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.

TERRATEST® App from now on in Google® Playstore

Our Light Weight Deflectometer TERRATEST5000 BLU is worldwide the first instrument in its class to be controlled via tablet or smartphone. For that purpose, TERRATEST^® has developed an app from now on available in Google^® playstore. This app proves to be useful also when used with the TERRATEST^® 4000 STREAM model, as it enables measuring results directly to be transferred from the measuring electronics ROBUSTA to a smartphone. This feature considerably speeds up order handling, as the results still on the construction site can be processed, and logs in form of a .pdf file can be sent to the office or to the customer without delay. Analysis of a dynamical load plate test by means of a light falling weight this way is performed in no time. The quality of the logs transmitted by app exactly corresponds to the documentation prepared by means of the TERRATEST^® 2.0 software, and offer even the additional benefit of automatically integrating photos of the measuring position captured on site within the file. “We are very proud of being able to offer this comfortable control method for our falling weight deflectometers to the clientele”, declares Frank Georg Schulz, CEO of TERRAEST^® GmbH Berlin. The possibility of using this app also for our new cable instrument TERRATEST^® 4000 STRAM demonstrates our innovative power and the continuous progress of our product portfolio.” App versions loaded from the Google^® playstore automatically create an update message, so that the user is instantaneously informed about the new version available - so he can profit from the new functions, which permanently extend the scope of the instrument corresponding to the current state of further development.

New Delivery to Kuwait

In the beginning of February, two Light Weight Deflectometers of the 4000 Voice Series were delivered to the South Al Mutlaa site in Kuwait. They are intended to be used for dynamical load plate tests, to be executed in the course of development work taking place under the responsibility of the Turkish Kolin group. “For our purchase decision, the essential criterion was the dust-tight ROBUSTA box housing the electronics”, explains project coordinator Mr. Mustafa Hakan. “When working in desert, safe protection of internal components is imperative, that’s easy to understand. I have been using TERRATEST® equipment in Turkey already for a long time, and it turned out to be absolutely reliable.” South Al Mutlaa currently represents the largest construction site in Kuwait and will be the core of a new Mega City with 30,000 houses, comprising a project volume of 1 billion US$.