The article analyses the effect of finely crushed glass on the properties of hardened cement paste. Materials used for the test: Portland cement CEM I 42.5 R, finely crushed glass (particle size ≤75 µm), and water. Seven compositions of cement paste mixes with different amounts of crushed glass (0%, 5%, 10%, 15%, 20%, 25%, 30%) added by weight of cement were designed. Compressive strength, density and ultrasonic pulse velocity of modified hardened cement paste with different content of crushed glass were measured in the tests. The test results revealed the increase of density, ultrasonic pulse velocity and compressive strength in specimens of hardened cement paste containing 5% and higher percentage of crushed glass after 7, 28 and 56 days of hardening. Microstructure tests revealed that crushed glass had an effect on the microstructure of hardened cement paste after 7 days of curing. X-ray analysis revealed the effect of crushed glass on the physical composition of hardened cement paste hydration products. Hardened cement paste containing 5% of crushed glass by weight of cement was found to have higher strength and density compared to unmodified cement paste.

Concrete mix made of cement CEM I 42.5 R, silica fume, fine aggregate sand of 0/4 fraction and superplasticizer was tested. Five batches of specimens were made with different silica fume content, where up to 10 % of the binding material was replaced with silica fume. Compressive strength, water absorption, density and resistance to alkali silica reaction were tested in concretes modified with different amounts of silica fume addition. The effect of silica fume addition on the expansion of modified concrete conditioned in 1M NaOH solution for 56 days was tested. Concrete modified with silica fume at 10 % by weight of cement was found to be the most appropriate for structures exposed to alkaline environment. The control specimen without mineral addition had the expansion of 0.113 %, which exceeds the limit value by 0.1 %, whereas the expansion of specimens modified with 2.5 % of silica fume was equal to the limit value, i.e. 0.1 %. The expansion values reduced in specimens modified with 5 % and 7.5 % of mineral addition. After 56 days of testing, the expansion values of these specimens were 0.093 % and 0.082 % respectively. The lowest expansion value was obtained in specimens with the highest content of silica fume, i.e. 10 %. The expansion of these specimens was 0.07 % after 56 days of conditioning in 1M NaOH solution of 80 °C temperature. The tests revealed that concrete modified with silica fume replacing 10 % of cement had better resistance to alkali silica reaction and better durability characteristics and thus can be used as structural concrete.

An assessment of parts of transportation infrastructure in terms of hazards to roadside territory is considered. It is suggested to assess individual segments of road and railway network by estimating risks posed by potential fires and explosions on road and rail. Boiling liquid expanding vapour explosion of tanker trucks and tank cars is identified as the most hazardous and likely high consequence accident in the land transport. It is proposed to express the risk to built roadside objects by means of an annual damage frequency. This frequency is considered to be a specific physical characteristic of the road or railway segment under analysis. It is shown that estimating the damage frequency requires assessing effects of a potential explosion on road or rail and developing a fragility function for the roadside object ana­lysed as a potential target. An example case study is presented. It considers a potential thermal damage to a reservoir (stationary tank) built in the vicinity of a highway. The damage can be caused by an explosion of a propane tanker truck. Results of the risk assessment are expressed in terms of probabilities of specific damage events.