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30Apr 2017
A good designed and placed concrete should serve its intended purpose for its entire service life. Several challenges can be encountered after placement of concrete and one of such challenges is Dusting

Dusting

Dusting is characterized by powdering at the surface of the concrete slab. This powdered surface may weather and expose the aggregate. During placement, bleed water carries cement and finer particles to form a layer of laitance on the slab surface. Several factors contribute to dusting, some of which include:

  • Excessive bleed water on the surface which can create a porous skin layer
  • Very rapid drying of the surface from wind/weather may reduce the water available at the surface for cement to hydrate fully, leaving a dusty surface.
  • Improper curing of slab thereby producing weak surface

Prevention

The following can be adopted:

  • To prevent dusting, do not carry out finishing operations with excess water on the surface. Concrete should have finished bleeding before any operation is carried out.
  • Ensure effective curing, which gives a stronger surface, more resistance to abrasion, etc, by using plastic sheet or hessian cloth.
  • Control water cement ratio. Use a moderate slump mix of not more than 125mm
  • Protect slab from weather during concreting and curing
  • Avoid using polythene sheet when laying slab.

Repair

Dusting can be rectified by one of the following:

  • Grinding off existing weak layer of the concrete thereby exposing the concrete layer with adequate strength.
  • Application of a concrete densifier, sealer or hardner on concrete surface after inspection of concrete floor
12May 2014

This seminar will assist participants to better understand the mechanics, problems and avail solutions to extend service life of concrete and steel structures. Specifiers will be better equipped with the tools and knowledge to confidently provide de-signs and detailing where required. Contractors will equally be better prepared with installation methodology and options avail to meet specification.

HOST SPEAKER

The Webinars will be conducted by professionals with significant research and consulting experience, Dr. Ivan Razl, Ph., D., P.Eng, is the technical director of Gemite Products. Dr. Razl has extensive experience in research and development of specialty chemical systems, such as polymer and cement composite systems, concrete protection and restoration materials. He is a holder of a number of patents in Canada, USA and internationally. He has published various professional journals and presented a large number of scientific papers in his field.

 

WHO SHOULD PARTICIPATE

  • Bridge Engineers
  • Materials Engineer
  • Asset Managers
  • Project Managers
  • Consultants
  • Structural Engineers
  • Contractors
  • Developers/Owners
  • State/Federal Ministries

 

AGENDA

The session will describe typical problems of concrete structures in waste water facilities, including sludge tanks, digesters, manholes and sewers, methods of re-pair, waterproofing and chemical protection. The cur-rently used protection systems will be reviewed and compared with products offered by Gemite Products Inc. in this area. The typical case histories in restoration and new construction projects will be presented. The following products and their use will be described, and the session will conclude with a question/answer period.

  1. 1
    Concrete Restoration
    • Rust-proofing of exposed rebar – Fibre Prime
    • Hand or spray applied, thin repair mortar up to 12 mm – Gem-Plast TC
    • Overhead, hand applied repair mortar – Fibre-Patch OV
    • Wet process shotcrete material for larger volume re-pairs – Spray-Con WS ST
  2. 2
    Concrete Protection and Waterproofing
    • Flexible, polymer modified mortar, with high resistance to sulfuric acid, generated by microbiological conversion of hydrogen sulfide – Cem-Kote Flex CR
    • Waterproofing coating – crystalline waterproofing – Cem-Kote CW Plus
    • High acid resistance system combining water vapor barrier Cem-Kote Barrier Cote 100 and acid resistant epoxy coating – Gem-Cote EP 100
  3. 3
    Problems

    This part describes the cement toppings/coatings and poly-mer sealers/coatings for exterior protection and water-proofing of exterior slabs.

    • Rust protection – Fibre-Prime
    • Crack treatment – Cem-Kote Flex ST with Reinforcing Fabric HD or NW
    • Thin, polymer modified, high flow, mortar topping (overlay) – Gem-Crete HF ST
    • Thicker waterproofing, high abrasion and impact resistant, fibre reinforced Gem-Crete HDO
    • Patching – Fibre-Patch OV (vertical and overhead), ST (horizontal) and ES (early strength).
    • Penetrating Sealers – solvent borne Gem-Gard SL ST and Plus, Gem-Seal WA ST and Plus.
    • Coloured, water borne sealer – Gem-Cote WA Plus
  4. 4
    Concrete
    • High toughness and abrasion resistance polymer modified cement coating – Cem-Kote Barrier Coat 100
    • Flexible Polymer Modified Cement Coating – Gem-Crete TWM Plus
    • Flexible acrylic roof coating with micro-spheres (insulating) Thermo-Coat Roof

The session will be dealing with three subject areas: industrial floor, parking deck and roof slabs the products and their use will be described and the session will conclude with a question/answer period.

  1. 1
    Problems and protection of Industrial Concrete Floorse

    This part of the presentation will introduce thin cement based coating/toppings, clear, waterborne coloured seal-er, and epoxy coatings.

    • Polymer modified cement based toppings – Gem-Crete HF ST
    • Polymer modified cement based coating – Cem-Kote Bar-rier Coat 100
    • Epoxy coatings – Gem-Cote EP 100 and 300
    • Clear sealers – silicate based Nano-Gard 100 ST and Plus (hydrophobic), water borne, acrylic Gem-Seal WA ST and water borne Gem-Seal MB ST and Plus
    • Coloured water borne, acrylic sealer – Gem-Cote WA Plus
  2. 2
    Problems repair and protection of parking garage slabs, runways, tarmacs

    This part describes the cement toppings/coatings and poly-mer sealers/coatings for exterior protection and water-proofing of exterior slabs.

    • Rust protection – Fibre-Prime
    • Crack treatment – Cem-Kote Flex ST with Reinforcing Fabric HD or NW
    • Thin, polymer modified, high flow, mortar topping (overlay) – Gem-Crete HF ST
    • Thicker waterproofing, high abrasion and impact resistant, fibre reinforced Gem-Crete HDO
    • Patching – Fibre-Patch OV (vertical and overhead), ST (horizontal) and ES (early strength).
    • Penetrating Sealers – solvent borne Gem-Gard SL ST and Plus, Gem-Seal WA ST and Plus.
    • Coloured, water borne sealer – Gem-Cote WA Plus
  3. 3
    Concrete Roof Decks
    • High toughness and abrasion resistance polymer modified cement coating – Cem-Kote Barrier Coat 100
    • Flexible Polymer Modified Cement Coating – Gem-Crete TWM Plus
    • Flexible acrylic roof coating with micro-spheres (insulating) Thermo-Coat Roof

This session deals with restoration and protection of concrete bridge structures. It is divided into three parts: repair of bridge substructure, protection and waterproofing (repaired and new structures), and repair and protection of bridge decks. The description of products and their applica-tions, including case histories, will be presented. The presentation covers only the use of Gemite products in this application and is not intended to provide a comprehensive treatment of the “bridge” subject.

  1. 1
    Repair of Concrete Sub-structure

    Concrete restoration

    • Rust-proofing of exposed rebar – Fibre Prime
    • Hand or spray applied, thin repair mortar up to 12 mm – Gem-Plast TC
    • Overhead, hand applied repair mortar – Fibre-Patch OV
    • Wet process shotcrete material for larger volume re-pairs – Spray-Con WS

     

    Concrete Protection and Waterproofing – repaired and new structures

    • Polymer modified cement – Cem-Kote ST
    • Clear penetrating silane sealer – Gem-Gard SL ST and Plus
    • Coloured, non-flexible, waterborne acrylic sealer – Pri-mer #300 used as a coating
    • Flexible, waterborne coating system – Primer #300 and Tuff-Flex CA
  2. 2
    Decks
    • Migrating corrosion inhibitor – Gem-Gard MCI
    • Penetrating sealer (silane) – Gem-Gard SL Plus
    • Polymer modified cement coating – Cem-Kote Barrier Coat 100
    • Polymer modified cement overlay – Gem-Crete HF ST (up to 6 mm)
    • Fibre-reinforced deck overlay – Gem-Crete HDO – 12 mm plus

The session deals with the repair and protection of reinforced concrete sub-structure of wharfs and piers as well as decks. It is divided into three parts: repair of marine sub-structure, protection and waterproofing (repaired and new sub-structures), and repair and protection of reinforced concrete decks. The description of products and their applications, including case histories, will be presented. The presentation covers only the use of Gemite products in these applications and is not intended to provide a comprehensive treatment of the “marine” structures repairs subject.

  1. 1
    Repair of concrete sub-structure

    Concrete restoration

    • Rust-proofing of exposed rebar – Fibre-Prime
    • Hand or spray applied, thin repair mortar up to 12 mm – Gem-Plast TC
    • Overhead, hand applied repair mortar – Fibre-Patch OV
    • Wet process shotcrete material for larger volume repairs – Spray-Con WS ST
    • Dry process shotcrete material for larger volume repairs – Spray-Con DS ST

     

    Concrete Protection and Waterproofing – repaired and new structures

    • Polymer modified cement – Cem-Kote ST
    • Crystalline waterproofing – Cem-Kote CW Plus
    • Flexible, polymer modified cement waterproofing – Cem-Kote Flex ST
  2. 2
    Deck repair
    • Migrating corrosion inhibitor – Gem-Gard MCI
    • Penetrating sealer (silane) – Gem-Gard SL Plus
    • Polymer modified cement overlay – Gem-Crete HF ST (up to 6 mm)
    • Fibre-reinforced deck overlay – Gem-Crete HDO – 12 mm plus
    • Concrete overlay modified with micro silica admixture – Adi-Con CSF R
    • Concrete overlay modified with crystalline waterproofing admixture – Adi-Con CW Plus

The following areas and products will be reviewed:

  1. 1
    Wall coatings and sealers
    • Water borne, highly flexible wall coatings and textured
    • Wall coatings – Tuff-Flex CA /Primer #300; Tuff-Coat SNR (short nap roller), FF (fine float), GF (grain float)
    • Water borne, wall sealer/coating, pigmented – Rain-Shield Stain OP WB – opaque waterborne; and clear – Rain-Shield SX WB (water borne) and SX VOC – VOC solvent borne
  2. 2
    Parking Garages
    • A thin overlay – 3-6 mm – Gem-Crete HF ST (high flow)
    • Flexible traffic membrane – Gem-Crete TWM Plus (traffic waterproofing membrane)
    • Clear traffic sealers – Gem-Gard SL WB (water borne) and Gem-Gard SL ST/Plus and pigmented – Gem-Coat WA Plus, water borne, Gem-Gard OP SB; and silicate sealers.
    • Negative side waterproofing – Cem-Kote CW Plus and Cem-Kote Flex ST
  3. 3
    Balconies
    • Rust-proofing of exposed rebar – Fibre-Prime
    • Overhead, vertical and horizontal repair mortar – Fibre-Patch OV
    • Castable, flowable repair mortar – Fibre-Patch RM
    • Waterproofing membrane – Gem-Crete TWM Plus (Cem-Kote Flex ST)
    • Colored sealer, water borne – Gem-Coat WB Plus
  4. 4
    Miscellaneous
    • Swimming pool waterproofing – Cem-Kote Flex ST/TC
    • Fuel and Water tanks– Fibre Pime
    •  Insulating roof coating, steel, concrete – Primer #300, Thermo-Coat Roof Coat (microsphere fillers)