scholarly journals Effect of Concrete Retempering Methods on Fresh and Hardened Concrete Properties for Normal and High Strength Concrete

2019 ◽  
Vol 14 (23) ◽  
pp. 8903-8911
Author(s):  
M.A. Abdel-Aziz ◽  
M.A. Arab ◽  
R.M. Hussien
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Hardened Concrete ◽  
Strength Concrete ◽  
Concrete Properties

scholarly journals Recycled Aggregate Self-curing High-strength Concrete

2017 ◽  
Vol 3 (6) ◽  
pp. 427-441 ◽  
Author(s):  
Alaa Ali Bashandy ◽  
Noha M. Soliman ◽  
Mahmoud Hamdy Abd Elrahman
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Water Evaporation ◽  
Hardened Concrete ◽  
Curing Agent ◽  
Conventional Concrete ◽  
Strength Concrete ◽  
Concrete Properties

The use of recycled aggregates from demolished constructions as coarse aggregates for concrete becomes a need to reduce the negative effects on the environment. Internal curing is a technique that can be used to provide additional moisture in concrete for more effective hydration of cement to reduce the water evaporation from concrete, increase the water retention capacity of concrete compared to the conventionally cured concrete. High strength concrete as a special concrete type has a high strength with extra properties compared to conventional concrete. In this research, the combination of previous three concrete types to obtain self-curing high-strength concrete cast using coarse recycled aggregates is studied. The effect of varying water reducer admixture and curing agent dosages on both the fresh and hardened concrete properties is studied. The fresh properties are discussed in terms of slump values. The hardened concrete properties are discussed in terms of compressive, splitting tensile, flexure and bond strengths. The obtained results show that, the using of water reducer admixture enhances the main fresh and hardened properties of self-curing high-strength concrete cast using recycled aggregate. Also, using the suggested chemical curing agent increased the strength compared to conventional concrete without curing.

scholarly journals Nano Alumina Based High Strength Concrete

2020 ◽  
Vol 9 (4) ◽  
pp. 256-363
Keyword(s):  
Mechanical Properties ◽  
High Strength Concrete ◽  
High Strength ◽  
Pulse Velocity ◽  
Hardened Concrete ◽  
Normal Concrete ◽  
Conventional Concrete ◽  
Tem Analysis ◽  
Strength Concrete ◽  
Nano Alumina

Very recently, the world of nano technology has initiated to fabricate new materials owing to the demand for their use in enhancing the properties of different materials in general and, materials used in the construction industry in particular. In this study, the results of an exhaustive experimental analysis, on the use of nano alumina with cement powder to enhance the grade and strength of concrete has been undertaken. The influence of the nano alumina in concrete with different proportions has been studied to assess mechanical properties of concrete with reference to normal concrete. The test results indicate that the use of nano alumina in concrete has enhanced the mechanical properties of hardened concrete. This nano alumina based high strength concrete (HSC) has an enhanced compressive strength of 64.17 N/mm2 (MPa) after 28 days, which is a significant improvement over normal concrete. All the mixes having nano alumina in different proportions gave better results as compared to normal conventional concrete mix. The Rebound Hammer, Ultrasonic Pulse Velocity, SEM and TEM analysis further validate the above findings.

Specimen Size and Shape Effects on the Concrete Properties, Thermal Conductivity and Heat Generation from Hydration for Different Concrete Types

2019 ◽  
Vol 16 (10) ◽  
pp. 4072-4091 ◽  
Author(s):  
Ola Adel Qasim
Keyword(s):  
Thermal Conductivity ◽  
Reinforced Concrete ◽  
Heat Generation ◽  
High Strength Concrete ◽  
Concrete Beam ◽  
Concrete Strength ◽  
High Strength ◽  
Strength Concrete ◽  
Concrete Properties ◽  
The Difference

The environmental impact, manufacture and the application of concrete have many influences, some of which are influential and complex. Construction engineers are looking for modern ideas and methods that make the building more efficient in terms of functionality, cost, high strength, reduced overloads and increased efficiency of unlimited geometric shapes. The main factor in the improvement and development of concrete structures rely on the engineering characteristics of the substances. The developments in the construction materials, mix proportions, dimensions, mixing, and conditions (temperature) used to enhance the concrete technology, have important impacts on characteristics of concrete strength and heat development manner. The heat generation from concrete reveals the components of concrete materials and mix balances as well as the innovations in structure and environmental circumstances. This research presented an experimental investigation of the significance of the specimen’s shape and the size of the concrete properties durability, thermal conductivity and heat generation. Cylinders, prisms, and cubes of different sizes and shapes will be used. This research concluded that the effect of molds shape and size decreased when the (strength in compression, splitting tensile strength, flexural strength, and concrete density) increasing, that’s mean for ultra-high-strength concrete the difference is much smaller. The concrete hydration due to heat increases with increasing of the concrete strength and size, and the difference in heat transfer with the increasing of specimen’s size decreasing with increasing of concrete size. It is completely identified that the deformation and intensity of reinforced concrete beams depend on the size of the beam. Effect of concrete types (normal 26 MPa, high 46 MPa, and ultra-high-strength concrete 61 MPa) on the design of reinforced concrete beam was studied with three different depth (170, 155 and 150 mm). Results revealed that high strength and ultra-high-strength concrete was able to substitute for the reduction in beams size with the same strength. For concrete that is high or ultra-high-strength a reduction in the beam depth of about (8.82%) and (11.76%) compared to the normal concrete beam where achieved.

scholarly journals Thermal Properties of Conventional and High-strength Concrete

2018 ◽  
Vol 245 ◽  
pp. 06005 ◽  
Author(s):  
Tatiana Musorina ◽  
Alexsander Katcay ◽  
Mikhail Petrichenko ◽  
Anna Selezneva
Keyword(s):  
Thermal Properties ◽  
Thermophysical Properties ◽  
High Strength Concrete ◽  
High Strength ◽  
Temperature Fluctuations ◽  
Conventional Concrete ◽  
Freeze Thaw ◽  
Strength Concrete ◽  
Concrete Properties ◽  
Cold Chamber

Important characteristics for the Nordic countries: a freeze-thaw resistance and an ability of a material to keep heat inside the building. This paper aims to define the thermophysical properties of a high-strength concrete, compare the discovered performance with the conventional concrete properties. With this object in mind two experiments in cold chamber “CHALLENGE 250” have been conducted and followed by analysis. In these experiments, the insulation of facades is beyond the framework of the investigation. Only the thermophysical properties of concrete are taken into account. The samples were affected by temperature fluctuations. Results from the experiments show that strength characteristics of a material are in indirect ratio to accumulation properties of a structure. This conclusion is directly related to porosity of material and additives. During 70 minutes, with outside temperature being below zero, the temperature inside the concrete dropped to an average. As the outside temperature increases significantly to more than zero, the temperature inside the concrete has become below average (continued to decline) in 70 minutes. The more strength of material, the better thermophysical properties. High-strength concrete is less susceptible to temperature fluctuations, therefore more heat-resistant. As mentioned in the paper below, the material has one disadvantage: this is a large cost per cubic meter.

Experimental Analysis of the Proposed High-Strength Concrete

2015 ◽  
Vol 1106 ◽  
pp. 77-80 ◽  
Author(s):  
Vladimír Suchánek ◽  
Michal Radouš
Keyword(s):  
Experimental Work ◽  
Experimental Analysis ◽  
High Strength Concrete ◽  
High Strength ◽  
Research Centre ◽  
Hardened Concrete ◽  
Strength Concrete ◽  
Laboratory Facilities ◽  
Training And Research ◽  
Is Design

This article deals with the description and evaluation of experimental work carried out by the Department of Transport Structures of Jan Perner Transport Faculty, University of Pardubice in the laboratory facilities of the Training and Research Centre in Transport.This is design of high-strength concrete according to three recipes using two different approaches in the design of concrete.The article also describes results of test bodies made of fresh and hardened concrete.

Factors determining the correlations between high strength concrete properties

2011 ◽  
Vol 25 (5) ◽  
pp. 2214-2222 ◽  
Author(s):  
Hakan Nuri Atahan ◽  
Osman Nuri Oktar ◽  
Mehmet Ali Taşdemir
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Strength Concrete ◽  
Concrete Properties

scholarly journals ASSESSMENT OF MECHANICAL PROPERTIES OF HIGH STRENGTH CONCRETE (HSC) AFTER EXPOSURE TO HIGH TEMPERATURE

2018 ◽  
Vol 24 (2) ◽  
pp. 138-144 ◽  
Author(s):  
Tomasz DRZYMAŁA ◽  
Wioletta JACKIEWICZ-REK ◽  
Jerzy GAŁAJ ◽  
Ritoldas ŠUKYS
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Strength Concrete ◽  
High Performance Concrete ◽  
High Strength ◽  
Hardened Concrete ◽  
Explosive Spalling ◽  
Polypropylene Fibres ◽  
Strength Concrete ◽  
Temperature Conditions

There has been a tendency to design ever slender building construction using high strength concrete in recent years. Application of HSC is also growing in tunnel construction. One of the most important challenges is to control explosive spalling of concrete and the method recommended by Eurocode 2 (EN 1992-1-2:2008/NA:2010P) is addition of polypropylene fibres to the mix. The purpose of the research described in this paper was to evaluate the changes of mechanical properties of HSC exposed to the effect of high temperature. The tests were carried out on three types of high strength concrete: air-entrained concrete, polypropylene fibre-reinforced concrete and reference concrete having constant water/cement ratio. The properties of hardened concrete including compressive strength, tensile splitting strength, flexural strength and E-modulus were studied. The latter tests were carried out on both on concrete cured at 20 °C and concrete subjected to high-temperature conditions at 300 °C, 450 °C and 600 °C. The results enabled us to evaluate the effect of high-temperature conditions on the properties of high-performance concrete and compare the effectiveness of the two methods designed to improve the high-temperature performance of the concrete: addition of polypropylene fibres and entrainment of air.

High Strength Concrete with Enhanced Properties by Addition of Chopped Basalt Fibres

2017 ◽  
Vol 908 ◽  
pp. 164-170 ◽  
Author(s):  
Iveta Nováková ◽  
Lenka Bodnárová
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Negative Influence ◽  
Advanced Materials ◽  
Hardened Concrete ◽  
Test Results ◽  
Polypropylene Fibres ◽  
Strength Concrete ◽  
Materials Used ◽  
Temperature Exposure

Use of high strength concrete (HSC) becoming inevitable in case of modern structures, which require application of advanced materials. High strength of concrete can be reached by higher dose of cement or addition of various kinds of fibres as a dispersed reinforcement. In practice are most commonly used steel, glass and polypropylene fibres, but basalt fibres are still under investigation. Basalt is highly resistance to aggressive chemicals and stable in high temperatures in comparison to other materials used for dispersed reinforcement. This study focuses on use of chopped basalt fibres in purpose to enhance properties of harden concrete. Six mixes with various dose of cement and chopped basalt fibres were designed for evaluation of properties of fresh and hardened concrete. As it was expected, chopped basalt fibres have negative influence on workability of fresh concrete but in comparison to other types of fibres the decrease is not that dramatic. Test results indicate increase of compressive strength after 28 days and even higher gain of strength after 90 days in case of mixes with addition of chopped basalt fibres. Reduction of strength due to exposure to 400 and 800 °C is also evaluated and in case of 400 °C temperature exposure the results are very promising.

An Experiment Investigation on Physical and Mechanical Properties of High Strength Concrete with Suitable Admixture

2019 ◽  
Vol 972 ◽  
pp. 10-15
Author(s):  
B.C. Gayana ◽  
Mallikarjuna Shashanka ◽  
Avinash N. Rao ◽  
Karra Ram Chandar
Keyword(s):  
Mechanical Properties ◽  
High Strength Concrete ◽  
Construction Material ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Steel Fibers ◽  
Partial Replacement ◽  
Hardened Concrete ◽  
Conventional Concrete ◽  
Strength Concrete

Concrete is an essential construction material. Even-though conventional concrete performs and satisfy the structures under normal conditions, a few special situations require very high compressive strength of concrete. An experimental investigation is done to develop high strength concrete with suitable admixtures and steel fibers. The properties of fresh and hardened concrete with alccofine as partial replacement for binder and poly-carboxylate ether (Glenium 8233) and steel fibers is investigated for the workability and mechanical properties i.e., compressive, splitting tensile and flexural strength of concrete. Based on the results, the strength increased with the addition of alccofine compared to the control mix. Hence, by optimum percentage of alccofine, high strength of concrete of 112 MPa can be obtained.

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