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Quality of Water. Materials of Construction Dr. TALEB M. AL-ROUSAN. Quality of water. Very important Impurities in water may: interfere with the setting of cement. Adversely affect strength of concrete. Cause staining of concrete surface. Lead to corrosion of reinforcement.

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quality of water

Quality of Water

Materials of Construction

Dr. TALEB M. AL-ROUSAN

quality of water1
Quality of water
  • Very important
  • Impurities in water may:
    • interfere with the setting of cement.
    • Adversely affect strength of concrete.
    • Cause staining of concrete surface.
    • Lead to corrosion of reinforcement.
    • Cause efflorescence.
    • Reduce durability.
    • Volume instability.
mixing water
Mixing Water
  • Water should be fit for drinking.
  • Limits may be set on chlorides, sulfates, alkalies, and dissolved solids.
  • Dissolved solids < 2000 ppm
  • If drinking water has high concentration of Sodium or Potassium it will be unsuitable to be used for mixing because of danger of Alkali-Aggregate reaction.
  • Alkali Carbonate & bicarbonate (Na, K) affect setting times of different cement (accelerate or retard), and if available in higher contents may cause strength reduction.
  • Sulfates: High sulfate content may cause expansive reactions and deterioration.
mixing water cont
Mixing Water Cont.
  • Oils: Mineral oils (Petroleum) has less effect than animal or vegetable oils. Oils > 2.5% by mass of cement tends to reduce strength.
  • Water carrying sanitary sewage: Treated water that has up to 20 ppm solids is OK to be used.
  • Acid water : depends on pH (< 3 cause handling problems).
  • Water used to wash out truck mixers can be used because solids in it are concrete ingredients.
  • Wash water & industrial water: can be used but high solid content will reduce strength.
mixing water cont1
Mixing Water Cont.
  • Sugar:
    • Small amounts of sucrose (0.03 – 0.15% by mass of cement) retard setting of cement, and may improve 28 days strength and reduce the 7 days strength.
    • Sugar > 0.25% of cement may cause rapid setting and reduce 28 days strength.
  • Water not fit for drinking can be used.
  • Rule: Any water of (pH = 6.0 – 8.0 which doesn’t taste saline or brackish) is suitable for use.
mixing water cont2
Mixing Water Cont.
  • Sea water can be used but generally inadvisable.
    • Leads to higher early strength but a lower long-term strength (15% loss).
    • Sea water or any water with high chlorides content tend to cause efflorescence and persistent dampness. Should not be used where appearance of concrete is of importance.
    • Sea water increase the risk of corrosion of reinforcement.
    • When reinforced concrete is permanently in water (sea or fresh) the use of sea water seems to have no ill-effects.
curing water
Curing Water
  • Generally, water satisfactory for mixing is also suitable for curing purposes.
  • Iron or organic matter may cause staining.
  • Curing water should be free from substances that attack hardened concrete such as: water containing free CO2 (water formed by melting ice or condensation), which dissolves Ca(OH)2 and causes surface erosion.
tests on water
Tests on Water
  • To determine water suitability for mixing compare setting time of cement and strength of mortar cubes using water in question with results obtained using known good water.
  • 10% variation is tolerated for strength.
  • Such tests are also recommended when water contains dissolved solids in excess of 2000 ppm or alkali carbonate or bicarbonate in excess of 1000 ppm.
  • For curing water, performance tests involving simulated wetting and evaporation can be done to check for staining which can not be done using chemical analysis.
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