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This paper presents the testing of the durability of concrete where a part of cement was replaced with ground panel cathode ray tube glass (CRT) finer than 63 µm. The percentage of cement replaced with glass is 5%, 10%, 15%, 20%, and 35%, by mass. The highest percent share of mineral admixtures in CEM II (Portland-composiste cement) cement was chosen as the top limit of replacement of cement with glass. In terms of the concrete durability, the following tests are performed: freeze-thaw resistance, freeze-thaw resistance with de-icing salts-scaling, resistance to wear according to the Böhme test, sulfate attack resistance, and resistance to penetration of water under pressure. A compressive strength test is performed, and shrinkage of concrete is monitored. In order to determine the microstructure of concrete, SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-ray Spectroscopy) analyses were performed. The obtained research results indicate that the replacement of a part of cement with finely ground CRT glass up to 15% by mass has a positive effect on the compressive strength of concrete in terms of its increase without compromising the durability of concrete. The results obtained by experimental testing unequivocally show that concrete mixtures made with partial replacement (up to 15%) of cement with finely ground CRT glass have the same freeze-thaw resistance, resistance to freeze/thaw with de-icing salt, resistance to wear by abrasion, and resistance to sulfate attack as the reference concrete. In terms of environmental protection, the use of CRT glass as a component for making concrete is also very significant. [ABSTRACT FROM AUTHOR]

This paper presents the application of a hybrid approach for damage localization in concrete plates of arbitrary geometric shapes and a constant thickness. The hybrid algorithm utilizes fast discrete wavelet transformation, energy approach and time of flight criteria for the purpose of the localization of single- and multi-damage problems inside or on the periphery of concrete plates. A brief theoretical background of the hybrid method as well as numerical procedures for modeling the piezoelectric smart aggregate and ultrasonic wave propagation are presented. Experimental and numerical verification of the damage localization were performed on square samples/models with one or two damages and with 16 positions of piezoelectric smart actuator/sensor aggregates. After the verification of the hybrid method, a numerical simulation was performed on models with one or two damages for plates of arbitrary geometric shapes. Based on the obtained results, it was concluded that the proposed method can be applied to damage localization in concrete plates of arbitrary geometric shapes. The presented method and numerical procedure can be further used in research through varying the geometry, number and position of damages as well as the number and position of piezoelectric smart aggregates. [ABSTRACT FROM AUTHOR]

One of the essential requirements in modern civil engineering is a sustainable building, with the aim of reducing the harmful impact on the environment. Since the early XXI century, usage of recycled materials has been insisted on, which could, at least partly, substitute traditionally used materials. Although there is no serial manufacturing of TV sets with cathode ray tubes anymore, piles of cathode ray tube glass (CRT) at the waste disposal sites have still been on the increase. This experimental research was supposed to determine the potential for using subtly milled CRT glass as a supplementary cementitious material and to check the resistance of similar concretes to the sulphate action. Six testing concrete batches were made. The percentage of cement replacement percentage with CRT was: 5%, 10%, 15%, 20% and 35%, by mass. Durability assessment of concrete to sulphate action was done by visual estimation of concrete appearance as well as through testing the compressive strength variations of treated concrete specimens 3, 6, 12 and 36 months old. After soaking the specimens in a 5% solution of Na2SO4 for 36 months, concretes with 15% to 20% of replaced cement with finely ground CRT glass have simultaneously satisfactory compressive strength and resistance to sulfate attack. In this sense, this range of replacement of cement with finely ground CRT glass can be recommended for practical application. [ABSTRACT FROM AUTHOR]

A timber-concrete composite system is increasing the use of timber in construction. Some structures cannot be built by timber alone, but this type of composite system makes it a possibility. The deterioration of structures in service is generally uncertain over time. The appropriate approach therefore for a structural analysis is a time-dependent reliability analysis which considers the randomness and uncertainties of the deterioration process over a specific time period. This paper describes two methods for time-dependent reliability analysis, a random variable deterioration rate model and a gamma process deterioration model. It also, compares the deterioration prediction as well as service life estimation of timber-concrete composite beams under normal use, based on proposed models. [ABSTRACT FROM AUTHOR]