Effects of Water-Binder Ratio and Coarse Aggregate Content on Interior Humidity, Autogenous Shrinkage, and Drying Shrinkage of Concrete

2014 ◽  
Vol 26 (1) ◽  
pp. 184-189 ◽  
Author(s):  
Jun Zhang ◽  
Yu Dong Han ◽  
Yuan Gao
Keyword(s):  
Coarse Aggregate ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Aggregate Content ◽  
Binder Ratio ◽  
Water Binder Ratio

scholarly journals Synthesis of a New Polycarboxylate at Room Temperature and Its Influence on the Properties of Cement Pastes with Different Supplementary Cementitious Materials

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Shuncheng Xiang ◽  
Yingli Gao ◽  
Caijun Shi
Keyword(s):  
Room Temperature ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Cementitious Materials ◽  
Heat Evolution ◽  
Hydration Heat ◽  
Supplementary Cementitious Materials ◽  
Cement Pastes ◽  
Binder Ratio ◽  
Water Binder Ratio

Three polycarboxylates with different comb structures (i.e., the same degree of polymerization in side chains but different main chains) were synthesized via radical polymerization reaction at room temperature. The effect of polycarboxylates on the surface tension and the flowability in cement pastes was determined. The best product was selected to study its effects on the hydration heat evolution, compressive strength, autogenous shrinkage, and drying shrinkage of cement pastes with different kinds and contents of supplementary cementitious materials. The results showed that with the increase of molar ratio between AA and TPEG to 6 : 1, we could synthesis the best product. When the water-binder ratio was 0.4, with the increase of polycarboxylates, the cement hydration heat evolution had been slowed down, and the more the dosage was, the more obvious the effect was. Adding supplementary cementitious materials to cement under the same experimental conditions also played a mitigation role in slowing down the hydration heat. When the water-binder ratio was 0.3, supplementary cementitious materials could increase the strength of cement by 24.5% in maximum; its autogenous shrinkage and drying shrinkage could be decreased, respectively, by 60.1% and 21.9% in the lowest.

Analysis of Concrete Early-Age Shrinkage Based on the Theory of Humidity Diffusion

2011 ◽  
Vol 462-463 ◽  
pp. 183-187 ◽  
Author(s):  
Yun Feng Li ◽  
Rong Qiang Du ◽  
Fan Ying Kong
Keyword(s):  
Cement Content ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Analytical Models ◽  
Early Age ◽  
Free Shrinkage ◽  
Shrinkage Cracking ◽  
Binder Ratio ◽  
Water Binder Ratio

The early-age shrinkage cracking of concrete plays an important role to the accelerated deterioration and shortening the service life of concrete structures. Modern concretes are more sensitive to cracking immediately after setting, which is due to material characteristics (lower water/binder ratio and higher cement content) and external environmental fluctuations (humidity and temperature change). Determination of concrete free shrinkage is the basis of shrinkage cracking research. Analytical models of the autogenous shrinkage and drying shrinkage are established in this paper. The calculated results agree well with the experimental results.

Effect of Styrene-Acrylic Emulsion on Crack Resistance of Cement-Based Materials

2021 ◽  
Vol 1036 ◽  
pp. 288-300
Author(s):  
Jun Peng Mei ◽  
Hai Nan Li ◽  
Zhi Dong Xu
Keyword(s):  
Elastic Modulus ◽  
Crack Resistance ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Cementitious Materials ◽  
Strength Ratio ◽  
Acrylic Emulsion ◽  
Cement Based Materials ◽  
Binder Ratio ◽  
Water Binder Ratio

In this paper, the brittleness coefficient, elastic modulus-to-strength ratio, drying shrinkage and autogenous shrinkage and cracking sensitivity were used to investigate the effect of styrene-acrylic emulsion (SAE) on crack resistance of cement-based materials under ultralow water binder ratio (0.22). Then the pore structures, hydration products and surface morphology were also studied to explore the mechanism of SAE on improving the crack resistance of cement-based materials. Results show that, the addition of SAE significantly reduces the elastic modulus, brittleness coefficient, elastic strength ratio, drying shrinkage and autogenous shrinkage of the specimen. The cracking susceptibility is also decreased by the incorporation of SAE and when the dosage of SAE was 5%, the initial cracking time would be extended by 43 hours. In addition, incorporation of SAE can reduce the amount of pores that have an adverse effect on shrinkage, refine the microstructure and decrease the calcium hydroxide formation and microcracks of cement-based materials. Such results would be expected to provide guidance on enhancing the anti-cracking ability of high-performance cementitious materials by the dosage of SAE under low water-binder ratio in practical engineering.

scholarly journals Experimental Study on Durability Improvement of Fly Ash Concrete with Durability Improving Admixture

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Hong-zhu Quan ◽  
Hideo Kasami
Keyword(s):  
Fly Ash ◽  
Experimental Studies ◽  
Drying Shrinkage ◽  
Replacement Ratio ◽  
Fly Ash Concrete ◽  
Air Content ◽  
Carbonation Resistance ◽  
Binder Ratio ◽  
Water Binder Ratio

In order to improve the durability of fly ash concrete, a series of experimental studies are carried out, where durability improving admixture is used to reduce drying shrinkage and improve freezing-thawing resistance. The effects of durability improving admixture, air content, water-binder ratio, and fly ash replacement ratio on the performance of fly ash concrete are discussed in this paper. The results show that by using durability improving admixture in nonair-entraining fly ash concrete, the compressive strength of fly ash concrete can be improved by 10%–20%, and the drying shrinkage is reduced by 60%. Carbonation resistance of concrete is roughly proportional to water-cement ratio regardless of water-binder ratio and fly ash replacement ratio. For the specimens cured in air for 2 weeks, the freezing-thawing resistance is improved. In addition, by making use of durability improving admixture, it is easier to control the air content and make fly ash concrete into nonair-entraining one. The quality of fly ash concrete is thereby optimized.

Proportion Design of Autoclaved Cement Concrete Based on High Strength

2011 ◽  
Vol 391-392 ◽  
pp. 161-164
Author(s):  
Tie Quan Ni ◽  
Chang Jun Ke ◽  
Li Zhang
Keyword(s):  
Coarse Aggregate ◽  
High Strength ◽  
Orthogonal Test ◽  
Mineral Admixture ◽  
Mix Design ◽  
Hydration Reaction ◽  
Cement Concrete ◽  
Binder Ratio ◽  
Four Levels ◽  
Water Binder Ratio

According to the particularity of the autoclaved cement concrete that partial aggregate could participate in hydration reaction in the process of autoclaving, the optimal gradation of coarse aggregate and the optimal slurry aggregate ratio is studied, and the effect of water reducing agent for fluidity of cement paste is also studied. The optimized mix design of autoclaved cement concrete based on high strength (compressive strength and flexural strength) is done by orthogonal test with four factors (water-binder ratio, type of mineral admixture, amount and sand ratio) and four levels.

scholarly journals Self-Compacting Concrete with Recycled Coarse Aggregate and Manufactured Sand

2019 ◽  
Vol 9 (1) ◽  
pp. 3868-3873
Keyword(s):  
Coarse Aggregate ◽  
Recycled Aggregate ◽  
Fine Aggregate ◽  
Fresh Properties ◽  
Self Compacting Concrete ◽  
Manufactured Sand ◽  
Recycled Coarse Aggregate ◽  
Recycle Coarse Aggregate ◽  
Binder Ratio ◽  
Water Binder Ratio

This article mainly focused on the influence of recycle coarse aggregate and manufactured sand on the properties of self compacting concrete (SCC). The main purpose of this research is reuse of recycled aggregate in SCC and also to reduce use of fine aggregate by replacing manufactured sand. The SCC mixtures were prepared with 0, 25, 50, 75 and 100% replacement of recycle coarse aggregate in natural coarse aggregate and M-Sand in fine aggregate with a Water/Binder ratio of 0.36. Different test covering fresh properties of these SCC mixtures were executed the results were compared with EFNARC guidelines and IS 10262:2019. The feasibility of utilizing recycled aggregate and M-Sand in self compacting concrete has been examined and found that it is suitable for concrete.

Effect of High Volumes of Fly Ash on Flowability and Drying Shrinkage of Engineered Cementitious Composites

2011 ◽  
Vol 675-677 ◽  
pp. 61-64
Author(s):  
Yu Zhu ◽  
Ying Zi Yang ◽  
Yan Yao
Keyword(s):  
Fly Ash ◽  
Drying Shrinkage ◽  
Ash Content ◽  
Experimental Results ◽  
Replacement Ratio ◽  
Slump Flow ◽  
Binder Ratio ◽  
Deformation Test ◽  
Flow Deformation ◽  
Water Binder Ratio

In order to investigate flowability and drying shrinkage of ECC, mini-slump flow deformation test and drying shrinkage are employed to analyse the influence of fly ash on the flowability and shrinkage of ECC. The water-binder ratio is kept at 0.25. The replacement ratio of cement by fly ash is 50%, 60%, 70% and 80%, respectively. The experimental results show that fluidity of fresh cment paste increases obviously as the fly ash becomes larger. The drying shrinkage of ECC specimens is greatly reduced as the content of fly ash increases from 50% to 80%. The measured drying shrinkage strian of ECC specimens with 80% fly ash at 28 days is less than 1000×10-6. 25% reduction of drying shrinkage of ECC is found when the fly ash content increases from 50% to 80%.

scholarly journals Experimental Study on Autogenous and Drying Shrinkage of Steel Fiber Reinforced Lightweight-Aggregate Concrete

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Shunbo Zhao ◽  
Changyong Li ◽  
Mingshuang Zhao ◽  
Xiaoyan Zhang
Keyword(s):  
Steel Fiber ◽  
Volume Fraction ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Fiber Reinforced ◽  
Aggregate Concrete ◽  
Binder Ratio ◽  
Water To Binder Ratio

Steel fiber reinforced lightweight-aggregate concrete (SFRLAC) has many advantages applied in structural engineering. In this paper, the autogenous shrinkage and drying shrinkage of SFRLAC for up to 270 days were measured, considering the effects of types of coarse and fine aggregates with the changes of water-to-binder ratio and volume fraction of steel fiber, respectively. The properties of mix workability, apparent density, and compressive strength of SFRLAC were also reported and discussed in relation to above factors. Test results show that the development of autogenous and drying shrinkage of SFRLAC was fast within 28 days and tended to be steady after 90 days. The development of autogenous shrinkage of SFRLAC reduced with the increasing water-to-binder ratio and by using the expanded shale with higher soundness and good water absorption, especially at early age within 28 days; the later drying shrinkage was reduced and the development of drying shrinkage was slowed down with the increasing volume fraction of steel fiber obviously; manufactured sand led to less autogenous shrinkage but greater drying shrinkage than fine lightweight aggregate in SFRLAC. The regularities of autogenous shrinkage and drying shrinkage of SFRLAC expressed as the series of hyperbola are analyzed.

scholarly journals Shrinkage Effects of Using Fly Ash instead of Fine Aggregate in Concrete Mixtures

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Dongsheng Zhang ◽  
Pengfei Han ◽  
Qiuning Yang ◽  
Mingjie Mao
Keyword(s):  
Fly Ash ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Experimental Results ◽  
Fine Aggregate ◽  
Ordinary Concrete ◽  
Concrete Shrinkage ◽  
Substitution Level ◽  
Concrete Mixtures ◽  
Binder Ratio

China is the world’s largest emitter of fly ash, an industrial by-product of coal combustion. Motivated towards greener development, China’s engineering industries must determine how to effectively utilize this by-product, while ensuring environmental and public safety protections. This study investigated the use of fly ash instead of fine aggregate in concrete mixtures with a focus on concrete shrinkage. A series of experiments were performed in which fly ash substitution levels, water-binder ratios, and ambient humidities were each respectively and exclusively varied to determine changes in the concrete’s drying and autogenous shrinkages. Experimental results indicated that the substitution of fly ash consistently decreased the drying shrinkage relative to ordinary concrete; a substitution level of 25% optimally reduced the drying shrinkage by 20.81%. A substitution level of 15% decreased the autogenous shrinkage relative to ordinary concrete, whereas higher levels (25, 35, and 45%) increased it. Ambient humidities also affected the concrete shrinkage, but the water-to-binder ratio effects were negligible. Drying shrinkage largely occurred before 28 d, whereas autogenous shrinkage continued after 28 d. Based on these experimental results, we evaluated common theoretical shrinkage models and subsequently developed a modified shrinkage model for application to concrete containing fly ash as fine aggregate.

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