"Concrete Masonry" from the early 1900s

[dkellogg3]

We are currently working on a project in which the unreinforced concrete structure is referred to on the existing drawings (1914) as "3/4" Stone Concrete Masonry". Does anyone have any references listing properties, or mix proportions, or any information on this material?

Thanks!

 

[SlideRuleEra]

During that time period concrete was proportioned by volume, with a typical mix being designated:
1: 2: 4
That is, 1 part cement, 2 parts sand, and 4 parts aggregate. This was done since these dry "ingredients" were delivered, separately, to a job site. Then, workers would "charge" a mixer with shovels... a shovel full of cement, 2 shovels of sand, 4 of aggregate.

The mix proportions, and aggregate size would be changed depending on the type structure. Tell us what type structure you are looking at; I may be able to give you the proportions that were common.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[concretemasonry]

Slide rule has it correct. The early mixes were proportioned on a volume basis, which lends itself to variations because of the moisture and bulking of the fine aggregate, which is the major component.

Unfortunately, this lead to excessively high cement contents.

The standards at that time did not really exist, so there were local variations.

The important thing is that most concrete block after about 1904 were closer to a zero slump than a conventional concrete mix. Since the block were manufactured using a zero slump or "dry tamp" mix, the cement was dosed to provide green strength adequate to enough to strip from the mold after less than a minute. Usually, the strengths were excessive after a month or two. The 3/4" that the original poster referred to was the maximum aggregate size, with most of the aggregate being much finer (well graded sand) because of manufacturing requirements, that continue today. Most block today have a #4 maximum size.

The earliest codes had requirements that were not really different from current code standards for strength, despite the ability of modern equipment to economically produce block 2 or 3 times the current ASTM minimums (up to 8500 psi). The old standards(1920's)really did not address dimensions and tolerances, because many of the units were made with irregular faces, but did have strength requirement similar to modern codes and standards. There was a trend toward using net compressive strengths instead of gross compressive strengths. At least the design standards have permitted engineers to take of the advantages if they knew how to.

You will never find any mix designs for 1914 block unless they are rare documents in a museum.

If you

 

[dkellogg3]

-

Thanks for the info, guys (gals?).

SlideRule, The structure is a gatehouse for a drinking water reservoir which lies on the south end of a dividing weir separating the reservior into two basins.

concretemasonry, I am actually talking about an underinforced concrete stucutre, not block, but you provide good info.

Thanks again.


-

 

[SlideRuleEra]

dkellogg3 - I assume the gatehouse would be considered "walls". If that is reasonable, then the proportions common for that type structure could be
1: 3: 6
This comes from my 1937 edition of "Trautwine"... but don't let the date fool you, the info itself is from the early 20th century. Trautwine did not try to present the "latest" information, just what had been in common use.

I intend to scan and post sections from Trautwine on my website, will see if I can get this one done in the next week or two.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[dkellogg3]

I guess I could have been a little more specific. The operating level is at El. 592. From there down to the top of the gates is about 27 feet, and the strucutre is 31-feet wide, so we've pretty much got a mass concrete structure with vertical sluiceways for the gates. Above the operating leve there are walls that are about 3'-6" thick that are also butressed to support the roof framing, which is reinforced concrete for road traffic above.

Thanks again for the help, and when you get that stuff scanned could you send a respose to this thread so I'll be notified? Great knowing there's people like you around to pass on the knowledge.

 

[kslee1000]

I believe the prevalent winsdom at that time was 1:3:6 could produce a concrete with fc' = 2000 psi, and 1:2:4 for 2500 psi. For the massive wall, 1:3:6 is more likely been used.

 

[dik]

I don't know if the wall was constructed of masonry units. If it was, early concrete walls were constructed of masonry units that had 'scalloped' faces to mimic cut stone. This was common to the early 1920's.

Dik