Rational Compounds of Low-Strength Concrete with Improved Coefficient of Efficiency of Cement Use

2019 ◽  
Vol 968 ◽  
pp. 26-34
Author(s):  
Andriy M. Netesa ◽  
Nykolay I. Netesa ◽  
Anatoliy Valentinovitch Radkevich ◽  
Sergiy O. Yakovlev
Keyword(s):  
Compressive Strength ◽  
Concrete Mixture ◽  
Unit Mass ◽  
Mathematical Planning ◽  
Strength Concrete ◽  
Fine Grained ◽  
Concrete Mix ◽  
Research Findings ◽  
Low Strength ◽  
Low Strength Concrete

The purpose of the research findings, given in article, is aimed to determine the rational compounds of concrete with an average cubic compressive strength less than 20 MPa with minimum required expenditures of cement. To reach the goal, mathematical planning of the experiment was used with variability of cement consumption from 90 to 190 kg / m3 in the compositions of the concrete mixture, and for the fine-grained filler from tails of processed ores, the consumption was like at 100 to 400 kg / m3. The result of processing experiments has shown us the dependences of the change in strength and coefficient of efficiency of the use of cement of the factors involved. Optimized values increase most intensively with minimum cement consumption and a change in the consumption of fine filler within the limits of the study. The highest coefficient of efficiency of use of cement is expressed by the ratio of the achieved strength per unit mass of used cement in the concrete mix and it was obtained at a cement consumption of 90 kg / m3 and a filler of 400 kg / m3. Using the obtained dependences of optimized values on the factors under study, the composition of concrete may be predicted with a strength up to 20 MPa with the required amount of filler.

Mechanical properties of low-strength concrete at exposure to elevated temperatures

2017 ◽  
Vol 8 (4) ◽  
pp. 418-439 ◽  
Author(s):  
Muhammad Masood Rafi ◽  
Tariq Aziz ◽  
Sarosh Hashmat Lodi
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Ambient Temperature ◽  
Elevated Temperatures ◽  
Explosive Spalling ◽  
Content Type ◽  
Strength Concrete ◽  
Testing Programme ◽  
Low Strength ◽  
Low Strength Concrete

Purpose This paper aims to present the results of testing of low-strength concrete specimens exposed to elevated temperatures. These data are limited in the existing literature and do not exist in Pakistan. Design/methodology/approach An experimental testing programme has been employed. Cylindrical specimens of 100 × 200 mm were used in the testing programme. These were heated at temperatures which were varied from 100°C to 900°C in increment of 100°C. Similar specimens were tested at ambient temperature as control specimens. The compressive and tensile properties of heat treated specimens were determined. Findings The colour of concrete started to change at 300°C and hairline cracks appeared at 400°C. Explosive spalling was observed in few specimens in the temperature range of 400°C-650°C which could be attributed to the pore pressure generated by steam. Significant loss of concrete compressive strength occurred on heating temperatures larger than 600°C, and the residual compressive strength was found to be 15 per cent at 900°C. Residual tensile strength of concrete became less than 10 per cent at 900°C. The loss of concrete stiffness reached 85 per cent at 600°C. Residual Poisson’s ratio of concrete increased at high temperatures and became nearly six times larger at 900°C as compared to that at ambient temperature. Research limitations/implications The parameters of the study included heating temperature and effects of temperature on strength and stiffness properties of the concrete specimens. Practical implications Building fire incidents have increased in Pakistan. As a large number of reinforced concrete (RC) buildings exist in the country, the data related to elevated temperature properties of concrete are required. These data are not available in Pakistan presently. The study aims at providing this information for the design engineers to enable them to assess and increase fire resistance of RC structural members. Originality/value The presented study is unique in its nature in that there is no published contribution to date, to the best of authors’ knowledge, which has been carried out to assess the temperature-dependent mechanical properties of concrete in Pakistan.

Bond behaviour of low-strength concrete

1992 ◽  
Vol 44 (160) ◽  
pp. 195-203 ◽  
Author(s):  
A. Z. Mohamed ◽  
L. A. Clark
Keyword(s):  
Bond Behaviour ◽  
Strength Concrete ◽  
Low Strength ◽  
Low Strength Concrete

Optimization of Exposed Concrete Pigmented with FexOy

2021 ◽  
Vol 903 ◽  
pp. 203-207
Author(s):  
Inna Juhnevica ◽  
Artūrs Čurakovs
Keyword(s):  
Compressive Strength ◽  
Strength Criteria ◽  
Strength Concrete ◽  
Concrete Mix ◽  
Two Parameters

Lately concrete has been used not only as backbone of structure but as esthetic construction art. The challenge is to combine these two parameters and predict concrete behavior. The target of this paper is to successfully develop easily controllable, visually attractive concrete that provides with necessary compressive strength criteria. Two mix designs with Fe2O3 and Fe3O4 pigments were tested for 1, 3, 7, 14, 28-day compressive strength. Concrete samples were left indoors and outdoors to investigate migration of salts also called as efflorescence. Concrete mix designs without pigment additive showed higher compressive strength as well as density compering to pigmented concrete. Pigmented concrete outdoor specimens showed increased migration of salts on surface comparing to indoor specimens.

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