Technical Stagnation

Technical Stagnation

Postby don.mullin on Wed Dec 09, 2009 12:56 am

Too heady? … or maybe you think it doesn’t pertain to you! Well wake up pal, or you will fall more victim to this oversight than your manufacturer did.

Our product has become so much more than standard “bread and butter” 3000-psi concrete. We possess the ability to expand into such things as Rapid Setting concrete, latex modified concrete, flowable fill, and pervious concrete. I recently attended a pervious concrete seminar in my home town that was very well attended by architects, engineers, town planners, and many environmentally conscious individuals who expressed more interest in concrete than I have seen in twenty years. Our present equipment is not only capable, but better suited to produce these products compared to a ready-mix truck.

Properly staged, a volumetric mixer can out perform a transit or central mix batch plant without delays and inconsistencies. An important component of this industry, we are not recognized for this type of work by the majority of the industry. The National Ready Mix Concrete Association sponsored this particular meeting I attended. An NRMCA national resources director who was a full time marketing promoter for them presented the program. When I asked during the program to mention or bring awareness to volumetric mixers, he stated that he had heard of them, but was under the impression that they were only good for producing a couple yards of concrete. Trying not to interrupt the whole program, I explained to him that there are 10 yard volumetric trucks and 14 yard trailers that are capable of producing large amounts of product in a short period of time, and are common around the country. It’s hard for me to believe that the VMMB, which is housed in the same building as the NRMCA, has not gotten the message out about the capabilities and advantages of these trucks. For those of you that don’t know, many units are producing hundreds of yards of concrete on-site for DOT’s, shopping centers, bridge-decking, and flowable fill for utility work 24/7. A variety of smaller jobs continue to present themselves on a smaller scale such as pervious driveways, parking lots (to eliminate the need for a retention ponds), and rapid setting concretes that smaller repairs municipalities or contractors might require. The Volumetric Concrete Industry has to be willing to stop the complacency and get motivated to promote our industry and get our piece of the action!

Ultimately, it is in the best interest of all Volumetric Mixer owner/operators as well as manufacturers, to move our industry forward and out of the mire of technical stagnation and complacency.

My take is that it is unbelievable that the VMMB is nearly invisible within the NRMCA. I think its time for the industry to band together and get rid of the do-nothing “good ole’ boys network” known as the VMMB, and start a new association that includes the manufacturers and well as the owner/operators, more like the NRMCA. VMMB is not serving the industry and is obviously doing nothing to promote and market our equipment within the NRMCA. Not sure what we can do, but I think mobile mix help would be a great place to start a petition to get people on board to start a new association, inside or out of the NRMCA. Any thoughts, suggestions, and input are greatly appreciated!

Footnote: (Did you know that nearly all the states in the USA have a provision in their construction specs for volumetric production of concrete by mobile mixers? It is worded to suit the specific state, but generally refers to “small individual pours, patching and bridge deck overlays.” The reason this clause is here because conventional ready mix cannot generally handle these specific areas of application efficiently. Now shall we discuss the comparative carbon footprint, cubic yard for cubic yard?
Don Mullin
Concrete Express, Inc.
(860)625-1428

http://www.concrete-express.com
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Re: Technical Stagnation

Postby LeeMR on Wed Dec 09, 2009 11:18 pm

Thanks Don!

I've owned my first volumetric truck for just a little over a year. Thanks to Don, as well as the members of this site, I've been lucky to have a good support group.

I have to agree with Don on the technical stagnation. As winter approaches, we here in the northern climates are all faced with the reality of the limitations of our units when it comes to cold weather concrete deliveries. Now, I'm no fan of working in the cold weather, but I'm also not a fan of having to tell my regular customers that I can't service them because it's not going to be 35 degrees and rising.

Matter of fact, I just got a call today for a night pour to be done in the next week or two. Perfect job for a volumetric! Plus, it's a new customer! Good chance to show off volumetric capability. Ahhhh...sh**....then reality sets in! Night pour in December....mmm....not likely to be above 35 degrees! I have to do my dog and pony act about my limitations, before I can get to even show this potential customer my advantages. So...there goes a $250 delivery, $300 night pour charge, not to mention 8 cy of concrete!! On top of that, I may have missed a chance to pick up a new repeat customer!

Now, these units have been around since at least the 60's. And no one has made a serious attempt at winterizing these machines? Stagnation! I rest my case.

Lee G.
Lee Gentile

MIX-RITE CONCRETE
http://www.mix-rite.com
888-MIX-RITE (649-7483)
228 Dedham Street
Norfolk, MA 02056
lee@mix-rite.com
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Re: Technical Stagnation

Postby smnstn on Sat Dec 12, 2009 9:44 am

Once again, Lee -- it's not the inability of the machines to produce concrete in cold weather, but rather what happens to that concrete after it is discharged. If your customer's pour were inside a building -- even an unheated one -- it might be feasible with insulating blankets applied over top after finishing. Even outside below ground, as in a manhole or sewer, or even a protected culvert, the ground temp will be considerably higher than the surrounding air. Ready mix, delivered in the conventional fashion, simply is apt to come from a larger supply facility where they can heat the materials before they are combined to make concrete. The fact that they are contained in a confined space while being rolled around tends to retain and even build a little heat from hydration. But as soon as that concrete is discharged, you have mud that is already on its way to becoming "old" and is subject to the same conditions as your mud. You still have the edge on quality. With up to 2% calcium chloride by weight of cement, and warm aerated aggregates, you have a mix that should work reasonably well in average winter conditions. If it's really downright frigid, the human factor should apply: it's just too danged cold to do the work.

smnstn
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Re: Technical Stagnation

Postby LeeMR on Sun Dec 13, 2009 10:56 am

Hey Simon,

You're right...I agree on limitations such as the human factor etc. And if there is not proper ability to protect the concrete in winter conditions, after pouring, that also is an issue. But for whatever the reason, lately I have had several calls from people doing commercial work on interiors of buildings, looking to fill trenches in slabs, etc.

I have to relay this one to you. On Friday, I had one of those pours. Inside slab repair from underground plumbing work. It was only projected to be in the low 20's on Friday, with blustery winds. I've already had one incident in the cold that left a sour taste in my mouth about cold weather pours. So, as you can imagine, I was not real excited about going out.

But, being Italian, and a little thick headed, I decided to give a try anyways. I warned the customer this time though, that we may have issues. He wanted to give it a try. This time however, I did a little preparation. The Zim mixers are different from all the other mixers, far as I know, in that there is a tunnel down the interior of the bins for the feed chains to return through. So, while still in the warm shop, I took a 50,000 btu propane salamander, and propped it up behind the cab, directing the output into the tunnel area. I blocked off the opposite end of the tunnel as best I could, and let it run.

Then, I shut off my admix tanks and water tank and dropped the sediment bowls. I took one of those rubber test plugs with the wing nut, and inserted it in the end of the water line going to the mixing hopper. I then turned on the manual switches for the water feed and admix feeds. This allowed me to pressurize the main water line, and with the end of water line going to the mixing hopper blocked, it back fed air to the admix lines, and blew all the lines out at one shot. It worked pretty slick.

I heated the water in the water tank with my pressure washer, as that is all that I have at this point to produce hot water. Which by the way, if I switch my pressure washer to steam (250-300 degrees), it does a pretty quick job of heating the water. Not as good as the system Don uses, but it's what I have right now.

Before I left, I blocked the front of my tunnel, so that no air could rush down the tunnel as I drove down the road. I have to tell you, when I reached my hand inside the tunnel, it was very hot!

When I got to the job, I just reinstalled the sediment bowls, turned on the admix and water shutoffs, purged the lines, and I was ready to pour. I was holding my breath, but it worked flawlessly! When I finished, I went through the same procedure to drain the water and admix lines, and I was off down the road.

With a little more time and modification, I'm convinced that I can make cold weather pouring relatively painless. My goal is not to have to tell my regular customers to go to the drum guys during the winter. Like you said, it's no picnic working in the cold, but knowing now that if I have to, I can do it, a good feeling.

Lee
Lee Gentile

MIX-RITE CONCRETE
http://www.mix-rite.com
888-MIX-RITE (649-7483)
228 Dedham Street
Norfolk, MA 02056
lee@mix-rite.com
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Re: Technical Stagnation

Postby rich on Thu Dec 17, 2009 8:11 am

run your exhaust into the tunnel any questions call rich 845 724 5455
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Re: Technical Stagnation

Postby smnstn on Sat Dec 19, 2009 10:55 am

This is just the kind of resourcefulness that can pay off. You did a great job! Just two points I would consider. On the issue of hot water, many of the valves, lines and gauges in the water line fail at temperatures over 140 degrees. You likely have a steel or aluminum water tank (which could be wrapped in fiberglass batting to retain heat), but those using plastic tanks may have a failure threshold there of 140 degrees also. And check the impeller in the water pump. There may be a heat limit on it, although I think those things routinely get hot when operating but not moving water. As for the tunnels, when heating those in the shop, wouldn't it be better to allow the hot air to circulate out the front end, thus allowing fresh heated air into the chambers continually? But I like the idea of blocking the fronts of the tunnels going down the road.

Finally, you could have an insulated bubble in which to deliver concrete, but what happens to it after you no longer have control? Once it hits the ground, Mother Nature is in charge.

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Re: Technical Stagnation

Postby holcombe on Fri Jan 29, 2010 4:19 pm

Technical awareness is a timely subject for me to embrace. With rapid technological growth and more advanced materials, I find your article of great interest!

Quick Mix Inc. was founded in 1984 with a mixer design based on the idea of simplicity and reliability. This design successfully served its customers and the company well for many years. In 2006, Quick Mix was purchased by Brent and Cathy Holcombe. In a short time, it became apparent that although the product design we had purchased was still finding a market in various parts of the Western US and foreign countries, the technology of the design had fallen behind. In 2008, armed with a Mechanical Engineering degree and a passion for the industry, I focused on more modern and efficient applications and set out to undertake a major re-design of the mixer. I talked to many customers to find out what was working and what wasn't, analyzed industry trends, and weighed new technology opportunities from many different suppliers. Armed with this research, it became apparent that there were things that customers liked about their mixers, but there were also things that customers felt needed to be improved. In 2009, Quick Mix released its new mixer design and named it after its designer and owner, "The Holcombe Mobile Mixer".

This new design incorporates a balance of simplicity with efficiency, reliability, and performance. For example, customers have come to expect electric over hydraulic control of their mixer with the option of a wireless remote. However, with the convenience, they did not want to give up the reliability of having manual hydraulic controls to run the machine in the case of losing a solenoid while in the middle of a pour. Another example is that customers want the reliability of a chain driven conveyor system. However, they did not like the maintenance and mess associated with oiling a roller chain. Finally, customers stated that they wanted a hydraulic system that didn't dissipate excess heat, did not leak and would control ALL of the mixer functions, including the cement metering.

As a result, the Holcombe Mobile Mixer implemented a hydraulic valve system with redundant manual and electric controls for all functions. This ensures that even if electric power is lost to any function, the hydraulics can still be run and the pour can be completed. For the conveyor system, the decision was made to use a belt over pintle chain to eliminate lubrication and maintenance of the conveyor. This eliminates the environmental consequences of having oil leaking onto the ground. Finally, the hydraulic system was designed to use a pressure compensated variable displacement hydraulic pump with load sensing capability. Although this technology has been used widespread throughout the world for many years, it is actually just starting to get implemented into the Volumetric Mixer industry. The advantages are numerous. Variable displacement hydraulic systems pressurize a motor or cylinder only when oil is required. This reduces heat in the system, which in turn reduces leaks in fittings and break down of motors and cylinder seals over time. Using a pressure compensated system ensures that all functions will work reliably and produce accurate volumes of materials even when non-priority functions are turned on such as hydraulic swing. Using hydraulic motors to directly control cement and conveyor functions reduces the maintenance of chain synchronous systems and provides more flexibility to easily change the ratio of cement to sand and stone on the fly by just changing the amount of hydraulic flow to the motors.

In these difficult economic times, it is more important than ever that our industry embraces the best technology that is available in order to provide the owner, the operator, and the end customer with the best possible product at the best possible price. If we as an industry, both manufacturers and owners/operators strive to do this together, we will all succeed.
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