Why Is The Cement/concrete So Darn Hard?

[buadhai]

I've been doing a few projects around the house which require me to drill some small (6mm X 25 mm) holes in both the interior and exterior walls of the house where I'm staying. I can't believe how difficult this has been. I have a reasonable cordless drill and bought some Black & Decker masonry bits.

Each hole is taking about 15 minutes, meaning I can almost get two done before the drill needs recharging.

I had a concrete house in Saipan and was able to drill similar holes in almost no time.

What makes the concrete and cement plaster so much harder here?

[Khun Jean]

A cordless drill often has not enough power. I don't know the english name but without a "hammer" function it is almost impossible to drill a hole in concrete.

If you could do that in Saipan with an drill of the same type it says more about the quality of the concrete in Saipan.

I have a "hammer" drill and can drill a hole 6-10mm in seconds. Without the hammer function i just scratch the surface

[lopburi3]

You have concrete walls? Normal construction here is concrete pillars but not walls. The support pillars will be full of rock and rebar so not a quick drill. Walls are normally only half inch or so of cement over blocks or bricks and not hard to drill at all. But you should be using a hammer drill with normal masonry bits. If you can find the tr angler shaped diamond bits a normal drill will work with them but I only use to cut tile as they are easy to break inside wall if you don't keep drill level.

[mrbojangles]

If it is the concrete you are drilling into, a "Percussion Drill" is far better than a "Hammer Drill" and i doubt those Black and Decker Masonary Bits are much good !

Don't know why the concrete seems to be harder though.

Mr BoJ

[buadhai]

I think I've figured it out. In Saipan, the sand and gravel used to make cement and concrete was limestone (calcium carbonate). I'm guess that here the sand and aggregate are some much harder igneous rock, hence the difference in hardness.

And, for sure, if I do this again I'll get a reciprocating drill. (Note to self, never, ever buy another tool from Lotus....)

[chownah]

Things that make concrete hard...or not:

1. The aggregate...this means the rock and sand used. If they are hard then it helps make the concrete hard...and visa versa.

2. The type of cement used. Straight portland cement gives strong/hard concrete. Cements with additives usually/often give weaker/softer concretes.

3. The amount of cement used. If you don't use enough to fill all the spaces between the sand and gravel then the concrete will be weaker/softer.

4. The proportions of and sizes of the aggregates. The best/hardest concrete is made with a broad mixture of sizes of rock and then just enough sand is used to fill the spaces between the rocks.

5. The amount of water used in the mix. The less the better....as long as you can still get the concrete into the forms and consolidated properly.

6. Proper consolidation so that air voids are eliminated, excess water is driven off, and the rock and sand do not seperate from each other creating soft spots.

7. Proper cureing. The concrete should be kept wet for a minimum of 7 days after placing.....14 days is better but 7 days is enough for house building.

Can't think of any other common problems....there are some uncommon problems like mixing sugar in with the concrete is a big no no since sugar strongly interferes with the hardening process.....salt, on the other hand, is not really so bad except it will promote corrosion of the reinforcing steal.

[buadhai]

Thanks for the tips, folks. I found I could make the holes about ten times faster if I just held the bit in my hand and whacked it (the bit, not my hand, although that happened as well) with a hammer while slowly twisting it.

And, yes, the house is standard Thai construction with clay brick walls covered with cement plaster. But even the plaster, about 20 mm thick, was too hard for my drill.

Anyway, jobs are done.

[lopburi3]

For now. But there will be other holes to drill and pictures to hang so an inexpensive hammer type drill might be a good investment - especially when you have to drill in ceramic tile. Lotus does sell them by the way. You want multi speed and hammer functions.

[Jai Dee]

For now.  But there will be other holes to drill and pictures to hang so an inexpensive hammer type drill might be a good investment - especially when you have to drill in ceramic tile.  Lotus does sell them by the way.  You want multi speed and hammer functions.

I would not recommend buying an inexpensive tool if you expect to do any amount of reasonable work with it.

I did exactly that... bought a cheap hammer drill for the exact same purpose as Mike... within a couple of changes of drill bits, the chuck mechanism packed it in...

The key didn't fit the chuck properly in the first place, and now I've got to bash the chuck with a hammer to get it to close around a drill bit.

Buy quality tools... you'll be much better off in the long run.

[olaus]

I think the drill is moving the wrong way. It should move clockwise. Check the drill- machine. I myself made this mistake once. I could not even make a hole in wood.

[lopburi3]

For now.  But there will be other holes to drill and pictures to hang so an inexpensive hammer type drill might be a good investment - especially when you have to drill in ceramic tile.  Lotus does sell them by the way.  You want multi speed and hammer functions.

<{POST_SNAPBACK}>

I would not recommend buying an inexpensive tool if you expect to do any amount of reasonable work with it.

I did exactly that... bought a cheap hammer drill for the exact same purpose as Mike... within a couple of changes of drill bits, the chuck mechanism packed it in...

The key didn't fit the chuck properly in the first place, and now I've got to bash the chuck with a hammer to get it to close around a drill bit.

Buy quality tools... you'll be much better off in the long run.

<{POST_SNAPBACK}>

Well I have a consumer grade B&D hammer drill I got from Lotus many years ago and use often (including many contractors when they don't have there Borsch on site) and have never had a problem. The poster is not expecting to be doing much heavy work I suspect.

[buadhai]

I think the drill is moving the wrong way. It should move clockwise. Check the drill- machine. I myself made this mistake once. I could not even make a hole in wood.

<{POST_SNAPBACK}>

Nah, it's going the right way. I think a decent hammer drill is the answer.

But, I just moved to LOS a few months ago and have already broken the budget in the tool department.

Then again, my birthday is coming up!

[Jai Dee]

For now.  But there will be other holes to drill and pictures to hang so an inexpensive hammer type drill might be a good investment - especially when you have to drill in ceramic tile.  Lotus does sell them by the way.  You want multi speed and hammer functions.

I would not recommend buying an inexpensive tool if you expect to do any amount of reasonable work with it.

I did exactly that... bought a cheap hammer drill for the exact same purpose as Mike... within a couple of changes of drill bits, the chuck mechanism packed it in...

The key didn't fit the chuck properly in the first place, and now I've got to bash the chuck with a hammer to get it to close around a drill bit.

Buy quality tools... you'll be much better off in the long run.

Well I have a consumer grade B&D hammer drill I got from Lotus many years ago and use often (including many contractors when they don't have there Borsch on site) and have never had a problem. The poster is not expecting to be doing much heavy work I suspect.

B&D power tools are fine for normal home handyman stuff.

I bought a chinese no-name knockoff.

You get what you pay for...

Mike... get yourself a decent birthday present... go shopping in a man's toys supermarket and stock up on tools!

[penzman]

I ve got a hammer drill. I often dont even bother using the hammer setting when drilling the through walls. Get better drill bits, I've been had once.

[buadhai]

I ve got a hammer drill. I often dont even bother using the hammer setting when drilling the through walls. Get better drill bits, I've been had once.

<{POST_SNAPBACK}>

Any particular brand you recommend, or recommend avoiding? I bought B&D at Home Pro because that was the only one I recognized.

[penzman]

I remember buying a brand that came from the U.S.. Package was red-white-blue. Bought at True Value. Avoid the ones with a cheap silvery/aluminium color coating. Good brands usually have a different harder metal for the tip, you can clearly see the difference in colour.

I went through a whole bunch at first, made in Thailand, they don't last at all.

Same for hand grinder blades, Makita are excellent, they probably make drill bits as well.

The spelling on the package speaks for itself

[buadhai]

Thanks. I guess with "Lone Lief" on the package there's no chance of any false advertising claims!

[chownah]

I ve got a hammer drill. I often dont even bother using the hammer setting when drilling the through walls. Get better drill bits, I've been had once.

<{POST_SNAPBACK}>

Any particular brand you recommend, or recommend avoiding? I bought B&D at Home Pro because that was the only one I recognized.

<{POST_SNAPBACK}>

I bought a Makita 1/2" chuck combination drill/hammer drill. It is awesome. We built the entire house with it.....drilled lots of holes in concrete and I had them make some very hard concrete so it wasn't always easy going. It's still going strong...have had no problems....best drill I ever owned!! As I recall it ran about 4,000 baht or maybe a bit more (bought it 4 years ago)....but well worth it.