The Dynamic Elastic Modulus and Microstructure Study of High Performance Concrete in Sulfate Environment

2010 ◽  
Vol 113-116 ◽  
pp. 1371-1374 ◽  
Author(s):  
Hong Xia Qiao ◽  
Hong Fa Yu ◽  
Zhong Mao He
Keyword(s):  
Portland Cement ◽  
High Performance ◽  
Elastic Moduli ◽  
High Performance Concrete ◽  
Fine Aggregate ◽  
Test Results ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Sulfate Solutions ◽  
Better Than

Aimed at determining the durability of concrete in very salty regions, this paper describes a study carried out to examine the performance of various high performance fine aggregate concrete in a sulfate environment, such as high performance concrete inside a composite additive, and Portland cement concrete, and sulfate resistant cement concrete. They experienced dry-wet cycles in sodium sulfate solutions. By examining the changes of elastic moduli and analyzing the SEM of the concrete, the test results show that the salt resistances of sulfate resistant cement concrete is no better than Portland cement concrete in the extremely aggressive dry-wet cycle environment, and high performance concrete containing a composite additive has better resistance to a sulfate environment. Besides, the composite additive can create the environment for a second hydration to reduce the amount of Ca(OH)2 inside the concrete, and build additional C-S-H gel to reform the microstructure of concrete effectively. Finally, the paper offers some advice for mixing concrete in salt regions.

The Durability Study of Concrete in Sulfate Environment

2012 ◽  
Vol 204-208 ◽  
pp. 3137-3141
Author(s):  
Hong Xia Qiao ◽  
Yu Li ◽  
Zhong Mao He ◽  
Jin Mei Dong
Keyword(s):  
Portland Cement ◽  
High Performance ◽  
Elastic Moduli ◽  
High Performance Concrete ◽  
Salt Resistance ◽  
Fine Aggregate ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Sulfate Solutions ◽  
Better Than

Aiming at determining the durability of concrete in very salty regions, this study examines the performance of various high performance fine aggregate concretes in a sulfate environment, such as high performance concrete inside a composite additive, and Portland cement concrete and sulfate resistant cement concrete, all of which experienced dry-wet cycles in sodium sulfate solutions. By examining the changes of elastic moduli and analyzing the SEM of the concrete, this paper has found that the salt resistance of sulfate resistant cement concrete is no better than that of Portland cement concrete in the extremely aggressive dry-wet cycle environment but high performance concrete containing a composite additive has better resistance in a sulfate environment. Besides, the composite additive can create the environment for a second hydration to reduce the amount of Ca(OH)2 inside the concrete, and build additional C-S-H gel to reform the microstructure of concrete effectively. Finally, the paper offers some advice for mixing concrete in salt regions.

Strength Studies of High Performance Concrete with Fly-Ash and Gangue

2012 ◽  
Vol 446-449 ◽  
pp. 3544-3553
Author(s):  
Yun Fang Meng ◽  
Ya Yun Tan ◽  
Rui Li
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Supplementary Cementitious Materials ◽  
Optimum Level ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
And Performance

The main purpose of this research was to enhance the strength and durability of concrete in both design and construction of high performance concrete. Particularly, the strength in high performance concrete is achieved by optimising the gangue, fly ash and silica fume replacement for cement. The gangue has been used as a cementitious material. Using data from tests on laboratory studies, comparisons are made of the properties and performance of the gangue, fly ash and silica fume concrete with conventional Portland cement concrete of similar and same mixture proportions. The many technical benefits available to high performance concrete user, such as reduced heat evolution, lower permeability and higher strength at later ages, at the same time, in order to increase resistance to sulphate attack and alkali silica reaction. A number of recommendations are given for the effective use of gangue and fly ash in high performance concrete. The results show that 10% gangue, 15% slag, 15% fly ash, 10% silica fume of replacement was found to be an optimum level and demonstrated excellent performance in strength. Literature review on the use of different supplementary cementitious materials in concrete to enhance strength was also reported. The paper is intended to provide guidance for those concerned with the design, application and performance of high properties concrete in practice where gangue and fly ash can also help to reduce costs and energy demands in the production of concrete compared with conventional Portland cement concrete.

Study on the Performance and Application of High Performance Pavement Portland Cement Concrete

2013 ◽  
Vol 639-640 ◽  
pp. 411-416 ◽  
Author(s):  
Ai Ping Liu ◽  
Jian Yin ◽  
Wei Min Song
Keyword(s):  
Portland Cement ◽  
Abrasion Resistance ◽  
High Performance ◽  
Heavy Traffic ◽  
Environmental Benefits ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Compressive Performance ◽  
Practical Engineering ◽  
Pavement Concrete

Because of some drawbacks including low strength, poor dimensional stability, low abrasion resistance, easy to crack and other shortcomings, Portland cement concrete was limited to use as a dominant pavement material in highway construction. This paper studied the feasibility of making high performance pavement concrete by adding 20-40% of high-quality composite ultra-fine fly ash (CUFA) technology to achieve high-performance of concrete roads have been studied. The test results indicated that: with cementitious material content of 360~400 kg/m3 and CUFA content of 20% ~ 40%, adding CUFA improved the workability of concrete significantly; in the meantime, the 28d compressive strength was as high as 50 MPa, and the later strength of concrete continued growing. The designed concrete satisfied the requirements of opening to traffic after 3 days after the construction and heavy and extra heavy traffic in 28 days. The durability, especially the abrasion resistance, and the crack-resistance were improved significantly. The designed pavement concrete not only had a good compressive performance for practical engineering but also had good technical, economic, social and environmental benefits.

scholarly journals Performance of a Fly Ash Geopolymeric Mortar for Coating of Ordinary Portland Cement Concrete Exposed to Harsh Chemical Environments

2015 ◽  
Vol 1129 ◽  
pp. 573-580 ◽  
Author(s):  
Walid Tahri ◽  
Z. Abdollahnejad ◽  
Jorge Mendes ◽  
F. Pacheco-Torgal ◽  
José Barroso de Aguiar
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Epoxy Resin ◽  
High Performance ◽  
Ordinary Portland Cement ◽  
High Performance Concrete ◽  
Surface Treatments ◽  
Concrete Durability ◽  
Portland Cement Concrete ◽  
Chemical Attack

Premature degradation of ordinary Portland cement (OPC) concrete infrastructures is a current and serious problem with overwhelming costs amounting to several trillion dollars. The use of concrete surface treatments with waterproofing materials to prevent the access of aggressive substances is an important way of enhancing concrete durability. The most common surface treatments use polymeric resins based on epoxy, silicone (siloxane), acrylics, polyurethanes or polymethacrylate. However, epoxy resins have low resistance to ultraviolet radiation while polyurethanes are sensitive to high alkalinity environments. Geopolymers constitute a group of materials with high resistance to chemical attack that could also be used for coating of concrete infrastructures exposed to harsh chemical environments.This article presents results of an experimental investigation on the resistance to chemical attack (by sulfuric and nitric acid) of several materials: OPC concrete, high performance concrete (HPC), epoxy resin, acrylic painting and a fly ash based geopolymeric mortar. Two types of acids, each with high concentrations of 10%, 20% and 30%, were used to simulate long term degradation by chemical attack. The results show that the epoxy resin had the best resistance to chemical attack, irrespective of the acid type and acid concentration.

scholarly journals Some Mechanical Properties of Cement Treated Base (CTB) Incorporating Waste Portland Cement Concrete Under Different Corresponding Conditions

2018 ◽  
Vol 7 (4.37) ◽  
pp. 138
Author(s):  
Asst. Prof. Dr. Khawla H. H. Shubber ◽  
Eng. Sajjad Hashim Mohamed
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Portland Cement ◽  
Granular Materials ◽  
Compression Strength ◽  
Cement Content ◽  
Strength Increase ◽  
Test Results ◽  
Portland Cement Concrete ◽  
Cement Concrete

This research represents a trial of understanding and improving mechanical properties of base or subbase granular materials, used in pavement construction, stabilized with Portland cement known as cement treated base (CTB) in terms of density, optimum water content (O.W.C), and compression Strength of three curing ages (3, 7, 28) days under different situations. Different Portland cement percent of (0, 5, 7, 10, 12, and 15) % by weight were added to selected base course granular materials (type B according to local standard specification in Iraq). Results showed that the density of mixture increase with increasing added cement percent, while O.W.C takes its maximum value around 7% cement content, and compression strength increase with increasing cement content and curing age. Then effect of replacing 50% of natural granular materials by waste Portland cement concrete (WPCC) was investigated on the results of (0, 7& 15)% cement content on density, O.W.C and compression strength in the three curing ages. Results reveled although density of mixture cooperating WPCC for 0% cement content was higher, CTB of natural granular material were denser. On the other hand compressive strength decrease in case of using WPCC for all percent cement added and curing ages. Finally, effect of soaking in water on CTB with (7 &15)% cement compressive strength of three curing ages was studied, under three period of soaking (1 week, 2 weeks, &one month). Test results exposed that, CTB Compressive strength increase with increasing soaking period but still less than that of un-soaked and for all curing ages. For each test stage mathematics relationships with acceptable correlation were presented proofing test results tendency.  

scholarly journals Behavior of Geopolymer Concrete Confined by Circular Hoops

2018 ◽  
Vol 159 ◽  
pp. 01018
Author(s):  
Muslikh ◽  
N. K. Anggraini ◽  
D. Hardjito ◽  
Antonius
Keyword(s):  
Portland Cement ◽  
Concrete Cover ◽  
Geopolymer Concrete ◽  
Test Results ◽  
Portland Cement Concrete ◽  
Reinforcing Bars ◽  
Cement Concrete ◽  
Conventional Concrete ◽  
K Value ◽  
Steel Bar

This paper discusses the behavior of geopolymer concrete subjected to passive confinement under compression loads. The confinement is induced by the use of lateral hoops, assembled from un-deformed reinforcing bars. To compare the effect of confinement, identical specimens were produced using conventional concrete with the similar concrete compressive strength. The cylinder specimens were 100 mm in diameter and 200 mm in height, and the hoops were placed on the outer most fibers of the cylinders, perpendicular to the line of loading, with no concrete cover. The parameters analyzed in this study were the steel bar to concrete volumetric ratio, the hoop spacings and the steel yield stresses. The experimental results show that unconfined geopolymer concrete were very brittle compared to the unconfined Portland cement concrete. The strength enhancement (K value) of the confined geopolymer concrete was higher than K value of Portland cement concrete. Confined geopolymer concrete also has better deformability compared to the confined Portland cement concrete. The average confinement effectiveness of geopolymer concrete also has a higher value than that commonly used in the Indonesian Concrete Standard (SNI), that is 4.1. The results were further assessed to the most recent experimental test results conducted in this area.

Effect of Flat Glass Powder on the Slump Test and Microstructure of Portland Cement Concrete

2016 ◽  
Vol 881 ◽  
pp. 259-264
Author(s):  
Edson Jansen Pedrosa Miranda Jr. ◽  
A.E.M. Paiva
Keyword(s):  
Portland Cement ◽  
Glass Powder ◽  
Flat Glass ◽  
Waste Glass ◽  
Fine Aggregate ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Slump Test ◽  
Electron Microscopy Analysis ◽  
Powder Content

A differential feature of this study was the analysis of the slump test and microstructure of Portland cement concrete containing a little-studied type of waste – flat glass powder. The concrete was produced using 5%, 10% and 20% (by mass) of waste glass in place of sand, and water-to-cement (w/c) ratios of 0.50, 0.55 and 0.58. The slump of concrete decreased with increasing glass powder content at the three w/c ratios and its fluidity was impaired with 20% of waste glass at the w/c ratio of 0.50. A scanning electron microscopy analysis revealed a reduction in voids as the waste glass content increased from 0% to 10%. At the above mentioned percentages, flat glass powder shows a promising potential for use as fine aggregate in Portland cement concrete. However, the use of plasticizers should be considered for concrete with low w/c ratios (less than 0.50) and high waste glass percentages (more than 20%).

scholarly journals The Influences of Iron Ore Tailings as Fine Aggregate on the Strength of Ultra-High Performance Concrete

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Zhigang Zhu ◽  
Beixing Li ◽  
Mingkai Zhou
Keyword(s):  
Particle Size ◽  
Frost Resistance ◽  
High Performance ◽  
Iron Ore ◽  
High Performance Concrete ◽  
Fine Aggregate ◽  
Ultra High Performance Concrete ◽  
Iron Ore Tailings ◽  
Better Than

The present study looks for the feasibility of preparing UHPC with iron ore tailings (IOT for short) as fine aggregate. To enhance outstanding high performances, some influences on UHPC mortars were investigated such as different kinds of sands, different mix ratio of sands, and different largest particle size of fine aggregate. The results show that IOT have negligible poorer aggregate performance than silica sands but better than river sands. The strength of UHPC reaches the highest point when silica sands were instead 60% by IOT. As the largest particle size of fine aggregate is decreasing, the strength and frost resistance of UHPC were improved, but the liquidity was decreased. Micropowder of IOT affects the strength and the optimal content was 4%.

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