Water permeability of recycled aggregate concrete containing new pozzolan micronised biomass silica material
Natural Aggregate (NA) is an essential ingredient for producing concrete. However, NA is a depleting resource and the quarrying and mining process are not environmentalfriendly. Thus, Recycled Aggregate @A) is introduced as an alternative material to replace NA Such an approach has been widely accep...
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| Main Authors: | , , , |
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| Format: | Monograph |
| Published: |
Universiti Tun Hussein Onn Malaysia
2011
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/1778/ http://eprints.uthm.edu.my/1778/1/0385x.pdf |
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| Summary: | Natural Aggregate (NA) is an essential ingredient for producing concrete. However, NA
is a depleting resource and the quarrying and mining process are not environmentalfriendly.
Thus, Recycled Aggregate @A) is introduced as an alternative material to
replace NA Such an approach has been widely accepted in developed countries like
United Kingdom, United States, Netherland, Denmark and Hong Kong. Nevertheless,
concrete containing RA or known as Recycled Aggregate Concrete (RAC) has certain
weakness in terms of permeability. This study is conducted in depth to explore ways to
overcome these problems. Micronised Biomass Silica (MBS) has been recognised as a
material with a good potential for such application. MBS is derived from controlled
incineration of rice husk which is amorphous and with silicon dioxide (SiOz) content for
about 87.67%. The reduction of MBS particle size to 25.77 pin was by means of jar mill.
The grade of 25 MPa concrete was produced with cement content 450 kg/m3 and w/c
0.5. MBS are used as cement replacement material for up to 12% by weight and RA was
used for up to 100%. Comparative study was conducted with three different conditions
namely; concrete with RA, concrete with MBS and MBS-RA concrete was carried out.
It was found that the incorporation of 12% MBS and 100% RA has produced concrete
with water permeability coefficient 7.94 x 10'12 d s and water penetration depth 64.5
rnm for 28 days age of concrete and its compressive strength is 35.40 MPa. Furthermore,
Scanning Electron Microscopy (SEM) was used to examine the microstructure of RAC
and Natural Aggregate Concrete (NAC). It was observed that the quality of RAC
significantly influences by ITZ. Regression analysis was also conducted to establish the
relationship among different parameters (compressive strength, water permeability
coefficient and water penetration) for RAC, NAC, MBS concrete and MBS-RA
concrete. It was discovered that compressive strength has strong relationship with water
permeability coefficient and water penetration. Two equations were proposed for
predicting the compressive strength and water penetration for RAC and MBS-RA concrete. For proposing these equations, SPSS 14 was used. A nomograph chart as a
guideline to designing RAC (with or without MBS) was also developed as the outcome
of this study. This chart named as Nomograph Chart MBS-RA Concrete which
comprises four axes represent cement content, compressive strength at 28 days or 365
days, percentage of RA and water penetration. Nomograph Chart MB S-RA Concrete is
proposed to be used for designing MBS-RA concrete at 28 and up to 365 days. |
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