Elevated Temperature Performance of Reactive Powder Concrete Containing Recycled Fine Aggregates (original) (raw)
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Concrete is a building material commonly used for ages. Therefore, in the result of repairs or demolition of building structures, large amounts of concrete rubble are created, which requires appropriate management. The aim of the realized research was to determine the influence of heat and mechanical treatment of concrete rubble on the properties of recycled aggregate concrete. The research experiment included 12 series, with three variables: X 1-roasting temperature (300, 600, 900 • C), X 2-time of mechanical treatment (5, 10, 15 min), X 3-content of coarse recycled aggregates (20, 40, 60% by volume). Two additional series containing recycled aggregate without treatment and natural aggregate were also prepared. Established properties of individual aggregates have confirmed a positive effect of thermo-mechanical treatment. Then, based on the results of compressive strength, flexural strength, Young's modulus, volumetric density, water absorption, water permeability and capillarity, the most favourable parameters of heat and mechanical treatment of concrete were determined. The test results showed that appropriate treatment of concrete rubble allows to obtain high-quality coarse aggregate and valuable fine fraction. This was also confirmed by the macro-and microscopic observations of the aggregate and separated cement paste. Works realized on the concrete recycling method resulted in obtaining a patent PAT.229887.
Effect of Elevated Temperature on the Compressive Strength of Recycled Aggregate Concrete
Effect of elevated temperature on the compressive strength of concrete element with recycled aggregate was investigated. Natural aggregates were replaced with recycled aggregates during casting at 0, 25, 50, 75 & 100 percentages using water cement ratio of 0.60.The natural aggregates used were quarried granites from parent igneous rock with maximum sizes of 19mm. While the recycled aggregates were gotten from demolished old concrete building, crushed manually and sieved to also get maximum sizes of 19mm.Total of 75 concrete cubes of 150mm x 150mm sizes were cast and properly cured for 28 days. The concrete cubes were then subjected to different level of temperatures (50°c, 100°c, 200°c, 300°c, and 400°c) for a period of eight (8) hours in the electronic oven. Test results showed an average of38% reduction in strength for all percentage replacements with recycled aggregates within temperature ranges not above 200°c compare to about 25% reduction in strength of samples with 100% natural aggregates. For temperature ranges between 300°c and 400°c, an average of 55% reduction in strength was observed for samples with various percentage replacements with recycled aggregates.
Influence of Elevated Temperatures on the Behavior of Economical Reactive Powder Concrete
2013
In this investigation, the effects of elevated temperatures of 200, 300, 500℃ for 2 and 4 hours on the main mechanical properties of economical type of reactive powder concrete (RPC) are studied. The main variab les in this study are cement content and steel fibers content in reactive powder concrete samples as well as elevated temperature and heating time. Co mpressive strength and tensile strength of RPC are obtained after exposure to elevated temperatures. It is found that, RPC can be use at elevated temperature up to 300°C for heating times up to 4 hours taking into consideration the loss of strength. Also, using steel fibers enhance the residual strength of high cement content RPC samples.
EFFECT OF TEMPERATURE ON RECYCLED AGGREGATE CONCRETE (RAC
This work studied the effect of temperature on concrete made from recycled aggregates. In the investigation, compressive strength test were carried out using a total of seven batches of concrete mixes. The concrete mixes consists of 0%, 10%, 20%, 30%, 40%, 50% and 100% replacements of natural aggregates with recycled aggregate sourced from the base course of a failed highway at Mgbirichi, Umuagwo, Owerri west local Government of Imo State, Nigeria. Watercement ratio of 0.55 was used and batching of concrete was done by weight in accordance with the American Standard for testing and Materials (ASTM). The workability of the concrete was measured using the slump test apparatus. The results showed that the workability of the recycled aggregate concrete reduced considerably as the amount of recycled aggregate increased. The specimen were cured for 28days and afterwards were subjected to temperatures of 400 o C, 800 o C and 1200 o C for 2hours in a kiln.As the temperature increased from 0 o C to 1200 o C, the compressive strength for all the percentage replacements, reduces consistently. However, at the maximum temperature of 1200 o C, the maximum compressive strength of 27.56 N/mm 2 was realized for the 20% replacement. When exposed to a temperature of 1200ºC, recycled aggregate concrete showed percentage reduction in compressive strength of 16.10%, 16.31%, 14.67%, 26.06%, 29.28% and 17.54% for 10%, 20%, 30%, 40%, 50% and 100% replacements of natural aggregates with recycled aggregates respectively; meanwhile the natural aggregate concrete showed a percentage reduction in compressive strength of 47.22%. It was therefore concluded that, at various percentage replacements of natural aggregates with recycled aggregates, the RAC showed a higher resistance to reduction in compressive strength when exposed to extreme temperature rise than its natural aggregate concrete counterpart
IOP Conference Series: Earth and Environmental Science, 2018
Concrete is the chief material of construction and it is non-combustible in nature. However, the exposure to the high temperature such as fire can lead to change in the concrete properties. Due to the higher temperature, several changes in terms of mechanical properties were observed in concrete such as compressive strength, modulus of elasticity, tensile strength and durability of concrete will decrease significantly at high temperature. The exceptional fireproof achievement of concrete is might be due to the constituent materials of concrete such as its aggregates. The extensive use of aggregate in concrete will leads to depletion of natural resources. Hence, the use of waste and other recycled and by-product material as aggregates replacements becomes a leading research. This review has been made on the utilization of waste materials in concrete and critically evaluates its effects on the concrete performances during the fire exposure. Therefore, the objective of this paper is to review the previous search work regarding the concrete containing waste material as aggregates replacement when exposed to elevated temperature and come up with different design recommendations to improve the fire resistance of structures.
Mechanical Behavior of Modified Reactive Powder Concrete with Waste Materials Powder Replacement
Periodica Polytechnica Civil Engineering, 2021
Across the world, a huge amount of waste materials is deposited from different industrial or construction activities. Out of this massive waste quantity, a petite is recycled and remaining is dumped in vulnerable lands. This paper deals with the potential utilization of solid waste in reactive powder concrete, practically powdered glass originating from waste glass bottles and powdered ceramics tile from waste of construction process. First, the optimum ratio of waste pozzolanic material (ceramics to glass ratio) was obtained by pozzolinic activity test. Then, the optimal waste pozzolanic material was incorporated in reactive powder concrete at several substitution levels. The waste pozzolanic material in 5 %, 10 %, 15 %, 20 %, and 25 % were added in the reactive powder concrete mixes as fractional supplement of silica fume. Strength and water absorption of the modified reactive powder concrete were evaluated. A significant enhancement was observed in mechanical behavior of modified...
Construction and Building Materials, 2011
Influence of high temperature on the properties of concrete containing non-ground granulated blast-furnace slag (GBFS) and coal bottom ash (BA) as fine aggregate was presented. Six series of concrete mixtures were prepared by partially replacing fine aggregate separately with GBFS and BA. Replacement percentages were between 10 and 50% with an increment of 10% by dry weight of fine aggregate. Then 0.2% polypropylene fibres (PP) were added to last three mixtures that has the same mixture with the first three series. The first series is control concrete, the second series contained GBFS and the third series contained BA. All the concrete specimens were exposed to 800°C temperature at the age of 90 days. Tests were conducted to determine loss in weight, compressive strength, and dynamic modulus of elasticity. Also surface crack observations were conducted with microscope. Test results showed that it is possible to partially replace fine aggregate with GBFS or BA even if such concretes were to be subjected to high temperature response. Performance of BA concrete was found to be better than GBFS as replacement material.
Materials
The increasing volume of waste and the requirements of sustainable development are the reasons for the research on new waste management concepts. The research results presented in this paper show the effect of recycled aggregate on the selected properties of cement concrete. The aggregates obtained from three types of wastes are tested: recycled concrete paving, crushed ceramic bricks, and burnt sewage sludges. The recycled aggregates replaced 25% and 50% of the volume of the fine aggregate. The tested aggregates worsen the concrete mixes’ consistency and decrease, to some extent, the compressive strength of the concrete. However, the tensile splitting strength of the concrete with recycled aggregates is similar to that of the reference concrete. Using recycled aggregates worsens the tightness of the concrete, which manifests itself by increasing water penetration depth. The thermal properties of concrete are slightly affected by the type and content of the recycled aggregate. Consi...