Over the past decade, many countries have heavily invested in wind energy. While the quality control, routine inspection, and performance monitoring of the turbine and the blades have significantly developed over the past few years, the quality control and monitoring of the foundation elements is often overlooked. This is essential in keeping these massive towers grounded and secure.

Wind Turbine foundation can be as large as 10-15 meters (diameter), the Foundation block can be as thick as 1 to 2 meters, depending on the tower size, and soil characteristics. Due to their relatively large size, these foundations are often considered mass concrete.

This can lead into buildup of significant heat (from the cement hydration process) and develop massive temperature gradient in the foundation block. This may result in thermal contraction cracking shortly after the concrete hardens — compromising the structural integrity and durability of the foundation.

Excessive heat development and dissipation may result in thermal contraction cracking shortly after the concrete hardens — compromising the structural integrity and durability of the foundation.

Wind Turbine Foundations have sophisticated congested steel reinforcement to provide stability against dynamic loads. This will make the placement of concrete challenging, and it may result in poor quality patches in the foundation.

​While the use of Self-Consolidating Concrete (SCC) and steel fibres can help overcome some of these challenges, by reducing the amount of steel bars, and proper placement. However, the quality of foundations needs to be evaluated ahead of installing the tower and the turbine.

​4- Ground Penetrating Radar
Ground penetrating radar (GPR) is a very useful technique for nondestructive concrete imaging and scanning. GPR uses pulsed electromagnetic radiation to scan concrete. GPR consists of a transmitter antenna and a receiver antenna, and a signal processing unit. GPR emits electromagnetic pulses (radar pulses) with specific central frequency to scan the subsurface medium. The reflected waves from subsurface layers, and objects are captured by the receiver antenna.

Cracks in Wind Turbine Foundation
It is critical to repair early age cracks in wind turbine foundations. Wind turbine structures are subject to dynamic loads from the oscillation of tower, blades, and the operation of turbine. Due to this changing load, the cracks can progress in width, and depth, creating durability related issues and structural performance concerns. epoxy injecting into these cracks can help control these cracks at the early stage. ​

​For concrete and cementitious screeds to receive a floorcovering we know that the base must be suitably “dry enough”. This is to prevent damage to the flooring material and to ensure a proper bond with adhesives. So, what is “dry enough” and how long does it take for concrete to reach this goal?

Water is a vital component in the manufacture of concrete and the concrete must be kept moist during the critical curing phase to ensure the intended concrete strength. During the curing phase,  the process of Hydration chemically binds a large portion (approx. 50%) of the water with the cement paste which sets and hardens. What moisture is left after this reaction is either physically bound moisture that is trapped in the pores of the concrete, or what is known as Free Moisture.

This Free Moisture is what must be allowed to evaporate in order to reduce the moisture in the concrete to that acceptable level of “dry enough”. Although a the rule of thumb is to allow an inch per month (or mm per day), a number of factors such as slab depth will greatly influence the drying time. We will briefly look at these.

But to consider how long this will take we first need to establish what measurement can be regarded as “dry enough” and what methods of testing can be used. The simplest and most fool-proof method of testing moisture in concrete and screeds is with an impedance type moisture meter. Impedance type moisture meters commonly provide quantitative measurements (as opposed to qualitative, 0-100 reference readings) and give a very quick and helpful indication of the overall moisture content of the concrete in percentage measurements of moisture content by weight, MC%.

More and more flooring covering and adhesive manufacturers are specifying the readings with this measurement that suit their products. This makes life very easy for the flooring installer as the test is extremely fast and has a low potential for user error. A common measurement specified by many manufacturers is ≤4% for products which are not designed to be moisture tolerant. Products which have a high moisture tolerance can be specified with readings as high as 6%.

The British Standard Relative Humidity Hood test has been the most relied upon test method for many years and is specified by many UK manufacturers of flooring products. An insulated, impermeable box is affixed to a position on the surface of the slab which has been identified as the highest reading position (with an impedance meter preferably). The box is sealed with butyl tape to a clean, dust free surface and the airspace inside is allowed to equilibrate with the RH within the slab. Equilibration can take anything from 4 hours to 72 hours depending on the slab thickness.

Once equilibrium is established a reading can be taken and compared to a second reading 4 hours later (or 24 hours later in the case of a 72 hour test) and, in most cases, a slab can be considered ‘dry enough’ when a reading of 75% or less is recorded with no change from the  first measurement to the second, although floor covering manufacturers specifications should also be consulted.

(For more detailed instruction see BS5325, BS8201 & BS8203).

The RH Hood test is useful in that it is non-destructive and fairly simple to perform, as long as the steps are followed correctly and the box is not disturbed during the equilibrium period. However, the potential for user error is high, in that the possibility of skewed readings due to temperature change can easily be missed by ignoring the British Standard advice for a follow up test, 4 hours or 24 hours later as mentioned. A solution to this problem may be found by using a data-logging probe.

A commonly asked question is how the RH Hood method and the Moisture Content method correlate and this is a useful point to note: In a laboratory situation where temperature and humidity are constant at say 80%RH & 20ºC , a sample of average quality concrete will eventually equalize at approx. 4% MC. In the field, however, conditions are usually anything but stable and so temperature changes can cause large swings in RH test results and a high ambient RH of over 65% can result in condensation on the surface of the slab, causing higher MC% readings. However, other factors also affect the correlation between RH% and MC%, especially the water-cement (w/c) ratio.

A sorption Isotherm chart such as the one in Figure 1, provides a helpful indication of the measurements that should be expected so that when readings are far apart from each other and do not correlate as expected, it can be a good indication that one reading could be very wrong and that further investigation is needed. As such, we can see that performing two different tests is worth much more than the sum of their parts. The in-depth Relative Humidity Sleeve Method has been included in British Standards since 2011 and is growing in popularity.

This method is similar to the RH Hood method in that a trapped airspace is allowed to equilibrate with the RH within the slab. This test is destructive, however, involving drilling a hole into the slab to a specified depth of the total thickness, placing a plastic tube (or sleeve) into the cleaned hole and sealing with a plastic cap. Once equilibrium is established a hygrometer probe is placed into the sleeve and given 30 minutes to acclimate before taking a reading.

It is vital, to ensure a proper reading, that the probe is not placed in the hole too early as the heat from the drill will disturb the equilibrium. The benefit of the RH Sleeve method is that the entrapped airspace is much smaller and therefore equilibrium is established much faster than is possible with the RH Hood method. If following probe manufacturers’ instructions, the test can be performed in a shorter period of 24 hours or less in some cases.

​However, the complication with this test method is sometimes in regard to confusion over the drying goal reading values required. It has been shown that readings taken with the RH Sleeve method can be higher than the RH Hood method, commonly by between 5%-10%. Floor covering manufacturers who specify the in-depth sleeve method will often specify an upper limit of 85% instead of the 75% associated with the RH Hood. See Figure 2.

Having established our “drying goals” and ‘what is dry enough?’, we can now turn back to estimated drying times and the question of ‘how long?’. In concrete construction a large amount of water is initially used in the mix, often ca. 180 litres per cubic meter. This amounts to approx. 10-14% of the total weight of the material, depending on the water-cement (w/c) ratio. As discussed, approx. 50% of this water becomes chemically bound in the curing phase.

The w/c ratio is an important factor affecting the drying time of concrete. The lower the w/c ratio (i.e. less water & more cement) the finer the pores in the pore structure, which in turn reduces the transport velocity of moisture in the concrete and therefore produces a slower rate of drying. However, the lower water content of course also reduces the amount of water that has to evaporate, which should result in an overall shorter drying time. These and other factors are illustrated in the following charts which are interpreted from testing produced by the Swedish Concrete Association.

All drying times listed are to reach a drying goal of 4%MC (Impedance Method), 75%RH (RH Hood Method), and  85%RH (In-depth RH Sleeve Method). Drying time for upper floor, above-grade slabs (drying from both sides) with different thickness and w/c ratios (Days) in normal drying conditions: 60%RH & 18ºC:

Low strain pile integrity test is a common nondestructive test (NDT) procedure for quality control and quality assurance (QC/QA) in deep foundation construction. The test can be used to identify physical defects (voids or discontinuity, referred to as pile integrity) in piles, or determine unknown length of existing deep foundations.

Low Strain Pile Integrity Test belongs to the family of shaft head impact tests, where the response of an impact made on the head of pile head is recorded by a motion transducer (i.e. accelerometer), and used for analysis. Alternatively, engineers can use other tests such as crosshole or down-hole tests for the purpose of integrity test.

5- Striking Pile Head: Where, How, How Many?
The low strain impact should be applied to the pile head within a distance of 300 mm from the sensor.  It is also important to place the transducer far from the pile edge to reduce the effect of edge. Make sure that the impact is applied axially. For inclined piles, make sure the transducer is place perpendicular to the pile surface (parallel to pile longitudinal axis), and the strike direction is parallel to this direction.

For circular (diameter less than 500 mm) and rectangular cross sections, place the sensor near the center of the pile and strike several times around the pile head (i.e. 10 impacts). Increasing the number of impacts will reduce the effect of background noise, and helps enhance repeatable parts, which will make interpretation easier. For piles with larger diameter (i.e. Diameter > 500 mm) additional locations should be considered to obtain useful integrity information about the pile.

We are very excited to announce that we have signed with FPrimeC Solutions Inc. a partnership agreement to expand sales network and support centres for iPile™ | Pile Integrity Testing-PIT in Europe and the Middle East. Great times ahead for your concrete testing. 

Concrete piles and drilled shafts are an important category of foundations. Despite their relatively high cost, they become necessary when we want to transfer the loads of a a heavy superstructure (bridge, high rise building, etc.) to the lower layers of soil. Quality control and quality assurance has been a popular, yet challenging task for geotechnical engineers, inspectors, and piling contractors, mainly because these elements are generally buried under ground, with only pile head being accessible most of the time. Different intrusive and non-intrusive methods have been developed over the past decades to help engineers with easy, reliable and cost-effective evaluation of quality in these elements. Pile Integrity test is referred to a group of nondestructive tests that aim to provide quantitative data on physical dimensions of pile elements, their continuity, and last but not least, consistency of the pile material.

Pile integrity test (PIT), or as ASTM D5882 refers to it as "low strain impact integrity testing of deep foundation is a widely used nondestructive test method for the evaluation of pile quality, integrity and to help estimate the unknown length of existing piles and foundations. Pile integrity test can be either used for for forensic evaluations on existing piles, or quality assurance in the new construction. The integrity test is applicable to driven concrete piles and cast-in-place piles. The following image provides a visual summary of major integrity issues in deep foundations.

Low strain impact integrity testing provides acceleration or velocity and force (optional) data on slender structural elements (ASTM D5882). Sonic Echo (SE) and Impulse Response (IR) are employed for the integrity test on deep foundation and piles. The test results can be used for evaluation of the pile cross-sectional area and length, the pile integrity and continuity, as well as consistency of the pile material; It is noted that this evaluation practice is approximate. The PIT method works best for column type foundations, such as piles and drilled shafts. The method provides a rapid and simple tool for evaluation of a number of piles in a single working day.

How to Perform PIT?

Surface preparation is the first thing to do when performing a pile integrity test. Any type of contamination should be removed (using a grinder) to reach to solid and sound concrete surface. The pile head surface should be accessible, above water, and clean of loose concrete, soil or other foreign materials resulting from construction. This step is so vital, because then connection between the sensor and concrete should be solid (firm contact). The acceleration sensor should be placed on concrete firmly. To do so, a couplant material should be used to attach the acceleration sensor the pile head.  An impactor (usually a hand-held hammer) is used for impacting pile head; the impact should be applied axially with the pile. Motion transducer should be capable of detecting and recording the reflected echos over the pile top. Acceleration, velocity, or displacement transducers can be used for this purpose. At the minimum, acceleration transducer should have an Analog to Digital Converter with 12 bit resolution; and a Sample Frequency of at least 25 KHz. The location of the sensor should be selected away from the edges of the pile. The integrity testing should be performed no sooner than 7 days after casting or after concrete strength achieves at least 3/4 of its design strength, whichever occurs earlier.

Geomorph Instruments is very happy to announce a new, strategic partnership with RTUTec and the appointment of the latter as our representative in Israel. 

RTUTec was founded for the purpose of identifying innovative technologies. Ron Pincu and Dr. Amos Frishling founded RTUTec in 2014. 

Ron was a member of the founding team of the NDT lab in the Israeli air-force. He holds NDT Level II certifications, has a first degree in Engineering and an MBA from Hartford University in England. Over the years, Ron has specialized in finding original solutions for testing requirements. If in Aerospace industry, Oil & Gas, research and more. Ron has been instrumental in developing cutting edge portable X-ray systems for field NDT requirements.

RTUTec is currently offering a variety of products in different technologies among which are portable digital radiography systems, mobile cabinet X-ray and tomosynthesis equipment, Dosimeters & Survey meters, portable X-ray sources, thermographic devices and Ultrasonic & Radio-frequency based solutions. 

We are very happy to announce that we are DUNS registered. 

The Dun & Bradstreet D‑U‑N‑S Number is a unique nine-digit identifier for businesses. This number, identifies a company as being unique from any other in the Dun & Bradstreet Data Cloud. The D‑U‑N‑S Number is used as the starting point for any company's Live Business Identity, the most comprehensive and continually updated view of any company in the Data Cloud.

D‑U‑N‑S Numbers are often referenced by lenders and potential business partners to help predict the reliability and/or financial stability of the company in question. D‑U‑N‑S, which stands for data universal numbering system, is used to maintain up-to-date and timely information on more than 300 million global businesses. The D‑U‑N‑S Number also enables identification of relationships between corporate entities (hierarchies and linkages), another key element of Live Business Identity and commercial risk assessment practices.

The need to detect and assess jellyfish is driven by a variety of interests and concerns. Certainly most of us are aware that the sting from some species of jellyfish may cause painful wounds or even death, prompting the use of warning flag systems, barrier nets, and advanced sonar systems to protect swimmers at public beaches.  Compounding this threat of physical harm, jellyfish populations in many of the world's oceans are know to dramatically and suddenly fluctuate, and often without cause or explanation. Despite the significant hazards posed by contact with jellyfish, the mechanisms controlling their movements and population dynamics are not well understood.  Scientific echosounders are a proven, reliable instrument for the detection and measurement of jellyfish, and these specialized sonar systems are used by researchers worldwide for a wide range of studies.  Their body structure of a jellyfish is dense enough to reflect pulses of sound (pings) emitted by sonar, and thus jellyfish are quite well-suited for the use of hydroacoustics.  Over recent years, researchers around the globe have developed a wide range of interesting sonar methods and equipment for their study and this article documents just a few of these projects and case studies.

Due to shifts in ocean temperatures and currents, populations of so called “giant jellyfish” can rapidly increase or “bloom” and spread to new areas. Blooms of these massive creatures wreak havoc on commercial fishing operations by fouling nets and reducing fish catches.  Predicting the movements and locations of giant jellyfish can help fishermen avoid the animals, and thereby increase fishing catch rates and efficiencies.
 
Dr. Kyounghoon Lee, of Chonnam National University in South Korea, has extensively studied the giant jellyfish, Nemopilema nomurai, using a split beam echosounder integrated with an acoustic camera and CTD sensor deployed from research vessels while conducting mobile surveys.  Results from Dr. Lee’s work provide information about the sizing distribution and migration patterns of the animals in the Yellow Sea and East China Sea.  Below you can see images of the giant jellyfish

Another Korean researcher, Dr. Kang Do-Hyung with the Korean Institute of Ocean Science and Technology (KIOST) has done extensive work using a multi-frequency BioSonics split beam echosounder studying the acoustic target strength (TS) of several jellyfish species, including the giant jellyfish Nemopilema nomurai Kishinouye.  Some of Dr. Kang’s work involved using tethered jellyfish in net cages with the echosounder transducer affixed to the top of the cage.  TS data derived from this research can be used for developing acoustic scattering models, and surveying giant jellyfish distributions and biomasses.  Below, you can see a diagram of Dr. Kang's experiment with tethered jellyfish and a sonar echogram showing the jellyfish

​Jellyfish increasingly cause significant problems for power plants, and other industrial facilities that intake large amounts of cooling water, when swarms of the organisms enter the water intakes and clog intake screens. Clogging events due to jellyfish blooms require laborious clean-up efforts and have caused total shutdowns of nuclear power plants in the United States, Scotland, Sweden, Japan, and Israel.  Financial losses from such unplanned, sudden shutdowns can exceed 1 million USD per day.  Below you can see power plant employees working to remove tons of jellyfish from water intake structures.

We are glad to present our customer’s find of a numismatic treasure – a witness to early currency reforms and noticeable effects on present world currencies: Several silver coins identified as Spanish Dollars were detected with the ground scanner Rover C II in northern Peru and can be dated back to the late 16th century.

Pieces of Eight: The Basic Concept of World Currencies
The numismatic value of this find is fascinating in many respects: The coins became a popular trade currency of the Spanish Empire and still have impact on the designation of the present dollar. The discovery and conquest of mineral wealth in Peru and Mexico in the 15th and 16th century empowered the Spanish Empire and initiated early monetary reforms. One of the most famous silver coins of that time is the ‘Piece of Eight’, named after its divisibility into several bits. This concept is still common for breaking down currency values such as the US-Dollar into Half Dollar and Quarter Dollar.

Treasure Hunters’ Serendipity and our Technical Expertise
Thanks to its powerful performance and various special features, the multi-purpose metal detector Rover C II identifies hidden cavities and precious metal objects in different types of terrain: such as the silver coins which were found in the Sechura Desert approx. 60 cm (1.97 ft) deep – deeper than conventional detectors are able to explore.

The 3D ground scanner Rover C II combines metal detection with geoelectrical measurement in order to:

• localize and visualize position, depth and size of treasures, tombs and cavities
• discriminate between ferrous and non-ferrous metals
• detect coins and metal artifacts in significant depths.

Source: Palawan News (www.palawan-news.com)

The Department of Environment and Natural Resources (DENR) is set to charge the management of a beach hostel in El Nido after the discovery of its “illegally installed” polymerizing vinyl chloride (PVC) pipeline within the easement zone over the weekend.

A statement sent to Palawan News Tuesday by the DENR MIMAROPA Region said the PVC pipeline was excavated from the beachfront of Outpost Beach Hostel in Barangay Corong-Corong through the use of the ground penetrating radar (GPR) by a survey team of the regional and central offices of the Mines and Geosciences Bureau (MGB).

“The pipeline measuring six inches in diameter and six meters in length was uncovered in front of Outpost Beach Hostel in Corong-Corong. It was also found discharging black and foul-smelling liquid directly into Bacuit Bay, one of the province’s ecotourism sites undergoing massive rehabilitation,” the statement said.

The DENR MIMAROPA said to confirm the source of the wastewater, the Environmental Management Bureau (EMB) used a green tracer solution into Outpost Beach Hostel’s last chamber to which the excavated pipe was connected.

The DENR regional and central offices survey team is seen in this photo using the ground penetrating radar (GPR) to detect the presence of the illegally installed sewerage pipe in front of the Outpost Beach Hostel in Corong-Corong, El Nido. (Photo courtesy of the Mines and Geosciences Bureau)

“After almost 20 minutes, the green solution drained into the said pipe, indicating that the said establishment was the one discharging wastewater from the tank. The EMB shall be conducting further investigation to determine if there are other sources of wastewater discharge aside from the hostel,” it pointed out.

Paul Sepulveda, one of the co-owners of Outpost Beach Hostel, reportedly admitted that they owned the pipe.

Nevertheless, the statement said DENR MIMAROPA regional executive director Henry Adornado ordered the immediate removal of the sewage line as it violates the provisions of Presidential Decree 1067 or the Water Code of the Philippines, which prohibits structures within the easement zones without permission from the government.

Meanwhile, the excavation site was filled with sand using the backhoe sent by the local government of El Nido. The end of the cut pipe was left open for sampling and analysis by the EMB.

“We have to remind everyone that we are preparing Bacuit Bay as Water Quality Management Area so we shall be conducting regular water sampling and analysis not only to Outpost Beach Hostel but also to other establishments to ensure they do not discharge untreated wastewater into Bacuit Bay,” EMB Regional Director Michael Drake Matias said.

Besides regular effluent sampling, the DENR and the MGB have been conducting a GPR survey of the coastal areas of El Nido since March 18 to detect buried waste pipelines. They are calling business establishments to take Outpost Beach Hostel as an example to avoid interruption in their business operations.

“You cannot hide them (pipes) forever. We will eventually uncover them so we advise you to remove your illegal sewage lines and comply with the laws for your own good,” MGB MIMAROPA regional director Roland De Jesus was also quoted in the statement.

The DENR, EMB, and MGB in MIMAROPA vowed to impose the maximum penalty to any establishments found continuously breaking environmental rules and regulations; and employ unified action to ensure environmental protection remains as a top priority.