Monday, August 29, 2011

#96 Equipment: Loader with Forklift Attachment

Description:  The piece of equipment pictured above is a loader and is standard among most job sites in the United States and around the world.  It is typically used to move earth, sand, or gravel around a construction site.  The current configuration of this machine, however, has forks to load thinks such as pallets or pieces of equipment onto and off of the back of trucks or around the construction site.  Forks like these are adjustable and can be widened or narrowed to fit different objects.  When the operator is finished using the forks he can simply switch the forks out for a bucket and begin to move scoopable materials again.  The ability to switch attachements on the loader makes it one of the most versatile machines used in construction today.

Friday, August 26, 2011

#95 Tool: Concrete Chainsaw

Description: This is a powerful tool known as a concrete chainsaw.  Working on the same principle as a wood chainsaw it is very capable of cutting through concrete, asphalt, and rock materials.  This particular unit is powered by hydraulic fluid being pumped through the hoses coming out of the handle on the right side of the unit.  Saw chains for this unit are many times laced with diamond grit cutting heads and are very effective at cutting through tough materials.  Concrete chainsaws are particularly good at making square cuts, because unlike circular concrete saws they don’t have to cut past the edge of the hole to complete the cut.

Thursday, August 25, 2011

#94 Baffle Peirs in Dam Spillway

Description:  This is the spillway of a medium sized dam on the Huron River in Michigan.  When water is released down the spillway it exits under a sluice gate in the supercritical flow state.  Supercritical flow, however, has too high a velocity for the natural river bottom and will cause an erosion issue.  To prevent this fast flowing erosive water force concrete blocks, called baffle piers, are added just downstream.  This causes a hydraulic jump to occur transferring the flow from supercritical flow to subcritical flow.  Subcritical flow is closer to natural river flow and is therefore less of an erosive force.  The baffle piers of this dam can be seen under the water about two-thirds from the bottom of the picture.

Wednesday, August 24, 2011

#93 Cofferdam for Bridge Peir Construction

Description:  This is a cofferdam used in the construction of a bridge pier.  Cofferdams like this one are used to create a dry area so construction can take place on infrastructure that is in the water.  A careful eye will be able to see epoxy coated rebar in the bottom of this cofferdam, as well as the water being pumped out near the top right of the picture.  Many times cofferdams are not completely watertight and require nearly continuous pumping.

Tuesday, August 23, 2011

#92 Concrete Crew Finishing a Mat Foundation

Description: Above is a concrete placing crew working on a large mat foundation.  The workers must coordinate their efforts in order to complete the job before the concrete cures.  The workers near the bottom of the picture are consolidating the concrete with vibrators. While another worker, not pictured above, gives the initial leveling with a tool called a screed.  The final touch for this rough finish job is a broom finish done by the worker in the orange hard hat. 

Monday, August 22, 2011

#91 Suspension Bridge Cable Enbankment

Description:  Seen here is the cable anchorage for the Ambassador Suspension Bridge over the Detroit River.  This large mass of concrete is designed to deliver the opposing force on the main cables of the bridge after they have passed over the towers of the bridge.  Inside the concrete mass the seemingly large single cable actually breaks apart into the smaller cables it is made of for anchoring purposes.  The length of each cable embedded in the concrete is very important to prevent pull out of the cables and is calculated according to reinforced concrete code ACI 318.

Monday, August 8, 2011

#90 Pile Point on H Pile

Description:  Seen above is a steel H pile that will be used on a bridge project.  The end of the pile is not strong enough to be directly driven into the ground so a protective tip, called a pile point, is welded on the end.   Without the pile point the flanges could separate from the web and greatly affect the strength of the pile and make driving it further into the ground very difficult.  In soft ground many times pile points are not needed, however, as a precaution against boulders and other debris, some firms use them almost always when driving piles.