining agent (B) Foaming agent (C) Oily-agent (D) All the above
Last Answer : (D) All the abov
Description : The strength of concrete using air entraining cement gets reduced by (a) 5 to 10% (b) 10 to 15% (c) 15 to 20% (d) 20 to 25%
Last Answer : (b) 10 to 15%
Description : The basic purpose of a retarder in concrete is (A) To increase the initial setting time of cement paste in concrete (B) To decrease the initial setting time of cement paste in concrete (C) To render the concrete more water tight (D) To improve the workability of concrete mix
Last Answer : Answer: Option A
Description : The process of conversion of plastic concrete to solid stage is called [ A ] Hydration [ B ] Hardening [ C ] Setting [ D ] Curing
Last Answer : [ C ] Setting
Description : ick up the incorrect statement from the following: (A) Admixtures accelerate hydration (B) Admixtures make concrete water proof (C) Admixtures make concrete acid proof (D) Admixtures give high strength
Description : Which type of following cement is used for mass concrete work a) High Alumina cement b) Quick setting cement c) Rapid hardening cement d) Low heat cement*
Last Answer : d) Low heat cement*
Description : Air entrainment in the concrete increases (A) Workability (B) Strength (C) The effects of temperature variations (D) The unit weight
Last Answer : (A) Workability
Description : Workability of concrete is inversely proportional to (A) Time of transit (B) water-cement ratio (C) The air in the mix (D) Size of aggregate
Description : Pick up the correct statement from the following: (A) Continuous grading is not necessary for obtaining a minimum of air voids (B) The omission of a certain size of aggregate is shown by ... in concrete increases the workability but also increases the liability to segregation (D) All the above
Last Answer : Answer: Option D
Description : The entrained air in concrete (A) Increases workability (B) Decreases workability (C) Decreases resistance to weathering (D) Increases stress
Description : The entrained air in concrete [ A ] Increases the strength [ B ] Decreases the resistance to weathering [ C ] Increases the workability [ D ] Decreases the workability
Last Answer : [ C ] Increases the workability
Description : Differentiate between retarding and accelerating admixtures with following points. i) Hydration process ii) Setting time iii) Weather condition iv) Use
Last Answer : The accelerating and retarding admixtures can be compared as follows. Accelerating Admixture Retarding Admixture Hydration process Due to accelerating admixture, hydration process completes ... where slow hardening of concrete is necessary i.e. in mass concrete structures.
Description : State two purposes of using accelerating admixtures in the concrete.
Last Answer : i. To accelerate the initial setting of concrete ii. Permit early removal of formwork in cold climate. iii. Reduce the required period of curing iv. Speed of the work can be boosted by early removal of formwork
Description : The continuous strain, which the concrete undergoes due to application of external loads is called [ A ] Creep [ B ] Bleeding [ C ] Workability [ D ] Segregation
Last Answer : [ A ] Creep
Description : Pick up the correct statement from the following: (A) Water enables chemical reaction to take place with cement (B) Water lubricates the mixture of gravel, sand and cement (C) Strength of concrete structure largely depends upon its workability (D) All the above
Description : Grading of sand causes great variation in (A) Workability of concrete (B) Strength of concrete (C) Durability of concrete (D) All the above
Description : For given water content, workability decreases if the concrete aggregates contain an excess of (A) Thin particles (B) Flat particles (C) Elongated particles (D) All the above
Description : Wp and Wf are the weights of a cylinder containing partially compacted and fully compacted concrete. If the compaction factor (Wp/Wf ) is 0.95, the workability of concrete is (A) Extremely low (B) Very low (C) Low (D) High
Last Answer : Option D
Description : Proper proportioning of concrete, ensures (A) Desired strength and workability (B) Desired durability (C) Water tightness of the structure (D) All the above
Description : In order to obtain the best workability of concrete, the preferred shape of aggregate is (A) Rounded (B) Elongated (C) Angular (D) All of the above
Description : If the slump of a concrete mix is 60 mm, its workability is (A) Very low (B) Low (C) Medium (D) High
Last Answer : Answer: Option C
Description : Higher workability of concrete is required if the structure is (A) Made with cement concrete (B) Thick and reinforced (C) Thin and heavily reinforced (D) Thick and heavily reinforced
Description : Pick up the correct statement from the following: (A) Higher workability indicates unexpected increase in the moisture content (B) Higher workability indicates deficiency of sand (C) If the concrete mix is dry, the slump is zero (D) All the above
Description : Pick up the correct statement from the following: (A) An increase in water content must be accompanied by an increase in cement content (B) Angular and rough aggregates reduce the workability of the ... The slump of the concrete mix decreases due to an increase in temperature (D) All the above
Description : C.R.R.I. charts are used to obtain a relationship between strength of concrete and (A) Water cement ratio (B) Workability (C) Grading of aggregate (D) Fineness modulus
Description : Workability of concrete is measured by (A) Vicat apparatus test (B) Slump test (C) Minimum void method (D) Talbot Richa
Last Answer : Answer: Option B
Description : An excess of flaky particles in concrete aggregates (A) Decreases the workability (B) Increases the quantity of water and sand (C) More than 15% are not desirable (D) All the above
Description : Workability of concrete mix with low water cement ratio is determined by (A) Tensile strength test (B) Slump test (C) Compaction factor test (D) Flexural strength test
Description : Workability of concrete for a given water content is good if the aggregates, are (A) Rounded aggregate (B) Irregular aggregate (C) Angular aggregate (D) Flaky aggregate
Description : Pick up the correct statement from the following: (A) Segregation is necessary for a workable concrete (B) Consistency does not affect the workability of concrete (C) If the concrete mix is dry, the slump is maximum (D) None of these
Description : Pick up the correct statement from the following: (A) A highly absorptive aggregate reduces the workability of concrete considerably (B) The specific gravity of aggregate is important for the determination ... and porosity of an aggregate influence the property of the concrete (D) All the above
Description : Workability of concrete is directly proportional to (A) Aggregate cement ratio (B) Time of transit (C) Grading of the aggregate (D) All of above
Description : For concreting of heavily reinforced sections without vibration, the workability of concrete expressed as compacting factor should be (A) 0.75 - 0.80 (B) 0.80 - 0.85 (C) 0.85 - 0.92 (D) Above 0.92
Description : Slump test for concrete is carried out, to determine (A) Strength (B) Durability (C) Workability (D) Water content
Description : The workability of concrete can be improved by adding (a) Hydrated lime (b) Fly ash (c) Calcium chloride (d) All the above
Last Answer : (d) All the above
Description : The workability of concrete is expressed by (a) Water-cement ratio (b) Slump value (c) Compaction factor (d) Both (a) and (b)
Last Answer : (d) Both (a) and (b)
Description : The workability of concrete is defined as the (a) Ease with which it can be mixed, transported and placed in position in a homogeneous state. (b) Bearing up of cohesion in a mass concrete. (c) Separation of water from the freshly mixed concrete. (d) None of these.
Last Answer : (a) Ease with which it can be mixed, transported and placed in position in a homogeneous state.
Description : The workability of concrete is mostly influenced by its [ A ] Water cement ratio [ B ] Aggregate cement ratio [ C ] Cement content [ D ] Water content
Last Answer : [ A ] Water cement ratio
Description : Workability of concrete for a given water content is good, if the aggregates are [ A ] Rounded [ B ] Irregular [ C ] Angular [ D ] Flaky
Last Answer : [ A ] Rounded
Description : Workability of a concrete – mix is determined by (i)Slump cone test (ii)Compaction factor test (iii)Vee bee test [ A ] i [ B ] ii [ C ] i and ii [ D ] i, ii and iii
Last Answer : [ D ] i, ii and iii
Description : If the slump of a concrete mix is 50 to 100 mm, its workability is [ A ] Very low [ B ] Low [ C ] Medium [ D ] High
Last Answer : [ C ] Medium
Description : Workability of concrete mix with low water cement ratio is determined by [ A ] Tensile strength test [ B ] Slump cone test [ C ] Compaction factor test [ D ] Flexural strength test
Last Answer : [ C ] Compaction factor test
Description : While determining the workability of concrete mix, the compaction factor test is ------than the slump cone test [ A ] Less accurate [ B ] More accurate [ C ] Approximate method [ D ] None of the above
Last Answer : [ B ] More accurate
Description : Slump cone test is used to determine [ A ] Shrinkage of concrete mix [ B ] Creep of concrete [ C ] Workability of concrete mix [ D ] Soundness of concrete
Last Answer : [ C ] Workability of concrete mix
Description : Increase in water content in a cement concrete (i) Increases workability (ii) Increases the strength [ A ] i [ B ] ii [ C ] both (i) and (ii) [ D ] neither (i) nor (ii)
Last Answer : [ A ] i
Description : The separation of water or water cement mixture from the freshly laid concrete is known as [ A ] Workability [ B ] Segregation [ C ] Bleeding [ D ] Creep
Last Answer : [ C ] Bleeding
Description : The most commonly used admixture which prolongs the setting and hardening time is (A) Gypsum (B) Calcium chloride (C) Sodium silicate (D) All of the above
Last Answer : (A) Gypsum