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2015SpringShotcreteEMag

Nozzleman Knowledge cleaner drums than suppliers who do not make factors, a swing vote may be achieved by deter- the drivers chip their own trucks. mining the cost differences in short load and wait Depending on job factors, such as temperature time charges. Some other charges that may be a and volume, the ability to have a steady flow of factor are color addition and cleanout charges, as trucks becomes increasingly important to the well as returned material charges. Make sure to quality of the finished product. Fresh concrete is get a complete list of all applicable charges so always preferred, and on some jobs concrete that there are no surprises. We have seen exorbitant is more than 90 minutes old may not be placed. charges for high-range water-reducing admixtures Due to the slower nature of shotcrete placement, (upwards of $20 per yd3 $26 per m3 for medium a lot of times 6 or 7 yd3 (4.6 or 5.4 m3) trucks dosages) and other admixtures. If you are aware provide needed flexibility for a particular job. I of these charges going into the job, you can choose find that trucks that only have 7 yd3 (5.4 m3) are to add some or all of the admixtures to the truck much more consistent throughout the mixture than on-site to save money. trucks with 9 or 10 yd3 (6.9 or 7.7 m3) in them. I Price per yd3 (m3) can vary wildly depending also prefer to completely pump my hopper down on mixture, location, admixtures, and availability in between trucks to make sure that the concrete of materials locally. Make sure to get a quote in in the hopper of the pump is as fresh as possible. writing for your specific mixture design, including A supplier who has enough trucks available to get the admixtures. Some plants will quote you a low a quick cleanup load to complete a job is also a per-yard (meter) price but it will not include the great benefit, as sometimes shotcrete jobs can be necessary admixtures to make the mixture work- difficult to accurately calculate the amount of able. Some plants will quote the material and the material needed due to irregular shapes and the haul charge separately. Some plants will only amount of rebound or sluff that is removed once allow for 3 minutes per yard (meter) of unloading a particular shape is cut/sculpted. time and then start the clock on wait time. As we The knowledge and temperament of the ready all know, it is not feasible to place a 6 yd3 (4.6 m3) mix drivers is an often overlooked but key de - truck in 18 minutes from arrival on-site. It usually ciding factor. This information is much harder to takes 10 minutes to get the mixture to a usable come by than just a quick phone call or trip to their state before the discharge cycle even starts. This plant. Information about the drivers who work for amount of time can increase with a supplier who a particular supplier is usually relayed from others’ does not understand slump and how to accurately experiences and your own experience with a par- gauge slump, and will not send the mixture as ticular supplier. Drivers who show up with bad desired. We find it disheartening at how few sup- attitudes can really sour the mood of a jobsite, pliers are able to batch concrete based on a spe- which leads to lowered productivity and quality. cificw/cm. Most will ask for the desired slump, Drivers who lack the knowledge of how to but few will be able to consistently and accurately properly operate their trucks can be a big problem. deliver as desired. There can be several key issues involved—from With all that being said, the best way to choose the driver’s inability to keep the hopper full a supplier is to get a reference from another com- (which leads to surging at the nozzle), to over- pany that performs work similar to what you are flowing the hopper and making a giant mess, to doing. Their experience is the best gauge on how a host of other issues. We once had a driver who well a particular supplier will work for your par- was chipping his truck with a hammer while ticular situation. We find that most contractors are discharging and letting big chunks fall into the more than willing to share their experience pump. This caused a couple of blockages before regarding a particular supplier. we determined the root cause of the blockages. Needless to say, the driver was banned from ever coming to our job again. We have had numerous drivers who refuse to listen to instructions and ACI Certified Nozzleman Mark would not spin the drum enough to adequately Bradford is an ASA member mix the concrete; they would then add water who actively works as a nozzle- without permission, creating an unusable mixture. man on numerous projects. Standby time and short load fees are a factor He is COO of Spohn Ranch, in choosing a plant, but not as big of a factor as Inc., which has specialized in those previously mentioned. If you have multiple skatepark construction using suppliers that are all similar in the other deciding shotcrete worldwide since 1992. 46 Shotcrete • Spring 2015


2015SpringShotcreteEMag
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