Magdaléna Šefflová

The Properties of Fine-Aggregate Concrete with Recycled Cement Powder

The main aim of this contribution is verification of properties of concrete with partial replacement of cement by recycled cement powder originating from waste concrete. The main topic of this article is the study of influence of partial replacement of cement by recycled cement powder (RCP) to the cement paste properties, workability of fresh concrete and strength development and dynamic modulus of elasticity of fine aggregate concrete with partial replacement of cement. The workability of fresh concrete were tested by flow table test. The compressive strength, tensile strength in bending and dynamic modulus of elasticity were tested at the age 7, 14, 28 and 90 days. Partial replacement of cement was 0, 5, 10 and 15 % for all these tests. Mechanical properties were investigated by using cubic and prismatic specimens. The determination of the initial setting time of cement paste were measured by automatic Vicat apparatus for replacement rate of cement 0, 5, 10, 15 and 25 %.

Behavior of Concrete Containing of Fine Recycled Aggregate

The use of coarse recycled aggregate in concrete is already accepted in the Czech Republic but with specific restrictions. The problem is the use of fine recycled aggregate (FRA) in concrete. This paper is focused on behavior of concrete containing FRA. FRA, which originated from recycling plant in the Czech Republic, was used in an experimental part. FRA was obtained from demolished and crushed concrete structures. Four concrete mixtures were designed and prepared. The first concrete mixture was reference which did not include FRA. Natural sand was replaced by FRA in other concrete mixtures in varying ratio. There were tested physical, mechanical and deformation properties of concrete. According to test results it is possible to say that the use FRA as partial replacement of natural sand in concrete mixtures.

Study Replacement of Cement with Recycled Cement Powder and the Environmental Assessment

This investigation is focused on possibility of partial cement replacement in concrete mixture and its environmental assessment. The cement in concrete mixture is replaced by recycled cement powder from modified construction and demolition (C&D) waste. Recycled cement powder were prepared in laboratory from C&D waste of high quality road concrete. The main goal of this investigation is optimize amount of recycled cement powder used as partial replacement of cement in concrete mixture according to mechanical, deformation and physical properties of concrete and environmental impact. The properties of the fine-aggregate concrete with partial replacement of cement by recycled cement powder were tested for this verification. The life cycle analysis was calculated for this optimization. The properties and environmental assessment of the fine-aggregate concrete with partial replacement of fine aggregate by fine recycled aggregate were examined for comparison.

Non-Destructive Testing of Concrete with Fine Recycled Aggregate

This paper is focused on non-destructive testing of concrete containing fine recycled aggregate (FRA). FRA was obtained from demolished concrete structures and crushed in the laboratory on fraction 0 – 4 mm. There were prepared four concrete mixtures. The first concrete mixture was control, did not include FRA. In other mixtures was natural replaced natural sand by FRA. There were tested workability of fresh concrete mixture and physical properties of hardened concrete. Finally, it is possible to say that the use of FRA influences the physical properties of concrete. The physical properties of concrete are connected with the durability of concrete. Therefore, it is necessary to focus on durability testing of FRA concrete in further research.

The Comparison of Different Recycled Aggregate Types Properties

This paper is focused on properties of recycled aggregate. Three types of recycled aggregate were used for experiment (designation REC A, REC B and REC C) and for comparison natural aggregate (designation NA). The geometrical and physical properties of recycled aggregate were tested. The test results were comparison with natural aggregate. The results confirmed that the quality of the recycled aggregate depends on kind of demolishing process and subsequent recycling process in the recycling plant.

The Behavior of FRA Concrete with High Replacement Ratio

This study deals with determination of the properties of the fine recycled aggregate (FRA) concrete with partial replacement of natural sand in concrete mixtures. The FRA was obtained from concrete waste and crushed on fraction 0 – 4 mm by laboratory jaw crusher. The geometrical and physical properties of natural sand and the FRA were tested. The main goal of this study is evaluation of the basic physical and mechanical properties of the concrete with partial natural sand replacement by the FRA such as workability, water absorption capacity, compressive strength and flexural strength. A total four concrete mixtures were prepared. The first concrete mixture was prepared only with natural sand, did not include the FRA. In other concrete mixtures, natural sand was replaced by the FRA in various replacement ratios (40 %, 50 %, and 60 %). All concrete mixtures were designated with the same parameters for clear comparison. The workability of fresh concrete mixtures and physical and mechanical properties of hardened concrete were tested.

The Carbonation Depth of Fine Recycled Aggregate Concrete

This paper is focused on carbonation resistance of fine recycled aggregate (FRA) concrete. Durability of FRA concrete is connected with uncertainties and doubts. One of the most unknown aspects of FRA cocnrete is carbonation resistance. This paper presents results of carbonation depth of FRA concrete. The FRA was originated from crushed construction and demolition (C&D) waste. There were prepared a total four concrete mixture. The first mixture was reference, did not include the FRA. In other concrete mixtures, natural sand was replaced by the FRA in various replacement ratios, specifically 10%, 20% and 30%. All prepared concrete mixtures were designated with the same parameters for clear comparison. From the test results it is possible to say that the use of the FRA as partial replacement of natural sand in concrete influences carbonation resistance of concrete. The carbonation depth was higher for concrete samples with the use of FRA. However it is possible to say that according to the carbonation resistance, the FRA concrete is possible to be used in the same applications as conventional concrete but it is necessary to verify this results.

Carbonation Resistance of Fine Aggregate Concrete with Partial Replacement of Cement

The main aim of this contribution is verification of durability properties of concrete with partial replacement of cement by recycled cement powder (RCP) sourced from pure waste concrete. The main topic of this article is the study of influence of partial replacement of cement by RCP to the carbonation resistance of fine aggregate concrete with partial replacement of cement. The compressive strength, tensile strength in bending and depth of carbonation were tested after 56 days of CO2 curing. Partial replacement of cement was 0, 5, 10 and 15 % for all these tests. The properties were investigated by using prismatic specimens.

Non Destructive Testing of Concrete with Recycled Cement Powder

This study deals with determination of the physical properties of fine-aggregate concrete with partial replacement of cement in concrete mixture. Cement was replaced by recycled cement powder originating from construction and demolition waste. The main goal of this study is evaluation of the basic physical properties of the fine-aggregate concrete with partial cement replacement by recycled concrete powder such as density, water absorption capacity and capillary water absorption. The fine recycled concrete which was used as partial replacement of cement had the same grain size as cement. The replacement rate was 0 %, 5 %, 10 % and 15 %. Physical properties were investigated by using cubic and prismatic specimens.

Study of the Mechanical Properties Development of Concrete Containing Fine Recycled Aggregate

This paper is focused on the mechanical properties development of fine recycled aggregate (FRA) concrete. FRA was obtained from recycling plant in the Czech Republic. There were prepared four concrete mixtures in the laboratory. The first mixture was reference (REF) with fine natural aggregate (FNA). FNA was replaced in concrete mixtures R10, R20 and R30 in varying replacement ratio. The concrete mixtures R10, R20 and R30 contained 10 %, 20 % and 30 % FRA. There were tested properties of concrete. Finally, it is possible to say that the use of the FRA in concrete influences concrete properties. It is necessary to verify of probably an improvement of compressive strength of FRA concrete in future research. However, FRA concrete is possible to be used in the manufacturing of building structures, but it is necessary to test durability and lifespan of FRA concrete.