Civil Engineering Related Important Questions With Their Answers

 

In this article,I am presenting few important most important questions with their answers, taken from various IS codes and books of civil engineering.These questions could be of your great help for your interview and general awareness about civil engineering. Please go through it.I hope it will expand your knowledge.

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(1.) Sand does not give strength to mortar but it helps in adjustment of strength of mortar due it helps in adjustment of strength of mortar due to change in its quantity. For example-1:1 mortar has more strength compared to 1:2, 1:3, 1:4 mortar.

(2.) 1 cum of wet mortar=1.25 cum of dry mortar.

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(3.) Round aggregate-Presence of round aggregate in concrete its workability because round aggregates have minimum surface area.Hence, same volume of cement paste would be able to lubricate more no. of round aggregate.

Presence of round aggregate decrease strength as for the given volume of aggregate.Because, development of friction in concrete is less due to its smoothness and lesser availability of surface area.

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(4.) Angular aggregate increases strength of concrete, because-

(i) Better interlocking is provided

(ii) Surface area is more

(iii) More rough than round aggregate

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(5.) Flakiness Index-Flakiness index represents the % of particle present in it whose smallest dimension is less than 3/5th or 0.6 times its mean dimension.

(6.) Elongation Index-Elongation index represent the % of particle, present in given sample having their longest dimension 9/5 or 1.8 times of its mean dimension.

(7.) Fineness Modulus-Fineness modulus is defined as sum of qumilitive percentage weight retained on the sieves of standard size/100.

(8.) Fineness modulus varies 2 to 3.5 for fine aggregate and 5.5 to 8 for coarse aggregate.

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Also Read:Determination of dry density of soil in place by the core-cutter method

(9.) Standard Sieves are-

(i) 150 micron 

(ii) 300 micron 

(iii) 600 micron 

(iv) 1.18 mm

(v) 2.36 mm

(vi) 4.75 mm

(vii) 10 mm

(viii) 20 mm

(ix) 40 mm

(x) 80 mm

(10.) Fineness modulus of  'Z' represent third sieve 600 micron is average size of sample.Similarly, fineness modulus '5' represents average size of 2.36 mm.

(11.) 

Sl. No.	Fineness Modulus	Range
1	Fine Sand	2.2 to 2.6
2	Medium Sand	2.6 to 2.9
3	Coarse Sand	2.9 to 3.2

(12.) In ordinary sand, bulking varies from 20 to 40% for increase in moisture content 5 to 8 %.

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(13.) Stages for concrete production are-

(i) Batching   

(ii) Mixing        

(iii) Transportation

(iv) Placing 

(v) Compaction

(vi) Finishing

(vii) Curing

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(14.) For most important works, weight batching is used.

(15.) 1 Bag cement=Wt. 50 Kg.=Volume 35 Litres=Vol. 0.035 cum

(16.) Workability-Workability is defined as the property of concrete which determines the amount of useful internal works necessary to produce full compaction.

Or, in simple words, workability is how ease you can mix, transport, placed, 100% compact, finish the concrete.

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(17.) Measurement of workability-

(i) Slump Test

(ii) Compacting Factor Test

(iii) Vee-Bee Consistometer Test

(iv) Flow Table Test

(18.) 

Sl. No.	Name of Test	Value
1	Combined flakiness and elongation test	Shall not exceed 40% for uncrushed or crushed aggregate
2	Aggregate crushing value	30 % maximum
3	Aggregare Impact value
	(i) For wearing surfaces (such as runways, roads, pavements etc.)	30 % maximum
	(ii) For other than wearing surfaces	45 % maximum
4	Aggregate Abrasion Value
	(i) For wearing surfaces	30 % maximum
	(ii)For non-wearing surfaces	50 % maximum

(19.) Target strength for mix proportioning-

f'ck=fck+1.65s

(20.) Characteristic Strength-The characteristic strength is defined as the strength of the concrete below which not 5% of the test results are expected to fall.

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(21.) 

Sl. No.	Nominal maximum size of aggregate	Maximum water content
1	10 mm	208 kg
2	20 mm	186 kg
3	40 mm	165 kg

(22.) 

Sl. No.	Name of material	Specific gravity
1	Cement	3.15
2	Water	1
3	Coarse aggregate	2.74
4	Fine aggregate	2.74
5	Admixture	1.145
6	Fly ash	1

(23.) Percentage strength of concrete at various age:-

Sl. No.	Age	Strength Percentage
1	1 days	16%
2	3 days	40%
3	7 days	65%
4	14 days	90%
5	28 days	99%

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(24.) Rolling and margin:-

The deviation in weight as per IS code-1786 for several dia is given below:-

(i) 8 mm to 10 mm- +-7 %

(ii) 12 mm to 16 mm- +-5 %

(iii) 20 mm and above- +-3 %

(25.) In transit mixer maximum rotation is 16 nos. per minute and minimum rotation is 4 nos./minutes.

(26.) Binding wire shall be a minimum of 18 SWG (1.22 mm) soft annealed steel wire.

Also Read:Important one liner questions with their answers, Part-10

(27.) In general, steel for main and secondary reinforcement shall be high yield deformed bar of grade FE 500D for rebars upto 16 mm and FE 500 D (Ductile) rebars i.e. 20 mm, 25 mm, 32 mm and 40 mm.

(28.) Concrete mixing, transportation and placing should be completed within 1 hour.

(29.) The permissible slump should be 75+-25 mm (IS:1199)

(30.) For pumpable concrete slump should be 100+-25 mm.

(31.) Each layer of concreting may not be more than 400 mm to 450 mm in the thickness.

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(32.) Thermometer accuracy =+-1⁰C (Check it 15 minutes there after the concrete reached at site.Rod of thermometer will inserted in concrete more than 50 mm and time will be minimum 2 minutes.)

(33.) The store temperature of cement shall not exceed 40⁰C.

(34.) The platform of cement bags will be more than 150 to 200 mm.

(35.) Concrete cover/Starter's grade will be always 1 grade higher than specified concrete. Sometimes also used Forsec conbertra GP2.

(36.) For hand mix concrete 10 % extra cement is used.(As per CPWD guidelines)

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(37.) JMR-Joint Measurement Record

(38.) Variation of cube results=+-15 %

(39.) Plastisizer (5 to 10 %) and super plastisizer (upto 20 % reduce the water) is a water reducing admixture.

(40.) Both flaky and elongated particles may have adress effects on concrete and bituminous mix. They tend to lower the workability of concret and for bituminous mix, they particle may liable to breakup and disintegrate during traffic load.

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(41.) Calculation for mix ratio 1:2:4 (M-15)

1+2+4=7

7 is the mixing proportion.

Volume of wet cement concrete=1.54 to 1.57

Unit weight of cement=1440 kg/cum

1 bag of cement=50 kg/bag

                          =50/1440 cum

                          =0.034722 cum

Cement=1.54/7

            =0.22

            =0.22/0.03472

            =6.33 bags

1 bag cement=50 kgs.

                     =6.33 X 50 

                     =316.82 Kgs.

Sand=0.22 X 2

        =0.44 cum

Metal=0.22 X 4

         =0.88 cum 

(42.) Mortar is a mixture of matrix (Binding materials eg. cement, lime etc.) + Adultrants (Sand, Surkhi etc.)

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(43.) Types of cement-

(a.) OPC (33, 43 and 53 grade)

(b.) Rapid hardening cement

(c.) Extra rapid hardening cement

(d.) Quick setting cement

(e.) Sulphate resisting cement

(f.) Super sulphate cement

(g.) Portland slag cement

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(h.) Portland pozzolana cement

(i.) Low heat cement

(j.) Hydophobic cement

(k.) IRS T-40 cement

(l.) High alumina cement

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(44.) Chemical laboratory test of cement-

(a.) Loss of ignition test

(b.) Chemical composition test

(45.) Clinker is obtained as a result of fusion at a temperature of about 400⁰C to 1500⁰C, generally 1300⁰C temperature is kept in kiln.

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Written By-

Ritesh Raj

Email Id-rajritesh.motiharirr@gmail.com