Introduction. The article examines the testing method of monolithic slabs of bridges deck with permanent reinforced concrete formwork [1] using the method of optical-digital speckle-correlation of images [2]. Problem statement. A promising direction in cast-in-situ bridge construction is using of various types of permanent formwork during slab concreting. However, using of such formworks has not been studied much till today. Therefore, it is advisable to conduct a test of full-scale models of slabs. In domestic practice, mechanical devices, strain gauges, optical microscopes, etc. are used during laboratory studies and field tests of building structures to measure relative deformations and movements, as well as to visually observe the formation and development of cracks. All these devices require constant checking and maintenance and it is not always possible to do this. However, for the needs of laboratory tests with the method of optical-digital speckle correlation of images, a digital image of the object at different load levels is mostly sufficient. It is only necessary to choose the right optics according to the experimental area and ensure sufficient lighting. Purpose. The purpose of the work was in experimentally determining of the expediency of using the optical-digital speckle-correlation method of images in the models testing. Metods of study. According to the results of exploratory researches, it is proposed to apply the method of optical-digital speckle correlation of images. Results. The expediency of using the method of optical-digital speckle-correlation of images in the investigation of bridges deck models has been established. Conclusions. Using the method of optical-digital speckle-correlation of images makes possible to investigate the change of relative deformations and the movement of individual points or areas during the study of concrete surfaces. This, in turn, allows to investigate the places and nature of the formation of cracks and enables practical use - during the examination of existing structures, it is possible to record the places of future cracks and the relative deformations of individual areas.

Shortening the terms of objects construction is one of the most important economic tasks in modern conditions. But it is worth considering the fact that fully prefabricated structures have a number of disadvantages that affect the further operation of the transport facility. Among them are problems related to the impossibility of ensuring reliable waterproofing of the prefabricated elements joints and as the result corrosion of concrete and reinforcement. Taking into account the experience of using prefabricated structures, domestic engineers, as well as foreign colleagues, came to the conclusion that monolithic and prefabricated-monolithic structures provide greater durability of the structure in general. That is why the use of prefabricated monolithic span structures in the construction of transport facilities has become widespread. The use of permanent formwork during the installation of a monolithic deck slab is a promising trend in modern bridge construction. This is especially relevant in the construction of overpasses and flyovers in dense urban areas, where the use of inventory scaffolding for slab concreting is impossible or significantly complicates existing traffic. Although permanent formwork has been used for many years, its work as а part of the structure has not been studied much. It is possible to cite many examples of use of permanent formwork both abroad and in domestic practice. Crack resistance is a pressing issue both individually of permanent formwork tiles and of the prefabricated monolithic in general. The article deals with formwork in the form of flat reinforced concrete slabs with pre-tension reinforcement. The production of such plates is quite economical, despite the use of prestressing, especially by the extrusion method, with subsequent cutting into segments of any shape and length. Study of the experience of using permanent formwork in different countries was the first stage of the research. In order to understand the expediency of using permanent formwork slabs, it is proposed to test samples of such slabs to determine their efficiency and suitability for further operation. The tests were carried out on a power bench with two concentrated forces using the "pure bending" method. The test results for such plates are also given in the article.