scholarly journals Impact of Air Entrainment on the Microstructure and Mechanical Performance of High Performance Mortar

2014 ◽  
Vol 629-630 ◽  
pp. 358-365
Author(s):  
Jeroen Dils ◽  
Veerle Boel ◽  
Geert de Schutter
Keyword(s):  
Pore Structure ◽  
High Performance ◽  
Mercury Intrusion Porosimetry ◽  
Mechanical Performance ◽  
Air Entrainment ◽  
Air Bubbles ◽  
Mercury Intrusion ◽  
Freeze Thaw ◽  
Air Content ◽  
Air Entraining Agents

High performance self-compacting mortar has the ability to push out air bubbles under its own weight. Consequently, the resistance against freeze-thaw cycles with or without deicing salts can decrease due to the total air content reduction. In order to assure the necessary expansion zones1,2 air entraining agents (AEA) are commonly used to increase the amount of stable air bubbles. Depending on the mixture, the workability and rheology decrease or increase by the entrained air bubbles3. This will depend on the ratio between the surface tension and the shear stress applied during the test. If the latter can overcome the first, the bubbles will deform and increase the fluidity of the mixture. Besides the influence on the durability and the fresh concrete, air entraining agents also alter the pore structure and the mechanical performance of the mortar. The effect of AEA on these properties is the subject of this paper. The pore structure is examined on two different levels. On the one hand, mercury intrusion porosimetry is used to investigate the capillary porosity, ranging from 10 nm to 10 μm. On the other hand air void analysis and fluorescence microscopy is performed to evaluate the larger air bubbles ranging from 0.1 mm to 1 mm4. Both techniques showed an overlap in their measuring range. Consequently it was possible to compare the techniques critically. Similar as in literature, mercury intrusion porosimetry underestimates the amount of larger air bubbles in mortar, due to its measuring principle5. Furthermore, the bubbles with a diameter of 80 μm increase significantly by the addition of AEA. This confirms the average air bubble size often used in literature to explain the influence of AEA on the workability and rheology3. The influence of air entraining agent on the mechanical performance was tested by the compressive and bending tensile strength. In conclusion, a good balance is necessary between the air content necessary for a proper freeze-thaw resistance without changing the mechanical performance drastically.

Bubble Characteristics as they Pertain to Compressive Strength and Freeze-Thaw Durability

1987 ◽  
Vol 114 ◽  
Author(s):  
Paul F. Gutmann
Keyword(s):  
Compressive Strength ◽  
Air Entrainment ◽  
Organic Chemicals ◽  
Freeze Thaw ◽  
Wood Resin ◽  
Chemical Agents ◽  
Bubble Characteristics ◽  
Air Entraining Agents

There are numerous chemical agents to achieve the specified air entrainment system. Generally, these are organic chemicals which are broadly classified as soaps and detergents. One of the best known chemical agents of this type is known in the art as Vinsol resin, manufactured by Hercules, Inc., which is a wood resin salt and is the standard against which other air-entraining agents are tested under ASTM C-233.

scholarly journals Ink-bottle Effect and Pore Size Distribution of Cementitious Materials Identified by Pressurization–Depressurization Cycling Mercury Intrusion Porosimetry

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1454 ◽  
Author(s):  
Yong Zhang ◽  
Bin Yang ◽  
Zhengxian Yang ◽  
Guang Ye
Keyword(s):  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Mercury Intrusion Porosimetry ◽  
Cementitious Materials ◽  
Limestone Powder ◽  
Accurate Estimation ◽  
Mercury Intrusion ◽  
Pore Size Distributions

Capturing the long-term performance of concrete must be underpinned by a detailed understanding of the pore structure. Mercury intrusion porosimetry (MIP) is a widely used technique for pore structure characterization. However, it has been proven inappropriate to measure the pore size distribution of cementitious materials due to the ink-bottle effect. MIP with cyclic pressurization–depressurization can overcome the ink-bottle effect and enables a distinction between large (ink-bottle) pores and small (throat) pores. In this paper, pressurization–depressurization cycling mercury intrusion porosimetry (PDC-MIP) is adopted to characterize the pore structure in a range of cementitious pastes cured from 28 to 370 days. The results indicate that PDC-MIP provides a more accurate estimation of the pore size distribution in cementitious pastes than the standard MIP. Bimodal pore size distributions can be obtained by performing PDC-MIP measurements on cementitious pastes, regardless of the age. Water–binder ratio, fly ash and limestone powder have considerable influences on the formation of capillary pores ranging from 0.01 to 0.5 µm.

Physical and Chemical Influence of Polyacrylate Latex on Cement Mortars

2011 ◽  
Vol 261-263 ◽  
pp. 807-811 ◽  
Author(s):  
Ye Tian ◽  
Zong Jin Li ◽  
Hong Yan Ma ◽  
Xian Yu Jin ◽  
Nan Guo Jin
Keyword(s):  
Pore Structure ◽  
Cement Hydration ◽  
Bending Strength ◽  
Mechanical Performance ◽  
Air Entrainment ◽  
Hydration Products ◽  
Cement Mortars ◽  
Cement Based Materials ◽  
Physical And Chemical ◽  
Chemical Influence

In this research, the physical and chemical influence of polyacrylate (PA) latex on cement-based materials were studied using polymer modified mortars with polymer/cement (P/C) ratios of 0%, 5% and 10%. Physically, the mechanical performance of PA latex modified mortars was investigated with compression toughness energy and bending strength. Further more, a comparison of the pore structure and porosity between PA latex modified and unmodified mortars was conducted. The chemical reactions between PA polymer and cement hydrates were clarified with thermogravimetric (TG) analysis. It can be concluded from this research that PA polymer can refine the pore structure of cement mortars and link the cement hydration products together chemically. While, at the same time, PA latex addition can cause air entrainment which will weaken the physical behavior of cement mortars. So there is an optimum P/C ratio to achieve the best mechanical properties. And in this research, the optimum P/C ratio is 5%.

scholarly journals Study on the Pore Structure Characteristics of Ferronickel-Slag-Mixed Ternary-Blended Cement

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4863
Author(s):  
Won Jung Cho ◽  
Min Jae Kim ◽  
Ji Seok Kim
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Pore Structure ◽  
Mercury Intrusion Porosimetry ◽  
Chloride Transport ◽  
Blended Cement ◽  
Cement Matrix ◽  
X Ray ◽  
Mercury Intrusion ◽  
Ferronickel Slag

Pore structure development in Portland cement, fly ash, or/and ferronickel slag (FNS) was investigated using mercury intrusion porosimetry and X-ray CT tomography. The progress of hydration was observed using X-ray diffraction (XRD) analysis and compressive strength while durability of concrete was monitored by chloride penetration resistance and chloride profiles. Mercury intrusion porosimetry (MIP) results suggested that the blended cement had a higher porosity while lower critical pore size. The major reason to this increased porosity was the formation of meso and micro pores compared to ordinary Portland cement (OPC). In terms of chloride transport, replaced cement, especially ternary-blended cement had higher resistance to chloride transport and exhibited slightly lower development of compressive strength. X-ray CT tomography shows that the influence of pore structure of ternary-blended cement on the ionic transport was strongly related to the pore connectivity of cement matrix.

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