Radar Moisture Meters for Concrete Mixers SONO MIX

The SONO MIX is a heavy-duty inline radar moisture sensor specifically developed for accurate, real-time measurement of moisture, electrical conductivity (cement content indicator) and temperature in fresh concrete directly inside all common types of concrete mixers (pan mixers, planetary mixers, twin-shaft mixers, ring-trough mixers, etc.). It features a replaceable wear-resistant probe head made of stainless steel with a tungsten carbide plate and a special ceramic radar window. Two designs are available: round sensor (medium carbide) and rectangular sensor (standard). The sensor is also suitable for disk mixers, intensive mixers, counter-current mixers, ribbon mixers, conveyor belts and screw conveyors.

Principle of Operation

SONO MIX uses patented TRIME®-TDR technology (Time Domain Reflectometry) at 1 GHz radar frequency. A high-frequency TDR pulse travels along the waveguides, generating an electromagnetic field that penetrates the surrounding fresh concrete. The propagation time (1-picosecond resolution) directly correlates with the dielectric constant, which is dominated by water content. The internal processor performs up to 10,000 measurements per second, validates, filters and averages them (cycle ~280 ms). Conductivity (EC-TRIME / RbC) is measured simultaneously to determine cement concentration. Six operating modes are available: CA (cyclic averaging), CF (floating averaging for inhomogeneous flows), CS (sequential), CC (cumulative for batch processes), CH (hold), CK (Kalman filter). Automatic wear compensation, temperature compensation (default TempComp = 0.2) and gap/metal scraper filtering ensure stable readings even in harsh mixer environments.

Specifications

• Moisture range: 0 % to saturation (up to 90 % with special calibration); typical 0–20 % or 0–30 %

• Accuracy: ±0.05 % (single measurement in precision mode); ±0.1 % in CA/CF/CH/CC/CK modes

• Conductivity (EC-TRIME/RbC): 0–50 dS/m (decreases above ~50 % moisture)

• Temperature range: 0 … +70 °C (material & environment); special versions up to 120 °C

• Power supply: +12 … +24 V DC; ~3 W total (~1.5 W electronics)

• Analogue outputs: 2 × 0/4–20 mA (Output 1: moisture, adjustable range e.g. 0–20 %; Output 2: conductivity, temperature or standard deviation; optional split 4–11 mA temperature / 12–20 mA conductivity, 5 s cycle); max. load 500 Ω; optional 0–10 V via 500 Ω resistor

• Digital interfaces: RS485 or IMP-Bus (galvanically isolated current loop)

• Dimensions: Standard Ø108 × 132 mm; Compact Ø108 × 71 mm (without plug)

• Weight: 3.70 kg

• Protection class: IP67

• Special features: Automatic wear detection & compensation (LED: continuous = OK; 1 s flash ≈75 % wear; 0.3 s flash ≈90 % wear); up to 15 calibration curves (Cal1–Cal15, linear/non-linear up to 5th order); universal Cal9 MIX curve for sand/gravel; air/water balancing; gap & scraper filtering; measurement field 50–80 mm depth

Main Application Areas

• Real-time moisture & cement content monitoring in all types of concrete mixers

• Automatic water and cement dosing in ready-mix and precast concrete plants

• Quality control of fresh concrete directly in the mixing process

• Integration into PLC systems for fully automated batch optimisation

• Conveyor belts, screw conveyors and intensive mixers for continuous flow monitoring

Advantages of SONO MIX Radar Moisture Meters

• Extremely high accuracy (±0.05–0.1 %) and repeatability even in abrasive, inhomogeneous fresh concrete

• Automatic wear compensation and long probe head lifetime (replaceable head)

• Simultaneous moisture + conductivity measurement → precise cement content control

• Superior to capacitive sensors – completely insensitive to material density, colour, salinity and metallic scrapers

• Six intelligent averaging modes for stable readings in any mixer type

• Robust IP67 stainless-steel construction, proven in thousands of concrete plants worldwide

• Simple air/water calibration, up to 15 material-specific curves

• Easy integration via 4–20 mA and IMP-Bus into existing plant control systems

• Significant reduction of water/cement errors → higher concrete quality and lower costs