Monday, May 22, 2006

Credibility! Tampers!

So far two readers of this blog have taken the time and consideration to write.

The first letter was about our "credibility" and how that "credibility" might be increased (or improved, I can't remember which) if we were to give our "real identity."

Having given it months of thought, I (rammed earth) have come to the conclusion that "credibility" is only an issue for two groups of people: those trying to sell and those wanting to buy.

The purpose behind this blog is to LIBERATE YOU from the ENDLESS CYCLE of DISAPPOINTMENT in the CREDIBILITY SWEEPSTAKES.

Thousands, if not millions of times a day, lonely consumers hit the streets looking for a credible merchant who's gonna treat them right! Millions more go looking for one who won't treat them wrong. Eager sellers splash on a little 'Old Spice' and hope their web of deception will dazzle these buyers into suspending their disbelief long enough to let go of their credit cards. The overwhelming majority (on either side) will be disappointed in that transaction--though not so much that they change their behavior.

That's not how we roll here. No nothing for sale here. I don't want your 16 digits and expiry date. This is a site where INFORMATION is SHARED. I urge you to take this information (and everything you read and hear, especially on the internet) with a healthy shovel full of skepticism.

Letter number two inquired about tampers, specifically if one tamper "does the job faster" than another. Here's what we know about tampers:

The Chinese did not use pnematic rammers and air compressors when constructing The Great Wall. The centuries-old compacted-earth structures that exist in myriad climactic and seismic zones were built with human-powered wood tampers.

While some would assert that a heavy, high powered ramming unit makes you feel you are really getting the job done, I would counter that one could build a rammed earth wall of excellent compressive strength with wood dowels, if your mix was right and your laborers energetic and concientious.

With that in mind, I would like to direct the attention of any interested parties to the products of the Henry Air Tool and Top Cat Service (Not like we're selling anything here...)

Both companies manufacture two models of sand rammer typically used to compact sand in foundry molds with identical model and part numbers;the 1350 and the 1320.

Our experience with the 1350 has been positive, they're light (14lbs) and easier to control and work around the form. The test results of core samples taken from walls tamped with these units had more than adequate strength (i.e. the rammers were providing adequate compression.)

For our next project we're going to try out their 1320 which is even lighter (11lbs) and has a shorter stroke (2" as opposed to 4") but delivers 1750 blows per minute over the 1240 bpm.

(Which one is "faster?" Stay tuned and we'll let you know)

According to Houben and Guilaud in their classic tome "Earth Construction: A Comprehensive Guide", the longer stroke is preferrable, though they specify 20 cm, double the length of the 1350s (which work just fine.) They also caution that "pneumatic rammers must neither be too powerful, as they might destabilize the formwork and cause the rammed earth to bulge".

I've heard of this happening recently, the rammers used were too powerful for the formwork causing the formply to bow, giving the resulting wall a quilted, tuck and roll effect. Using formply that is too thin can have the same result.

I'm also eager to try out a smaller 2 3/8" steel head for those hard-to-reach spots. Whatever you do, DON'T GET THE RUBBER HEAD, it will leave a mark on your formwork if you so much as brush against it when ramming. This mark be transferred to your wall surface, leaving an UGLY BLACK SKIDMARK which may be difficult, if not impossible, to remove without damaging the surface of your wall. Stick to the steel.




Don't kill yourself or your workers with heavy, unwieldy tampers. Less is More. Probably lower fuel costs too.

(But is it faster?)

6 comments:

kdriven said...

Sweet blog!!! I just picked up a tamper off Ebay, Inersoll Rand 341 something or other...if you're intersted I'll send you a review. I also read on another earth building site that some RE contractors like the Jet-2T...I priced them around 550 new.

XG Power said...

If you are looking for quality tools and discounted prices, take a look at XGPower. A huge inventory of construction tools as well as tools and equipment for the home and garden.

Bryan said...

Thank you for the information on types of tampers. I hope to use rammed earth here in Honduras.
BwanaB3

berkhatn said...

Hello!
Do you know the the impact energy of the 1320 and 1350 series floor rammers (or JET-2T at least)? I need it to compare with products that available in my country(Ukraine).
I prefer two rammers, that made in Russia: 4 joules and 20 joules is a big difference, but they look the same, have the weight +/- 2 kg, need the same compressor.
Henry Tools doesn't answer my email letter.
Thank you!

berkhatn said...

Hello!
Do you know the the impact energy of the 1320 and 1350 series floor rammers (or JET-2T at least)? I need it to compare with products that available in my country(Ukraine).
I prefer two rammers, that made in Russia: 4 joules and 20 joules is a big difference, but they look the same, have the weight +/- 2 kg, need the same compressor.
Henry Tools doesn't answer my email letter.
Thank you!

Rammed Earth said...

As of 22/8/14 the 1320 floor rammer is $525USD and the 1350 is $545USD, both from Henry Tool.
The 1350 weighs 14.3 pounds (6.5 kg), the 1320 weighs 11 pounds
(5.1 kg).

The larger model is going to be harder to handle but will compact the soil faster.