Flakiness Test of an Aggregate

 

Flakiness test is an important test of aggregate.Because, aggregate is important ingredient of concrete. Aggregate is how much flaky, it will acceptable or not, it is known by flakiness test.I am representing here flakiness test.  

Flakiness Index-If aggregate least dimension is less than 3/5th or 0.6 of its mean dimensions, then it is called Flaky.

Flakiness Gauge (Image Source:iricen.gov.in)

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Used IS Sieve:-

25 mm           

20 mm

16 mm

12.5 mm

10 mm

6.3 mm

Flakiness Gauge (Image Source:Amazon.in)

Also Rest:Important terms on the basis of IS codes

Test Procedure:-

(i) To arrange all IS sieves in descending order as mentioned above.

(ii) Take approx 7.5 kg. sample, weight of that sample and according to sieve size order, we will sieving them.

(iii) Sieving as good method and on each sieve retaining 200 and 200 pieces of aggregate taken separately.(means 200 nos. for flakiness test and 200 nos. for elongation test)

(iv) Suppose on 16 mm. IS sieve some aggregates are retaining, in which we will separate 200 and 200 nos. of aggregate.

(v) Suppose 200 pieces of aggregate weight=2128 gm, then it will use for flakiness test.

(vi) Flakiness gauge will kept on pan.

Flakiness Gauge (Image Source:Amazon.in)

(vii) We seen that on flakiness gauge 20 to 16 mm is mentioned that means it will 20 mm from passing and retaining through 16 mm. If whichever is passed, then it will fall on bottom pan and whichever is not passed, will kept on separate pan/container.

(viii) Now taken passing sample weight (w1)=258 gm

(ix) Now, next IS sieve we will separate 200 and 200 nos. for both tests and 200 nos. will passes  through flakiness gauge and whose passing weight and sample weight will write on format.

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

(x) Format for flakiness test:-

Wt. of sample taken(gm)=7500 gm

Reference-IS 2386 (Part-1) 1963

Test 402.3 of QAH vol-II (Page no.-65 to 66)

Example:-

Passing through IS Sieve (in mm)	Retained through IS Sieve (in mm)	Wt. of fraction consisting of at least 200 pieces	Thickness gauge size (0.6 times the mean sieve)	Wt. of aggregate in each fraction passing through the thickness gauge
63	50	w1=	33.9	m1
50	40	w2=	27	m2
40	31.5	w3=	21.5	m3
31.5	25	w4=	16.25	m4
25	20	w5=	13.5	m5
20	16	w6=2128	10.8	m6=258
16	12.5	w7=1613	8.55	m7=112
12.5	10	w8=562	6.75	m8=61
10	6.3	w9=406	4.89	m9=42
Total		w=4709		m=473

Also Read:Important terms/points of civil engineering

Now,

Flakiness Index=473/4709x100

                         =10.04 %

Note:-As per IS code 383:2016, page no.-3, clause no.-5.3, the combined flakiness and elongation index so obtained shall not exceed 40 percent for uncrushed or crushed aggregate.

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Written By-

Ritesh Raj

Email Id-rajritesh.motiharirr@gmail.com