PRELIMINARY DATA SHEET
Name: MEGINO, Kim L.
Group No. 5
Course/Section: CE161P/A14
Date: October 19, 2017
Experiment No. 1 WATER CONTENT IN SOIL
Sieve No. Trial No.
#4
#10
1
2
1
2
Weight of wet soil + container (grams)
87.6
77.4
84.8
83.4
Weight of oven-dry soil + container (grams)
85.68
73.96
83.29
81.30
20
20
20
20
Weight of oven-dry soil (grams)
18.08
16.56
18.49
17.9
Weight of container (grams)
67.6
57.4
64.8
63.4
Moisture loss (grams)
1.72
3.44
1.51
2.1
Water content, w (%)
10.62
20.77
8.17
11.73
Weight of wet soil (grams)
Average water water content content (%) Average water water content content (%)
_____________ ___________________ ____________ ______ Student’ Student ’s Signature
15.7
9.95 12.83
_____________ ___________________ ___________ _____ Instructor’s Signature
Sample Computations Given/Data Collected: Weight of wet soil + container: 87.6 g Weight of oven-dry soil + container: 85.68 g Weight of container: 67.6 g Computations: Weight of wet soil: = + − = 87.6 − 67.6 = 20
Weight of dry soil: = + − = 85.68 − 67.6 = 18.08
Moisture loss: = − = 20 − 18.08 = 1.92
Water Content,
=
=
( − ) − ( − ) ( − )
∗ 100%
(87.6 − 67.6) − (85.68 − 67.6) (85.68 − 67.6)
= 10.62%
Given/Data Collected: Weight of wet soil + container: 84.8 g Weight of oven-dry soil + container: 83.29 g Weight of container: 64.8 g Computations: Weight of wet soil: = + − = 84.8 − 64.8 = 20
Weight of dry soil: = + − = 83.29 − 64.8
∗ 100%
= 18.49
Moisture loss: = − = 20 − 18.49 = 1.51
Water Content,
=
=
( − ) − ( − ) ( − )
∗ 100%
(84.8 − 64.8) − (83.29 − 64.8) (83.29 − 64.8) = 8.17%
∗ 100%
ANSWER TO QUESTIONS:
1. Why is it not recommended to leave an oven-dried sample in the open air for a long time before measuring its dry weight? It is not recommended to leave an oven-dried sample in the open air for a long time before measuring its dry weight since the samples has the possibility to get moisture from its surroundings. However, its moisture might come from the change in temperature of the soil sample. Thus, definite errors might come from the weight of the oven dried sample which it is highly recommended for students to use the desiccators in measuring of weight in order to save time.
2. Excluding oven drying, are there other methods to determine the water content of soils? There are two other methods to determine the water content in soils which are indirect and direct method. Using Indirect method includes Pressure plate apparatus, pressure membrane, neutron scattering method, gypsum blocks, and tensionmeter. While using direct method includes calcium chloride and methyl alcohol.
3.
Is it possible to measure the water content of sands?
Sand is considered as soil so it is possible to measure its water content. Using the process of infiltration of soil, the water content of the sand may be determined by its texture.
4. Why do we use a fixed temperature range to dry soils? What is the effect on soils of microwave drying? Using a fixed temperature range to dry soils is an advantage especially when it comes to its weight where it will be constant which is a very ideal in determining the water content of the soil. In using the Microwave, there may be a change on the soil structure and on its organic matters due to the decrease of its swelling potential. There may be a lot of ways to dry the soil but using the microwave may be considered as one of the fastest way.
5. What is the function of the container lid and dessicator when determining the water content of soil? Due to the change in temperature of the surroundings, the container lid and dessicator are preventing the absorption of moisture from the air.
INTRODUCTION A. PRINCIPLES OF THE EXPERIMENT Water content,
, is defined as the ratio, expressed as a percentage, of the weight of
w
water in a given soil mass to the weight of solid particles. The amount of water associated with a given volume or mass of soil is a highly variable property. It can change on time scales of minutes to years. However, most soil properties are more stable, and should be referenced to dry soil weight. Water contained in soil is called soil moisture. The water is held within the soil pores. Soil water is the major component of the soil in relation to plant growth. If the moisture content of a soil is optimum for plant growth, plants can readily absorb soil water. Not all the water, held in soil, is available to plants. Much of water remains in the soil as a thin film. Soil water dissolves salts and makes up the soil solution, which is important as medium for supply of nutrients to growing plants. The soils hold water (moisture) due to their colloidal properties and aggregation qualities. The water is held on the surface of the colloids and other particles and in the pores. The forces responsible for retention of water in the soil after the drainage has stopped are due to surface tension and surface attraction and are called surface moisture tension. This refers to the energy concept in moisture retention relationships. The force with which water is held is also termed as suction.
B. INTERPRETATION OF RESULTS In this experiment entitled “Water Content in Soil”, the purpose of the test performed is to determine the hygroscopic water content of soils by oven drying to constant weight. Most natural soils, which are sandy and gravelly in nature, may have water content of about 15-20%. Thus, there is a higher water content percentage in fine-grained soils than the course grained soils and water can easily pass through voids of course grained soils. However, as the sieves no. decreases, greater volume of soil particles can pass through so it will give off a lesser water content percentage. In every laboratory experiment, sources of error cannot be prevented. Errors may occur from the moisture of surroundings, especially in deliberat ely measuring the soil sample after ovendrying. Also, using the container lid and dessicator can lead to inaccurate measurement. According from the manual, the drying time will depend on the kind of soil and size of sample. Unfortunately, the time for oven drying was not indicated for the specific sample of soil that was experimented. Thus, insufficient or perhaps a great amount of time was allotted for oven drying. Lastly, miscalculations can also lead to imprecise data. Incorrectness can be avoided with focus. Soil water content is widely studied and reported on the literature due to its extensive and profound role. It is a key part of the hydrological cycle, provides support to organisms, interacts with climate, and is a major consideration in ground and surface water supply, environmental and geo-technical aspects.
C. APPLICATION OF EXPERIMENT Soil types behave differently of various levels of moisture. ASTM D-2116, D-3017, D-4643 and AASHTO T-265 establish the standard methods of determining the moisture content of soils. In this experiment, D-2216 was performed which determined the water content of soil using the conventional oven method. In soil science, hydrology, and agricultural sciences, water content has an important role for groundwater recharge, agriculture, and soil chemistry. Some agriculture professionals are beginning to use environmental measurements such as soil moisture to schedule irrigation. This method is referred to as “Smart Irrigation”. Most soils have water content less than porosity, which is the definition of unsaturated conditions, and they make up the subject of vadose zone hydrogeology. This is of importance to agriculture, contaminant transport, and flood control. Study of soils (Such as its water content) and their utilization are vital espec ially in planning foundations for structures and highways.
CONCLUSIONS: After performing the experiment, we were able to satisfy the scope of this experiment. We were able to determine the hygroscopic water content of soils by oven drying to constant weight. For sieves no.4 the average water content was 15.7% and for sieve no. 10 the average water content we had was 9.95%. Based on studies and research, fine grained soils has a higher water content percentage than coarse grained soils because water can easily pass through the voids of coarse grained soils. Also most soils have a water content less than porosity, which is the definiti on of unsaturated conditions, and they make up the subject of vadose zone hydrogeology. This is important to agriculture, contaminant transport, and flood control. To conclude, we learned a lot from this experiment. We were able to visualize or have a better understanding of the concept of how water content affects the soil.
REFERENCES
Jamal, H. (n.d.). Soil Mechanics Engineering, advanced soil mechanics lecture notes. Retrieved from Civil Engineering Portal, Retrieved from http://www.aboutcivil.org/soilmechanics.html
Abbas,
A.
(1996).
ASTM
International.
Retrieved
from
Mechanics.
Retrieved
from
https://www.astm.org/Standards/D854.htm
Davison,
L.
(2000).
Soil
http://environment.uwe.ac.uk/geocal/SoilMech/classification/default.htm
Dynamix
Agitators
Inc.
(2015).
Dynamix
Agitators.
Retrieved
from
http://www.dynamixinc.com/specific-gravity
Guwahati,
I.
(2012,
June
26).
NPTEL.
Retrieved
from
http://nptel.ac.in/courses/105103025/5
Willits,
C.
(1951).
ACS
Publications.
http://pubs.acs.org/doi/abs/10.1021/ac60056a003
http://geo.verruijt.net/software/SoilMechBook2012.pdf
Retrieved
from
