Engineering Commons^™

An Investigation Into The Effects Of Fly Ash On Freeze-Thaw Durability Prediction, Yancy Schrader

Graduate Theses and Dissertations

Air is purposefully entrained into concrete primarily to improve resistance to freeze-thaw deterioration while saturated with water. Air entraining admixtures (AEAs) are chemical admixtures designed to entrain air into the concrete to provide adequate resistance to the effects of freezing and thawing. One of the challenges associated with air entrainment in concrete is the interaction of an AEA with supplementary cementitious materials present in the concrete, particularly fly ash. Fly ash is a by-product of the coal fired electrical generation industry, and often contains residual unburned carbon and other components that can increase the AEA demand of a particular concrete …

Fly Ash Based Geopolymer For High Temperature And High Compressive Strength Applications In Aggressive Environment, Aaryan Manoj Nair, Akm S. Rahman

Publications and Research

Geopolymers are the results of geosynthetic reactions between aluminosilicates and strong bases. This results in chemical bonds between aluminum (Al), Silicon (Si)and oxygen (O) composing polymer rings in tetrahedral coordination. These bonds give them widespread useful applications such as high heat bearing ceramics, and base construction material whilst being far more environmentally conscious. The purpose of the experiment is to examine the effect of Silicon Carbide whisker and inorganic glass particles on thermal and mechanical properties of Geopolymers. This study will help understand the effect of various compositions and concentrations of SiO₂ in mechanical strength. In this experiment, the …

Experimental And Numerical Investigation On The Irregularity Of Carbonation Depth Of Concrete Under Supercritical Condition, Hao Bao Masc, Min Yu Dr., Jianqiao Ye Dr., Lihua Xu Dr., Yin Chi Dr., J Ye

International Conference on Durability of Concrete Structures

The heterogeneity of a cement-based material results in a random spatial distribution of carbonation depth, which may significantly affect the mechanical properties and durability of the material. Currently, there is a lack of both experimental and numerical investigations aiming at a statistical understanding of this important phenomenon. This paper presents both experimental and numerical supercritical carbonation test results of concrete blocks. The random fields of porosity and two-dimension random aggregate model of concrete were proposed for the simulation. The carbonation depths are measured and distributed along the carbonation boundary by the proposed rapid image processing technique, which are then statistically …

Fluid Isolator, Purdue Ect Team

ECT Fact Sheets

The reliability of concrete infrastructure is vital to ensuring daily life, as well as commerce, can progress without interruption. From the pavement of interstate highways to the driveways and sidewalks in a local neighborhood, concrete is expensive to install and often even more expensive, and intrusive, when it needs to be replaced. Unfortunately, to maintain functionality in winter climates concrete is heavily exposed to deicing salts. This not only affects the roads, driveways, and sidewalks where salt is applied directly, but many other areas such as parking and residential garages where vehicles (and people) will track salt along with water …

Healing Mechanism Investigation Of Self-Healing Concrete By Microencapsulated Calcium Nitrate, Gabriel Andres Arce Amador

LSU Doctoral Dissertations

Durability of reinforced concrete structures depends highly on the integrity of the concrete which protects the structure from the environment. However, concrete is a brittle material and as such it is prone to cracking which allows for detrimental agents to penetrate the structure and produce early deterioration. Embedding microcapsules with chemical healing agents in concrete materials for self-healing applications as well as implementing SMAs as reinforcement of concrete structures for self-closing of cracks are both state-of-the-art techniques with enormous potential for enhancement of concrete infrastructure durability. In this work, both techniques are combined as an alternative for superior self-healing of …

Integration Of Shape-Memory Alloys And Self-Healing Microcapsules To Enhance Concrete Durability, Luis Adolfo Bonilla

LSU Doctoral Dissertations

Self-healing is a term that has not been used for building material until a few decades ago. The concept of developing a material that mimics what living organisms do, such as identify and repair damage, rather than interesting, constitutes a necessity in today’s deteriorated infrastructure. Concrete is one of the main building blocks that support our society’s roads, buildings, and dams. Increasing the service life of such structures will have an important socio-economic benefit in our society. Self-healing methods in concrete have been studied in order to minimize human intervention in maintenance procedures. Previous research in this area has provided …

Compression Testing And Failure Modes Of Steel-Concrete Composite (Sc) Structures For Nuclear Containment, Patrick Michael Wanamaker, Amit H. Varma

The Summer Undergraduate Research Fellowship (SURF) Symposium

Although being able to provide much cleaner power than burning coal and other fossil fuels, nuclear power plants are still a tough sell to the general public due to their history of being spontaneously dangerous. The containment structures surrounding these nuclear plants, however, can play a huge role in reducing the risks associated with them. Relatively new designs for these containment assemblies, known as SC (steel-concrete composite) structures, aim to increase the strength and durability of the containment facilities while keeping costs down. By varying the spacing between shear studs, the ratio of concrete to steel, and the ratio of …

Development Of A Structured Concrete Thermocline Thermal Energy Storage System, Bradley M. Brown

Graduate Theses and Dissertations

The past couple of decades have shown a concern when considering the way the world obtains its power. The focus has been switching from fossil fuels that have been used for hundreds of years to renewable energy sources, such as the sun. Solar energy is readily and infinitely available for harnessing. One problem with solar energy, though, is its inability to be used during the night time and during cloud covered weather. A solution to this problem is the use of energy storage mechanisms. For solar plants that use solar thermal energy (concentrating solar power plants), thermal energy storage (TES) …

Electrochemical Detection For The Corrosion Of Reinforcing Steel In Concrete During Immersion And Drying Cycles, Bing-Li Jia, Fa-He Cao, An-Na Chen, Jian-Qing Zhang

Journal of Electrochemistry

The corrosion behavior of reinforcing steel in concrete under dry-wet cycle condition has been studied by electrochemical noise(EN) compared with the electrochemical impedance spectroscopy(EIS),SEM micrographs and EDS.The statistical method has been employed to analyze the EN data of reinforcing steel in concrete,which revealed three different corrosion stages of reinforcing steel in concrete,including the dissolution of the passive film,the active corrosion and the cumulation of corrosion product.The wavelet transform has also been employed,which indicated that steel in concrete with pH 1 is associated with uniform corrosion,while steel in concrete with pH 3 and pH 7 are associated with localized corrosion,such as …

Studied Corrosion Behaviors Of Reinforcing Steel In Concrete By A Single-Dimensional Array Electrode, Lan-Qiang Li, Shi-Gang Dong, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

A single-dimensional array electrode was developed as a new electrochemical technique to image corrosion potential,galvanic current and polarization curves of reinforcing steel in concrete during corrosion process.Combining with the polarization behavior for each micro-electrode,the interactions between corrosion macrocell and corrosion microcell of the steel in concrete were evaluated.It was noticed that the corrosion macrocell and microcell occurred independently in difference regions at the initial stage of corrosion.The corrosion macrocell current can be in situ followed by corrosion potential imaging.The corrosion propagation of steel in concrete is closely related to the interactions between corrosion macrocell and corrosion microcell.

Effect Of Naphthalene Water Reducer On Corrosion Behavior Of Reinforcing Steel In Concrete, Yu-Ming Tang, Jie Zhang, Yu Zuo

Journal of Electrochemistry

The influence of naphthalene water reducer on corrosion behavior of reinforcing steel in concrete was studied by the methods of corrosion potential measurement,linear polarization and EIS test.The values of concrete resistance(Rc) and polarization resistance(Rp) of the samples with naphthalene water reducer were higher than those without naphthalene water reducer,especially in the concrete with 0.2 percent naphthalene water reducer.A suitable amount of water reducer can improve the pore structures of concrete,increase the concrete compactness and impermeability,and decrease corrosion rate of rebars in concrete.

Effect Of Cracks On Corrosion Of Rebar In Concrete Studied By Wire Beam Electrode, Guo-Xi Li

Journal of Electrochemistry

The effects of crack and ethanolamine on corrosion of rebar in concrete were studied by measuring the distribution of corrosion potential and polarization resistance of iron wires in 10% NaCl solution.The results showed that the diffusion of water,oxygen and chloric ion toward concrete was accelerated by the crack which intensified the nonuniform corrosion of iron wire with the regions near to crack as anode and the uncracked regions as cathode.Ethanolamine could diffuse into the body of concrete and absorb on the surface of iron wire,which reduced iron corrosion evidently and successfully inhibited the nonuniform corrosion caused by crack without changing …

The Lineal Polarization Method For Corrosion Rate Measurement Of Reinforcing Bar Of Concrete In Situ, Ai-Ling Du, Wen-Tao Hou, He-Ming Zhang, Jian-Qun Luo

Journal of Electrochemistry

A linear polarization method was applied to measure corrosion rate of reinforcing bar of concrete in situ. Generally in the experiment, the area and shape of the reinforcing bar as a working electrode can be changed and adjusted according to our needs. But polarization area cannot be defined when reinforcing bar is polarized in situ, so that a real R p can't be obtained. Thus the purpose of present work is to improve the measurement system. We used the double_ring auxiliary electrodes made by ourselves. The size of the double_ring auxiliary electrodes was adjusted repeatedly until the real polarization area …

An Investigation On The Corrosion Potential Imaging At The Interface Of Concrete/Reinforcing Bar In Corrosion Media, Rong-Zong Hu, Chang-Jian Lin, Xiang Zhou, Jian-Guang Tan, Xiong-Chao Zhao

Journal of Electrochemistry

The iron array electrode covered with concrete as a new electrochemical technique is applied to map the potential imaging and to investigate on the iron electrode corrosion process under concrete: In Cl - solution the corrosion of the iron array electrode covered with concrete had been prevented for a short term since the concrete protection, but the corrosion still occurreed and developed after immersed for a long time. In SO 4 2- solution although the sample had being immersed for a long time and the concrete was possibly broken, the corrosion did not develop. In Cl - solution the corrosion …

Synthesis And Application Of Polymeric Corrosion Inhibitor For Reinforced Concrete, Weiwei Lin, Shengxian Wang, Jianqing Zhang

Journal of Electrochemistry

A new polymer E Twas synthesized and used as a corrosion inhibitor for reinforced concrete. The inhibitive behavior and mechanism were studied with linear polarization ,Tafel polarization,EIS and XPS method in simulated pore solution system with concrete samples.The result showed that the polymer was a mixing type inhibitor. A 1% dosage was sufficient to imhibit the corrosion of steel in simulated pore solution system. The salt endurance was enhanced from 0.02 mol/L to 0.10 mol/L.The result also showed the good synergetic effect of NaNO 2,especially in low NaNO 2 concentration.The EIS showed that E_T has dual function on reinforced concrete,i.e.,densifying …

Physical And Mechanical Properties Of A New Type Of Polymer Concrete, Kyan Bin Khoo

Theses

A new type of Polymer concrete is an admixture of a special Latex, Portland cement and Sand. It has high bond strength, quick curing, durability and adequate strength. The Mechanical and Physical properties were investigated in this paper. Reinforcement with Glassfiber was done and its properties compared to those of control specimens. The heat generation in Polymer Concrete (PC) and its relationship with the properties of PC was also investigated.

A new type of Polymer concrete is an admixture of a special Latex, Portland cement and Sand. It has high bond strength, quick curing, durability and adequate strength. The Mechanical …

Concrete In Dairies, D Roger Buchanan

Journal of the Department of Agriculture, Western Australia, Series 4

PRIME requirements for exposed concrete surfaces in dairies are that they should be easily cleansed and should not deteriorate in contact with milk and milk products.

In milking stalls, animal races and on loading platforms hardwearing surfaces which offer good foothold are also necessary.