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DEF diagnoses

. DEF diagnoses. Four main features:Presence of gaps completely encircling aggregatesWider gaps around large aggregate than around small aggregateAbsence of external sulphate sourceHigh temperature heat curing history . . Gaps around aggregate in field concrete. Railroad sleeper. Fluorescent light. .

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DEF diagnoses

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    3. DEF diagnoses Four main features: Presence of gaps completely encircling aggregates Wider gaps around large aggregate than around small aggregate Absence of external sulphate source High temperature heat curing history

    4. External Sulphate Attack The microscopic appearance is variable. Features near the attacked surface: Surface parallel cracks Presence of gypsum and ettringite Depletion of calcium hydroxide Decalcification of C-S-H Causes the paste to expand and gaps around aggregates are formed. The features present depend on many factors such as the quality of the concrete, exposure time, temperature, concentration, and chemistry of the water. develops mineralogical and chemical zoning which can be studied in the optical fluorescence microscope and the scanning electron microscope

    5. External Sulphate Attack The microscopic appearance is variable. Features near the attacked surface: Surface parallel cracks Presence of gypsum and ettringite Depletion of calcium hydroxide Decalcification of C-S-H Causes the paste to expand and gaps around aggregates are formed. The features present depend on many factors such as the quality of the concrete, exposure time, temperature, concentration, and chemistry of the water. develops mineralogical and chemical zoning which can be studied in the optical fluorescence microscope and the scanning electron microscope

    6. Acid Attack Diagnosis Two main features Absence of calcium hydroxide in the cement paste Surface dissolution of cement paste exposing aggregates

    7. ASR Diagnosis four main features Presence of alkali silica reactive aggregates Crack pattern Presence of alkali silica gel in cracks and/or voids Ca(OH)2 depleted paste

    8. Porosity differences at surface of concrete viewed in fluorescent light mode.

    9. Chemical Attack Chemicals in many plants attack the concrete pastes and can lead to expansive forces or softening of the concrete The degree of attack depends on Type of chemical Concentration of the chemical Frequency of exposure Concrete porosity Type of cement used

    10. Concrete Consultancy Services Concrete Testing Concrete, Aggregates, Cement, SCM’s, Concrete Products

    11. Conclusion Proper planning essential Training & standards required for all tests; even VI Accurate recording of data vital Different professions require different Equipment Engineering Consultants Crack magnifier, Cover meter (with scancar), Digi Schmidt Professional Deteriologist Above + Ph indicator, Potentials, Resistivity, Pull off Tester, Porosimeter, Corrosion Monitoring, Impact Echo Contractors Crack magnifier, intelli-Rock Maturity Kit Premix Engineer Digi Schmidt, intelli-Rock Maturity Kit Precaster intelli-Rock Maturity Kit, Digi-Schmidt, Tico Ultrasonic,

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