Infrared Thermometer Luke M. Snell Concrete Industry Management Del E. Webb School of Construction Arizona State University Tempe Arizona

Traditional Approx of Temperature  Steel Temperature:. Dull Red Color- 550 C. Yellow Hot Color C. White Hot Color C

Emissivity Theory Used for Infrared Thermometer Infra-red

How IR Thermometer Works  Emitted Energy indicates the temperature of the object.  When IR thermometer senses the energy and converts to temperature

Product Description  Temperature range : -18 to 275 C  Accuracy: ± 2%, or ± 2°C whichever is greater  Response time: 500mSec  Ambient operating range: 0 to 50 C  Power: 9V alkaline or NiCd Battery included  Temperature display: C or F, selectable

Limitations  Measures only surface temperature,not the internal temperature  Can not shoot through windows  Laser Warning- need to be careful  Obstruction – smoke and dust particles

Application in Concrete Construction IR thermometer can: IR thermometer can:  Measure forms and reinforcement temperatures prior to placement (Less than 50 C)  Estimate concrete temperatures during placement (4 to 30 C).

Application in Concrete Construction IR Thermometer can:  Measure temperature of soil/base ( must be above freezing)  Monitor curing environment for first 7 days (should be maintained above 4C)

Temperature control Temperature control

Temperature control using IT  Materials and Mixture temperatures  Placement temperature  Temperatures maintained during curing

Temperature (C) Curing temperatures graph (C) Disco nnected time Time (hour)

T= 0.22 (TaMa + TcMc) + TwMw 0.22 (Ma + Mc) = Mw T = temperature of concrete, C Ta,Tc,Tw = temperature of aggregate, cement, water, C cement, water, C Ma,Mc,Mw = Mass (weight) of material in mixture, kg

EXAMPLE: Mixture, kg per cubic meter Mixture, kg per cubic meter Aggregates, C Aggregates, C Cement, C Cement, C Water, C Water, C Temperature of Concrete = 31.8C Need to chill water to 17C if concrete temperature is required to be less than 30C

Using IR in Mongolia  Water heated to 56 C  Fine aggregates - 18 C  Coarse aggregates - 19 C  Bags of cement - 19 C  Calculated temperature 4 C  IR temperature 1C

Where do you measure temperature with IR? Research project – measure concrete at :  Forms, wheel barrows or buggies  Revolving drum  Chute

Chutes provide accurate temperatures

Conclusion  IR thermometer can be used by the contractor to monitor the temperature of the concrete.  IR thermometers to determine if adequate curing of the concrete is achieved in hot /cold weather construction.