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 …

Evaluation Of Bagasse Ash As Cement And Sand Replacement For The Production Of Engineered Cementitious Composites (Ecc), Gabriel Arce, Marwa Hassan, Sujata Subedi, Ana Rivas, Samantha Hidalgo, Hugo Eguez

Publications

The objective of this study was to develop novel Engineered Cementitious Composites (ECC) materials implementing sugarcane bagasse ash (SCBA). To this end, the effects on the mechanical and physical properties of ECC materials of: (1) Louisiana raw SCBA (RBA) as a partial and complete replacement of sand (i.e., class S mixtures); (2) Louisiana post-processed SCBA (PBA) as a partial replacement of cement (i.e., class C mixtures); and (3) Ecuador raw SCBA (EBA) as a partial and complete replacement of sand (i.e., class S-E mixtures) were studied. Sand replacement levels with RBA and EBA evaluated were 25, 50, 75, and 100% …

Colloidal Silica: Cement Enhancing Admixture Product Evaluation, Lieska Halsey, David Hansen

Nebraska Department of Transportation: Research Reports

As Class F- fly ash (F-ash) becomes scarce, PCC engineers will look to other supplemental cementitious materials (SCM) to replace F-ash and its ASR mitigating properties. Colloidal silica (CS), or nano-silica, has been shown to mitigate ASR at certain replacement levels; however, CS cannot be a full replacement of F-ash. Engineers at the Nebraska Department of Transportation (NDOT) learned of CS from a presentation given by Intelligent Concrete, Inc. at the 2019 Nebraska Concrete Professionals Association Conference and decided to investigate the potential use of CS in NDOT concrete mix designs.

About The Technology Of Making Reinforced Concrete Sleep By Heating Concrete At Low Temperature, Turgunbaev Urinbek Jamolovich, Movluda Umirova

Journal of Tashkent Institute of Railway Engineers

The article discusses the properties of cement stone with the use of complex chemical additives to improve the technology for the production of sleepers from prestressed concrete. With the use of superplasticizer, the volume of intergranular space and, consequently, capillary porosity, which is a determining factor for both strength and frost resistance and corrosion resistance of concrete, are significantly reduced. Also, during thermo-wet processing, at a temperature of 40 ° C, there was no decrease in the strength of cement stone and sufficient strength at the initial stage of the curing period, 36 MPa with the addition of Glenium 27 …

Quantitative Resistance Assessment Of Sfrp-Strengthened Rc Bridge Columns Subjected To Blast Loads, Ahmad Alsendi, Christopher D. Eamon

Civil and Environmental Engineering Faculty Research Publications

The blast resistance of a typical reinforced concrete bridge pier column design was modeled with a nonlinear finite element approach that considers material damage, fracture, and separation. While varying concrete strength, amount of longitudinal reinforcing steel, and gravity load, the effect of applying an externally bonded steel fiber reinforced polymer (SFRP) wrapping was assessed. The presented approach uniquely quantifies column blast resistance in terms of charge weight. It was found that blast capacity was roughly linearly related to concrete strength and steel reinforcement ratio, the former of which is most influential. It was further found that a single layer of …

Application Of Internal Curing To Improve Concrete Bridge Deck Performance, Arman Abdigaliyev, Yong-Rak Kim, Jiong Hu

Nebraska Department of Transportation: Research Reports

Due to the relatively high cement content and low water-to-cement ratio (w/c) used, bridge deck concrete is prone to premature cracking. Internal curing has been found to greatly reduce the chance of premature cracking as well as concrete deterioration. This research project was intended to develop internally cured bridge deck concrete based on a local mix design in Nebraska. Four different lightweight fine aggregate (LWFA) as internal curing agents were evaluated, and their effects on fresh, mechanical, durability, and shrinkage properties of concrete were studied. To identify the most effective LWFA dosage for shrinkage reduction, different replacement rates of sand …

Production Of Fire-Resistant Concrete Based On Technogenic Waste, Uzmonjon Turgunaliyevich Yusupov

Journal of Tashkent Institute of Railway Engineers

The article notes that at present, with the development of the construction industry, the need for fire-resistant concrete is also increasing. In increasing the volume of construction, concrete and other components are some of the resources available at the price of finished objects achieved through cost reduction. It is determined that the developed fire- and heat-resistant concrete, prepared according to the technological requirements developed by us and the established standards, will provide the facility with reliable fire safety and longevity

Evaluation Of Tie-Bar Anchoring Methods: Non-Shrink Grout Vs. Epoxy, Wally Heyen, Lieska Halsey, Tim Krason, Brandon Varilek, David Hansen

Nebraska Department of Transportation: Research Reports

Tie bars are epoxy coated steel bars that connect the longitudinal joints in concrete pavement. Tie bars prevent faulting and joint separation between lanes Tie bars can be placed into the plastic concrete or inserted after curing by drilling and anchoring with epoxy or non-shrink grout. The specification for the tie bars requires the use of a No. 5 bar, 18 inches long and shall meet ASTM A775 / A775M [1], Section 1020.The Nebraska Department of Transportation “Standard Specifications for Highway Construction,” (Section 603.03) requires contractors to mechanically insert tie bars into the face of pavements during construction. Tie bars …

Development Of An Ndt Tool For In-Situ Assessment Of Prestress Loss, Bibo Zhong, Jinying Zhu, George Morcous

Nebraska Department of Transportation: Research Reports

The research objective is to develop a non-destructive testing (NDT) method to evaluate the prestress loss in prestressed concrete bridge girders using ultrasonic waves. The work principle is based on acoustoelastic effect - ultrasonic wave velocity varies with stress level in prestressed concrete. A self-reference test setup was proposed to measure wave velocity in two orthogonal directions (prestress and unstressed directions) in the girder. This setup will be able to reduce effects of material variation and temperature change.

The concept was first validated on small concrete specimens (cylinders and beams) in laboratory. A signal analysis algorithm was developed to reliably …