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The
primary difference between these admixtures and conventional water-reducing
admixtures is that high range
water reducing (HRWR) admixtures, often referred to as superplasticizers, may reduce the water
requirement by more than 30%, without the side effect of excessive retardation.
Potential Advantages of HRWR:
1.
Significant water reduction;
2.
Reduced cement contents;
3.
Increased workability;
4.
Reduced effort required for placement;
5.
More effective use of cement;
6.
More rapid rate of early strength development;
7.
Increased long-term strength; and
8.
Reduced permeability.
Potential Disadvantages of HRWR:
1.
Additional admixture cost (the concrete in-place cost may be reduced);
2.
Slump loss greater than conventional concrete;
3.
Modification of air-entraining admixture dosage;
4.
Less responsive with some cement;
5.
Mild discoloration of light-colored concrete; and
6.
Air-void and color blemishes on exposed and formed finishes.
(Reference:
NRMCA Publication No. 158)
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