How to repair concrete

[Nemesis]

http://www.architectsjournal.co.uk/designingbuildings/materials/2008/11/how_to_repair_concrete.html

 

[Jon Maine]

There are those on this forum who would suggest one of these, I personally feel that this is a tricky area of conservation which will involve lots of debate upon what is worth keeping and what is not. I am not entirely convinced about some buildings which have been protected whilst I do realise there is an argument to save examples from across the board. They are not all like Castle House, I am glad I am not having to make those decisions. I am pleased that my main interests lie in vernacular 150 years+ old. http://www.bbc.co.uk/history/programmes/restoration/2004/sw_castle_house_01.shtml

 

[Nemesis]

Listed, saved, re-used:

http://www.malmaison-newcastle.com/

Building Name: Cooperative Wholesale Society Warehouse
Parish: Newcastle Upon Tyne
District: Newcastle Upon Tyne
County: Tyne And Wear
Postcode: NE1 3DE
LBS Number: 304797
Grade: II
Date Listed: 30 March 1987
Date of Last Amendment: 30 March 1987
Date Delisted:
National Grid Reference: NZ2575064115

Listing Text:

NZ 26 SE NEWCASTLE UPON TYNE QUAYSIDE
12/466 C.W.S. Warehouse
G.V. II
1891 and 1900. by T.G. Gueritte of L.G.Mouchel's firm, and F.E.L. Harris of C.W.S.
Architects. Reinforced concrete, the exterior finished to resemble Portland stone.
Raft foundation to overcome marshy site. 6-storey elevation in austere classical
style. 3-bay Giant Order of plain pilasters (without frieze) stretched through 5
storeys, supporting a heavily bracketed cornice and resting on triple-arched bonded
podium with cornice. Pair of square windows in each bay; each window divided into
9 large pairs (6 on top floor). Interior has slab floors and beamwork supported
by square columns with diagonal spandrels. Modifications except to top storey,
which has barrel-vault across centre with metal strip windows along its base.
Source: L.G. Mouchel Hennebique Ferro-Concrete 4th ed. 1921.


Listing NGR: NZ2575064115

 

[Gareth Hughes]

The first one on this page:
http://www.derelictlondon.com/id1535.htm


SOUTHWARK

TQ3473SW LORDSHIP LANE
636-1/70/492 (East side)
08/04/94 No.549
and gate piers

GV II

House. 1873. By Charles Drake of the Patent Concrete Building
Company. Mass concrete walls, rendered, with artificial stone
dressings and slate roof with cresting.
PLAN: L-shaped plan, with projecting ground-floor bays and
porch in angle. Rendered stacks on outside flank of both
wings. All windows sashes under pointed arches, those to the
ground and 1st floors with foliate capitals.
EXTERIOR: 2 storeys and attics. In the projecting wing to
left, a 3-light canted bay has 2 lights on the 1st floor over
and one in the attic. To the right are 2 windows on the ground
floor and one on the 1st. Between these ascending compositions
the door is set under a gabled porch, within pointed arch with
round columns. Panelled door.
INTERIOR: principal interiors have elaborate cornices and
ceiling roses.

 

[Penners]

Listed, saved, re-used:

http://www.malmaison-newcastle.com/

I remember your post about Malmaison a year or two ago (it wandered off into a Joe Strummer appreciation wonderland, if I remember correctly!).

But surely buildings like this are very much a rarity in the concrete body of work, aren't they? The majority of vernacular concrete structures are perceived (at least by ignorami like me) as ugly slabs - simply utilitarian and of little aesthetic merit. As such, I imagine that few people would mourn their passing.

The matter of concrete deterioration is a puzzling one. Many years ago I spent a day at the Cement & Concrete Association (mainly discussing materials handling) and was shown an experiement that had been running for decades there. Essentially it consisted of a series of test pieces of concrete whose hardness was measured every year, to discover the length of time that the hardening process was still measurable. The scientist who showed it to me said that measurable hardening was still occurring after fifty years.

So if this material is initially immensely strong, and continues to get stronger, I wonder whether the deterioration is all down to the incorporation of reinforcing rods within it?

 

[Nemesis]

Many structures of interest were built from concrete - not all are ugly slabs, but it was the building material of the twentieth century which enabled elaborate constuctions no other material allowed.


I have no doubt that iron bars corroded and other defects in construction alled to stresses and strains have aided deterioration. However, there is no doubt that methods of repair will be increasingly needed by conservationists in future.

http://www.heritagegateway.org.uk/Gateway/Results_Single.aspx?uid=106&resourceID=1 Simple but interesting structure.


And of course:

--------------------------------------------------------------------------------
Building Name: Smithfield Poultry Market
Parish: City Of London
District: City Of London
County: City Of London
Postcode:
LBS Number: 481569
Grade: II
Date Listed: 24 July 2000
Date of Last Amendment: 18 August 2005
Date Delisted:
National Grid Reference: TQ3169281680

Listing Text:




TQ 3181 NE Smithfield Poultry Market
627/2/10210
24-JUL-00

GV II



Poultry market. 1961-3 by T P Bennett and Son, structural engineers Ove Arup and Partners, job engineer Jack Zunz. Reinforced concrete frame, with external cladding of dark blue brick. Reinforced three-inch concrete shell paraboloid roof clad in copper, with circular rooflights, and surrounded by individual copper-clad gable roofs on all four sides. Square plan, with double-height market hall in centre flanked to north and south by delivery bays; first floor gallery with offices on all four sides; basement cold storage and public house (the Cock Tavern).

The exterior is a remarkable piece of `pop architecture', that is absolutely `of its time'. Nine-bay facades to north and south with hexagonal lozenge lights, resembling those found in pavements lighting basements, with full glazing in metal frames to first floor. Clerestorey glazing at sides under the individual roofs. Clerestory glazing on all sides under projecting copper-clad shell. The market is entered under the canopies to either end. There are no formal doors to the market itself. These are concrete frames with infill glazing; that to east forms a physical link with the listed meat market of 1866-7 by Horace Jones. Good, consistent 1960s' style lettering to doorways, such as to the Cock Tavern in the basement. Commemorative plaques dated 1962 on east wall.

The interior is a particularly striking composition. The market hall is set out with stalls, all with blue fascias and contemporary-style signage, forming a strong period composition, that forms an entity with the tile and formica surrounds to the balcony fronts and outer walls. The entrance is tiled, with patterned end walls and timber handrail. The interiors of the offices, basement store and of the Cock Tavern are not of special interest.

Smithfield was developed as a meat market in the 1860s, after a separate market for live cattle was built off the Caledonian Road, Islington. The present Poultry Market was built to replace that of 1873-5 which burned down in 1958. The shell dome, conceived with Ove Arup and Partners, was reported to be the largest of its kind in the world when constructed, with a span of 225 feet by 130 feet x 60 feet high, and built at a cost of �1,800,000. A complex system of more than one thousand preformed plywood shuttering sheets were used in the construction, each one a different shape. Shell construction was first introduced to England in the late 1930s, with the building of Doncaster Municipal Airport (demolished) and the Wythenshawe Bus Garage. Experiments in shell domes only began after the war, however, and were exemplified by the nine relatively small ones at the Brynmawr Rubber Factory, Wales. Shell concrete domes were a pleasingly aesthetic way of achieving large, uninterupted spans using relatively little steel. They were thus eyecatching yet relatively cheap, and the technique was adopted here for speed of construction. While shells used in industrial premises are rarely set over interesting buildings, those in markets could form the basis of an attractive composition. However, the opportunity was not grasped, except here. The result was `the most efficently equipped centre for the exchange of dead meat in Europe' (Architects' Journal, 21 August 1963.)

Sources
The Builder, 2 December 1960, p.1025
Architect and Building News, 7 December 1960, pp.726-7
Interbuild, January 1961, p.3
Civil Engineer and Public Works, January 1963, p.11
Architects' Journal, 21 August 1963, p.369
Industrial Architecture, August 1963, p.536

 

[Nemesis]

Then of course there is this World Heritage Site: http://whc.unesco.org/en/list/166

http://www.britishprecast.org/creativityaward.php

http://www.sydneyoperahouse.co.uk/

 

[Penners]

I accept that there is a considerable, and growing, collection of fine "monumental" concrete buildings, but I was really referring to your plain, everyday vernacular stuff. Blocks of flats, office blocks, and so on.

 

[Nemesis]

Possibly many are not worth worrying about, but that's not the case for all:

http://www.laurenceking.co.uk/product/Concrete+Architecture.htm

 

[Nemesis]

And:

http://www.heritagegateway.org.uk/Gateway/Results_Single.aspx?uid=495906&resourceID=5


also the one I was married in, which certainly relies on concrete for much of its construction:

http://www.imagesofengland.org.uk/details/default.aspx?pid=1&id=443538

 

[Feltwell]

So if this material is initially immensely strong, and continues to get stronger, I wonder whether the deterioration is all down to the incorporation of reinforcing rods within it?

Yes, it does continue to get stronger. If you go to a civil engineering project such as a new bridge, you will find them making several 100mm cubes of concrete in special metal moulds from each batch, which they then crush usually at 7 and 28 day periods to test it's strength. If memory serves me right (it's been a few years) the concrete reaches between 80 and 90% of it's "eventual" compressive strength after 28 days, but it trends towards it's ultimate strength - so in theory never reaches it.

Concrete is very strong in compression but weak in tension, the reason for it needing steel reinforcement. But - if that reinforcement corrodes, the products of corrosion (i.e. rust) occupy a greater volume than the steel itself, so it creates a pressure within the concrete and eventually bursts the surface cover off - "spalling" - the reinforcement usually only being around 2" below the surface. Have the reinforcement much deeper and it doesn't do it's job as well.

Why does the reinforcement corrode? Several reasons - in the 1960's especially they liked to use a variety of chemicals to speed up the gain of strength in new concrete, makes it quicker to build with. Calcium chloride was a favourite - not a great idea, since like sodium chloride (i.e. "salt") it corrodes steel in time. This was generally what the media were on about with their "concrete cancer" scaremongering a few years ago.

Contamination from salts in the atmosphere can play a part - especially in roads structures, if de-icing salt is used and if poor quality control means the steel reinforcement is too close to the surface of the concrete. Contaminated aggregates or mixing water can also be a cause, especially if you consider that a lot of aggregate is/was dredged.

So there you go - all you (never) wanted to know about concrete.

Wake up at the back please.

 

[Nemesis]

Actually I did know all that - but thanks anyhow!

You forgot to mention the 'concrete boots' and final resting places (allegedly) of some villians or the victims of them, whch may not be quite so final when certain structures are demolished.

 

[Feltwell]

Actually I did know all that - but thanks anyhow!

Ahhh, but not everyone's as exciting as you or I Nemesis........ :wink:

I'm still an honorary member of the Concrete Society, a prize I won for my university research on corrosion inhibition in reinforced concrete. A fact which is guaranteed to make you a sure-fire hit at dinner parties everywhere, and one which should only be revealed under an alias on an internet forum

Not sure about dead bodies, but I can tell you for certain that when they come to demolish some bridges just off the M6 junction 10, they will find several tape measures bearing my name. Ohh, and when they demolish some retaining walls for the Sheffield Supertram they may just discover the walkie-talkie that a young engineer dropped one day during a concrete pour!

 

[Nemesis]

Well, maybe we should get together - the subjects I can empty a room with grow daily though, be warned!

Ferro-concrete floors were used for many buildings, for fireproofing purposes, around a century ago.

Here's one, the history of which, as a II* listed building, is really dreadful:

http://www.cromp.com/work/pdfdocs/durnford.pdf


But our very trad looking church hall in the nearby town of Haltwhistle dating from 1908 is another. All the records of its construction are in a bundle in Northumberland Records Office. I suspect I was the first person to look at them for many decades; fascinating reading.