Researchers in Indonesia have developed a bendable concrete that is twice as strong as conventional concrete in bending, can be poured in thin slabs, and used for pavement. They hope that future pavement projects will be cast in a factory and slabs delivered to the job site. For information check out this link.
A common deterrent to personal enjoyment in multi-family buildings is sound transmission.Often determining what is too loud is subjective and measured by the sensitivity of our ears. The Building Code requires that walls and ceilings meet an STC (Sound Transmission Class) rating of 50 and an IIC (Impact Insulation Class) of 50. STC is related to airborne noise like a television, speech, or music and IIC correlates to footfalls or a dog’s toenails when they impact a tile floor.
At an STC rating of 50, loud talking cannot be heard but load music can be noticed. We usually are asked to investigate sound transmission concerns in wood framed buildings when the thuds of foot traffic of the resident or their pet, above, is perceived to be disturbingly excessive.Many condominiums have rules related to the percentage of the floor area that must be covered by carpet.This is likely because most carpeted floors comply with a IIC 50 sound rating.
Manufacturers of products used to construct wall and ceiling assemblies have their materials tested in a laboratory with various combinations of framing, drywall, and insulation to determine the STC rating.To inspect a noise concern, our first step is to review the available architectural drawings to determine the intended design and the associated STC rating for the wall and/or ceiling construction. Then we will cut a few holes at inconspicuous places to confirm if the drawings were followed. Most people are surprised to learn that no insulation was placed inside the wall or ceiling and that many assemblies can achieve the required STC rating without insulation.
Products are available that can be installed on floors, walls, and ceilings to reduce the offending sound transmission. Installing these materials can be limited to sleeping areas to save cost and the amount of disruption that the project has on a living space.
Satisfactory remediation of a sound problem can be difficult.Our ears will perceive a reduction in noise by one half when the STC rating is increased by about 10 points. Conversely, anything less than a10 point change is hard for people to distinguish. Finally, any expectation that a once noisy unit located within a multi-family building will become “sound proof” or like a recording studio after remedial work is complete is unrealistic
Researchers at the Delft University of Technology in the Netherlands are working on placing bacteria in concrete mixes to fix cracks in concrete and make it self-healing. This could make concrete less susceptible to damage related to water that infiltrates a beam by way of a crack and results in rebar corrosion.
What do you really know about your roof warranties? There may be separate warranties issued for various materials and the installing contractor may have also guaranteed workmanship. Each will expire at some point and there are things you should do to preserve your protections.
1. Review the documents and assure they were properly executed. If, for example the papers were never signed and returned to the manufacture, you probably don’t have a warranty.
2. Be aware of your responsibilities. Failure to properly maintain the system could void warranties.
3. Properly notify all involved parties (manufacturers, contractor, etc.) of problems within the 10 to 30 days typically required.
4. Be sure that repairs are made using approved materials and contractors certified by the manufacturer. Unapproved materials and repairs may void coverage, at least in the areas affected by repairs.
5. Have a knowledgeable person evaluate the roof covering periodically and within six months to one year in advance of warranty expiration dates. There may be conditions that could be corrected at no cost before coverage lapses.
Some warranties can be extended or renewed for additional cost; however it may not always be advantageous to do so. The manufacturer could impose maintenance or rehabilitative requirements that are unreasonable when compared with the value of the coverage. Spending $100,000 to get a five-year warranty extension on a $200,000 roof might not be the best use of the money.
Installing linoleum or similar covering directly on concrete floors can be problematic if there is moisture in the slab. This is especially a concern with on grade slabs where there may be moisture under the slab that can permeate upward. Linoleum and similar floor coverings act as a barrier that can cause moisture to be trapped under the flooring. When this happens, the floor covering can unbond, warp and become a serious hazard.
Carpet covering will let moisture vapor pass through and normally are not a problem. Carpet can be a solution where other floor coverings are adversely affected by moisture.
If a linoleum or similar covering needs to be installed, it is important to understand and analyze the moisture present in and/or under the slab. Various types of moisture testing can be performed to help verify that the concrete is dry enough to allow the installation of an impermeable floor covering.
Researchers at the University of Maryland have found a way to make wood transparent, which could change the way that we utilize this building material.
We recently ran into an unusual item at a property – two hour, fire rated windows. The assemblies looked like “regular” windows but after some digging through the building drawings, it was determined that the windows were fire rated. The building code requires that exterior building walls within ten feet of a property line must be constructed using recognized fire rated assemblies. This includes the glazing.
Fire rated windows have special steel frames (fiberglass, vinyl and aluminum cannot stand up to the heat) and multiple layers of glass (up to about 1-1/4” thick) that allows them to provide protection against radiant heat, smoke, and fire. They have been tested to confirm their ability to resist fire and even the force of a fire hose stream in accordance with ASTM and NFPA standards.
Fire rated windows may look like a normal window, but these windows with super powers cost significantly (about 15 to 20 times) more than a standard window
Advances in imagining and sonic technology have long been embraced by engineers and are being used every day to help evaluate buildings and building systems. These gadgets can allow for an in-depth, minimally invasive, and cost-effective inspection with rapid results. Plus, it is fun to pull out a toy that you might see in an action movie to help figure out a problem. The following are found in most local consultant’s arsenals.
Thermal Camera – Police, military, and ghost hunters use them and so do engineers. Infrared thermography allows us to “see” hot and cold areas and can allow for a rapid scan of a room, roof, electrical panel, radiator, or a building façade for thermal anomalies. These normally are found to be air and water leaks and help pinpoint locations that should be inspected more thoroughly. Blue areas are cold and red are hot.
Drones– Unmanned flying aircraft now are easier to maneuver and can take high resolution digital video and photos, which allows for the inspection of a roof or building exterior when access is extremely difficult or limited. Government regulations are still in a state of flux related to this equipment, but the rules are getting clearer as time goes on.
Ground Penetrating Radar – The same technology that allows police to scan a field for objects buried underground is used by engineers to emulate Superman and see what is in concrete. The 3-D version can generate an image of what is embedded in a concrete slab.
Impact-Echo – This device uses a special hammer and sound waves to measure the thickness of concrete and find buried defects that are not visible to the human eye by simply tapping the surface.
Moisture Meter – Used to measure the moisture content of wood, drywall, and other building materials to help narrow down if a water leak is active and where it may be coming from.
Boroscope – Spy movies show the hero inserting a fiber optic cable under a door or through an air vent to look into a room. Engineers use this same technology to look behind walls or under floors by drilling a small hole instead of making a large opening.
Infrared Thermometer – Allows an inspector to determine the temperature of an object without touching it. This is especially useful when checking to see if a wall is warm enough to be painted.
Ultrasonic Thickness Gauge – Measures the wall thickness of pipes or other metal objects using sound waves to help determine if they are corroded/damaged, inside, without having to remove a piece of the material.
While technology is great, we do not rely exclusively on the digital output. The best diagnostic tools we use are still those we are born with – eyes, ears, fingers, and brain. When an engineer combines their innate detective skills with modern gadgets, we begin to resemble a human Swiss Army Knife and can arrive at a solution for your building problem
It’s hard to find a building today without concrete surfaces stained by rust. Rust stains can adversely transform the aesthetics of a beautiful building. How can rust stains be removed? Let’s find out!
Once rust staining has occurred, it is important to remove the stains without altering the color or finish texture of the concrete. Two techniques which can be implemented are dry methods (i.e. sandblasting, wire brushing, grinding, etc.) and wet methods (i.e. waterblasting, chemicals, etc.). If surface texture is not a priority, the dry methods can be a quick and cost-effective way to remove stains. If the final finish is important, as is commonly the case with architectural concrete, chemical treatments are recommended.
Mild stains usually can be removed with an oxalic acid or phosphoric acid solution, applied to a water saturated concrete surface. Deeper stains typically require a poultice, which absorbs the chemical solutions and then forms a paste over the stain. Older buildings require more attention with stain removal because the chemical treatments may remove other contaminants in the concrete, creating a lighter color than the adjacent concrete.
The rule of thumb when putting a cleaning solution on your stained carpet or clothes applies with concrete. Be sure to test different chemicals on small, inconspicuous areas to evaluate the treatment. Also, the longer you let a stain sit, the more difficult it is to remove, so seek help quickly when rust stains appear!