Light Weight Deflectometer (LWD)

Quality Assurance & Quality Control of Earthwork Projects

Measure in-situ soil modulus to ensure soil compaction requirements are met project-wide on subgrade, subbase and roadbase. Designed and engineered at Olson Instruments' corporate office in Colorado, USA, this light weight deflectometer conforms to ASTM standard E2835-11 for plate deflection measurement due to an impulse load and is used with your user-supplied tablet. Importantly, the Light Weight Deflectometer LWD-1 measures the actual impulse force in order to calculate stiffness (peak force ÷ peak displacement) and modulus based on soil type (granular, clay, or mixed).

Olson's LWD-LAB option is a compact unit with a lighter weight to match loading pressure and impulse duration time in Proctor molds to in situ field testing for determination of the target soil modulus. Using LWD provided modulus and moisture content from field samples, our LWD plots ensure the lab Target elastic modulus has been achieved. A recently funded study by the Maryland Department of Transportation indicated that the LWD modulus-based compaction QA approach can replace conventional Nuclear Density Gauge testing of roadbase and subgrade compaction.

Features & Benefits

Embedded load cell measures actual impact force Calibrated geophone receiver measures plate deflection
Simple design embeds spring assembly inside falling weight Add-On Impact Weights available (5kg and 10kg)
Multiple plate diameters available (300, 200, 150 and 100 mm (~ 12, 8, 6 and 4 inch) Two additional external geophones can be added to the system for deflection basin or Spectral Analysis of Surface Waves (SASW) layer moduli determination
Durable stainless steel design/construction Transport Cart (included)
Quick and easy onsite testing; can be performed with little or no special certification with immediate results displayed in either english or metric units Portable and lightweight - single person operation


27 kg (60 lb) total unit weight 1.25 m (50 in) total unit height
600 mm (2 ft) drop height 6.9 kN (1,550 lb) impulse loading
15 - 20 millisecond impulse duration 10 kg (22 lb) impact weight

Hands-on training is available for all of our NDE test methods at our Wheat Ridge, Colorado (USA) location, which is a suburb located approximately 15 minutes northwest of downtown Denver. Training may be available at your location by one of our agents/engineers upon special arrangement.

Save money! Contact Olson when adding on to an existing system, or purchasing multiple systems as some of the components are common.

For complete details about any of our products, call our toll free number at 1-888-423-1214 or email Olson Instruments: