ThermoCrete: Smart Sensor System for Concrete Strength Prediction through Curing Temperature

Abstract

This paper presents ThermoCrete, a low-cost embedded smart sensor system for real-time prediction of concrete compressive strength through continuous curing-temperature monitoring. The system integrates a DS18B20 waterproof digital temperature sensor embedded in fresh concrete, an ESP32 microcontroller for data acquisition and maturity computation using the Nurse-Saul method, EEPROM/SD card for 28-day non-volatile data logging, and Bluetooth for wireless retrieval. A custom-designed PCB featuring an LM2596 buck converter and AMS1117-3.3 regulator ensures robust power management. Experimental validation on M25 grade concrete specimens (150×150×150 mm cubes, per IS 516) showed a strong logarithmic correlation (R² = 0.92) between the computed maturity index and actual compressive strength from standard cube crushing tests. The mean absolute error (MAE) remained below 8% across all tested ages (3, 7, 14, 28 days), confirming ThermoCrete as a reliable, non-destructive, and cost-effective alternative to conventional strength assessment.