Concretes prepared with recycled aggregate and metakaolin: aspects of mechanical resistance and electrical resistivity (original) (raw)
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Recycled Aggregate Concrete including Various Contents of Metakaolin: Mechanical Behavior
Advances in Materials Science and Engineering
This experimental research investigates the effect of utilizing metakaolin (MK) on the behavior of recycled aggregate concrete (RAC). The RAC incorporates recycled coarse aggregate (RCA) originated from crushing construction and demolition waste. The investigated parameters were RCA and MK contents. Tests of workability and mechanical properties such as compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity were conducted to evaluate the influence of MK on workability and mechanical behavior of RAC. In total, 19 mixes were prepared. These mixes are divided into four groups. Group zero (G0) includes a reference mix containing normal coarse aggregate (NCA) and 3 mixes made with 35%, 70%, and 100% of RCA. Each one of the other three groups (G1, G2, and G3) was made with one content of the three contents of RCA, and each group includes five mixes made with the contents of 4%, 8%, 12%, 16%, and 20% of MK. Empirical models among the mechanical prope...
International Journal of Engineering & Technology, 2018
As concrete is the second highest utilized material after water in the world, the improvement in the performances of concrete is the requirement of today’s era. In addition, the use of mineral admixture like Metakaolin helps to achieve good performance of concrete even prepared by utilizing recycled construction and demolition (C&D) waste aggregate and recycled ceramic waste aggregate. In present study Ordinary Portland cement has been partially replaced by Metakaolin in different grades selected recycled aggregate concrete(RAC) and recycled ceramic waste aggregate concrete(CAC). The deficiencies in different mechanical properties of these selected concretes with respect to reference concretes has been observed experimentally and there were retained by replacing cement with Metakaolin(MK) about 7.5% by weight of cement.
Nigerian Journal of Technological Development, 2021
In this study, locally produced Metakaolin (MK) was used as an admixture in recycled aggregate concrete of grades M 25 and M 30. The content of MK varied from 0-15% at 5% intervals. The physical and mechanical properties (bulk density, specific gravity, water absorption, aggregate crushing value and aggregate impact value) of aggregates were determined, the chemical composition as well as reactivity of MK was evaluated using X-Ray Fluorescence (XRF) technique and modified Chappelle test. The workability (slump) and strength (compressive and split tensile) properties of fresh and hardened RAC were examined relative to that of conventional concrete. The results of the experiments revealed that the specific gravity (SG), water absorption and aggregate impact value of recycled aggregates (RA) were 2.23, 5.35% and 32%, respectively. The MK used had an optimum reactivity of 2060.8 mg of Ca(OH)2 fixed at a temperature of 660 oC. The slump values for M 25 and M 30 control specimens were 72...
Concrete with recycled aggregates: the Portuguese experimental research
Materials and Structures, 2010
The main objective of this study is to define expedient procedures to estimate the properties of structural concrete that contains recycled aggregates. Experimental results from Portuguese research, most of which supervised by the first author, were used to establish a relationship between some properties of hardened concrete (compressive strength, splitting and flexural tensile strength, modulus of elasticity, abrasion resistance, shrinkage, water absorption, carbonation penetration and chloride penetration) and the density and water absorption of the aggregates' mixture and also the compressive strength of concrete at the age of 7 days. The workability and density were also analysed for fresh concrete. The graphic analysis of each property shows the relationship between those for recycled aggregate concrete (RAC) mixes and a reference mix using natural aggregates only (RC). The density and water absorption of all the aggregates in the mixture, for each substitution rate, were calculated in order to represent the exact proportion of each type of aggregate (natural and recycled). This method proved to be viable to estimate the variation of the properties of concrete with recycled aggregates by obtaining results for the three parameters mentioned above. This innovative procedure can contribute to increasing the use of recycled aggregates in the construction sector and make it a sustainable activity.
2021
In view of the improvement of construction techniques and technological innovations, civil construction still faces numerous problems. Uncontrolled exploitation of natural resources has caused major environmental impacts, in addition to the generation and accumulation of debris in urban areas. Thus, recycling appears as a sustainable alternative to reduce the accumulation of this waste. As an option, there is the use of Recycled Aggregates, obtained through Construction and Demolition Waste (CDW). In this sense, the present study aimed to analyze the feasibility of using the CDW through its application in the production of recycled coarse aggregates in concrete. For the tests, the coarse aggregate was replaced in the proportions of 0 (reference line), 10, 20, 30, 40, 50 and 100%, with three samples for each line and age. The dosage of the strokes followed the parameters established by the IPT / EPUSP method. The concretes were analyzed for compressive strength at 7, 14 and 28 days a...
Article ID: IJCIET_10_04_115 Concrete Made with Metakaolin, Foundry Sand and Demolition Waste
IAEME, 2019
Concrete had reached its increasing demand since the construction industry involved innovation in all forms of phenomenal infrastructural works. The main objective of our project lies in find a perfect solution for the diminishing resources of cement, fine and course aggregates. Our ideology was adding metakaolin, foundry sand and demolition waste to the concrete and studying the strength properties of concrete with the variation in nominal mix. i.e., to study the strength properties of concrete (M20 Grade) for mix ratio of 5%,10%,15%,20% and 25% at 7 and 28 days. The strength properties being studied in our theses are as follows: 1. Compressive strength 2. Split Tensile strength 3. Flexural strength These properties were then compared with the nominal concrete mix.
Materials Science and Engineering, 2022
This research work investigates the compressive strength of concrete specimens cured at the age of 7 & 28 days, the split tensile strength, and the flexural strength of concrete specimens cured at 28 days. Natural coarse aggregate (NCA) has been replaced with 0 percent, 25 percent, 40 percent, 60 percent, and 100 percent by RCA of construction & destruction (C&D) waste of 30-year-old building and Ordinary Portland cement (OPC) has been replaced with 10 percent metakaolin (MK).To understand the fresh properties of concrete of slump test was performed and to find satisfactory results. To analyze the hardening properties of MK with recycled coarse aggregate (RCA) base mix concrete, compressive strength was measured at the age of 7 and 28 days, and split tensile strength, the flexural strength was measured at the age of 28 days. Based on the experiment's study, it can be concise that the 40 percent substitute of NCA with RCA carried good results with 10 percent MK. This research presents the effect of MK as a cement substitute on the properties of fresh and hardened with RCA.
2012
The aim of this paper is to verify the influence of composition variability of recycled aggregates (RA) of construction and demolition wastes (CDW) on the performance of concretes. Performance was evaluated building mathematical models for compressive strength, modulus of elasticity and drying shrinkage. To obtain such models, an experimental program comprising 50 concrete mixtures was carried out. Specimens were casted, tested and results for compressive strength, modulus of elasticity and drying shrinkage were statistically analyzed. Models inputs are CDW composition observed at seven Brazilian cities. Results confirm that using RA from CDW for concrete building is quite feasible, independently of its composition, once compressive strength and modulus of elasticity still reached considerable values. We concluded the variability presented by recycled aggregates of CDW does not compromise their use for concrete building. However, this information must be used with caution, and experimental tests should always be performed to certify concrete properties.