Soil Tests in Construction

By -
There are many types of Soil compaction tests which are performed on soil. Some of these are :-
1) The Sand Cone Method (FDT)
One of the most common test to determine the field density of soil is the sand-cone method. But it has a major limitation that this test is not suitable for saturated and soft soils.
The formula used are
Volume of soil, ft3 (m3)=[weight of sand filling hole, lb (kg)] /[ Density of sand, lb/ft3 (kg/m3)]
% Moisture = 100(weight of moist soil – weight of dry soil)/weight of dry soil
Field density, lb/ft3 (kg /m3)=weight of soil, lb (kg)/volume of soil, ft3 (m3)
Dry density=field density/(1 + % moisture/100)
% Compaction=100 (dry density)/max dry density
Maximum density is found by plotting a density–moisture curve.
2) California Bearing Ratio (CBR)
The California bearing ratio (CBR) is used as a determine the quality of strength of a soil under a pavement. It also measures the thickness of the pavement, its base, and other layers.
CBR = F/Fo
where
F = force per unit area required to penetrate a soil mass with a 3-in2 (1935.6-mm2 ) circular piston (about 2 in (50.8 mm) in diameter) at the rate of 0.05 in/min (1.27 mm/min)
F0 = force per unit area required for corresponding penetration of a standard material.
3) Soil Permeability
Darcy’s law is applicable in determining the soil permeability. Darcy law states that
V = kiA
where
V = rate of flow, cm3 /s,
A = cross-sectional area of soil conveying flow, cm2
k = Coefficient of permeability which depends on grain-size distribution, void ratio and soil fabric. The value varies from 10 cm/s for gravel to less than 10–7 for clays.

Comments

Post a Comment

Popular posts from this blog

Inspection Testing Plan (ITP) VS Checklist

By -
Image
DEFINITION OF ITP? An Inspection and Test Plan (ITP) lays out a schedule of inspections at critical control points or 'hold points' within a process, in order to verify that things are progressing as they should be. It can be defined as the program of inspection, testing of materials, and survey to be prepared and submitted by the contractor to the Consultant for approval before usage and application to the site. An "Inspection and Test Plan" (ITP) might also be called a "Quality Inspection Plan (QTP)". Inspection and Test Plans set out critical control points or ' hold points ' at various stages within a process. Each control point is a scheduled inspection or verification activity, where you will make sure that things are progressing as they should be. Inspection and Test Plans (ITP) are often used as a way to satisfy the requirements of the ISO 9001:2015 standard related to control of production and service provision. Did yo
Read more

Classifying Soils for Highway Construction with AASHTO M145 / ASTM D3282

By -
Image
There is no doubt that highways, roads, and airfields are crucial for modern transportation, as they literally lay the ground for extensive movement. However, during road construction, the ground is not always guaranteed to be viable; this is dependent on the soil profile, so there is a need to comprehend the properties of soil at the sub-grade level. AASHTO M145 / ASTM D3282 -15:  (Standard Practice for Classification of Soils and Soil-Aggregate Mixtures for Highway Construction Purposes) classifies soils from any geographic location into groups. This it bases on the results of laboratory tests it details to determine the particle-size characteristics, liquid limit, and plasticity index of soils. AASHTO M145 / ASTM D3282 -15  includes classification tables drawn from the American Association of State Highway and Transportation Officials (AASHTO) system, which originated as the Public Roads Classification System when Hogentogler and Terzaghi developed it in 1929. Through this tab
Read more

Comparison: AASHTO & Unified Soil Classification System

By -
Image
Comparison between AASHTO and unifical soil classification system Comparison #  AASHTO M145 Classification System : American Association of State Highway and Transport Officials (AASHTO) soil classification system is based on both the particle size and the plasticity characteristics. According to this system, soils are classified into eight groups A-1 to A-8, the last being peat or muck. Soils within each group are evaluated according to the group index (GI) calculated from the following empirical formula – GI = 0.2 a + 0.005 ac + 0.01 bd Where a = that part of the percent passing US sieve No. 200 greater than 35, and not exceeding 75, expressed as a positive whole number (1 to 40); b = that part of the percent passing US sieve No. 200 greater than 15, and not exceeding 55 expressed as a positive whole number (1 to 40); c = that part of the liquid limit greater than 40, and not greater than 60, expressed as a positive whole number (1 to 20), and d = that part of the p
Read more