Special Construction Material
    ANTI-WASHOUT Underwater Concrete Admixture

    Introduction
    Dewater of hydraulic structures for construction and repair is difficult and expensive. In recent years, as concrete structures in harbor, bridge, and marine construction has become larger in the scale, the need for non-dispersible (or anti-washout) underwater concretes (UWB) to assure correct underwater placement has been increasing.
    Non-dispersible Under-Water Concrete (UWB ) can be placed and self-leveled and self-compacted at any place under water. It is mainly a special admixture called flocculent made the underwater concrete, which are composed of water-soluble high polymers, inorganic mineral powders, superplasticizers and other admixtures .The following effects are produced when the UWB flocculent is used in Concrete:

    [1]. Cohesiveness, mobility and self-leveling characteristics are increased. No pollution in water.
    [2]. High plasticity and suitable viscosity, and self-compacting in water.
    [3]. When the concrete is allowed to free-fall through water,there is hardly any segregation. No bleeding
    [4]. Retardation in setting and less change in flow with time when placed in water
    [5]. Good bond with old concrete and less strength loss in water.

    Application of the UWB flocculent
    1 Antiwashout
    The major requirements for the UWB are antiwashout or segregation resistance, flowability, self-leveling ability and bleeding control. The UWB concrete are produced by the addition of polymeric admixtures, namely flocculent or antiwashout admixtures, at ratios of 1.0 to 3.0% by weight of cement in the mix during the mixing of ordinary cement concrete.
    By using the polymer admixture, the ordinary concrete, which can't resist water washing, can be changed into the non-dispersible underwater concrete, which has very well workability and very high anti-washing ability. The UWB concrete is now an essential part of diversity and great reliability of underwater civil engineering wor k.

    2 Pumping property
    Non-dispersible concrete can be pumped easily, this is realized by adjusting the slump flow of the fresh concrete. Generally, 200m is the pumping distance.

    3 Save the construction cost
    Non-dispersible concrete can be poured into water filled form without a tremie pipe to produce dense structural repairs. This type of material has particular advantages over conventional concrete both in terms of the quality of the repairs produced and the reduction in placement cost associated plant and diver manpower requirements.

    Application areas
    In a word, the applications of the UWB concrete are outline below:
    •  Gap filling work, taking advantages of its flow properties;
    •  High-quality underwater concrete, particularly where material segregation is a concern;
    •  Construction work where particular attention must be paid to the prevention of water pollution;
    •  Underwater reinforced concrete structures;
    •  Corrosion-protecting linings for steel pipe piles and steel sheet piles;
    •  Consolidation of stones and ruffle mounds;
    •  Disaster recovery work, repairs, and reinforcement work.

    Market and Benefit
    Non-dispersible(antiwashout) underwater concrete is quite different in concept from conventional concrete. Many real construction projects showed that the effect of this concrete is not only to greatly improve the reliability of concrete placed under water (both fresh and salt water), but it has remarkable effects on environmental preservation in the construction area; fish can even observe the work.
    Substantial advances have been made in underwater concrete technology with our nearly 20 years experience in this field. The development of better understanding of material properties and mix proportioning practices affect the performance of underwater concrete. Generally, using UWB technology can save the comprehensive cost 20% or more.

    Items on technical service in place

    1.Technical data

    No.

    Test Items

    Specification

    Test Result

    Regular Type

    Retarder Type

    1

    Bleeding Rate %

    <0.5

    <0.5

    0.1

    2

    Air Content %

    <4.5

    <4.5

    3.0

    3

    Loss of Slump (cm)

    30min

    <3.0

    <3.0

    0.5

    120min


    <3.0

    0.5

    4

    Cement Segregation in water

    Turbidity                         Mg/L

    <50

    <50

    2

    PH

    <12

    <12

    11.1

    5

    Setting Time                         hr:min

    Ini.

    >5hr

    >12hr

    15hr10min

    Fin.

    <24hr

    <36hr

    22hr05min

    6

    Strength Ratio of concrete in water and in air %

    7d

    >60

    >60

    63

    28d

    >70

    >70

    76

    2 MUHU is dedicated to researching, developing and producing various cconcrete additives, and providing relevant technical services.

    3 If our UWB admixture was used, We will responsible for technical service in place. We can solve various problems with the builders and owner of the construction project together according to the requirement of concrete compressive strength, water cement ratio, pump placing and slump retention and the filed circumstances.

    Appearance, Packaging, Handle and Storage
    Appearance
    UWB flocculent or antiwashout admixtures, is solid and stable powder, packed into sacks which are made of kraft with plastic film liner. Net weight of each sack is 25.0 ± 0.2kg .

    Packaging and Handling
    Care should be taken during handling operation in order to avoid damage and rain-drenched. Protect from physical damage.   Handle with care and do not open toughly in  order to avoid dust.
    Storage
    The products should be stored in a suitable dry building.  Around 2 years of storage period is recommended for these products.  For storage periods in excess of  2 year, the products should be retested prior to use. Store in a cool, dry, ventilated area  away from sources of heat, moisture and incompatibilities.

    Disposal Considerations
    Whatever cannot be saved for recovery or recycling should be managed in an appropriate and approved waste facility. This material may exhibit one or more characteristics of a hazardous waste and require appropriate analysis to determine specific disposal requirements. Processing, use or contamination of this product may  change the waste management options. State and local disposal regulations may differ from federal disposal regulations. Dispose of container or sacks and unused contents is in accordance with federal, state and local requirements.