The infrastructure plays a vital role in stimulating economic growth. Any infra project requires proper planning, design, construction, quality control (QC), and quality assessment (QA). It is important to comply with QC and QA to avoid failure and enhance the long-term pavement performance in order to provide a safe and solid system of transportation. Researchers were replacing laborious and time-consuming density-based methods (sand cone and/or core cutter) with advanced stiffness or modulus-based NDT devices for the QC of compacted geomaterials. The lightweight deflectometer (LWD) is such a highly advanced and sophisticated device that was developed to evaluate the deformation modulus (ELWD) of compacted geomaterials as an alternative of density test. This device is portable, light-weight, user-friendly, and it is ideally suitable for all constructional  geomaterials. This study is intended to provide a state-of-the-art on the LWD device as well as presented the ranges of deformation modulus for various geomaterials from several studies. For instance, in the case of soils, aggregates, and asphalt materials deformation modulus values were found to be in the range of 35–60 MPa, 80–120 MPa, and 120–170 MPa respectively. In addition, several studies have been compiled to completely comprehend the relationship between LWD and various devices.

Geogrid-stabilised soil has been widely adopted to enhance performance in transportation and infrastructure sectors. In a study, the performance of unstabilised and triaxial-geogrid-stabilised sandy soils in terms of dynamic deformation modulus and elastic modulus was measured using lightweight deflectometer test and plate load tests respectively. The objective of the study was to evaluate: (a) determination of dynamic deformation modulus of sandy soils with different relative compactions from deflectometer testing and compare with the elastic modulus of sandy soils from plate load tests for a given relative compaction of 97%; (b) determination of modulus improvement factors of triaxial-geogrid-stabilised sandy soils through extensive laboratory testing; and (c) demonstration of compaction quality control of well-graded gravel using deflectometer testing through a field study. The triaxial-geogrid-stabilised sandy soil layer showed modulus improvement factors of 1.51 and 1.37 obtained from deflectometer and plate tests corresponding to an embedded depth of 50 mm respectively. The percentage differences in these values are in the range of 4% to 9% for all the embedded depths. Hence a lightweight deflectometer can be used instead of a plate load test as a quick and low-cost alternative for determining the modulus improvement factor of geogrid-stabilised sand soil, both in the laboratory and in the field.