scholarly journals Experimental Study on Freezing and Thawing Cycles of Shrinkage-Compensating Concrete with Double Expansive Agents

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1850
Author(s):  
Jinjun Guo ◽  
Ting Guo ◽  
Shiwei Zhang ◽  
Yan Lu
Keyword(s):  
Frost Resistance ◽  
Large Scale ◽  
Mass Loss Rate ◽  
Test Results ◽  
Freezing And Thawing ◽  
Expansive Agent ◽  
Hydraulic Concrete ◽  
Mix Proportion ◽  
Three Stages ◽  
Freezing And Thawing Cycles

The freezing and thawing of construction concrete is becoming an increasingly important structural challenge. In this study, a shrinkage-compensating concrete based on a double expansive admixture was developed and its frost resistance was assessed through rapid freezing and thawing cycling. The frost resistance of the concrete was derived through the measurement and calculation of the relative dynamic modulus of elasticity (RDME) and the mass loss rate (MLR), and the freezing- and thawing-cycle microstructures and products of concretes with different expansive agents were analyzed using scanning electron microscopy (SEM). It was shown that changes in the properties of the concrete under freezing and thawing could be divided into three stages: slow-damage stage, fast-damage stage, and stable stage. Compared to concrete without an expansive agent, a single-expansive-agent concrete demonstrated excellent frost resistance during the slow-damage stage, but the frost resistance rapidly decreased during the fast-damage age. After 150 cycles (the stable-damage stage), the concrete with a U-type expansive agent (UEA): MgO expansive agent (MEA) mix proportion of 2:1 had the best frost resistance, with RDME and MLR values 17.35% higher and 25.1% lower respectively, than that of an expansive-agent-free concrete. These test results provide a basis for the study of frost resistance in large-scale hydraulic concrete structures.

Study of Frost Resistance on Air-Entrained Concrete in Sulfated Medium

2006 ◽  
Vol 302-303 ◽  
pp. 125-130 ◽  
Author(s):  
Ge Yong ◽  
Yuan Jie ◽  
Wen Cui Yang ◽  
Bao Sheng Zhang
Keyword(s):  
Fresh Water ◽  
Frost Resistance ◽  
Plain Concrete ◽  
Sulfate Solution ◽  
Test Results ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Freezing And Thawing Cycles ◽  
Air Entrained Concrete ◽  
Sodium Solution

Frost resistance of plain concrete and air-entrained concrete subjected to freeze-thaw cycles in fresh water and 5 % and 7 % sodium sulfate solution are investigated in this paper. The test results show that the frost resistance of concrete is different in the different medium. The properties of concrete frozen in 5 % and 7 % sodium solution are different from that in fresh water, and entraining air into concrete properly can increase the frost resistance significantly whether in fresh water or in sulfate solution. Higher strength concrete could resist the degradation of freezing and thawing cycles in water, but some of them failed suddenly in midspan of specimens under the sulfate solution.

scholarly journals Proposed Model for Stress-strain Behavior of Fly Ash Concrete Under the Freezing and Thawing Cycles

2020 ◽  
Author(s):  
Ali Hemmati ◽  
Heydar Arab
Keyword(s):  
Fly Ash ◽  
Numerical Models ◽  
Test Results ◽  
Freezing And Thawing ◽  
Stress Strain ◽  
Strain Behavior ◽  
Fly Ash Concrete ◽  
Proposed Model ◽  
The Difference ◽  
Freezing And Thawing Cycles

Fly ash is a supplementary cement material using instead of Portland cement in concrete. Using this material concludes to less emission of greenhouse gas and less water demand of concrete. In this paper, an experimental investigation was carried out on compressive stress–strain behavior of three groups of concrete specimens with different water/cement ratios (0.45, 0.5 and 0.55), containing 0, 10, 20, 30 and 40 percent of fly ash (by weight), after subjecting to freezing and thawing cycles. 0, 45, 100 and 150 cycles of freezing and thawing were applied on these specimens according to ASTM C666 and the results presented. Numerical models for the stress–strain behavior of these frozen-thawed concrete were developed and compared with the available experimental data. Results show that the maximum compressive strength of these concrete specimens exposing cycles of freezing and thawing is gained by using about 10 % of fly ash. Moreover, there is a good agreement between the proposed models and test results and the difference is less than 5 %.

scholarly journals Durability of Hydrophobic/Icephobic Coatings in Protection of Lightweight Concrete with Waste Aggregate

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 101
Author(s):  
Danuta Barnat-Hunek ◽  
Jacek Góra ◽  
Marcin K. Widomski
Keyword(s):  
Frost Resistance ◽  
Lightweight Concrete ◽  
Physical And Mechanical Properties ◽  
High Porosity ◽  
Freezing And Thawing ◽  
Adhesive Properties ◽  
Surface Protection ◽  
High Durability ◽  
Before And After ◽  
Freezing And Thawing Cycles

The aim of the research presented in this paper is to evaluate the feasibility of using hydrophobic agents based on organosilicon compounds for surface protection of lightweight concrete modified with waste polystyrene. The experimental part pertains to the physical and mechanical properties of polystyrene-modified lightweight concrete. The concrete samples were prepared with the following ingredients: CEM I 42.5 R cement, recycled polystyrene (0–2 mm), quartz sand (0–2 mm), coarse river aggregate (2–16 mm), and water. Silane and tetramethoxysilane were employed for surface hydrophobization. Concrete with 20% polystyrene exhibits high porosity (25.22%), which is related to an increase in absorptivity (14.75%) compared to the reference concrete. The hydrophobized concrete is characterized by the lowest surface free energy (SFE) value, which is 7 or 11 times lower than the value of reference concrete, depending on the agents. The test on the contact angle (CA) was performed before and after the frost-resistance test (F–T test). Lower SFE translates into lower adhesive properties, higher resistance of the material to the infiltration of water and corrosive compounds, e.g., salts, and higher resistance to freezing and thawing cycles. Silane and tetramethoxysilane coating raised frost resistance by 54–58% compared to the reference samples. This agent reduced absorptivity by 30%. Recycled polystyrene can be successfully used to produce lightweight concrete (LC) with high durability provided by hydrophobic/icephobic coatings.

Sulfate and Frost Resistance of Mass Hydraulic Concrete

2006 ◽  
Vol 302-303 ◽  
pp. 191-196
Author(s):  
Pei Wei Gao ◽  
Sheng Xing Wu ◽  
Ping Hua Lin ◽  
Zhong Ru Wu ◽  
Ming Shu Tang
Keyword(s):  
Fly Ash ◽  
Frost Resistance ◽  
Sulfate Attack ◽  
Sulfate Resistance ◽  
Expansive Agent ◽  
Hydraulic Concrete ◽  
Binder Ratio ◽  
Water Binder Ratio

This paper discusses the sulfate resistance and frost of mass hydraulic concrete which containing fly ash, superplasticizer and a novel MgO-bearing expansive agent (HNM), at same time, the mechanisms and processes of sulfate attack on it have been proposed. Results showed that using a water/binder ratio of 0.48 in RCC containing 50 % fly ash and 8 % HNM a durability factor of over D300 can be achieved and sulfate resistance may be improved slightly.

scholarly journals Structural and Techno-Functional Properties of Cassava Starches and Application on Cheese Bread

2020 ◽  
Vol 11 (1) ◽  
pp. 7400-7409
Keyword(s):  
Functional Properties ◽  
Large Scale ◽  
Xrd Analysis ◽  
Technological Advancement ◽  
Freezing And Thawing ◽  
Sem Images ◽  
X Ray ◽  
Modified Starches ◽  
Diffraction Patterns ◽  
Freezing And Thawing Cycles

This study aims to evaluate the structural and techno-functional properties of native and modified cassava starches, focusing on the production of frozen cheese bun formulations. The structural and techno-functional properties of cassava starches, both native and modified, were evaluated via thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), baking properties, as well as, resistance to freezing and thawing cycles. The native sample containing 17% of amylose had the highest expansion rate among the tested starches. In contrast, pre-gelatinized acetylated starches showed little expansion capacity. The starch samples displayed resistance to up to 2 freezing and thawing cycles. The XRD analysis showed that native and modified starches had high crystallinity and similar diffraction patterns. SEM images revealed that modified starches possess smaller particles (32 to 52 μm) with a greater surface area when compared to the native samples. Modified samples also displayed surface indentations, which would explain their greater water absorption potential. TGA analysis has shown a reduction (P<0.05) in the modified starches thermal stability. These data are relevant technological advancement of the cheese bun industry since choosing adequate starch is crucial to ensure the final product's quality in large scale industrial production.

Study of Frost Resistance of 50 Years Concrete Exposed to Saline Areas

2013 ◽  
Vol 275-277 ◽  
pp. 1341-1346
Author(s):  
De Cheng Zhang ◽  
Yan Ping Lv ◽  
Zheng Mao Ye
Keyword(s):  
Frost Resistance ◽  
High Performance ◽  
Large Temperature ◽  
Freezing And Thawing ◽  
The North ◽  
Single Side ◽  
Concrete Mechanical Properties ◽  
Saline Area ◽  
Design Requirements ◽  
Freezing And Thawing Cycles

The Hong Run petrochemical oil depot is located in a saline area in the north of Weifang.This area is severe cold in winter and has large temperature span throughout a year. Due to the area's rigorous environmental conditions, concrete with 50 years durability and strength grade of C40 was fabricated with the ordinary Portland cement, high performance superfine mineral powder and high performance pumping agent. Tests using the onsite concrete samples show that concrete mechanical properties meet the design requirements. After 300 freezing and thawing cycles including accelerated freezing thawing method and single-side freezing thawing method, the quality loss rate and relative dynamic modulus both comply with the design requirements. This suggests that the sample concrete has excellent frost resistance ability.

Dependence of Relative Decreasing in Strength by Rate of Strain for the New Rapid Method for Determination of Concrete Frost Resistance

2015 ◽  
Vol 725-726 ◽  
pp. 505-510
Author(s):  
Olga Pertseva ◽  
Sergey Nikolskiy
Keyword(s):  
Tensile Strength ◽  
Rapid Method ◽  
Frost Resistance ◽  
New Method ◽  
Basic Method ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Freezing And Thawing Cycles ◽  
Non Destructive

The task of the project is obtaining the dependence between the relative decreasing of strength and rate of strain and substantiation of the new method for determination of concrete frost resistance. It has been analytically proved that using concrete’s rate of strain ε as a measure of damage, instead of decreasing of tensile strength R, increases freeze-thaw resistance’s accuracy of estimation a lot under otherwise equal conditions by the time of freeze-thaw cycling. Also it has been experimentally shown that ratio of relative decreasing R to ε in direction, perpendicular to compression, is assumed to be independent on values R and ε for a given concrete and on the ways of achieving them during mechanical or freeze-thaw cycling. To determine the dependence δR/R by ε (z) 8 specimens were tested by non-destructive method (RU 2 490 631) and two baths of 50 specimens by basic method (thermo cycling). Results of the non-destructive method are different from results by basic method for 6,3%. Dependence of relative decreasing in strength by rate of strain is near to linear and, therefore, value of z is constant. Taking this into account patented methods for estimation of concrete’s freeze-thaw resistance as per values R and ε received after freezing and thawing cycles of some specimens and their postlimenary failure by linear compression was substantiated.

Influence of Quality and Replacement Rate of Recycled Coarse Aggregate on the Frost Resistance of Recycled Concrete

2017 ◽  
Vol 898 ◽  
pp. 2046-2049 ◽  
Author(s):  
Gong Bing Yue ◽  
Qiu Yi Li ◽  
Jian Lin Luo ◽  
Yuan Xin Guo
Keyword(s):  
Frost Resistance ◽  
Coarse Aggregate ◽  
Mass Loss Rate ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Fine Aggregate ◽  
Freezing And Thawing ◽  
Aggregate Concrete ◽  
Ordinary Concrete ◽  
Recycled Coarse Aggregate

Compared with natural aggregate, the content of hardening cement in recycled aggregate is larger, which leads that the water absorption of recycled aggregate is larger and its performance such as robustness is poorer. And the engineering field pays much attention to the problem of the recycled fine aggregate which can be used in the durability requirements of recycled concrete or not. Using the method of fast freezing and thawing the influence of quality and replacement ratio of recycled coarse aggregate on the frost resistance of recycled concrete was researched basing on ordinary concrete frost resistance performance. The results showed that, in terms of the frost resistance capacity, the order is in: ordinary concrete>high-quality recycled coarse aggregate concrete>normal quality recycled coarse aggregate concrete. After 250 freeze-thaw cycles, the mass loss rate of general quality recycled coarse aggregate concrete is 5%, relative dynamic elastic modulus is 60% when replace rate was 100%.

scholarly journals Effect of Hydrophobic Treatments on Improving the Salt Frost Resistance of Concrete

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5361
Author(s):  
Guo Li ◽  
Chunhua Fan ◽  
Yajun Lv ◽  
Fujun Fan
Keyword(s):  
Water Absorption ◽  
Frost Resistance ◽  
Contact Angles ◽  
Water Repellent ◽  
Freezing And Thawing ◽  
Ordinary Water ◽  
Salt Scaling ◽  
Mass Losses ◽  
Hydrophobic Treatment ◽  
Freezing And Thawing Cycles

Hydrophobic treatment is an important method to improve the waterproof properties of concrete. To evaluate the effectiveness of hydrophobic treatments on improving the salt frost resistance of concrete, two representative commercial ordinary water repellent agents of silane and organosilicone emulsion were selected, and concrete specimens with three water/cement ratios were fabricated. After the application of repellent agents on concrete surfaces, accelerated saline (5% MgCl2) freeze-thaw cycles were conducted on the specimens. The mass losses and relative dynamic modulus of elasticity (RDME) of concrete were tested periodically. The contact angles and water absorption ratios of concrete with and without hydrophobic treatments were also tested. Results showed that the repellent agents could substantially enhance the hydrophobicity of concrete and greatly reduce its water absorption. Different repellent agents exerted diverse improvements on concrete hydrophobicity. Meanwhile, the repellent agents could improve concrete resistance against salt scaling and RDME losses to a certain degree, and concrete with strong hydrophobicity showed relatively high salt frost resistance. However, the ordinary water repellent agents cannot achieve the same enhancement on salt frost resistance of concrete as that on the water hydrophobicity of concrete. With saline freezing and thawing cycles, the hydrophobic layer formed by the repellent agents on superficial concrete was destroyed gradually. As a result, the salt frost resistance of concrete from the hydrophobic treatments was ultimately lost.

Study on Frost Resistance of Concrete Used in Pavement of Northeast China

2011 ◽  
Vol 71-78 ◽  
pp. 728-732
Author(s):  
Song Gao ◽  
Li Dai
Keyword(s):  
Compression Strength ◽  
Frost Resistance ◽  
Northeast China ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Silicon Powder ◽  
Early Spring ◽  
Good Prospect ◽  
Freezing And Thawing ◽  
Flexure Strength

According to the cycles of freezing and thawing frequently happened during early spring and late autumn in northeast china, this paper studies on the frost resistance of concrete using in highway pavement. Making experiments by adding flyash, silicon powder, air entraining and water reducing agent to normal concrete with different proportions and using flexure strength, compression strength and mass loss rate of concrete as evaluating indicators, a reasonable and economic concrete proportion is determined, which reaches high flexure strength and compression strength, good frost resistance. On the bases of the experimental results and economic analysis, it is shown that the concrete proportion can effectively enhance the frost resistance of concrete. Therefore, it has good use value and it is promising with a good prospect of application.

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