scholarly journals Durability of Portland Concrete Containing Polymeric Fillers and Fly Ash

2019 ◽  
Vol 26 (1) ◽  
pp. 103-108
Author(s):  
Witold BROSTOW ◽  
Nonso CHETUYA ◽  
Osman GENCEL ◽  
Hee Jae HONG ◽  
Noah MENARD ◽  
...  
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Crack Propagation ◽  
Abrasive Wear ◽  
Brittle Failure ◽  
Wear Loss ◽  
Polymer Swelling ◽  
Wear Rates ◽  
Freeze Thaw ◽  
Acidic Degradation

Portland concrete suffers in service brittle failure, extensive crack propagation, and wear rates increasing with time. In spite of all the effort expended, these problems persisted when we had started our project. We used several polymeric fillers and fly ash. Higher compressive moduli than the starting concrete are seen for some compositions, the highest for 5 % of one of the polymers + 5 % fly ash. The same composition has the lowest Taber abrasive wear loss. All composites show lower wear loss values than Portland concrete. After 25 days of acidic degradation in 4.0 molar aq. HCl, the starting Portland concrete suffers stronger degradation that our composites. Polymer swelling mitigates acidic degradation. Repetitive freeze-thaw cycles between 15oF and 85oF show disappearance of the deep voids present before the first cycle in our composites—but not in the Portland cement. While the use of fly ash mitigates contamination of the environment, it is the combination of fly ash with polymers which provides significantly improved properties - tribological, chemical and mechanical ones – of the Portland concrete.

Investigation on Two-Body Abrasive Wear Behavior of Tungsten Carbide Filled Glass Fabric-Epoxy Hybrid Composites

2010 ◽  
Vol 123-125 ◽  
pp. 1039-1042 ◽  
Author(s):  
S.P. Kumaresh Babu ◽  
Anand Chairman ◽  
N. Mohan ◽  
Siddaramaiah
Keyword(s):  
Abrasive Wear ◽  
Tungsten Carbide ◽  
Large Scale ◽  
Hybrid Composites ◽  
Wear Behavior ◽  
Constant Load ◽  
Glass Fabric ◽  
Wear Behaviour ◽  
Wear Loss ◽  
Wear Rates

The effect of tungsten carbide (WC) particulate fillers incorporation on two-body abrasive wear behaviour of glass fabric reinforced-epoxy (GE) composites was investigated and findings are interpreted. The wear behaviour of the composites were performed using pin-on-disc tester at varying abrasive distances viz., 25,50,75 and 100 m at a constant load of 20 N. The experiment was conducted using two different water proof silicon carbide (SiC) abrasive papers and at two different velocity under multi-pass condition. The wear loss of the composites found increasing with increase in abrading distances. A significant reduction in wear loss and specific wear rates were noticed after incorporation of WC filler into GE composite. This result indicates a significant improvement in wear resistance after incorporation of WC filler. The WC loaded systems exhibit less wear of matrix during abrasion which in turn facilitates lower fiber damage, due to the presence of WC particles on the counter surface which act as a transfer layer and effective barrier to prevent large-scale fragmentation. The worn out surface features were examined through scanning electron microscopy (SEM) in order to probe the wear mechanism.

Study on Abrasive Wear Behavior and Mechanisms of 7Cr7Mo2V2Si Steel as Drilling Tool Materials

2011 ◽  
Vol 239-242 ◽  
pp. 2986-2992
Author(s):  
Ye Fa Tan ◽  
Bin Cai ◽  
Xiao Long Wang ◽  
Guo Liang Jiang ◽  
Chun Hua Zhou
Keyword(s):  
Abrasive Wear ◽  
Wear Behavior ◽  
Normal Load ◽  
Fine Powder ◽  
Corrosive Wear ◽  
Wear Loss ◽  
Drilling Tool ◽  
Sliding Speed ◽  
Wear Rates ◽  
Abrasive Wear Behavior

In order to search for new wear resistant materials used as drilling tools and improve the service life and drilling efficiency, the 7Cr7Mo2V2Si steel was prepared and its abrasive wear behavior and mechanisms were studied under both dry and water wear conditions. The research results show that the wear losses of the 7Cr7Mo2V2Si steel increase with the increase of normal load and sliding speed at both of dry and water wear conditions. The wear losses become greatly increase at high sliding speed and heavy normal load wear conditions. The wear rates of the 7Cr7Mo2V2Si steel at water wear conditions are bigger than those at dry wear conditions. The existence of water will aggravate the wear loss of the steel because water can clean the tribo-interface by taking away the fine powder or debris, which may keep the corundum abrasives protruding and remaining sharp edge state to produce more serious two-body abrasive wear to the steel, and meanwhile the collaborative action of the friction stress and the corrosion may result in stress corrosive wear of the steel. The main wear mechanisms of the 7Cr7Mo2V2Si steel are micro-cutting wear, multi-plastic deformation wear at dry wear conditions and accompanied with stress corrosive wear at water wear conditions.

Freeze-Thaw and De-Icing Salt Resistance of Concrete Containing Mineral Admixtures and Air-Entraining Agent

2010 ◽  
Vol 163-167 ◽  
pp. 3122-3127 ◽  
Author(s):  
Xiao Lu Yuan ◽  
Bei Xing Li ◽  
Shi Hua Zhou
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Chloride Ion ◽  
Salt Resistance ◽  
Mineral Admixtures ◽  
Ion Diffusion ◽  
Chemical Corrosion ◽  
Freeze Thaw ◽  
Loss Of Mass

The effect of mineral admixtures and air-entraining agent on freezing-thawing and de-icing salt resistance of concrete has been studied. Concrete specimens made with ordinary Portland cement or ordinary Portland cement incorporating fly ash with the replacement of 10% or 20%, or 0.7/10000 air-entraining agent and fly ash with the replacement of 20%, or ground blast furnace slag with the replacement of 15% or 30%, were made and exposed to 500 cycles of freeze-thaw and de-icing salt environment. Concrete properties including loss of mass, relative dynamic elastic modulus, compressive strength, flexural strength and chloride ion diffusion coefficient were measured. Phase composition of samples was determined by means of x-ray diffraction (XRD). Results indicate that concrete exposed to freeze-thaw and de-icing salt environment is subjected to both physical frost action and chemical corrosion. Incorporation of mineral admixtures and air-entraining agent possesses more effect on internal deterioration, mechanical properties and permeability of concrete than on the scaling of concrete.

scholarly journals Influence of Air Stability of Each Air Entraining Agent on Freeze-Thaw Resistance of Fly-Ash with Moderate Heat Portland Cement in Concrete

2013 ◽  
Vol 24 (3) ◽  
pp. 149-159
Author(s):  
Noboru Sakata ◽  
Takumi Sugamata ◽  
Daisuke Hayashi ◽  
Jiro Sakue
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Freeze Thaw

Effect of Rapid Hardening Cement and Setting Accelerator on the Freeze-Thaw Durability of Fly Ash Concrete

2016 ◽  
Vol 711 ◽  
pp. 343-350
Author(s):  
Atef Badr ◽  
Socrates Ioannou ◽  
Haidar Al Maroof
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Residual Strength ◽  
Early Age ◽  
Second Phase ◽  
Portland Cement Concrete ◽  
Rapid Hardening ◽  
Freeze Thaw ◽  
Fly Ash Concrete ◽  
Freezing Condition

This paper presents the results of the second phase of an experimental research, which was carried out to investigate the freeze-thaw durability of fly ash (FA) concrete subjected to slow freeze-thaw cycles. The results of the first phase showed that FA had a significant detrimental effect on the freeze-thaw durability concrete. The lower resistance to freezing condition was attributed to the low early strength of FA concrete, at early ages, compared to Portland cement concrete. Therefore, rapid hardening Portland cement (RHPC) and setting accelerator (SA) were introduced, in the second phase, in a bid to modify the early age properties of FA concrete and, hence, enhance its freeze-thaw durability. The weight loss and residual strength of the specimens were assessed after specific number of freeze-thaw cycles. The results showed that the use of rapid hardening Portland cement (RHPC) and/or setting accelerator (SA) enabled earlier demoulding to take place and enhanced the early age strength of FA concrete. However, this did not necessarily improve the freeze-thaw durability of FA concrete. The effect RHPC and SA on the deterioration and residual strength of concrete containing fly ash was indifferent. Therefore, it is suggested that further research is needed to confirm the effect of RHPC and SA on the freeze-thaw durability of fly ash concrete.

Strength and durability of concretes containing 50% Portland cement replacement by fly ash and other materials

1990 ◽  
Vol 17 (1) ◽  
pp. 19-27 ◽  
Author(s):  
B. W. Langan ◽  
R. C. Joshi ◽  
M. A. Ward
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Abrasion Resistance ◽  
Air Entrainment ◽  
Replacement Level ◽  
Freeze Thaw ◽  
Void System ◽  
Strength And Durability ◽  
Air Void

Results are presented from an investigation on the compressive strength and durability of concretes containing substitute materials at a 50% replacement level (by mass) of Portland cement. Seven fly ashes (sub-bituminous, bituminous, and lignitic), together with limestone and an inert material (silica flour), were used as replacement materials. Durability studies included freeze–thaw testing (ASTM C666A), scaling resistance (ASTM C672), and abrasion resistance (ASTM C944). The air void system was assessed using the modified point count method of ASTM C457. The results indicate that although concretes with a 50% replacement level of cementitious material did not perform as well as the control concretes with no replacement, such concretes were able to meet minimum durability requirements. As anticipated, air-entrainment is the overriding factor that allows concrete to meet freeze–thaw durability requirements. In the context of this study, compressive strength does not appear to be a significant factor in freeze–thaw durability. Results indicated that concretes with compressive strengths of less than 10 MPa will still pass the freeze–thaw test, provided an adequate air void system is in place. Abrasion resistance tends to increase with compressive strength but not in all the cases. Key words: concrete, fly ash, compressive strength, durability, mineral admixtures.

COMPRESSIVE STRENGTH AND THERMAL CONDUCTIVITY OF WATER AND AIR CURED PORTLAND CEMENT-FLY ASH-SILICA FUME MORTARS

2018 ◽  
Vol 17 (9) ◽  
pp. 2023-2030
Author(s):  
Arnon Chaipanich ◽  
Chalermphan Narattha ◽  
Watcharapong Wongkeo ◽  
Pailyn Thongsanitgarn
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Silica Fume

scholarly journals Freeze–Thaw Resistance and Air-Void Analysis of Concrete with Recycled Glass–Pozzolan Using X-ray Micro-Tomography

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 154
Author(s):  
Marija Krstic ◽  
Julio F. Davalos ◽  
Emanuele Rossi ◽  
Stefan C. Figueiredo ◽  
Oguzhan Copuroglu
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
The United States ◽  
Adsorption Method ◽  
X Ray ◽  
Freeze Thaw ◽  
Void System ◽  
Spatial Parameters ◽  
Micro Tomography ◽  
Air Void

Recent studies have shown promising potential for using Glass Pozzolan (GP) as an alternative supplementary cementitious material (SCM) due to the scarcity of fly ash and slag in the United States. However, comprehensive studies on the freeze–thaw (FT) resistance and air void system of mixtures containing GP are lacking. Therefore, this study aimed to evaluate GP’s effect on FT resistance and characterize mixtures with different GP contents, both macro- and microscopically. In this study, six concrete mixes were considered: Three mixes with 20%, 30% and 40% GP as cement replacements and two other comparable mixes with 30% fly ash and 40% slag, as well as a mix with 100% Ordinary Portland cement (OPC) as a reference. Concrete samples were prepared, cured and tested according to the ASTM standards for accelerated FT resistance for 1000 cycles and corresponding dynamic modulus of elasticity (Ed). All the samples showed minimal deterioration and scaling and high F/T resistance with a durability factor of over 90%. The relationships among FT resistance parameters, air-pressured method measurements of fresh concretes and air void analysis parameters of hardened concretes were examined in this study. X-ray micro-tomography (micro-CT scan) was used to evaluate micro-cracks development after 1000 freeze–thaw cycles and to determine spatial parameters of air voids in the concretes. Pore structure properties obtained from mercury intrusion porosimetry (MIP) and N2 adsorption method showed refined pore structure for higher cement replacement with GP, indicating more gel formation (C-S-H) which was verified by thermogravimetric analysis (TGA).

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