Frank Georg Schulz | TERRATEST

What is Calibration of Light Weight Deflectometer (LWD) and Why is it Important?

Apr 23rd 2015 at 4:14 AM

Many construction projects that require the support of underlying soil must start with the measurement of the soil's bearing capacity. Bridge abutments, falsework or temporary support structures, and dams are some examples of structures that require underlying soil for support. Engineers must determine how much weight the soil can support. To do that, they must find out the type of soil and measure its bearing capacity using a light weight deflectometer. LWD provides a quick and easy way to test the soil's compaction quality and bearing capacity.

A light weight deflectometer is an innovative measuring device that can be customized to your project's requirements. It can be calibrated to suit your construction site and to match your standards in efficiency and performance. LWDs can be versatile devices, too. They can be used for the dynamic load plate test with a light falling weight deflectometer on projects like track laying, road construction, and earthworks.

A lightweight deflectometer measures the vertical deformation, which a falling mass imparts when it impacts the resting plate on the ground. The technology has been around for over two decades and it is reliable for quality assurance or quality control in earthwork construction. The device is found to be useful in asphalt compaction, too. In the US, LWD testing results like estimated dynamic soil modulus and soil deflection are used in a qualitative and relative sense due to acceptance criteria, which is based on moisture content and dry density.

There are different regulations for calibrating LWDs, and some of the best products follow international and German regulations. TP BF-StB part B 8.3 edition 2012 is an example of a German regulation and an engineering code for soil and rock in road construction. UNE 100807-2:2008 is a Spanish regulation and it is a plate load test using a light weight deflectometer. TB 10202-2004, J338-2004 is the Chinese regulation for soil testing in constructing railways. ASTM E2835-11 is the American standard test method to measure deflections by means of a portable impulse plate load test device.

LWDs on construction sites are subject to the toughest conditions. Hence, they must be able to withstand rain, extreme temperatures, dust, and vibrations. Manufacturers make sure that they follow international and American standards to ensure a fast, reliable, and precise light weight deflectometer for your testing needs. If you are looking for LWDs online, be sure that the products are delivered with a calibration certificate according to international or local standards, and make sure that the calibration system is accredited by known authorities, like the German Federal Road Research Institute.

About The Author:

TERRATEST GmbH is world leader in development and manufacturing of Light Weight Deflectometers for dynamic load plate test. They offer the world’s first light weight deflectometerTERRATEST 5000 BLU” with Bluetooth and voice navigation. For more information about their products visit their website!

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