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Wireless Concrete Sensors

A guide to wireless concrete sensors: radio types, single-use vs reusable, range and battery trade-offs, and how to pick the right sensor for precast, mass concrete, bridges, and field work.

Why Wireless Beat Wired

For decades, concrete temperature monitoring meant thermocouples on a long cable running back to a wired data logger. The setup worked but it was a wire-management problem on every pour: routing cables out of formwork, protecting them during placement, replacing them when crews cut them by accident. Field work and precast plants both wanted something simpler.

Wireless concrete sensors solve the cable problem. The sensor lives entirely inside the pour. It transmits over radio to a nearby phone or to a gateway on the plant network. The QC manager sees the data on a phone or laptop — without wires, without data loggers, without a tech truck for every pour.

Radio Choices: Bluetooth vs Sub-GHz vs Wi-Fi

Bluetooth Low Energy (BLE)

BLE is the radio in your phone, your earbuds, and most single-use concrete sensors. Practical range through air is 25–50 feet. Through concrete and rebar, range drops sharply — often to a few feet. BLE is excellent for short-duration slab work where the crew is on the slab; less so for buried sensors expected to transmit for weeks.

Sub-GHz (900 MHz, LoRa, etc.)

Sub-gigahertz radios penetrate concrete and rebar much better than 2.4 GHz Bluetooth. They reach a mile or more line-of-sight to a gateway. Sub-GHz sensors continue transmitting after the pour is buried, support multi-week cures, and work across a busy plant where the QC manager is in the office and the bed is 200 feet away. Sensytec's SensyCast uses sub-GHz radio for this reason.

Wi-Fi (2.4/5 GHz)

Wi-Fi has higher bandwidth but worse penetration through concrete and significantly worse battery efficiency. It's used in some bridge-deck and infrastructure sensor systems where a gateway can sit very close to the pour and battery isn't a hard constraint.

Single-Use vs Reusable

The most consequential decision is whether the sensor is single-use (entombed) or reusable (recovered after the pour).

  Single-use Reusable
Per-unit costLowerHigher
Cost per pour at 200+ poursHighVery low
Battery lifeWeeks3+ years (rechargeable)
InstallTie, pour, walk awayTie at retrievable location
Best forSlab on grade, tilt-up, <50 pours/yearPrecast plants, mass pours, >200 pours/year

Battery Life and Duty Cycle

Battery life depends on the radio, the transmission interval, and the sensing rate. A sensor that reads temperature once per minute and transmits once per hour can run for years on a small lithium cell. A sensor that reads and transmits every 30 seconds will burn through the battery in weeks. Reusable sensors with rechargeable batteries are sized for 3-year service life across hundreds of pours, recharging between cycles.

What to Measure: One Signal or Two

Most wireless concrete sensors measure temperature only. The maturity method computes strength from temperature, so temperature is the minimum viable signal.

A smaller category measures both temperature and electrical resistivity. Resistivity (per AASHTO T-358 surface and ASTM C1876 bulk methods) provides a second independent strength signal that is helpful when calibrations drift, and at later ages it correlates with chloride-ion penetration resistance — a key durability indicator. Sensytec's SensyCast is a two-signal wireless sensor.

Buying Criteria

  1. Pours per year. Below ~50: single-use. Above ~200: reusable. Between: depends on cost sensitivity.
  2. Where the QC manager is. On the slab: BLE works. In the office or off-site: sub-GHz with a gateway.
  3. Duration of monitoring. Hours: any radio. Weeks: rule out BLE for buried sensors.
  4. One signal or two. Temperature alone is the minimum. Resistivity gives a second strength check and a durability signal.
  5. Cloud platform. The sensor's strength flows from the cloud platform. Look at the dashboard, the alerts, the export formats, the audit trail. See SensyHub and the QC Module.
  6. Compliance. ASTM C1074 and AASHTO T-358 should be table stakes. Project specs may add ACI 318, AASHTO LRFD, DOT-specific requirements.

Sensytec's Wireless Sensors

  • SensyCast™ — reusable embedded sensor measuring temperature and electrical resistivity. Sub-GHz radio, 1-mile range, 3-year rechargeable battery. ASTM C1074, AASHTO T-358, ASTM C1876.
  • SensyRoc™ II — rugged portable wireless sensor with free iOS and Android app for mobile crews and field decisions.

Frequently Asked Questions

What is a wireless concrete sensor?

An embedded device that measures temperature (and sometimes resistivity) inside concrete and transmits the data over radio — no cable to a data logger.

Bluetooth vs sub-GHz?

Bluetooth: 25–50 ft through air, much less through concrete. Sub-GHz: 1+ mile to a gateway, transmits through concrete. Sub-GHz wins for buried sensors and large plants.

Battery life?

Single-use: weeks. Reusable rechargeable: 3+ years across hundreds of pours.

How accurate?

95–99% correlation with cylinder breaks via ASTM C1074 maturity method. Wireless link doesn't affect accuracy — the temperature sensor and calibration do.

Single-use vs reusable?

Single-use: simpler install, lower per-unit cost, entombed. Reusable: higher unit cost, much lower cost per pour at scale, recovered after each cure.

DOT acceptance?

Yes. State DOTs accept ASTM C1074 maturity-method data regardless of radio type. Wireless sensors gain an audit advantage from automatic cloud upload of the temperature record.

Reusable, long-range, two-signal.

SensyCast: temperature plus resistivity, sub-GHz radio, 1-mile range, 3-year rechargeable battery. ASTM C1074, AASHTO T-358, ASTM C1876.

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