BS ISO 20244:2018 pdf download

BS ISO 20244:2018 pdf download.Soil quality — Screening method for water content — Determination by refractometry
1 Scope
This document specifies a method for rapid determination of water content in soils. The method is based on refractive index measurement of a sucrose solution after it is mixed with a soil sample. It is applicable to the determination of water content in geological or geotechnical research as well as geotechnical engineering. In addition, it can be used for commercial work in a variety of fields, e.g. agriculture and civil engineering. The working range is up to approximately 50 % moisture content. The precision of the method typically ranges between 0,5 % and 1 % and depends on the type of refractometer that is used. The result of this method is strongly influenced by soil matrices. Higher contents of clay and/or organic matter will lead to significant lower values for water content compared to standard methods such as that described in ISO 11465.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1 refractometer
device for measurement of a refractive index
3.2 saccharimeter
refractometer (3.1) that indicates a sucrose concentration instead of a refractive index
3.3 Brix degree
mass fraction percentage of sucrose in solution, which is related directly to a refractive index
3.4 temperature correction
function for a refractometer (3.1) or a saccharimeter (3.2) to correct measurement deviation caused by atmospheric temperature when measurement is carried out at a temperature other than 20 °C
4 Principle
When a soil sample is mixed with a sucrose solution, the sucrose solution is diluted with water contained in the soil.
6 Procedure
6.1 Selection of a temperature correction mode Confirm that a temperature correction mode has been selected in the refractometer. If temperature correction parameters are required for correction, input required the parameters by following the instruction manual given by the manufacturer.
6.2 Creation of a correlation curve A correlation curve is necessary to convert the measured refractive indexes or Brix degrees of the sucrose solution to water contents of the unknown soil. The correlation curve should be prepared prior to on-site determination of water contents. Establish a correlation curve between refractive indexes (or Brix degrees) and water contents as follows.
a) Prepare a sucrose solution by carefully dissolving an exact amount of sucrose into measured water and dilute to 50 % in concentration. NOTE In case a correlation curve has a gentler slope or solutions are difficult to handle because of high viscosity, sucrose solutions at lower or higher concentrations can be used, unless there is a problem with inaccurate water content quantification.
b) Set up a correlation curve by adding different amounts of water to the sucrose solutions, for the relevant range. For instance, if 10 g sucrose solution is used, add in the range of 0 to 4 g water to the 10 g of sucrose solution. Plot a curve with the amount of water added on the horizontal axis and the measured refractive index or Brix degree on the vertical axis.