the order of mixing cement

I am mixing cement of 1 part Portland cement to 3 parts sand. And the old traditional way is to thoroughly mix the sand and cement and then
add water and slowly mix the dry portion with the wet.
But I am challenging that old wisdom with experimenting with other sequences. Yesterday I tried it backwards where I add the water first into the tub, then I added the cement and mixed it into a gray soup. Lastly I added sand until it was mixed and ready to use.
So I am testing the old wisdom of mixing cement, and or concrete. Has anyone done this experiment in a professional science experiment as to the sequence order of cement mixing. Order is important in chemistry, but is the order important for cement.
Archimedes Plutonium www.iw.net/~a_plutonium whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies
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a snipped-for-privacy@hotmail.com wrote:

You might check with the pros, but I believe the chemistry that leads to hardening of the cement begins when you add water. Adding it at the last gives you more time to use and work the cement.
With small batches, order should not matter.
Atty (More cement overshoes, anyone?)
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Well this is exactly where I need the chemistry experiment to find out if there is a time lag in which the order of mixing does not matter in achieving the strongest bond. If there is a time lag, then my favorite way of mixing of adding water first then 2 parts sand plus 1 part cement and then mixing into a soup, then add the final bucket of sand and mix and if still too runny wet, simply add a small portion of sand plus cement to zoom in on a nice batch.
I suspect there is a time lag and that is what I want a chemistry lab to confirm.
Archimedes Plutonium www.iw.net/~a_plutonium whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies
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There may be a theoretical reason for the order of mixing of mortar or concrete....but there certainly is a very practical reason. Water is a minor constituent, and the amount needed varies dramatically depending on whether the sand is classed as moist, wet, or very wet.
If I dump two gallons of water into a tub, add cement and sand, and find that the mix is sloppy because the sand was very wet.... I may have to add a great deal more cement and sand. If it's at hand. Run to Lowe's, buy another sack of cement and five of sand....while the batch in the tub hardens..... Or if the mix is too dry, I end up adding water anyway.
On the other hand, if I start with the cement-sand mixture, and add water a little at a time, it's much easier to creep up on the right mix. (Partly because the library books all show the conventional method, and they show what the mix looks like at various stages.) And I get much closer to the desired amount of mortar.
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snipped-for-privacy@hotmail.com wrote:

Yes I am wondering what the theoretical reasons for the order sequence for mixing the ingredients of mortar or concrete. The maximum strength of the mix, whether it has to be of a unique order. Or, whether there is a small time parameter for which the order does not matter in achieving the strongest end result. I am assuming, and this is where I could be utterly wrong, is that there is a time lag involved for which it does not matter in which order the water, sand and cement are mixed. But if there is theoretically, no time lag to achieve the strongest bond end result, then that order sequence must be taken.

I was experimenting because I was finding that too much dry mix was not getting mixed properly. So I was searching for the *easiest* and fastest way to thoroughly mix the ingredients. So far the easiest for me has been to add the water first then add 2 buckets of sand and add 1 bucket of cement and then mix and it fastly is mixed thoroughly and easily. Finally add the 3rd bucket of sand for the final mix. I have found this sequence the fastest and most thorough mixing. The old way written in books tends to leave unmixed dry components, especially on the bottom of the tub and along the sides. And my way takes 1/3 of the time that the old way takes. So if the old way takes 15 minutes for a tub of cement, my new way takes 5 minutes, from start to finish.

When there is no problem of running out of cement or sand, then I am not concerned about creeping up onto a nice batch of cement, rather instead I would be more concerned about quickness of a nice batch and of ease and of thorough mixing. But if I am at the end of the supply of cement or sand then I would try to creep in with adding water little at a time.
When I have plenty of ingredients, I rather creep or focus on the nice batch by adding more sand and cement.
Another consideration for adding water early to the mix is health concerns. I do not want to breathe any of that cement and so I want to add the water firstoff so as I add the sand and then the cement that the wetness reduces the airborne dust and reduces my chances of inhaling cement. I wear a respirator when working with cement but not when mixing and so I prefer mixing wet ingredients rather than the dry stuff.
Archimedes Plutonium www.iw.net/~a_plutonium whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies
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On 29 Aug 2005 10:04:42 -0700, a snipped-for-privacy@hotmail.com wrote:

Mixing cement is chemistry.
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Terry Harper
URL: http://www.btinternet.com/~terry.harper /
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a snipped-for-privacy@hotmail.com wrote:

Correct, a bit strong in cement ratio IMHO, I prefer 1 to 7, with a touch of lime.

The cement started hydrating when you mixed the cement with the water, so the clock starts ticking at that point. You could add some retarder to slow down the setting. But the traditional way will also have the same problem, as sand is not normally dry! Answer is to mix as fast as possible, that gives you the longest useable time.

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Ron Jones
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I prefer the 3 sand to 1 cement with no lime because it achieves for me the strongest bond. I once had to tear apart this mix when cured and was amazed by its hardness. Lime is just a help on workability but it decreases the strength of the end result.
Yes, the cement started to hydrate but has anyone experimented to find out if there is a time lag involved so that it does not matter what sequence order of mixing takes place.
Yes the sand that is not completely dry tends to form small ball shaped objects in the mix and my hoe has to break those balls apart, so I reverted to a new sequence where I add the water first then 2 parts sand plus 1 part cement and mix and then no balls form, finally the one more bucket of sand and if too runny then a wee-bit more of sand + cement in a 3 to 1 ratio to make a nice batch.
I was wondering whether the cement trucks have a specific order of mixing and whether any of them start with the water first and then add sand and cement.
Archimedes Plutonium www.iw.net/~a_plutonium whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies
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I suspect there is a time lag and that is what I want a chemistry lab to confirm.(snip) Giving you a chemistry lab would be like giving whiskey and car keys to gang teenagers.-Jitney
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The correct order is: 1) Prepare a form for the concrete cast. Wood is typicaly used for the purpose. It can 2) Take X parts of sand/gravel + Y part of cement and thoroughly mix it dry with a shovel in a large vat or cement mixer. Then start adding water in small repeated doses while turning the mix with a shovel. With vigorous mixing, a porridge-like slush is eventualy produced. Please dry mix first and take care not to drown the mix with too much water. 3) Put a body of Archie Pooh into the form and weigh it down with at least 10 bricks or corresponding quantity of scrap metal. 4) Pour a copious amount of the concrete slush all over. It is imperative that the entire body is covered and no appendages or part of torso sticks above the surface of concrete slush. 5) Allow the cast to harden undisturbed for at least 3 days. Keep it from freezing in cold weather. Cover it with a sheet of plastic against rain or small animals/children wandering around. 6) Take the form apart. Use appropriate lift or crane to load the formed monolith on a truck. 7) Find a deep-water place for the dump. Highway overpass over a large river or lake is suitable for the purpose but a steep sea cliff is best. 8) Have your insurance and registration ready - in case that they see you dumping.
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As they say, you could look it up
MACHINE MIXING INSTRUCTIONS QUIKRETE Concrete Mix can be mixed in a barreltype concrete mixer or a mortar mixer. Choose the mixer size most appropriate for the size of the job to be done Allow at least 1 cu ft (28 L) of mixer capacity for each 80 lb (36.3 kg) bag of QUIKRETE Concrete Mix to be mixed at one time For each 80 lb (36.3 kg) bag of QUIKRETE Concrete Mix to be mixed, add approximately 6 pt (2.8 L) of fresh water to the mixer Turn on the mixer and begin adding the concrete to the mixer
and
HAND MIXING INSTRUCTIONS Empty concrete bags into a suitable mixing container For each 80 lb (36.3 kg) bag of mix, add approximately 6 pt (2.8 L) of clean water http://www.quikrete.com/Spec_Data/concrete_mix.pdf
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