Influence of Mineral Admixtures on early Shrinkage of Ordinary Concrete

2012 ◽  
Vol 450-451 ◽  
pp. 135-139 ◽  
Author(s):  
Li Feng Zhang ◽  
Jun Ying Lai ◽  
Xiao Qian Qian ◽  
De Long Hu
Keyword(s):  
Fly Ash ◽  
Mineral Admixtures ◽  
Plastic Film ◽  
Replacement Ratio ◽  
Building Research ◽  
Ordinary Concrete ◽  
Building Research Institute ◽  
China Academy ◽  
Binder Ratio ◽  
Water Binder Ratio

In this paper the influence of mineral admixtures on early shrinkage of ordinary concrete with the same water-binder ratio is studied by self-made equipment and CABR-NES deformation instrument developed by China Academy of Building Research Institute. All concrete specimens are cured with one surface exposed to air and others are covered with plastic film. The replacement ratio of mineral admixtures is 10%, 20% and 30%, respectively, and a mixture of a combination of both fly ash and slag is also studied. The results indicate fly ash reducing the early shrinkage of ordinary concrete, and the shrinkage decreases with the increasing of replacement ratio, but the effect is not so significant when the replacement ratio is above 20%. Slag also reduces the early shrinkage of ordinary concrete, and the shrinkage decreases with the increasing of replacement ratio, but the effect is not so significant when the replacement ratio is below 20%. Mixture with a combination of both fly ash and slag has lower shrinkage than mixture with fly ash.

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.

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%.

Influence of the Fly-Ash Content of Concrete at Low Water-Binder Ratio on Hydration Degree of Binders and Cement

2011 ◽  
Vol 250-253 ◽  
pp. 445-449
Author(s):  
Li Wei Xu ◽  
Jian Lan Zheng
Keyword(s):  
Fly Ash ◽  
Temperature Rise ◽  
High Performance Concrete ◽  
Ash Content ◽  
Adiabatic Temperature ◽  
Mineral Admixture ◽  
Hydration Degree ◽  
Adiabatic Temperature Rise ◽  
Binder Ratio ◽  
Water Binder Ratio

The hydration degree of binders and cement is investigated by measuring the adiabatic- temperature rise of concrete at low water-binder ratio with different fly-ash content. The results denote that, with a constant water-binder ratio, both of the hydration degree of binders and that of cement decrease with the increasing fly-ash content in the early stage. In a later stage, however, the hydration degree of cement increases with the increasing fly-ash content and the hydration degree of binders peaks when the fly-ash content is 35%. Fly ash is one of the mineral admixture of which high-performance concrete is made up. It brings down the rise of concrete temperature significantly and helps solve the problems of shrinkage and crack of concrete structure. Because the hydration mechanism in common concrete is different from that in concrete with low water-binder ratio, and the hydration environment is different between concrete and cement pastes, to determine the adiabatic-temperature rise of concrete directly conforms to the actual situation. The adiabatic-temperature rise, adiabatic-temperature-rise rate, hydration degree of both binders and cement are investigated by measuring adiabatic-temperature rise of concrete with different fly-ash content.

Modeling the Heat of Hydration of Concrete Incorporating Fly Ash

2016 ◽  
Vol 705 ◽  
pp. 332-337 ◽  
Author(s):  
Zheng Gang Lu ◽  
Xiu Xin Wang
Keyword(s):  
Fly Ash ◽  
Temperature Rise ◽  
Heat Of Hydration ◽  
Hyperbolic Type ◽  
Adiabatic Temperature ◽  
Adiabatic Temperature Rise ◽  
Equivalent Age ◽  
Binder Ratio ◽  
Water Binder Ratio ◽  
Release Coefficient

The hydration evolution of concrete with different water-binder ratios and fly ash replacement percentages are studied by experimental investigation. Based on equivalent age concept, the effect of water-binder ratio as well as fly ash dosage on the ultimate temperature rise and heat release coefficient are analyzed with the hyperbolic-type calculating model of adiabatic temperature rise adopted. It is indicated that the adiabatic temperature rise will be reduced with the increase of water-binder ratio and the incorporation of fly ash. The hydration evolution process will be accelerated with the decrease of water-binder ratio, but slowed down when the amount of fly ash is enhanced.

Experimental Study on Workability and Strength of Green High Performance Concrete with High Volume Fly Ash

2013 ◽  
Vol 859 ◽  
pp. 52-55 ◽  
Author(s):  
Yong Qiang Ma
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
High Volume ◽  
Ash Content ◽  
Splitting Tensile Strength ◽  
Binder Ratio ◽  
Water Binder Ratio

A great deal of experiments have been carried out in this study to reveal the effect of the water-binder ratio and fly ash content on the workability and strengths of GHPC (green high performance concrete). The workability of GHPC was evaluated by slump and slump flow. The strengths include compressive strength and splitting tensile strength. The results indicate that the increase of water-binder ratio can improve the workability of GHPC, however the strengths of GHPC were decreased with the increase of water-binder ratio. When the fly ash content is lower than 40%, the increase in fly ash content has positive effect on workability of GHPC, while the workability begins to decrease after the fly ash content is more than 40%. The addition of fly ash in GHPC has adverse effect on the strengths, and there is a tendency of decrease in the compressive strength and splitting tensile strength of GHPC with the increase of fly ash content.

Study on Tensile Creep Characteristics of High Strength Concrete

2016 ◽  
Vol 835 ◽  
pp. 535-541
Author(s):  
Guan Guo Liu ◽  
Guo Rong Zhang ◽  
Yun Sheng Zhang ◽  
Lu Lu
Keyword(s):  
Fly Ash ◽  
High Strength Concrete ◽  
High Strength ◽  
Creep Testing ◽  
Tensile Creep ◽  
Free Shrinkage ◽  
Inhibition Effect ◽  
Creep Characteristics ◽  
Binder Ratio ◽  
Water Binder Ratio

A set of concrete tensile creep testing apparatus was constructed. The tensile creep characteristics of concrete under different loading ages (1d, 3d and 7d), different water-binder ratio (0.29, 0.33 and 0.37) and different fly ash proportion (0%, 20% and 40%) were researched. The results show that tensile creep increases with increasing of water-binder ratio obviously as well as with decreasing of loading ages. The tensile creep is inhibited by addition of fly ash, and the inhibition effect increases with the increase of fly ash proportion. Free shrinkage is counteracted 42%~62% by tensile creep. The internal tension of concrete is effectively relieved so that the possibility of cracking of concrete is decreased at early ages.

Study on the Workability of High Performance Concrete Mixture with Compound Mineral Admixtures

2013 ◽  
Vol 671-674 ◽  
pp. 1839-1843
Author(s):  
Yuan Gang Wang ◽  
Chao Wan ◽  
Kai Jian Huang ◽  
Gao Qin Zhang ◽  
Ya Feng Hu
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Orthogonal Experiment ◽  
Steel Slag ◽  
Mineral Admixtures ◽  
Impact Factors ◽  
Slag Powder ◽  
Granulated Blast Furnace Slag ◽  
Binder Ratio ◽  
Water Binder Ratio

Several compound mineral admixtures, such as steel slag powder, granulated blast furnace slag powder and silica fume, are mixed with proper proportion to improve the workability of High Performance Concrete（HPC）. Through the orthogonal experiment, workability of HPC is analyzed on water-binder ratio, sand ratio, the amount of superplasticizer and the amount of compound mineral admixtures. Results show that: workability of HPC was significantly effected by the amount of naphthalene sulphonate water-reducing admixture and water-binder ratio, the amount of compound mineral admixtures and sand ratio are impact factors on the workability in a certain extent.

scholarly journals Early Strength Development of Soft Clay Stabilized by One-Part Ground Granulated Blast Furnace Slag and Fly Ash-Based Geopolymer

2021 ◽  
Vol 8 ◽  
Author(s):  
Xiyao Zheng ◽  
Jun Wu
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Soft Clay ◽  
Strength Development ◽  
Granulated Blast Furnace Slag ◽  
Binder Ratio ◽  
Early Strength ◽  
Furnace Slag ◽  
Water Binder Ratio

One-part or “just add water” geopolymer is a cementitious material, which is friendly to environment and users in applications. However, the mechanical behavior of the soft soil stabilized by one-part geopolymer is not well acknowledged. In this study, soft clay was stabilized with ground granulated blast furnace slag (GGBFS) and fly ash (FA)-based geopolymer, which is a mixture of solid aluminosilicate precursor (Al-Si raw materials: GGBFS and FA), solid alkali activator, and water. The objective was to adopt one-part geopolymer as an alternative soil binder to completely replace ordinary Portland cement (OPC) for stabilizing the soft clay and evaluate the effect of the factors (i.e., GBFS/FA ratio in Al-Si precursor, activator/Al-Si precursor ratio, and water/binder ratio) that influenced the early strength. Results showed that the increase of the FA content in the Al-Si precursor increased the unconfined compressive strength (UCS) values significantly through the geopolymerization process. The highest UCS values were achieved with 90% GGBFS to 10% FA in the precursor when the activator/precursor and water/binder ratio is 0.15 and 0.7, respectively. The UCS values of geopolymer-stabilized clay could reach 1.5 MPa at 14 days at ambient temperature, which is much higher than that of OPC-stabilized clay. The microstructure and mineralogy analyses indicated that the prolific hydration products, such as calcium silicate hydrate (C-S-H), calcium aluminum hydrate (C-A-H), and calcium aluminum silicate hydrate (C-A-S-H), contributed greatly to strengthen the soft clay by forming the soil skeleton and infilling among clay particles, while sodium aluminosilicate (N-A-S-H) gel is only served to fill the part of porosities in the soil and cannot effectively enhance the UCS of the one-part geopolymer-stabilized soft clay. This paper results suggested that one-part GGBFS-FA–based geopolymers have the potential to replace OPC in the manufacture of stabilized soft clay.

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