Papers by Keyword: Concrete Surface

Abstract: The need of returning millions of tons of previously used materials to the production process is already a globally addressed fact. This also applies to building construction, where the construction materials can also be used repeatedly. The use of recycled materials is a crucial tool for sustainable development and reaching a compromise between economic progress and the preservation of the environment. Notable improvement has been recorded in the use of recycled material on road communication. There, the optimal solution is to use the „old surface“ to create a new one – this is advantageous for roads with concrete surfaces, as well as for the ones with bituminous surfaces. Though the effort is to use 100% of the recycled material, there are many cases where it is only possible to use a certain portion of the materials, depending on the type of processing. The remaining volume of milled material is either used to strengthen the subsoil of roads or for service roads. Recycled concrete is suitable as a low-cost alternative of gravel on less stressed structures and places, or as a replacement for quarry stone. The processes of using recycled concrete are actively being studied and improved on in laboratories. However, the portion of recycled concrete affects the consistency of the concrete mix and in order to maintain the required consistency, it is necessary to increase the dosage of mixed-in water, which results in reduced concrete strength. The use of recycled concrete must be assessed for each case according to the grading curve and with the impact on the values of load-bearing capacity, water absorption and frost susceptibility. The economic assessment must also be addressed, with an emphasis on traffic requirements and impact on the environment. The first important step is to offer the investor, architect or supplier a decision-making model which allows one to evaluate the usability of the recycled material, including the consideration of possible risks.

Abstract: Concrete pavements and airfields in the curing process of protection against desiccation, particularly, the application of the wax-polymer emulsion which forms a solid film, which persists for a long time in the initial period of operation of roads and airfields. The presence of the film changes the nature of the friction on the surface that could adversely affect traffic and aircraft. This paper investigates the friction of rubber on the surface of the treated concrete with an aqueous emulsion of paraffin series Emcoril. It was established that the friction on the paraffin film, unlike friction on the surface of the concrete does not respect the law of linear Coulomb. The degree of deviation from linearity, the higher the greater the thickness of the film. The frictional force on the film increases with the slip velocity. At high speed, friction in the film is greater than the frictional force on the concrete, and at low speed is much lower than the previous one

Abstract: This study was aimed to evaluate the protection effectiveness of various concrete surface treating materials. Four types of surface treating materials and six parameters were selected. Compressive strength test, absorption test and permeability test were performed. Taguchi method was adopted to identify the key factors influencing the protection effectiveness provided by the surface treatment. L₁₆ (8¹Î2⁶) orthogonal array was chosen to reduce the number of experiments. The major sequentially influential factors are type of coating material, w/c ratio of concrete substrate and coating thickness.

Abstract: This article presents a method of work tool modelling for machines for surfacing concrete in the form of a disc which has variable geometric friction elements. The method, based on the effectiveness criterion of the elementary interaction surface friction describes the impact of the disc material.

Abstract: Pursuant to evaluations obtained at solving this topics in 2010, when was successfully supplied filler at acrylate coatings with grind cullet (waste glass), was chosen referential mixtures of silicate coatings with optimum quality. In Those choice mixtures was made a filler modification by various quantity of the cullet. Used cullet is from crushed glass bottle, that can’t be used for recyclation no more. Filler modification was provided so, to the new filler mixtures was approximate to ideal grading curve. The sieve analysis of original filler materials was made and after comparison of the results were proposed mixtures of new modified mixtures of filler. These then was further analysed and modified. The basic characteristic that was on modifying materials monitored belongs to cohesion with basis, consistence, vapour diffusion and smash strength. Considering absence of coatings surface quality classification Methodist in Czech prescriptions, was for the work needs created a personal methodology for classification coatings surface quality classification.

Abstract: This research is devoted to the decision of a problem of modeling the wear process of concrete. In paper presents a wear model of concrete as heterogeneous material on the basis of the theoretical and experimental contact mechanics methods approach. The model predicts that its abrasion strength depend on physical and geometrical characteristics of cement matrix and aggregate. The theoretical modeling of a surface with the strengthened ore softening areas is applied to optimization of concrete structures. The experimental results support these theoretical predictions.

Abstract: This paper demonstrates application of laser confocal scanning microscope system for fair-face concrete surface evaluation. Measure system presents a new generation optical system for identification and description of esthetical imperfections of various building materials. System enables 3D observation and high-precision 3D measurement in real time.

Abstract: Paper deal with influence of on service life and degradation processes at construction of bridge piers and abutments before and after repair actions. Monitored dependencies are then reflect on degradation curves each for a singles construction characteristics (compression strength of concrete, degradation of surface, volume of carbonatation etc.) Pursuant to long-term monitoring of records from bridge piers surface diagnostic we have to be able to unite the records and use them for silicate coatings degradation dependence on bridge piers and abutments and laboratory simulated degradation.

Abstract: The aim of this study is to investigate the influence of concrete surface preparation when either steel or carbon fiber reinforced polymers (FRP) are applied for strengthening applications of R/C members. The present study also investigates the anchorage or not of the applied FRP strips on the volume of concrete. For this purpose special concrete specimens were fabricated and were used to attach CFRP or SRP strips with or without anchoring and with or without contact surface treatment. The experimental results indicate that the concrete surface preparation is important and results in an increase of the load bearing capacity when the FRP strip is not anchored. When an anchoring device is employed, the concrete surface preparation is of no significance. With a properly designed anchoring device, a significant increase in the bearing capacity was observed and the failure was that of the fracture of the FRP strips for all such specimens. The highest FRP material exploitation was achieved in the specimen that utilises the patented anchoring device together with two layers of SRP strips. Debonding of the FRP strips, or failure of the anchoring device, results as was to be expected, in relatively unsatisfactory FRP material exploitation.

Abstract: Hardened concretes were studied by several spectroscopic techniques (FTIR, Raman and XPS) to determine the surface composition after demoulding and after coating. After demoulding, most of the paste was constituted of calcite but some areas were identified by µRaman as portlandite, ettringite, belite, alite and ferrite phases. The FTIR (in ATR mode) allowed detecting portlandite and C-S-H but it highlighted also organic residues from the demoulding oil. XPS allowed recording interesting atomic ratios to study the extreme surface and the presence of contamination. After post-treatments, the main organic units were determined by FTIR and XPS at the concrete’ surface. Raman was also interesting: no vibration modes of organic species were detected but mineral/hydrated phases were clearly characterized under a thick organic layer. Due to their own specificities, these complementary techniques allowed identifying the mineral/hydrated phases and organic residues/coating at the concrete surfaces.