Light Weight Deflectometer re-calibration now

Light weight deflectometer are measuring very precise and highly reliable test results, therefore they have to be re-calibrated every twelve months according to the international standard ASTM E2583-07 (American Society for Testing and Materials) independent of how often it was used in the last 12 month. Regular calibration will guarantee, that test results are always reliable and precise and that the equipment is working correctly. To do this annual service, owners have to resend the entire equipment to the manufacturer, because remote or online calibration is not possible. Winter time is perfect to do this required re-calibration because bad weather conditions are making the use of LWD nearly impossible during this period in most countries of the world. The lead time of calibration service depends mostly on the transport time, which is needed for shipment of the equipment to and from manufacturer and back to customer. Inside European Community it needs three weeks including transport time, calibration for overseas customers needs about four weeks depending on customs clearance. Sending back the equipment from overseas best to use a custom procedure to send equipment as temporary import to avoid custom fee. Proforma invoice issued by users has to be less than 1000 USD for temporary import. This makes custom clearance easier. As soon as the equipment has arrived in Germany, manufacturer will start the calibration process immediately .

The manufacturer is doing re-calibration of light weight deflectometer using three in house designed calibration systems, all accredited by BASt Germany (Bundesanstalt für Strassenwesen, a department of ministry of traffic of the German government), which guarantees that customers do not have to wait a long time for calibration service. The third calibration system was just accepted by BASt in the middle of February 2022. Calibration service means the calibration of the central geophone which calculates the deflection of the soil as well as the calibration of the two external geophones (if part of the equipment) and the calibration of the load cell which is measuring the load of the falling weight. The device works with a 10 kg falling weight and even with 15 kg and 20 kg if the user has purchased these options. Calibration service is according to the international standard ASTM E2583-07 and the manufacturer is following the strict rules of the German calibration standard TP BF-StB 8.4 in addition to make sure, that light weight deflectometer made in Germany will be very precise and reliable when doing compaction tests of soil in the field. After a successfully calibration, a label with the period of the valid calibration year will be attached on the equipment.

The service includes the check up of all functions of the device as well to make sure that the light weight deflectometer will work bug free at least till the next re-calibration after twelve more months. If dust or sand is in the device, the parts will be disassembled and cleaned carefully by technical staff. Before a necessary repair, the manufacturer will ask the owner to approve a commercial offer send via email where all repairs are explained and listed.

The manufacturer reminds all customers every year via email with a special calibration reminder service, that the calibration period of their equipment is expired.

Light Weight Deflectometer (Part 1)

Light Weight Deflectometer (LWD) with Geophone

Light Weight Deflectometer is not like Light Weight Deflectometer. Watch out for the differences between two types of eqipment. It is a non destructive test (NDT) equipment for dynamic load testing of load bearing capacity. Light Weight Deflectometers are offering the most economic way to do non destruction test (NDT) of compaction quality of unbound or partially bound material in earthworks, road constructions, canal construction, railway constructions and utility trenches, all as one single solution. The one person test procedure is done in less than two minutes and still provides full results. No counterweight (truck or roller) is required and tests can be done in places hard to enter. The equipment has no radioactive sources and all tests can be done by one single person.

There are two different types of Light Weight Deflectomete in existence: One type is operating via a Geophone and one type is operating via an acceleration meter. TERRATEST® is the only manufacturer in the world producing both types. And there are many more differences of facilities between these two types of test instruments. The acceleration meter Light Weight Deflectometer (german dynamic load plate test) was invented in Germany several decades before. It meets the german specification TP BF-StB Part B8.3, the ASTM E2835-11, the Austrian specification RVS 08.03.04, the Spanish specification UNE 103807-2:2008, the cChinese specification TB 10102-2010, J338-2004 (standard for soil testing in railway construction), the Czech specification CSN 736192-1996 and the RIL 836 for track laying of Deutsche Bahn (German railway). The geophone type meets the ASTM E2883-07, UK standard IAN 73 and Italian standard UNI 11531-1.

Terratest as the leading manufacturer of Light Weight Deflectometer is asked frequently by customers from all over the world, which type is the best for which requirements. An answer is not as easy as it seems.

First of all customers have to follow the required specification of their specific project in their country. According to the required specification they have to choose the corresponding type. If no specification is required, the type should be chosen according the operation area.

The accelaration model is far easier to use. But it gives the user even less features than the geophone one. Following the instruction manual, one single person can handle the gauge immediately, no training is necessary. The test procedure does not require a counterweight like a truck or roller and the test procedure needs less than two minutes. Immediately after the test procedure users can printout a test protocol and will have the result in their own hands. In Germany results can be used according to the specifications ZTVA and ZTVE as an official compaction proof.

Thanks to the short time needed for each single test the compaction quality of all layers can be tested all over the construction site, even on natural ground before starting the earthworks.

It provides an immediate method to the workers in the construction site before, during and after the compaction process to determine the load bearing capacity of unbound soil to make a statement about the compaction quality. Moreover the compaction process can be managed directly at any stage of the procedure The Light Weight Deflectometer is used for self monitoring and even to provide official proofs.

Light Weight Deflectometer for Safe Foundation

The construction boom in Germany is continuously growing. Comfortable prefabricated houses and solid buildings are in progress all around. The bearing capacity of the soil is an imperative condition to be evaluated beforehand - particularly below the foundation plate, as this element represents the interface between house and subsoil. It is the purpose of the foundation plate to distribute the weight of the building in a homogeneous manner and to protect the building from heat/cold and vibrations of the ground. The available ground however is often not strong enough to carry the foundation plate without additional earthwork. Therefore besides deep sounding, analysis of the bearing capacity of the grown soil is required. A light weight deflectometer is an adequate instrument, since it is able to perform a measurement within only two minutes. The simple service as well contributes to a quick establishment of comprehensive measurement sequences. This way, a qualified assessment concerning the entire field is possible in no time. In the case of cohesive soil or inclination of the site, soil replacement has to be carried out. Sometimes several meters can be involved. For these works, it is important that the new soil is inserted by layers and that these layers are individually compacted by vibratory plate. Thickness of each layer should not exceed 30 cm, and evidence of qualified compaction must be provided each time. For this inspection, a light weight deflectometer is an ideal instrument. Minimum requirement for the bearing capacity of soil for private homes usually amounts to 30-40 MN/m² for the layer directly below the foundation plate.

„During each construction project, we carefully examine the quality of the earthwork for cellars and foundation plates. Compaction work and subsequent compaction control is of major importance. Particularly in places with difficult access, there is no alternative to light weight deflectometers. They do not need a counterweight, and the assessment is easy to perform “, declares project manager Kai Wolts. Mr. Wolts and his company recently invested in 14 light weight deflectometers produced by TERRATEST from Berlin. From now on, each construction gang disposes of its own measuring equipment and can immediately provide itself evidence for the compaction of the soil. „This fact ensures our independence from external geotechnical experts, thus saving time and money.”

All around Germany, light weight deflectometers make themselves indispensable, as settlement damages turned out to be a serious topic for several companies, causing major follow-up costs. Particularly for foundation plates, insufficient compaction of the subsoil gives rise to exorbitant expenses, as the whole building may be subjected to cracks. Therefore before pouring the foundation plates, measurement of the bearing capacity of the subsoil is imperative. „Since many years, we trust in light weight deflectometers, and are continuously in action in the vicinity of Berlin with three of them”, emphasizes construction engineer Norbert Wenzel from Frankfurt (Oder). „Besides prescribed core sounding, we are carrying out also measurements by means of light weight deflectometers, to ensure homogeneous bearing capacity and sufficient compaction quality of the soil, before pouring the foundation plate. This is an essential element of responsible construction management”, so his opinion.

The essential benefits of light weight deflectometers are obvious: 

• Measurements can be carried out by each capable member of the team in no time.
• Large measurement sequences are possible even under tight deadlines, as each measurement takes only two minutes.
• Counterweights like road rollers are not necessary.
• Compaction work for each layer can be accompanied by measurements.
• Homogeneity of bearing capacity can be checked already during insertion of the layers.

Light Weight Deflectometer at Bauma 2019

This was the fourth time in a row that we presented our light weight deflectometer for dynamic load plate test at BAUMA in Munich, since its market launch in the year of 2010. Also this year, the BAUMA broke all records with 620,000 visitors and 3,700 exhibitors from 63 countries – the best result in the 65-year history of this trade fair. Particularly the huge number of visitors from abroad (250,000 were counted) was remarkable. This became visible also at the TERRATEST® booth. “Again we could sell some light weight deflectometers to clientele from China and India, the Chinese client even ordered a set of several items”, resumes Frank G. Schulz, CEO of TERRATEST. ”Orders from Eastern Europe were received as well, and for the first time we did business with a company in Malawi (South Africa). That’s one more country in our list!”

The rush of professional visitors from numerous sectors like road, track and channel construction, civil engineering, gardening and landscaping exceeded all our expectations. Access to our booth sometimes proved to be difficult. Falko Weiß, sales manager of TERRATEST® mischievously smiles: ”A particular highlight was the complaint of one of our competitors. He asked from the fair management to cover our prices, because they were so low that he could not tolerate.”

One fact that our competitor did not take into consideration was the curiosity that covered price tags incite from visitors. “Oh, what kind of secret is hidden over here?” Finally visitors of course found out that our prices are so favorable, that ordering could not be a wrong decision, and the number of sold light weight deflectometers broke all records. TERRATEST this way achieved the highest turnover during a fair participation ever.

Fabrizio Schulz, the son of the company founder, was present as well.” I already belonged to the staff during the BAUMA in Delhi, but BAUMA Munich was far beyond my expectations. I even sold some instruments myself, and will definitely participate in the next BAUMA as well.” TERRATEST® presented the well-known light weight deflectometer for compaction tests of soil, available with cable and Bluetooth. The Bluetooth model was launched to the markets during a previous BAUMA fair, and meanwhile exists in an upgraded version with Bluetooth Low Energy (TERRATEST® 6000 BLE). Bluetooth models can be used with iPhone as well as with Android APP, so that measuring electronics do not need to be transported anymore to the construction site. These models can completely be operated via smartphone.

During this event, our new Light Weight Deflectometer TERRATEST 9000 LWD was also presented for the first time in Germany. This instrument features one central and up to two additional geophones (available upon request), furthermore a load cell which allows falling weight and falling height to be modified. The falling weight of 10 kg this way can be increased by two times five kg, i.e. to 15 and to 20 kg, to carry out the compaction test. This model has been developed mainly for exportation into countries with corresponding test specifications, i.e. for clients in UK, Italy, Korea, India, Saudi Arabia and many African countries.

Our staff is meanwhile preparing the next trade fair, because “After the BAUMA is before the BAUMA.” And thanks to our helpful competitor, we found a new slogan: ”Our prices should be forbidden!”                

Light Weight Deflectometer with Geophones and Load Cell

Four years of intense development work have been crowned with success. TERRATEST® on the bauma Shanghai is proud to present its new high-tech model of Light Weight Deflectometer TERRATEST 9000 LWD for the first time, thus reaching the top in the field of light weight deflectometers. This device for measurement uses a central geophone instead of an acceleration sensor, thus significantly increasing the precision in the case of high rigidity. “Meanwhile we are in contact with dealers in Saudi Arabia and Korea, ready to offer our devices in these countries”, explains Sven Krone, CEO of TERRATEST LWD GmbH. “This model is produced particularly for export, as no test specification in Germany for this type of instrument exists. The situation in USA, Canada, Great Britain, Italy, India and South East Asia however is different, so there is a strong demand.”< The configuration enables two external geophones to be attached additionally, in order to measure settlement at a distance of up to 60 cm. An integrated load cell is provided as well, so that falling height, plate diameter and mass of the falling weight can be optimized by the user whenever needed. The four plate diameters amount to 100, 150, 200 and 300 mm; falling weights with a mass of 10, 15 and 20 kg can be used. The load measurement is correspondingly taken into consideration for the calculation.

Production enhanced by Synergy Effects

For the production, TERRATEST® can exploit synergies, which becomes obvious by the optical appearance of the device, hexagonal shape of the falling weight and the inclined load plate handles. Development of smartphone App and software is based on proven resources as well.

The new light weight deflectometer TERRATEST 9000 LWD has been conceived for international markets, and results from a development phase of four years. The instrument features a central geophone and a load cell; two external geophones can be attached as well.

Light Weight Deflectometer in Use on Interstate Highway No.1

Bridge construction works for interstate highway no. 1 in Germany are currently successfully supported by TERRATEST’s model 4000 STREAM. For the Volmarstein viaduct with a length of 315 m, which is frequented everyday by more than 100,000 vehicles, recalculations of the statics have revealed the presence of flaws not to be corrected by sanitation. “For this reason, a completely new construction of the bridge proved to be necessary. For the abutments of the new bridge piers, we are establishing a reinforced soil construction”, explains builder’s manager Michael Rehmann. “This includes an integrated frost protection layer with a graining of 45 - and the lightweight deflectometer is a valuable assistance for performing dynamic load plate tests on each second layer of the gravel base, so its bearing capacity permanently remains under control.”

A reinforced soil construction represents a special form of retaining wall and was invented in the sixties of the past century by the French engineer Henri Vidal. Tensile loads are directed to a reinforcement inserted into the soil, and then conveniently distributed. This reinforcement is usually made of plastics in order to avoid corrosion problems. The new abutments and piers are placed between the former elements, so the length of the bridge is reduced to 285 m. Its width of 31 m exceeds the value of the old bridge by 2 m and offers three lanes in either direction. The construction is intended to be completed in the year of 2020.

An Application Engineer Knowing His Job

 

For years already, Falko Weiss Instructs our Clients in Detail

Falko Weiss from Berlin, an experienced member of our team, knows all the particularities concerning lightweight deflectometers and performs comprehensive practical training of new customers. He was responsible already for the delivery of over 1500 items and disposes of corresponding competence.

TERRATEST NEWS: Mr. Weiss, please give us a brief overview of your job.

Mr. Weiss: Well, new customers when starting first of all need an explanation of the PC software, not only of the instrument itself.

TERRATEST NEWS: What is the particular challenge of your duty?

Mr. Weiss: Often the products are ordered really in the last nick of time, so instant delivery and training are hard to achieve. Customers do not care about traffic jams and the weather. Since the compaction quality is essential for qualified execution of construction work, a qualified introduction to the equipment is necessary at once, all the same. Just-in-time delivery is no job for amateurs. Due to the continuously growing demand for our instruments and their increasing complexity, it is important to be perfectly prepared and to give the right answer promptly.

TERRATEST NEWS: What do you enjoy most in your job?

Mr. Weiss: Some customers really appreciate my work and have familiarized themselves with the details of the situation. In these cases, I can make my presentation as intended, supported by Power Point.

TERRATEST NEWS: Are you not bored with all these long travels on the highway?

Mr. Weiss: I enjoy driving. I guess you need to be the right type for this job. A positive echo of my audience always gives me motivation.