scholarly journals STUDY ON A SIMPLE METHOD FOR ESTIMATING THE COMPRESSIVE STRENGTH OF CONCRETE IN STRUCTURE SUBJECT TO HIGH TEMPERATURE HISTORY AT EARLY AGE

2004 ◽  
Vol 69 (579) ◽  
pp. 7-14 ◽  
Author(s):  
Hiroshi JINNAI ◽  
Yoshihiro MASUDA ◽  
Mitsutaka HAYAKAWA
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Temperature History ◽  
Early Age ◽  
Simple Method ◽  
Compressive Strength Of Concrete

The Use of Maturity Method for Estimating In Situ Compressive Strength of Concrete

2020 ◽  
Vol 309 ◽  
pp. 103-107
Author(s):  
Pavel Kasal ◽  
Václav Lorenc ◽  
Werner Wenighofer
Keyword(s):  
Compressive Strength ◽  
Monitoring System ◽  
Temperature History ◽  
Early Age ◽  
Retirement Home ◽  
Construction Time ◽  
Strength Based ◽  
Maturity Method ◽  
Concrete Mix ◽  
Compressive Strength Of Concrete

This paper describes four projects which were built with the use of concrete monitoring system of early age compressive strength based on maturity method. The paper also deals with experiences and benefits which came from the usage of monitoring system in these projects. First two examples are bridge projects „Petersdorfer See“ and „Seckachtal“ from Germany. The third project is a retirement home in Germany and the last example is Czech project of office building Vlněna in Brno. Maturity methods for estimating early age compressive strength of concrete are known since the 1950s. These methods use the principle that compressive strength is related to age, temperature history and concrete mix properties. Before the use of this method, each different concrete mix in use needs to be calibrated. Then temperature and time are measured since the concrete is poured. Several systems using maturity method for estimating real time compressive strength are available on the market. The use of these systems helps to determine earliest possible time for stripping the formwork, loading the structure, application of post tensioning forces and other critical operations during the construction time.

Experimental investigation on the compressive strength of PFGP-covered concretes exposed to high temperature

2019 ◽  
Vol 10 (4) ◽  
pp. 399-410
Author(s):  
Amir Hamzeh Keykha
Keyword(s):  
Experimental Investigation ◽  
Compressive Strength ◽  
High Temperature ◽  
Design Methodology ◽  
Polypropylene Fiber ◽  
Content Type ◽  
Gypsum Plaster ◽  
Compressive Strength Of Concrete

Purpose This study aims to investigate the effect of high temperature (600°C) on the compressive strength of concrete covered with a mixture of polypropylene fiber and gypsum plaster (PFGP). Design/methodology/approach To study the compressive strength of concrete specimens exposed to temperature, 16 cubic specimens (size: 150 mm × 150 mm × 150 mm) were made. After 28 days of processing and gaining the required strength of specimens, first, polypropylene fiber was mixed with gypsum plaster (CaSO4.2H2O) and then the concrete specimens were covered with this mixture. To cover the concrete specimens with the PFGP, the used PFGP thickness was 15 mm or 25 mm. The polypropylene rates mixed with the gypsum plaster were 1, 3 and 5 per cent. A total of 14 specimens, 12 of which were covered with PFGP, were exposed to high temperature in two target times of 90 and 180 min. Findings The results show that the PFGP as covering materials can improve the compressive strength lost because of the heating of the concrete specimens. The results also show that the presence of polypropylene fiber in gypsum plaster has the effect on the compressive strength lost because of the heating of the PFGP-covered concrete. The cover of PFGP having 3 per cent polypropylene fiber had the best effect on remained strength of the specimens. Originality/value The cover of PFGP having 3 per cent polypropylene fiber has the best effect on remained strength of the PFGP covered specimens exposed to temperature.

Laboratory and field tests with a new nondestructive apparatus

1990 ◽  
Vol 17 (6) ◽  
pp. 904-910 ◽  
Author(s):  
A. A. Al-Manaseer ◽  
K. W. Nasser
Keyword(s):  
Compressive Strength ◽  
Field Tests ◽  
Climatic Conditions ◽  
Early Age ◽  
Hardened Concrete ◽  
Penetration Test ◽  
Nondestructive Tests ◽  
Concrete Cylinders ◽  
Compressive Strength Of Concrete ◽  
Post Tension

A new nondestructive test for estimating the compressive strength of concrete and mortar at early ages is described in this paper. The pin penetration test was used to relate the early age strength of hardened concrete and mortar in the laboratory. It was found that the pin penetration tester can be used successfully, under laboratory conditions, to determine the compressive strength of concrete cylinders and mortar slabs at early age from 10 hours up to 28 days. For concrete and mortar cylinders, slabs, and cubes with a compressive strength of up to 27.6 MPa (4000 psi), the pin penetration readings were found to be linearly related to the compressive strength. The tester was also used successfully in the field to determine the compressive strength of a concrete floor slab in a new building in order to post-tension the strands and remove the forms. The building was constructed in winter under severe climatic conditions. Key words: early age, strength evaluation, concrete slabs, form removal, nondestructive tests, mortar testing, pin penetration test.

Influence of High-Temperature Curing on the Properties of the Concrete Containing Ground Iron and Steel Slag

2014 ◽  
Vol 507 ◽  
pp. 337-342
Author(s):  
Meng Yuan Li ◽  
Jin Hu
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Steel Slag ◽  
Curing Temperature ◽  
Early Age ◽  
Cement Concrete ◽  
Chloride Permeability ◽  
Iron And Steel ◽  
Negative Effect ◽  
Curing Condition

The influence of high-temperature curing on the compressive strength and chloride permeability of the concrete containing ground iron and steel slag (GISS) was investigated. Under standard curing condition (20°C), the early-age compressive strength of the concrete with GISS is much lower than that of the pure cement concrete. The activity of GISS is more sensitive to the increase of curing temperature than that of cement. The increase amplitude of early-age strength of the concrete with GISS is much greater than that of the pure cement concrete by increasing curing temperature. Increasing curing temperature tends to decease the late-age strength and enhance the late-age permeability of concrete. The negative effect of increasing curing temperature on the late-age properties of the concrete with GISS is smaller than that of the pure cement concrete.

scholarly journals Supervised Learning Methods for Modeling Concrete Compressive Strength Prediction at High Temperature

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1983
Author(s):  
Mahmood Ahmad ◽  
Ji-Lei Hu ◽  
Feezan Ahmad ◽  
Xiao-Wei Tang ◽  
Maaz Amjad ◽  
...  
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Supervised Learning ◽  
Mean Squared Error ◽  
Cement Content ◽  
Coefficient Of Determination ◽  
Percentage Error ◽  
Learning Methods ◽  
Inference System ◽  
Compressive Strength Of Concrete

Supervised learning algorithms are a recent trend for the prediction of mechanical properties of concrete. This paper presents AdaBoost, random forest (RF), and decision tree (DT) models for predicting the compressive strength of concrete at high temperature, based on the experimental data of 207 tests. The cement content, water, fine and coarse aggregates, silica fume, nano silica, fly ash, super plasticizer, and temperature were used as inputs for the models’ development. The performance of the AdaBoost, RF, and DT models are assessed using statistical indices, including the coefficient of determination (R2), root mean squared error-observations standard deviation ratio (RSR), mean absolute percentage error, and relative root mean square error. The applications of the above-mentioned approach for predicting the compressive strength of concrete at high temperature are compared with each other, and also to the artificial neural network and adaptive neuro-fuzzy inference system models described in the literature, to demonstrate the suitability of using the supervised learning methods for modeling to predict the compressive strength at high temperature. The results indicated a strong correlation between experimental and predicted values, with R2 above 0.9 and RSR lower than 0.5 during the learning and testing phases for the AdaBoost model. Moreover, the cement content in the mix was revealed as the most sensitive parameter by sensitivity analysis.

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