Demolition Safety Talks - Recycling

As the requirement for recycling continues to increase in the demolition industry, more and more pressure will be put on demolition sites to insure material is source segregated.  One such operation is the crushing of concrete and asphalt material.  This work is generally completed with the use of a portable crusher which is brought to the project site after a concrete pile has been created and the material is ready to be prepared into a base material.  The crushed material will then be left on site for the owners to use at their discretion.

Although this operation is generally handled in full by a crew that has been assigned the task of this operation, the entire demolition crew and anyone on the project site should be made aware of the dangers involved in completing this work. In many instances, the crushing contractor will request the assistance of the demolition contractor to help in various applications that might be needed to complete the crushing task.

The operation of crushing requires that feedstock be put into the crushing unit.  This will be the prepared concrete and asphalt material that has been placed into a large pile and has had the material sized and trimmed for this particular operation.  The crushing unit in most cases is placed within close proximity to the feedstock pile and takes a day or so to be set up.  During this operation all employees not directly involved with the set up should know to keep their distance from the area and allow the trained crew to complete their work.  The crushing unit has a multitude of pieces that require special placement and employees in the area should be aware that these are being moved and shifted to be set up in the correct manner.  As such, mobile equipment is a substantial hazard and should be one of the main concerns for all personnel on the project site.  This concern stems from the fact that in many cases, the demolition contractor still needs to complete portions of work on the project and has some various portions of work that must still be completed on the project site and therefore where multiple operations are taking place.  All employees and personnel should be made fully aware that it is their responsibility to know that the site is a shared area.  This means that there are more operations taking place then just the demolition work.  All personnel should know to keep a continuous eye out for moving equipment, flying materials or objects, and the general set up of other heavy equipment.

The setting up of the crushing equipment also includes the use of a conveyor system.  Why is this important to know?  Well, several reasons.  First, the conveyor system takes up a large area and is placed at various locations within the working area.  This means that employees should once again be aware that additional work is happening in a large area and they should be conscious that the set up operation will not be confined to an area directly next to the concrete and asphalt stockpile.  Secondly, conveyor belts are mobile pieces of equipment that have the ability to move during the actual crushing process.  This, of course, means that the conveyors may not remain stationary and that all employees should be aware that where the conveyor was when they saw it one time may not be the same place it is when they return to the area.  Finally, the conveyor is just that, a conveyor.  This means it uses a moving belt to convey the crushed material to a designated location.  As such, there is always the possibility of getting caught within the moving parts which carries a high amount of danger.  All personnel should be fully aware of these potential hazards and know to keep a safe distance from these conveyor systems.

We have discussed the setup of the equipment and the operation of the conveyor; now let’s discuss the crushing unit itself.  This is the heart of the crushing operation and in most cases it carries the majority of the highest safety risks.  The crusher itself is fed with concrete and asphalt material and uses metal jaws and compression to crush and grind the feed stock material into a usable base.  It does not need to be said then, that this operation involves tremendous amounts of power and compressive strengths.  With this power comes tremendous potential energy that no unprotected employee should be exposed to.  Knowing this and remembering the enormous power the equipment uses should be a warning to all personnel.

Keeping this in mind, all personnel working around the crushing unit need to know some basics of the operation.  The crushing unit is fed concrete and asphalt material from the stock pile by means of a front end loader, generally rubber tire.  This may be similar to a 980C.  This loader removes material from the prepared stockpile, takes its filled bucket to the crushing unit and drops the material into the hopper.  During this operation, all personnel working around the unit should be aware of the loader and its driving direction.  The material that is being picked up is not always in the same location and the return direction varies as well.  Keeping a continuous eye on the loader’s movement and direction will assure that all personnel are well out of its travel path.  Keep in mind that these loaders are not of a track variety and move significantly faster.  During the loading operation, the concrete material is fed into the cone of the crusher in large amounts and normal operations would dictate that some chunks of the material from the loader’s bucket will not make it inside the cone area and in turn will fall to the ground.  It is extremely important then, that all employees keep their distance from the crusher feed area so as not to fall victim to an injury due to falling material.

Once the material has been fed into the crusher, it is part of the normal operation of all conveyor belts that are running.  The conveyor belts not only include the long transfer belts as mentioned earlier, but the internal belts of the crusher as well.  These again pose a significant threat to all persons working in the area and should be considered very dangerous.  One belt of the crushing unit needs a special note.  This belt is known as the MAG Belt.  This conveyor or belt is very specific to the crushing unit and plays a key role in the removal of all the metal material that is imbedded in the concrete material.  During the crushing operation, the concrete and asphalt material is broken down to very small pieces and as such, the metal rebar, screws, wire and various others metal material is broken free from the concrete.  During the sizing process this MAG belt is used to grab the metal away from the broken concrete and literally flings it into a pile directly next to the crushing unit.  The area in which the metal material is flung needs to be dully noted by ALL personnel working on the site.  Although this metal material is sometimes dropped directly into roll off boxes, in many case it is deposited directly on the ground where it is eventually moved into boxes or trucks dedicated for the removal of the metal material. Knowing this operation consists of the metal flinging off the conveyor, all personnel need to know that this posses a significant hazard which can consist of flying metal objects.  Although the belt and system is designed to remove the material and stockpile it in a relatively close area next to the crusher, it is not a guarantee that all metal will be confined to this small area.  In fact, it is common for metal pieces to go well beyond the normal drop area and end up well beyond a location one would normally expect.  What does this mean?  That there is a significant hazard within the metal discard area during any time the crusher is in operation.  This also means that just walking by the area could result in a piece of metal flying out and hitting someone.  Although the risk is small, without safety glasses a piece of metal could impact the eye.  If larger pieces of metal are ejected from this area, it could result in a serious injury.  It should be emphasized that this area be considered a high hazard and treated as such.

In some cases the crushing contractor may ask for some help on the crushing unit itself.  This practice is common and should be undertaken only by a designated person from the demolition crew.  If this is to take place each member completing this activity should become fully versed in the operations taking placed and develop a complete understanding of the work they are expected to complete.  In addition to this, each employee should review the safety requirements of the task they are asked to complete as well as the specific requirements established under the guidelines issued by the crushing contractor.  In all cases extreme caution should be taken and a review of the work should be made by the on-site supervisor.

This is so that he or she is aware of the dangers involved and being taken on by one of his/her crew members.  In all cases, the designated operation being undertaken will carry with it some specific requirements for completion of the work as well as the requirements for specific PPE.  The person completing the work for the crushing contractor should never begin his duties without these two main items; proper training and the correct PPE to competently complete the required task.

During the crushing operation, a large amount of crushed concrete material is generated and deposited on the project site.  The finished material is generally stockpiled in a cone shape and can reach significant heights.  Each employee should be made fully aware that this material in general is unstable.  This would mean that it is not cohesive and therefore carries a potential to engulf an individual.  This situation seems highly unlikely but, nevertheless, should be brought to the attention of the employees.  This potential accident could be something as small as trying to retrieve something that fell on the pile and needs to be picked up.  Trying to climb up the pile will only result in more material falling.  Ensure that all employees working in the area are aware that climbing on an undisturbed pile is strictly prohibited at all times.  If the crushed material needs to be moved or disturbed, it should be done with the use of equipment and always with the site supervisor’s full knowledge.

Finally, all personnel should remember that the crushing operation is only temporary and that, at the completion of the crushing, all the equipment moved on site will be demobilized.  This means that all the equipment used to bring in the equipment will again be mobilized to remove the crushing units.   Once again, all employees should be made fully aware of the dangers of mobile equipment.  Time is money for these types of operations and working for a fast demobilization is a goal for the crushing contractor.  This is noted because all demolition employees should keep a safe distance from the demobilization operation because the people completing this work for the crusher may not be aware of your presence and this could have the potential for an unexpected situation.

Overall, the crushing of concrete and asphalt is a very specific operation but carries with it great potential hazards.  The people who work with and on this equipment do this everyday and are well trained in their required duties of operation.  This makes it our responsibility to make sure that the entire crew working on the site during this type of operation is made fully aware of the potential hazards that exist with the crushing activities.  Insuring that everyone is well trained and informed should help to insure a safe and satisfactory completion to a crushing operation.

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This was taken from Demolition Safety Talks – Copyright 2004 – National Demolition Association – The National Demolition Association views this as a guidance document.  The suggested safe work practices are NOT presented to institute a single method for performing each task involved in demolishing a structure or concrete crushing, but rather to provide the user with means of protecting the health and safety of a demolition worker.  This document is for informational purposes.

FOR INFORMATION ON DALLAS CONTRACTING CO., INC's CONCRETE CRUSHING AND RECYCLING SERVICES GO TO http://www.dallascontracting.com/concrete_crushing.html