Challenges of creating a safe environment in "ready mix industry" is compounded by the interlinked but distinct environment. RDC Concrete believe that the challenges are catalyst in creating safe working spaces.
Life is the invaluable gift given to us. For centuries, we survived on instinct and many of our forefathers perished as instinct is not always right and even if it is right, it is many times too late to react. This has now been recognised and form safety systems and audit have been put in place for many decades now. Developed world is far advanced in implementing safety systems and processes. In India, we are far behind. More specifically, construction is not known for complying with safety measures. Although wearing helmets and safety shoes are now compulsory, one can look at any site and we will find a large number of people working there bare-headed and in slippers.
Ready mix concrete (RMC) is not exactly construction industry but is inseparably linked with it. There are variety of hazards involved during the processes of receiving the raw materials, processing it in a plant (plant safety), transporting it on the road (road safety) and delivering the finish product at the customer construction site (site safety). At customer’s site, it is poured in to formwork manually or by pumping to a required height reaching up to 400 m. Challenges in creating a safe environment in ready-mix industry is thus compounded by the interlinked but three distinct environments. In RDC, the challenges are the catalyst in creating safe working spaces. While it is difficult to compute deaths in RMC industry in percentage terms; based on the data presented, it is quite obvious that "Falls" and "Road Accidents" constitutes the main element of deaths in this industry. Road accidents frequently occur because the transit mixer carrying RMC while rotating it in a drum is an additional hazard on the road. Falls occur because of working at height while pouring concrete at higher levels. These are the primary challenges that need to be addressed in this industry. RDC concrete has had zero fatality in the last many years.
Delivering concrete is basically a three step process 1) Manufacturing it at batching plant 2)carrying it to the customer site using transit mixer 3) Pumping and levelling it in to the desired shuttering. All these processes have their own safety, environmental and health impacts. To mitigate these hazards and impact, we trust that our systems shall be fool-proofed. In journey to achieve this aim we implemented many best practices in our plants, in transit mixers and at delivery sites also. Some of amongst them are:
Design safety: First and foremost important is the planning for safe operations, while making layout selection of equipment and building safety features during construction of RMC plant. Plant layout has to be good to avoid criss-crossing of vehicles and smooth flow with minimum reversing of any vehicle. Hence special attention is required during construction of RMC plant of all equipment suppliers, user and safety expert.
During construction stage all safety provisions in plant should be provided like barricading of moving parts like belt conveyor, blower, compressor, isolation lock out tag out during maintenance, containment of diesel storage, barricading of water tank pits, locking arrangement for silo ladder to avoid unauthorised access, fire extinguishers, water sprinkling system to prevent dust during aggregate unloading, bag filters for silos to contain cement/fly ash dust during unloading, RCCBs to prevent electrocution, fire extinguishers for different applications, proper covering of all electrical panels, adequate earthing and lightening arrestors, first aid box, PPEs, fall arrestor, etc.
Training: Training to staff and workers is one of the main aspects for improving safety compliance as attrition rate is very high among plant workers, drivers and pump gang. Display of safety provisions, SOP posters, assembly points, etc. should be done adequately in plant.
Health check: To ensure the good health of employee and workers routines check on blood pressure, sugar, eye sight and BMI, etc. are to be regularly carried out in the plant using portable BP/BMI machines or organising camp at plant. Employee’s annual health check is also should be done as per company policy to detect any warning signs.
Safety in plant operations
A-Type Lock: This is mechanical interlocking between the main operating panel and plant mixer’s gate, using two special lock having only one common key. As there is only one key operator can either keep the panel on or keep the mixer open, that means when the main panel is on no one can open mixer gate and when the mixer gate will open no one can start the mixer panel. This will completely eliminate chances of accidents during mixer maintenance, whenever people are inside the mixer for chipping or repairs.
Silo top PRV cover: Pressure release valves (PRV) are installed on silo top, which gets open in case of sudden increase in pressure inside silo during material filling. We must ensure that this safety item is procured from reputed parties and regularly cleaned to avoid dust accumulation, which hinders spring mechanism to function.
Flushing of Bulker during unloading: Due to faulty bulker design, all material like cement or fly ash is not getting unloaded in to silo by blowing at normal pressure of 0.9bar and driver resort to pressuring bulker by closing outlet and suddenly releasing it to flush out last left out material in bulker. This is leading to opening of PRV and discharging material in surrounding atmosphere creating pollution and nuisance for neighbors. To control this we created a handy cover over PRV to contain this emitted dust and transfer it to dust collector at bottom. The design is in-house made and created with very low cost, using spare/ used chemical drums, but giving excellent result in dust control.
Calibration from Ground floor: Earlier in plants, employees were risking their life by climbing on mixer top for calibration of cement hopper, this activity is now made risk free by extending cables from the cement hopper till ground floors, with platform hanging on it. This arrangement facilitate employees to do the calibration from ground floor itself, thus avoiding the hazard of falling from height.
Lifeline and grabber: Plant people have to regularly climb on vertical ladder of silo for many jobs Like, PRV checking, stock measurement, etc. All silo’s vertical ladders are now equipped with lifeline and grabber system, this eliminate the risk of falling from silo height. In case of person slip from ladder the grabber will get locked on lifeline and hold the person in its position. Alternatively scaffold staircase should be installed in silo for safe climbing with all silos interconnected at top.
Safety during transportation
To ensure the safety in transportation of concrete, all the aspects of road safety need to be covered. Concrete carrying trucks have agitator drum to delay onset of hardening process of concrete. This drum revolution of 3RPM, shifts concrete on one side leading to shifting of centre of gravity, which keep on changing at curve roads. At high speed at road turning, combined effect of tilting of drum and moment of inertia may lead to toppling of concrete trucks. Many instances of concrete truck toppling reported in various cities due to this reason. Hence training to driver is of utmost importance because driving a concrete truck is a different ball game than an ordinary truck.
To avoid road accident and toppling of trucks due to over speeding, speed limit for transit mixer has to be kept 40 km/hr, and it is to be made sure by installing speed governors in TM, which will not allow driver to increase speed beyond limit set in speed governor. GPS are being installed in trucks to get alert for over-speeding and also voice alert for drivers. Immediate SMS is also going to the truck owner, plant in-charge and safety officer of the organisation. Drivers are being rewarded for safe driving and with minimum violations. It additionally prompts for wearing seat belt also once vehicle is started.
On road, drivers have to deal with various unseen factors that can affect their driving and they have to be fully trained to handle such factors. Training on defensive driving should be given to improve their driving skills and reducing their driving risks by anticipating situations and making safe well-informed decisions.
Driving under the influence of alcohol and drugs is one of the major causes of all road accidents. Alcohol checking should be done for drivers before leaving and coming back to the plant and educate to them about the life threatening consequences of having alcohol during driving. Engagement programme by involving drivers family helps in improving behavior change were quite successful. A poster showing family and message saying "your family is waiting for you at home is fixed in all transit mixers and form that points onwards we observed a considerable reduction in rash driving cases. To improve the safety condition of transit mixer and safety of driver all the transit mixer should be well maintained and equipped with side guard, front guard, reflective stickers, condition of brakes, reverse horn and side mirrors. Drivers have to ensure that safety inspection of TM is done regularly and pictorial checklist is maintained. Drivers should be in full PPE during driving and on site. All the road safety rules need to be followed such as seatbelt, road signs, maintain safe distance, etc. One experienced driver can be entrusted the job of checking condition of all trucks by driving it for certain distance helps in identifying issues while driving.
Safety during pumping operations
Placing of concrete at site is done by various means like pumping, tower crane, builder’s hoist, etc. and it has to be ensured that all the safety rules are followed. During pumping of concrete, safe site condition needs to be ensured by proper inspection of site before placement of pump at safe location. Soil and ground condition where concrete pump need to be placed, should be properly levelled and clear accessibility of trucks to the concrete pump maintained. Pipe line should not be very old or with leakage as pumping pressure in pipeline is very high and deteriorated pipeline can leads to major accident. Magnetic thickness gauge should be used to check thickness of pipe and pipes with lesser thickness than desired should be discarded. Scaffolding condition of slab needs to be check before start of pipe line laying, which should be dependent of the scaffold supporting the pipeline to avoid transmission of jerk to the main slab scaffold. Bamboo scaffolding must be avoided proper interconnection is not possible as compared to steel scaffold which has locks and pins to ensure good connection.
Pipe lifting clamp: Site gang were struggling from long time to carry concrete pipes. As per earlier practice, two persons used to lift pipes facing each other, but after using this holding clamp, both person can now walk in forward direction. Pump gang should use proper PPEs required for the job like hard helmet, safety shoe, reflective jacket, safety harness and goggles. Training should be given to them about all possible hazards and their mitigation plan. Pump supervisor must be made responsible during shifting and laying of pipeline safely.
Pump should be maintained with necessary safety features and no bypassing should be allowed. Regular inspection by equipment manufacturer helps in detecting the bypassing of any safety feature. The concrete pump operator should be well trained in the operation of the pump and should be made accountable for the safety in and around the pump. He also ensures the placing crew and the ready-mix driver are observing safe practices for a successful concrete placement. Concrete pumping is the most efficient way to place concrete and if all safety concerns are addressed before, during, and after a placement, the chance for accidents will be minimized.
Barricade around slab is normally missing during concrete operations and it should be brought to the notice of contractor and installed. Slab openings left uncovered at lower floors with poor lighting also pose serious danger to the pipeline gang during pipe shifting operation. Lift shaft should be avoided for pipeline laying if intermediate platforms are not made for proper pipeline laying. No overhead crane should work just above the pump and truck position to avoid falling of any object due to loose material and serious damage.
Remote indicator for Pump at site: On the site when pump placed at ground floor and delivery going on at some elevated floor, gang supervisor many time need to come to the edge of shuttering to instruct pump operator, this involves high risk of falling from height. To eliminate this we developed remote signalling system for pump operator. Gang supervisor is using handheld remote control to give signal to pump operator to start or stop the pump without risking his life.
Hazards reporting: Hazards reporting is the key in plant safety, and we should make the best use of available technologies. Plant staff can use their smartphone to report hazards with a photograph in the Google forms and the same is instantly get shared with other plants for information and action. Almost all reports can be in Google forms or on Google Drive, which can save a lot of time, and thus help in immediate action to attend to safety issue.
The article is authored by Anil Kumar Banchhor, MD & CEO of RDC Concrete since June 2016. Earlier he was CEO- Concrete Business of ACC Limited and also worked in Tata Consulting Engineers. He is a civil engineer with PG Diploma in Business management having 30 years of experience in construction, consultancy and Ready mix concrete. He worked with several construction and consultancy assignments in India and abroad. He is a panel member of the codal committee of BIS (Bureau of Indian standards) and was council member of "Indian Roads Congress" in 2006.