Calibration Of Speedy Moisture Meter

JOB NO. 1

CALIBRATON OF SPEEDY MOISTURE METER. Murtaza Abbas 2007-CIVIL-140 SECTION-D 9/9/2009

GEOTECHNICAL ENGINEERING LABORTARY. UNIVERSITY OF ENGINEERING AND TECONOLOGY, LAHORE.

CALIBRATION OF SPEEDY MOISTURE METER A speedy moisture meter is a handy instrument to determine the moisture content of soil stratum but it gives the value of moisture content in terms of wet weight of the soil, wsp. Therefore it is important to convert this value for dry weight of soil solids, for the sake of accurate results. For quick determination of moisture content a calibration curve is drawn to compare values between the actual moisture content and the moisture content shown by the speedy moisture meter.

Apparatus: 1. 2. 3. 4.

Speedy moisture meter. Two steel balls. Pans. Electronic balance.

Procedure: 1- Weigh 200g of soil with an electronic balance. 2- Add water in soil equal to 5% of weight of soil.

3- Mix the water until a uniform mixture is attained. 4- Place this soil in oven to note the dry weight of soil, so that we can carry out the process of calculating moisture content ‘w’ of soil. FOR SPEEDY MOISTURE METER: 5- Weigh 26g of the wet soil with the speedy moisture meter balance and put it in the speedy moisture meter. 6- Check Zero error on the moisture meter. 7- Now, add 2 scoops of calcium carbide in the speedy moisture meter and follow it with the placing of steel balls (pulverize) inside the moisture meter. 8- Put the cap back on the moisture meter so that none of acetylene gas escapes. 9- Start shaking and rotating the moisture meter simultaneously. As a result the dial under the meter will start moving.

10-Note the value when the dial stops moving. This is wsp expressed as a

percentage. 11-Repeat the same process with further addition of water (8%, 11%, 14%,17%, 20% )

OBSERVATIONS AND CALCULATIONS: Error in dial gauge of speedy moisture meter = 0.6 Weight of soil in apparatus = 26 gm Weight of calcium carbide (CaC2) = 24 gm Dial gauge reading = 12.2 Corrected dial gauge reading = wsp = 12.2 - 0.6 = 11.6

Table 1.1

COMMENTS: Serial #

1

2

3

4

5

6

Moisture Content w’ %

5

8

11

14

17

20

Can No.

48

59

97

42

50

92

Empty weight W1 (gm)

13.72

15.62

14.06

15.98

14.03

14.05

Wet Wt.+

23.96

31.60

29.55

39.51

34.07

42.35

Oven dry wt. W3 (gm)

23.38

30.31

27.85

36.37

30.99

37.37

Moisture Content ‘w’ %

6.00

8.78

12.33

15.40

18.16

21.35

Speedy moisture meter reading ‘wsp’ %

5.6

7.8

11.6

13.4

16.8

25.2

Wt. of can W2 (gm)

1. When we use speedy moisture meter in field, it could be a chance that it gives moisture content more or less than the moisture content determined by any other method e.g. by oven drying method. 2. In this experiment we have observed the value of moisture in percentage obtained by speedy moisture meter sometimes increase or sometimes decrease from the predetermined moisture. 3. This is because of the fact that either the instrument is too old or it gives error in dial gauge reading. 4. Also due to availability of only one apparatus in lab we cannot get much idea about that, but it fulfills the cause. REMEDIAL MEASURES: 1. There are two ways of getting better results, i. If the apparatus is old or damaged, it is better to replace it with new one ii. Calibrate it. Calibration can be done from some good laboratory of any institution. UNDERSTANDING: This experiment helps us a lot in future life, if we will do some field job and encounter some problem related to calibration, and then this performance of calibration through graph makes it easy for us to calibrate the apparatus in field.