8/10/2019 BarChip Fibres Replace Steel in Chilean Housing

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FIBRES

Macro synthetic fibres replacesteel fabric in Chilean housingChile is experiencing prosperous growthand a booming local constRIctionindustry as the nation's averagehousehold disposable income sky-rockets. One of the companies battling tomeet demand is IPEC ConstRIctions whofound Barchip Macro synthetic fibre theperfect answer t increase efficiency.

Perez, lPEC's managing director. The drive to considersynthetic fibre was part of our strategy to continually

search out new technologies to improve our cost base. Andthis was the challenge 1 presented to Jim Phillips fromElas to Plastic Concrete. I think he will agree when 1say thegreatest challenge facing synthetic fibre was its performance in our concrete walls and tilt-up constructionmethod.

Jim Phillips. manager of Elasto Plastic Concrete inSouth America, worked with Miguel through the engineering design and construction of three condominium com

Figure 1: IPEeConstructions'

'Jardines del Sol l inRenaca, Chile -

constructed withBarchip Marco

synthetic fibre in thefoundations, slabs,

walls and roadways.

Syntheticf ibre isextremely light

nd portable,available in

convenient 3kgbags nd the site

requires nopreparation for

reinforcementprior to casting or

pouring.

ANDREW RIDOUT, EL STO PL STIC CONCRETE

The use of synthetic fibres in residential constructionremains relatively new. Only in recent years has the

pelformance of synthetic fibre improved to a level where itcan match traditional steel fabric in construction. Theincreasing cost of steel has contributed to making syntheticfibre a competitive co st option. One of the commonly overlooked advantages is the amount of handling and transportrequired by traditional steel fabric. Synthetic fibre isextremely light and portable, available in convenient 3kgbags and the site requires no preparation for reinforcementprior to casting or pouring. So has the Chilean constructionindustry gained a head start by replacing steel fabric withsynthetic fibre in housing?

n July 2007, lPEC completed its third condominiumcomplex 'Jardines del Sol 3' (Sun Gardens 3) usingBarchip Macro synthetic fibre to replace steel fabric in theconcrete foundations, slabs, tilt-up walls and roadways.

Our company has developed from civil and infrastructure projects into housing construction, so we are not newto the role of reinforcement in concrete, says Miguel

plexes: ' 'This is a very important point when you areattempting to introduce a new technolog y to any existingconstruction method. Understanding how a company operates and constructs is going to ensure the eventual performance of the product. There were many issues to address

from the best way to replace steel reinforcement, the handling of fibre at the batch plant; the mix design; in some situations how to combine synthetic fibre with steel reinforcement; and the traditional working methods of screeding and finishing.

Miguel says the outcome of using macro synthetic fibresproved very worthwhile, Our use of Barchip (synthetic)fibres has allowed us to significantly reduce conventionalsteel reinforcement. This means there is less handling andlabour involved in construction and we are able to achievegains in the time required to complete the project.

In the foundation and slabs we are no longer usingsteel fabric, which has been completely replaced withBarchip. But we are using steel bars for tie-down purposes.

n

the tilt-up walls we are using steel fabric in the first floorwalls but there is almost no steel in the second level walls,which relies completely on Barchip for reinforcing. This isan import ant point because it is from the top edge of thewalls that we tilt and lift the walls into position. We cast thetilt-up concrete walls (first and second level) directly ontothe floor slab and, generally, we let them cure for five daysbefore we erect them.

EPC developed the Barchip Macro synthetic fibre andhas undertaken comparative testing between its structuralsynthetic fibre and steel fabric (welded wire reinforcing)using what is known as the Large Round Panel Test(LRDP), which is similar to the ASTM C 1550 1) standardtest. The results reported by EPC over a range of low andhigh concrete strengths show that Barchip Mac ro outperforms steel fabric for crack widths up to 5mm.

''The advantage of Barchip Macro over fabric is that itreinforces through the full depth of the slab and preventsthe crack from propagat ing wherever it migh t start, saysJim. What interests most engineers, in civil and construction applications, is the performance of reinforcement atsmall deflections where cracks are on Iy I -2mm. A crack of5mm is considered a major failure regardless of the type ofreinforcement being used.

Miguel is quick to add that his research has shownimproved anti-seismic characteristics in the Barchip reinforced concrete due to the tri-dimensional nature of thereinforcement. The matrix of the fibre throughout theconcrete provid es greater control and the synthetic fibresproduce a more ductile structure that is able to absorb highlevels of energy. Additionally. 1have noticed problems thatwe were having with the appearance of very fine cracksdue to shrinkage while curing. which has been resolvedwith Barchip.

SEPTEM ER 2 7 CONCRETE

8/10/2019 BarChip Fibres Replace Steel in Chilean Housing

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FI RES

Figure 2 right: 'Jardinesdel Sol 3 ' in Val Parasio,

Chile - t i l t-up wal lconstruction using

Barchip Macrosynthetic fibre.

Figure 3 far right:Barchip Macro has been

used exclusively toreinforce the concrete

foundation and slab.The only steel used is

for t ie-down purposes.

Figure 4 right: BarchipMacro is added at the

concrete batchingplant. Mix

recommendations fromEPC indicate Barchipshould be added bag

and-all to initial waterand prior to adding

aggregate and cement.

Figure 5 far right:Fonnwork for ti l t-up

walls on the house slab.The formwork for two

walls can be seen. Alsothe 5mm round steel

peg used to secureformwork in to position.

Damage caused to thef loor surface from this

construction methodhas been reduced to nil

using Barchip Macrosynthetic fibre.

"In the tilt-up walls the use of fibre is very important.We place sheets of polystyrene in the wall for insulation,reducing the concrete thickness in sections to 50rnrn. Thefibre makes the walls more flexible than steel and thisaccommodates lifting the walls and positioning them usinga crane on site. Our ability to have thin waJJs with highinsulation helps reduce cost and our clients notice andappreciate the difference living in these thermally insulated

houses."We cast everything on-site and the walls of each house

are cast directly on one of the house slabs. In the past thismethod of construction has caused a great amount of damage to the flooring surface, requiring extensive repair workbefore installing the cerarn.ic flooring. With Barch.ip thereis no spalling when the 5rnrn steel bars we use to secure theform work are removed from the surface of the slab. This isimportant to us because the floor is used as a worlUng sur-

Barchip macro for eachapplication Foundations - the foundation is reinforced

with a dosage of 4kglm 3 Steel cages havebeen replaced. Starterbars remain for thepurpose of tie down.

Slabs - the slab is reinforced with a dosage of3kglm 3 Slab thickness has been reducedfrom 80mm to 6Omm.

Tilt-up walls - the wall is reinforced with adosage of 4kglm 3 . The walls includepolystyrene for thermal insulation. The firstlevel walls are reinforced with steel and fibre.The second level walls are reinforced onlywith fibre. A singleperimeter bar remains toassist with the load during tilting ofthe wallsinto position.

Internal roadways - the roadway is reinforced with a dosage of 4kglm 3 This fibre-reinforced concrete has completelyreplaced a traditional asphalt surlace.

I SEPTEMBER 2007 ON RETE

face not only to make the wal s but also all the concrete elements of the house inclucting the overhead beams."

Concluding remarksMiguel has also changed the traditional approach IPECConstructions took to building roadways within the condominium complexes by replacing asphalt with syntheticfibre-reinforced concrete.

"With roadways the main idea is to support a high levelof traffic. On a construction site with over 100 houses thereis a lot of heavy traffic with trucks and machinery.Combining research from Australia, the USA and theChilean Institute of Concrete, I found the EPC equivalencetables for fabric to fibre to be very accurate.

"The fibre-reinforced concrete pavement has an excellent appearance and functions very well when compared toasphalt under high temperatures. This change has alsocompletely removed our reliance on any asphalt contractor. We can now better control the cost of roadways anddoing the work ourselves means we have greater flexibilityin scheduling the work.

Our workers on-site do everything else so it is excel

lent that we can now also complete the roadways. Ourworkers have adapted easily to these changes, mainlybecause the concrete application is the same. We acquirethe concrete pre-mixed with the fibre from the concreteplant. There is no need for any workers to be involved inthis activity. There have been only minor changes to ourfinishing technique."

References:1. AMERICAN SOCIETY FOR TESTING AND MATERIALS,

ASTM C 1550.Standard test method for flexuraltoughness of fiber-reinforced concrete (using centrallylo ded round panel). ASTM, Pennsylvania, USA, 2004.