Effect of concrete specifications and inspection practices on freeze–thaw resistance: a field study

1990 ◽  
Vol 17 (2) ◽  
pp. 271-276
Author(s):  
M. A. Ward ◽  
B. W. Langan
Keyword(s):  
Compressive Strength ◽  
Statistical Analysis ◽  
Field Study ◽  
Key Words ◽  
Freeze Thaw ◽  
Air Content ◽  
Rigorous Statistical Analysis ◽  
Metropolitan Center ◽  
Concrete Materials ◽  
Job Site

In the late sixties significant durability problems were encountered in a major metropolitan center in Canada. A review of prevailing construction practices was undertaken, together with a rigorous statistical analysis of the air content and compressive strength results. The main outcome of that study was a conclusion that a significant amount of the concrete placed on the job site had an unacceptably low air content. It is understood that these results, coupled with a review of specifications used in other metropolitan centers, provided the basis for revising the concrete materials specification in 1970. A similar review of strength and air content results was carried out at the end of that year. It was evident that an increase of approximately 1% had occurred in the average measured air content together with a small increase in compressive strength as the result of the specification changes. To assess the effect of this specification and further changes that have occurred since 1970, a third review was carried out in 1987. It was noted that during the intervening period a further increase in air content had taken place. Reasons for these changes are reviewed with respect to current construction practices. Also included is a review of the current specifications for this class of concrete in use in Canada. Key words: air content, compressive strength, specifications, inspection, statistics, durability.

Effets du gel sur les infrastructures routières argileuses au Québec

1992 ◽  
Vol 29 (1) ◽  
pp. 131-142 ◽  
Author(s):  
Marius Roy ◽  
Jean Tardif ◽  
Serge Leroueil ◽  
Gaston Larose ◽  
Pierre La Rochelle
Keyword(s):  
Field Study ◽  
Key Words ◽  
Mechanical Behaviour ◽  
Clayey Soils ◽  
Freeze Thaw ◽  
Freeze And Thaw ◽  
Liquidity Index ◽  
Thaw Cycle ◽  
Laboratory Results ◽  
Freeze Thaw Cycle

This study deals with the freeze and thaw effects on the mechanical behaviour of the clayey subgrades exposed by cuts for the placement of road foundations. Twelve cut sites have been analysed in cooperation with the ministère des Transports du Québec. As damages were observed after the first winter on some of the sites, whereas none were apparent on other sites, it was possible to define the factors that may lead to such damages. In particular, the field study confirms the laboratory results showing that criteria based on liquidity index are sufficient to characterize the change of mechanical behaviour of the clayey soils subjected to one freeze–thaw cycle. Key words : clay, liquidity index, freeze-thaw, bearing capacity of roads, heaving, cut. [Translated by the Journal]

Béton produit en bétonnière mobile et en usine conventionnelle : comparaison des caractéristiques du réseau de bulles d'air

1988 ◽  
Vol 15 (3) ◽  
pp. 306-314
Author(s):  
Gaston Larose ◽  
Michel Pigeon
Keyword(s):  
Key Words ◽  
Laboratory Tests ◽  
Fresh Concrete ◽  
Mobile Unit ◽  
Freeze Thaw ◽  
Air Content ◽  
Spacing Factor ◽  
Void System ◽  
Concrete Mixer ◽  
Air Void

The durability of concrete to freeze-thaw cycles is dependent upon the existence of an adequate air-void system. There are very few studies on the air-void system of field concretes. Laboratory tests have proven that the air content measurement on the fresh concrete is not sufficient to judge the aptitude of the air-void system to protect the concrete from frost damage.This paper is a comparison of the air-void systems of field concretes produced in either a conventional plant or a mobile unit the use of which is becoming more and more frequent. The concretes produced in the conventional plant generally had sufficient air-void systems for air contents in the usual range (5–7%). The mobile unit showed that a slightly higher air content (8%) was needed to produce an adequate air-void system. Key words: concrete, mobile concrete-mixer, air-void systems, air-entraining agent, spacing factor, surface area, air content.

scholarly journals The Influence of Ambient Temperature on High Performance Concrete Properties

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4646
Author(s):  
Alina Kaleta-Jurowska ◽  
Krystian Jurowski
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Water Penetration ◽  
Ambient Temperatures ◽  
Freeze Thaw ◽  
Air Content ◽  
Flow Table

This paper presents the results of tests on high performance concrete (HPC) prepared and cured at various ambient temperatures, ranging from 12 °C to 30 °C (the compressive strength and concrete mix density were also tested at 40 °C). Special attention was paid to maintaining the assumed temperature of the mixture components during its preparation and maintaining the assumed curing temperature. The properties of a fresh concrete mixture (consistency, air content, density) and properties of hardened concrete (density, water absorption, depth of water penetration under pressure, compressive strength, and freeze–thaw durability of hardened concrete) were studied. It has been shown that increased temperature (30 °C) has a significant effect on loss of workability. The studies used the concrete slump test, the flow table test, and the Vebe test. A decrease in the slump and flow diameter and an increase in the Vebe time were observed. It has been shown that an increase in concrete curing temperature causes an increase in early compressive strength. After 3 days of curing, compared with concrete curing at 20 °C, an 18% increase in compressive strength was observed at 40 °C, while concrete curing at 12 °C had a compressive strength which was 11% lower. An increase in temperature lowers the compressive strength after a period longer than 28 days. After two years of curing, concrete curing at 12 °C achieved a compressive strength 13% higher than that of concrete curing at 40 °C. Freeze–thaw performance tests of HPC in the presence of NaCl demonstrated that this concrete showed high freeze–thaw resistance and de-icing materials (surface scaling of this concrete is minimal) regardless of the temperature of the curing process, from 12 °C to 30 °C.

Loss of freeze–thaw durability of concrete containing accelerating admixtures

1994 ◽  
Vol 21 (4) ◽  
pp. 605-613
Author(s):  
D. Stott ◽  
T. Rezansoff ◽  
B. F. Sparling
Keyword(s):  
Compressive Strength ◽  
Key Words ◽  
Hydration Product ◽  
Early Age ◽  
Concrete Durability ◽  
Test Results ◽  
Freeze Thaw ◽  
Void System ◽  
Air Void ◽  
Air Entrained Concrete

Rapid freeze–thaw durability tests on air entrained concrete mixes containing a proprietary nonchloride accelerating admixture or CaCl2 show that although early age compressive strength acceleration is achieved, the freeze-thaw durability is reduced when compared with the durability of control concretes of similar mix proportions, but without accelerating admixtures. Although the compressive strength gains were accelerated in mixes containing either the proprietary accelerating admixture or CaCl2, the tensile strengths at 28 days were similar for mixes with and without the admixtures.Petrographic analyses showed air contents and air void spacing factors in concretes with accelerating admixtures, either nonchloride or CaCl2, to be similar to the air systems in the control concrete, though more air entraining agent was required with the mixes containing accelerating admixtures. Local aggregates as well as aggregates from three alternate sources were used. Test results did not show any significant differences in durability on the basis of aggregate source.As the larger reduction measured in freeze–thaw durability for concrete mixes containing either chloride or nonchloride accelerating admixtures could not be attributed to either a deficient air void system in the cured concrete or inferior aggregate, it is believed that the cause is some characteristic or a hydration product in the cement paste microstructure produced by accelerated hydration. Key words: concrete, durability, freeze–thaw testing, strength acceleration, admixtures, air void system.

scholarly journals Investigation of the Effect of Freeze-thaw Cycles on the Mechanical Properties of Hardened Self-compacting Concrete

2020 ◽  
Author(s):  
Tuncay Kap
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Statistical Analysis ◽  
Fresh Concrete ◽  
The Other ◽  
Unit Weight ◽  
Self Compacting Concrete ◽  
Freeze Thaw ◽  
The Core ◽  
Average Compressive Strength

This study investigated the effects of freeze-thaw cycles on the mechanical properties of hardened self-compacting concrete for varying column heights. A column (100×20×300 cm) was fabricated by C30 self-compacting concrete in the laboratory and 10 cube samples (10x10x10 cm) were taken from fresh concrete as the references. After a period of 28 days, 160 core specimens (Ø67 mm in diameter) were taken from different column heights. Unit weight, water absorption, compressive strength, and freeze-thaw tests were performed on these 170 (10 reference cubic and 160 core) samples. The mechanical properties of the core specimens before freeze-thaw and after 8-56 freeze-thaw cycles were reported for varying column heights. The average compressive strength value of the reference cubic samples was determined as 40.28 MPa, while the compressive strengths of the core specimens before freeze-thaw were ranged from 40.25 MPa to 49.62 MPa, impying an increase in compressive strength values up to 23.18% compared to the reference cubic samples. Compressive strengths of the specimens subjected to 8 and 56 freeze-thaw cycles varied between 38.71‒48.07 MPa and 31.72‒39.11 MPa, respectively. Statistical analysis revealed that the compressive strength of the concrete exposed to 56 freeze-thaw cycles was significantly different from that of the other specimens.

scholarly journals Effect of Fast Freeze-Thaw Cycles on Mechanical Properties of Ordinary-Air-Entrained Concrete

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Huai-shuai Shang ◽  
Wei-qun Cao ◽  
Bin Wang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Life Prediction ◽  
Cold Region ◽  
Mathematical Formula ◽  
Laboratory Environment ◽  
Freeze Thaw ◽  
Cleavage Strength ◽  
Concrete Materials ◽  
Air Entrained Concrete

Freezing-thawing resistance is a very significant characteristic for concrete in severe environment (such as cold region with the lowest temperature below 0°C). In this study, ordinary-air-entrained (O-A-E) concrete was produced in a laboratory environment; the compressive strength, cubic compressive strength of C50, C40, C30, C25, and C20 ordinary-air-entrained concrete, tensile strength, and cleavage strength of C30 ordinary-air-entrained concrete were measured after fast freeze-thaw cycles. The effects of fast freeze-thaw cycles on the mechanical properties (compressive strength and cleavage strength) of ordinary-air-entrained concrete materials are investigated on the basis of the experimental results. And the concise mathematical formula between mechanical behavior and number of fast freeze-thaw cycles was established. The experiment results can be used as a reference in design, maintenance, and life prediction of ordinary-air-entrained concrete structure (such as dam, offshore platform, etc.) in cold regions.

A Rule-Breaking Approach to a Better Understanding of the Method of Tests for Slump, Air Content and Compressive Strength

2019 ◽  
Vol 57 (6) ◽  
pp. 433-440
Author(s):  
S. Komatsu ◽  
Y. Kondo ◽  
N. Ikawa ◽  
C. Hashimoto
Keyword(s):  
Compressive Strength ◽  
Air Content ◽  
Rule Breaking

Ritualinis mandagumas (ta’ârof) šiuolaikinio Irano visuomenėje ir tarpkultūrinėje komunikacijoje: Teherano šiaurinės dalies atvejis

2019 ◽  
Vol 19 (28) 2019 ◽  
pp. 169-190
Author(s):  
Dalia Sabaliauskienė
Keyword(s):  
Field Study ◽  
Key Words ◽  
Intercultural Communication ◽  
Capital City ◽  
Cultural Environment ◽  
City Culture ◽  
Face Maintenance

This paper examines the concept and practices of the Iranian ritual courtesy ta’ârof in northern Tehran, based on field-study findings, and analyses its expression in intercultural communication. It examines how contemporary Iranians perceive ta’ârof, what practices of ritual courtesy are commonly found, and whether configurations of the Iranian code of courtesy remain stable in the changing cultural environment. The study employs the theory of face maintenance and data from Iranian face and diaspora research. It shows emic perceptions of ta’ârof, and reveals its practices in Tehran, alongside tendencies of expression among Iranians living in Lithuania. Key words: ta’ârof, ritual courtesy, capital-city culture, intercultural communication, contemporary Iran.

Optimization Research of Mix Proportion of Frost Resistance Construction of Concrete Based on the MATLAB Language

2014 ◽  
Vol 584-586 ◽  
pp. 1917-1921
Author(s):  
Jun Jie Zhang ◽  
Rui Hong Shao ◽  
Xiang Yi Meng
Keyword(s):  
Compressive Strength ◽  
Objective Function ◽  
Frost Resistance ◽  
Unit Volume ◽  
Influence Factors ◽  
Multi Objective Optimization ◽  
Cold Region ◽  
Freeze Thaw ◽  
Performance Indexes ◽  
Mix Proportion

Analyze the influence factors of mix proportion affecting concrete freeze-thaw damage. Use the five main performance indexes of the concrete, which are compressive strength, strength of extension, impermeability grade, and frost resistance grade and per unit volume cost concrete, as the objective function of multi-objective optimization equation. Invoke the fgoalattain function in the MATLAB Optimization Toolbox to solve. The optimized parameters of mix proportion of frost resistance construction of unit concrete in cold region are: concrete 1532.6kg, water 910kg, sand 5510.6kg, 5-20mm cobblestone 3747.2kg、20-40mm cobblestone 3658.6kg、40-80mm cobblestone 4733.5kg、80-150mm cobblestone 4738.1kg, and the dosage of water reducing agent is 7.3kg.

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