Water penetration resistance of the self-compacting concrete by the combined addition of micro and nano-silica

Self-compacting concrete (SCC) is also considered as a concrete which can be placed and compacted under its own weight with little or no vibration without segregation or bleeding. The use of SCC with its improving productions techniques is increasing everyday in concrete production. It is used to facilitate and ensure proper filling and good structural performance of heavily reinforced structural members. Recently, nano particles have been gaining increasing attention and have been applied in many fields to fabricate new materials with novel functions due to their unique physical and chemical properties. Degradation of concrete members exposed to aggressive sulphuric acid environments is a key durability issue that affects the life cycle performance and maintenance costs of vital civil infrastructure. Sulphuric acid in groundwater, chemical waste or generated from the oxidation of sulphur bearing compounds in backfill can attack substructure concrete members. Moreover, concrete structures in industrial zones are susceptible to deterioration due to acid rain of which sulphuric acid is a chief component. In this work 40Mpa self-compacting concrete is developed using modified Nan-Su method of mix design. Slump flow, J-Ring, V-funnel tests are conducted to justify the fresh properties of SCC and are checked against EFNARC (2005) specifications. Specimens of dimensions 150x150x150mm were cast without nano silica and with two nano silica are added in different percentages(1%, 1.5% and 2% by weight of cement) to SCC. To justify the compressive strength for 7 and 28days, specimens are tested under axial compression. Durability properties were also studied by immersing the specimensin5% HCl and5% H2SO4. The particle packing in concrete can be improved by using Nano-silica which leads to densifying of the micro and nanostructure resulting in improved mechanical properties. Nano-silica addition to cement based materials can also control the degradation of the fundamental C-S-H (calcium-silicate-hydrate) reaction of concrete caused by calcium leaching in water as well as block water penetration and therefore lead to improvements in durability.

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The Compounding and Application Mechanism of Polycarboxylate-Based Superplasticizers in the Self-Compacting Concrete

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.250-253.711 ◽

2011 ◽

Vol 250-253 ◽

pp. 711-717 ◽

Cited By ~ 2

Author(s):

Miao Miao Gui ◽

Yun Hui Fang ◽

Zi Dong Lan ◽

Fei Yu Yu ◽

Tian Xing Lin ◽

...

Keyword(s):

Steric Hindrance ◽

Graft Copolymerization ◽

Raw Materials ◽

The Self ◽

Main Mechanism ◽

Self Compacting Concrete ◽

The Given ◽

Copolymerization Reaction

Polycarboxylate-based superplasticizers are synthesized by radical graft copolymerization reaction, and the products are divided into ester series (PC-1) and ether series (PC-2) on the basis of different big monomers. This article studies on influence of the different composition and dosages of the synthetic superplasticizers in the self-compacting concrete (SCC). The results show that the requirements of SCC workability can be achieved through simple adjustment kinds and dosages of the synthetic superplasticizers under the given mix proportions and the raw materials. And the main mechanism of the polycarboxylate-based superplasticizers is steric hindrance effect.

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Experimental Study and Extended Finite Element Simulation of Fracture of Self-Compacting Rubberized Concrete

Advances in Civil Engineering ◽

10.1155/2021/6622880 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Xinquan Wang ◽

Hongguo Diao ◽

Yunliang Cui ◽

Changguang Qi ◽

Shangyu Han

Keyword(s):

Finite Element ◽

Loading Rate ◽

High Performance Concrete ◽

The Self ◽

Experimental Results ◽

Crack Mouth Opening Displacement ◽

Displacement Curve ◽

Rubberized Concrete ◽

Extended Finite Element ◽

Self Compacting Concrete

Self-compacting rubberized concrete (SCRC) is a high-performance concrete that can achieve compacting effect by self-gravity without vibration during pouring. Because of its excellent fluidity, homogeneity, and stability, the application of self-compacting concrete in engineering can improve work efficiency and reduce project cost. The effects of loading rate on the fracture behavior of self-compacting concrete were studied in this paper. Three-point bend (TPB) tests were carried out at five loading rates of 1, 0.1, 0.001, 0.0001, and 0.00001 mm/s. The dimensions of the specimens were 100 mm × 100 mm × 400 mm. A precast crack was set in the middle of the specimen with a notch-depth ratio of 0.4. The experimental results show that the peak load on the load-CMOD (crack mouth opening displacement) curve gradually increases with the increase of the loading rate. Although the fracture energy a presented greater dispersion under the loading rate of 1 mm/s, the overall changes were still rising with the increase of the loading rate. Besides studying the softening characteristics of the self-compacting concrete, the constitutive softening curve of the self-compacting concrete was obtained using the bilinear model. Finally, curved three-point bending beams were simulated by using the extended finite element method based on ABAQUS. The fracture process of the self-compacting concrete under different loading conditions was analyzed more intuitively. The simulation results were compared with the experimental results, and the same conclusions were obtained.

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