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MAKING CONCRETE FROM OYSTER SHELLS AS AGGREGATE REPLACING CEMENT - Coggle…

- - - - https://www.rilem.net/images/publis/119303.pdf
  - - - sensitive to aggregate and mixture proportions of concrete
    - - https://theconstructor.org/concrete/determination-modulus-elasticity-concrete/2119/#Setting_Up_Compressometer
  - - - Bazant-Baweja B3 model
        
        http://www.civil.northwestern.edu/people/bazant/PDFs/Papers/S39.pdf
        
        Age of concrete when drying starts, usually taken as the age at the end of moist curing;
        
        Age of concrete at loading;
        
        Aggregate content in concrete;
        
        Cement content in concrete;
        
        Cement type;
        
        Concrete mean compressive strength at 28 days; Curing method;
        
        Relative humidity
        
        Shape of specimen
        
        Volume-surface ratio
        
        Water content in concrete
      - GL2000 model
        
        https://www.researchgate.net/figure/GL2000-model-compliance-function-Jt-t-0_fig2_265079277
        
        Age of concrete when drying starts, usually taken as the age at the end of moist curing
        
        Age of concrete at loading
        
        Relative humidity expressed as a decimal
        
        Cement type
        
        Concrete mean compressive strength at 28 days
        
        Volume-surface ratio
    - - For initial curing, ASTM C31/C 31M-08a specifies that the specimens need to be stored up to 48 hours in a temperature range from 20 to 26C
      - After moulding, each of the concrete filled moulds were covered immediately by individual plastic bags and tied with rubber bands to prevent moisture loss
      - Then, specimens were moved immediately to a place where they received initial curing and direct sunlight was avoided
      - Wet burlap was placed on all of them to avoid drying and evaporation without getting in contact with the concretes
      - These specimens were left for a day at the place to gain initial process of hardening, temperature measured every 5 hours
      - the specimens should be moist cured in a moist room or moist cabinet. Measure temperature and humidity
  - - - The effective length of the sample being measured is the distance between the two inner electrodes.
      - Modern voltage meters draw very little current so there is no significant current through the voltage electrodes and hence no voltage drop across the contact resistances
      - voltage is measured between the two inner electrodes
      - two end electrodes are used to inject current
      - applying a current using two electrodes attached to the ends of a uniform cross-section specimen
    - - generator produced an alternating current at a frequency of1,000 Hz
      - When an input voltage was applied to the primary coil,a toroidal voltage Vwas generated in the ring concrete samplethat acted as the secondary coil of the transformer
      - noncontacting electrical resistivity apparatus
      - toroidal current could be measured by a leakage current meter
      - resistivity of the concrete was calculated through V and I based on Ohm’s law
      - https://www.mdpi.com/2076-3417/10/24/9152/htm
- - - - the crushed seashells as replacement for coarse aggregate is more suitable to produce lightweight and low strength concrete, due to excessive flakiness
- - - - elastic modulus of oyster shell concrete decreases with an increase of oyster shell thickness
        
        increase in the amount of substitution has a negative impact on the compressive and flexural strengths
        
        when the content of oyster shell sand reached 20 percent replacement of natural sand in cementitious mortar, the compressive strength of cementitious mortar does not decrease significantly
      - The surface of oyster shell sand is relatively irregular, which means that particle friction is prone to affect the fluidity of cementitious mortar and reduce its working performance during the mixing process