Long-Term Testing Of Concrete Bond Durability

Source: Long-Term Testing Of Concrete Bond Durability   The definition of concrete durability can be explained as the ability of a specimen to resist any form of weathering action, namely abrasion, chemical, physical, or any other process of deterioration. In other words, the durability of concrete can also be defined as the ability to last a long period of time without significant deterioration or failure. Image Credit: Peshkova/Shutterstock.com Types of weathering include mechanical, physical, and chemical weathering of concrete including the alkali-aggregate reaction of sulfate attack and chloride attack. Different long-term testing methods have been used over the years and more research has been done to improve the existing methods to be more economical and environmental. Consideration has also gone into methods that reduce the time in which these tests can be completed and assessed. The Importance Of Long-Term Durability Testing It is important to test for the durability of concrete bonds because of the following reasons. Firstly, concrete testing will allow the designers to determine accurately the lifespan of a specific structure according to its specific needs or requirements. If a structure is intended to last a specific period of time, long-term concrete testing can reveal the combination that is required for it to last that long. There can be economic and environmental benefits to this testing. Economically, constant rehabilitation and patching up of structures are very expensive. Hence, long-term testing can reveal the right combination of concrete mixtures for durable structures, thereby reducing the number of times for rehabilitation. Environmentally, constant rehabilitation will require more use of natural resources such as sources of energy, gypsum, or steel to continuously rehabilitate worn-out structures. Continued rehabilitation increases the carbon footprint, which is not environmentally friendly. Developments In Concrete Bond Materials New studies have revealed that the addition of carbon fibers amounting [...]

Stress in Earth’s crust determined without earthquake data

Source: Stress in Earth's crust determined without earthquake data Scientists at Los Alamos National Laboratory have developed a method to determine the orientation of mechanical stress in the earth's crust without relying on data from earthquakes or drilling. This method is less expensive that current approaches, could have broad applicability in geophysics and provide insight into continental regions lacking historical geologic information. "We utilized the nonlinear elastic behavior in rocks and applied a new technique to monitor the orientation of the maximum horizontal compressive stress in rocks in parts of Oklahoma and New Mexico," said Andrew Delorey of Los Alamos. "The orientation of that maximum horizontal compressive stress reveals which fractures in the rock will be active." North-central Oklahoma was selected because induced seismic activity has been ongoing in the region after decades of injected wastewater from oil and gas operations. That seismic activity occurs on faults optimally oriented in the regional stress field. North-central New Mexico was selected to compare the results to a geologic setting straddling a continental rift separating the Colorado Plateau from a stable section of the earth's crust. The scientists determined that the earth exhibits stress-induced anisotropy of nonlinear susceptibility that is aligned with the maximum horizontal compressive stress in these two different geologic settings. Rocks become stiffer when compressed and softer when extended, but this effect isn't instantaneous. The rate is faster in the orientation where the ambient stress field is most compressive. By measuring this rate in different orientations, scientists can determine the orientation where ambient stress is most compressive. Determining the geophysical stress orientation, or the direction of maximum horizontal compressive stress, is usually determined by drilling narrow, deep boreholes. However, borehole drilling is expensive and only provides a single data point. Additionally for vast regions, the geophysical data simply hasn't been collected because [...]

HS2 tunneling machine completes first mile under the Chilterns

Source: HS2 tunneling machine completes first mile under the Chilterns The first 2,000 ton tunneling machine passed the one mile mark this week during the construction of the first tunnels for HS2. Launched in May, the 170m long Tunnel Boring Machine (TBM) covered the first mile cutting through a mix of chalk and flint beneath the Chiltern hills just outside London. The TBM – named Florence – is one of two identical machines excavating the twin ten-mile-long tunnels. A second machine, Cecilia, is a short way behind, with both TBMs expected to break out in around three years’ time. Designed specifically for the geology of the Chilterns, each machine is a self-contained underground factory, digging the tunnel, lining it with concrete wall segments and grouting them into place as it moves forward. Welcoming the progress, HS2 Ltd Project Client Rohan Perin said: “The 10 mile Chiltern tunnel will take HS2 underneath the hills and safeguard the woodlands and wildlife habits above ground as well as significantly reducing disruption to communities during construction and operation of the new railway. “Once complete, HS2 will offer low carbon journey options linking London with the major cities of the north and releasing capacity for more freight and local trains on our existing mainlines. It’s great to see how much progress has been made over the summer and I’d like to thank the crew of Florence and all the tunneling team for their hard work.” The first two TBMs are operated by HS2’s main works contractor, Align – a joint venture formed of Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick. A crew of 17 people keep the machines running, working in shifts and supported by over 100 people on the surface, managing the logistics and maintaining the smooth progress of the tunnelling operation. Align Project Director [...]

Landslide Prevention Near Sussex

Source: 'An engineering feat': Why this key section of railway is closed | ITV News Meridian Network Rail describes it as engineering feat, a two week project to stabilize three sections of Victorian railway embankment between Brighton and Hove. Until Saturday October 2nd 120 workers each day are working from up to 15 meters high to install rock bolts, soil nails and netting. All three interventions are designed to protect debris falling onto the tracks. In recent years landslides have led to significant delays for passengers on the network and climate change has made the chalk cutting incredibly vulnerable. Project manager, Tom McNamee says, "We've seen previously catastrophic failures of the embankment and that’s an unplanned failure, we have loose material fall onto the railway and that becomes a danger to trains and essentially we have to close the line in an unplanned, unexpected manor. "We really would like to thank our lineside neighbors, it is a massive inconvenience, we are using chainsaws and rock drills, loud and noisy equipment, right at the. Back of their properties for 14 days but we’re working closely with them and taking in all their concerns and considerations. If we were unable to do this work over 14 days we would have to do this over 12 weeks of night work and that would obviously have a bigger impact on the lives of people living here." 1,012 rock bolts being installed 1,000 soil nails being drilled in £5 million spent on the project Traveling between Brighton and Hove? This is what you need to know Trains between Brighton and London are unaffected No trains will run directly between Brighton and Hove/stations towards Littlehampton Trains will run to an amended timetable between Preston Park and Littlehampton and between Littlehampton and Portsmouth Harbour/Southampton Central Southern passengers will [...]

Researchers in Tasmania design special drill for million year old ice core project

Source: Researchers in Tasmania design special drill for million-year old ice core project to help find answers to climate crisis | The Singleton Argus | Singleton, NSW Answers to the world's climate crisis may be discovered in a 2.8 kilometer pole of million-year-old ice that is set to be extracted from Antarctica and delivered back to research labs in Tasmania for atmospheric testing. Australian Antarctic Division researchers in Tasmania have designed and manufactured a 400-kilogram drill for the million year old ice core project which is capable of operating in minus 55 degree temperatures. It will bore down into 2.8 kilometers of ice, which is believed to be up to 1.5 million years old, to extract three meter sections of ice, or ice core, at any one time. Up to 8 tons of ice will then be brought back to research labs for AAD researchers to extract data and information about past temperatures, sea ice levels and wind patterns in Antarctica. Australian Antarctic Division engineers spent two months preparing blocks of ice that would replicate Antarctic ice, which were then used to test the specially designed drill. Picture: Australian Antarctic Division   It will also be used to answer a "long standing mystery" in Antarctic research about the frequency of ice ages. The project is part of this year's Antarctic research season which has been dubbed the most ambitious season that the AAD have ever undertaken, with 500 scientists and up to 800 tons of cargo to be shipped to Antarctica. Australian Antarctic Division chief scientist Nicole Webster said the million year ice core project is an incredible milestone for climate research. She said layers in the ice core are like "pages in a diary", where tiny air bubbles trapped in the ice core contain atmosphere and other [...]

Informed Streets Pavement Management Solution

Source: Horrocks' Informed Streets Pavement Management Solution Road maintenance is an essential component of city infrastructure. However, deciding what needs to be fixed and when is often a subject of debate. That's where Horrocks' new pavement management system comes it. Using data-driven analysis, it takes some of the guesswork out of the entire process making road maintenance more cost-effective. This will be an exceptionally great tool for cities like Anchorage, Atlanta, Boulder, Chicago, Indianapolis, Little Rock, Los Angeles, San Francisco, New York, and Phoenix. Informed Streets for Pavement Management Horrocks’ new pavement management system has been dubbed Informed Streets. This is simply because it helps create road maintenance schedules, allowing our clients to maximize their budgets by applying the right treatment to the right road at the right time. This system assesses existing pavement conditions and uses predictive models to develop unique, data-driven management plans that optimize costs and upkeep. These plans are created through the following four stages: 1. Initial Assessment and Survey Horrocks’ mobile LiDAR unit during initial survey In the initial phase of service, Horrocks’ in-house survey crews complete a thorough survey and pavement assessment of the roadways. This is done using a truck-mounted Light Detection and Ranging (LiDAR) unit to assess the pavement by collecting one million survey-grade points every second. Our experts then use this data to develop a baseline for a pavement management plan by providing one of two pavement ratings, depending on our client’s needs: the Pavement Surface Evaluation and Rating (PASER) or Pavement Condition Index (PCI). 2. Data Analysis and Planning Once the pavement rating is complete, an online platform is set up for our client, which includes the Informed Streets3D Viewer. Horrocks’ Informed Streets 3D Viewer integrates GIS systems, LiDAR point clouds, and photography in one robust platform that allows for [...]

Breaking Uncommon Ground in the Kansas Countryside

Source: Breaking Uncommon Ground in the Kansas Countryside - Alpha-Omega Geotech, Inc. Look beyond I-435 to the west of Kansas City’s urban core and you’ll see a surge of new commercial development taking shape. It’s not all typical, flat farmland and turning it into opportunity requires a strategic approach. Before you put together plans for a construction project, consider a few pointers based on our experience. Don’t Be Surprised by a Predictably Unpredictable Subgrade. Be careful not to make assumptions about what’s just below the surface and deeper down, especially along K-10 in the vicinity of Lenexa. Every potential build site is different to some degree and variations from site to site can be substantial. Much of the landscape is hilly, and history has left behind miscellaneous man made factors that will impact everything from site selection to construction. Decades of variables ranging from undocumented subgrade material, buried trees and buried gravel roads to improperly filled farm ponds lurk underground, even in areas that appear to be untouched. In addition, old limestone mines abandoned as far back as the 1980s wind through the area and present ongoing challenges for developers. The proximity of mines isn’t necessarily a deal breaker when it comes to project site selection, but you’ll need to clearly understand the limitations of the subgrade above and around them. You’ll also need to be on the lookout for mine spoils material carved out over the years and buried for disposal. Uncovering subgrade wildcards and narrowing site selection is only possible through an extensive investigation. A precise boring plan with thorough soil testing will be critical in the hunt for a project site that’s feasible in context of your timeline and budget. Make sure your geotechnical engineering partner knows exactly how you expect foundations to perform so that they can pinpoint [...]

UD researchers study climate change impacts on soils at military installations

Source: The Ground Underfoot - Civil and Environmental Engineering UD researchers study climate change impacts on soils at military installations We walk over it, drive over it and build on it. Yet, it is probably safe to say, most of us rarely think about the ground beneath our feet. Underneath the grass, concrete, asphalt and other materials in our built environment, however, soil provides structure and stability for what lies above. The United States military wants to understand the role that climate impacts, such as flooding, storm surge or sea level rise, will have on soils at its coastal military bases and facilities, which are critical to national security. Soil conditions can affect the integrity of the ground underpinning buildings, roads, bridges and more. For example, if a soil’s pH were to rise significantly, due to increased salt content-containing ions such as sodium from storm surge, it could create saline conditions that could hamper the ground’s ability to support this necessary infrastructure. Understanding these threats will enable faster and more accurate routing and maneuverability for U.S. forces. The Delaware Environmental Institute (DENIN) is collaborating with the Engineer Research and Development Center (ERDC) of the U.S. Army Corps of Engineers and Louisiana State University to understand how vulnerable military installations along coasts may be affected by soil changes due to sea level rise and coastal flooding. DENIN has received $3.79 million in first- and second-year funding from the U.S. Department of Defense to start this work, and is eligible for an additional $3.82 million in continued funding over the following two years. Led by DENIN Director Don Sparks, Unidel S. Hallock du Pont Chair of Soil and Environmental Chemistry in UD’s Department of Plant and Soil Sciences, the UD effort includes interdisciplinary collaboration with Yan Jin, Edward F. and Elizabeth Goodman Rosenberg Professor [...]

Earthquake in Haiti Triggers Landslides

Source: Hundreds of landslides followed Haiti earthquake, Tropical Depression Grace - The Washington Post Source: Earthquake in Haiti Triggers Landslides After a 7.2 magnitude earthquake hit southwestern Haiti on the Saturday morning of August 14th, hundreds of landslides threatened the area. Landslides are one of the biggest causes of earthquake-related deaths. In 2010, the earthquake near Haiti's capital, Port-au-Prince, killed roughly 200,000 people and led to tens of thousands of landslides. The earthquake was centered about eight miles southeast of Petit-Trou-de-Nippes at a depth of six miles. USGS reported at least 150 landslides south of the epicenter, to the west of the town L'Asile. The mountains and south of Beaumont experienced hundreds more. “Even though a lot of the central and western parts of the epicentral area have been obscured by cloud cover, we haven’t seen too many landslides in the gaps in the clouds,” wrote Robert Emberson, a landslide researcher at NASA’s Goddard Space Flight Center. “We anticipate that the bulk of the landsliding (at least from the earthquake) is in the [Pic Macaya] National Park.” The National Hurricane Center predicted 5 to 10 inches of rain in Haiti with a possibility of up to 15 inches. Flash flooding, mudslides, and landslides were all expected following the rain. “With the ongoing tropical storm rainfall, further landslides are likely,” wrote Emberson. “In particular, landslide material mobilized by the earthquake may be washed downstream as debris flows. We will continue to monitor changes over the coming days to assess the exacerbated impact of the rainfall and provide situational awareness.” Landslides and earthquakes have recently in multiple parts of the world. Denali Park, Sichuan China, Battle Creek Michigan, and a recent Monsoon in India are just four of the most recently affected areas.

Parameters Variation Model Customization and Sensitivity Analyses

Source: Parameters Variation: Model Customization and Sensitivity Analyses Parameters Variation Model Customization and Sensitivity Analyses A well-known engineering challenge in the framework of finite element (FE) analysis-based design is the large number of input factors involved in geotechnical computational models. There is always a significant amount of uncertainties associated with the properties of geomaterials, being naturally highly heterogeneous materials. In the context of model calibration and validation, conducting a sensitivity analysis is very important. This can determine the key factors which govern the system and efficiently characterize the geotechnical variability for any considered design problem.   Powerful mechanisms for the consideration of parameter variation are also very interesting for speeding up FE model creation and automating results in post-processing. These are also quite useful in reducing model definition for specific types of engineering problems (excavation wall of a specific type under simple ground conditions, simple tunnel shape in uniform rock mass, etc.) to a limited number of parameters that can be inputted in a text file or Microsoft Excel spreadsheet without expert knowledge of the PLAXIS user interface and different modeling techniques and FE know-how. The sensitivity analysis and parameter variation tool in PLAXIS A sensitivity analysis determines how different values of an independent variable affect a particular dependent variable under a given set of assumptions. In other words, sensitivity analyses study how various sources of uncertainty in a mathematical model contribute to the model's overall uncertainty. The Sensitivity Analysis and Parameter Variation tool (see Figure 1) can be used to evaluate the influence of model parameters on calculation results for any particular PLAXIS FE model: The Select Parameters tab sheet will first provide information about all the parameters that can be changed to perform the sensitivity analysis. Available parameters include most model parameters of the data sets for soil and [...]

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