Engineering Commons^™

Effect Of Recycled Concrete Aggregates On The Long-Term, Elastic, Total Deflection And Strength Of Precast Prestressed Hollow Core Concrete Slabs, Lizeth Marisol Gomez Santana

Civil Engineering Theses

Concrete constitutes the largest portion of construction and demolition waste generated each year in the United States. The Environmental Protection Agency (EPA) estimates that the total production of construction and demolition of concrete waste during 2015 was 381.8 million tons. In order to reduce the economic and environmental effects of waste concrete, researchers have begun to incorporate it into concrete mixtures. However, the inherent variability in mechanical properties between RCA sources makes it difficult to quantify the maximum permissible replacement of natural aggregate and the end-result properties of concrete. This project investigates the use of recycled concrete aggregates (RCA) obtained …

Thin-Walled Steel Tubular Circular Columns With Uniform And Graded Thickness Under Bidirectional Cyclic Loading, Qusay Al-Kaseasbeh, Iraj H.P. Mamaghani

Civil Engineering Faculty Publications

Thin-walled steel tubular circular columns are becoming an increasingly attractive choice as cantilever bridge piers due to their architectural, structural and constructional advantages. This paper aims to evaluate the strength and ductility of thin-walled steel tubular circular columns with uniform thickness (BC) and graded thickness (BGC) under bidirectional cyclic lateral loading in the presence of constant axial force. The analysis is carried out using a finite-element model (FEM) which is substantiated based on the experimental results in the literature. Then, the proposed BGC column with size and volume of material equivalent to the BC column is investigated. As a part …

Development Of A Mix Design Adjustment Method For Fiber Reinforced Concrete And Super High Performance Concrete Based On Excess Paste, Joe Malloy

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

The main objective of this study was to develop a mix design adjustment method for Fiber Reinforced Concrete (FRC) that would maintain appropriate workability while improving hardened concrete performance. A literature review was conducted to examine existing methods for adjusting mix designs to account for fiber introduction. It was found that while increasing fine aggregate and cement paste content can make up for lost workability with the addition of fibers, no rational mix design adjustment method is available. Reference mix designs from the Nevada Department of Transportation and the Nebraska Department of Transportation were used, and this study focused on …

Multifunctional Lightweight Aggregate Containing Phase Change Material And Water For Damage Mitigation Of Concrete, Wenyu Liao, Aditya Kumar, Kamal Khayat, Hongyan Ma

Materials Science and Engineering Faculty Research & Creative Works

This paper presents an innovative concept of multifunctional lightweight aggregate, which is produced by loading phase change material (PCM) into the interior of lightweight sand (LWS) and sealing the surface pores using water. The PCM loaded in the LWS functionalizes it as a temperature management agent in concrete, and the water in surface pores enables internal curing. It has been found that the particle shape and pore structure of crushed expanded shale LWS makes it an ideal carrier for PCM, loading sufficient PCM and maintaining better (compared to natural sand) mechanical interlocking. When coupled with the internal curing effect, the …

Strength And Durability Of Hybrid Fibre Reinforced Binary Blend Geopolymer Concrete, Namasivayam Ganesan, P V Indira, R Sahana

International Conference on Durability of Concrete Structures

This paper deals with an investigation on the influence of hybrid fibres on the strength and durability of binary blend geopolymer concrete. Geopolymer concrete was prepared using Fly ash and GGBS as source material and mix design was carried out as per the guidelines of Professor Rangan of Curtin University, Australia. Different fly ash-GGBS proportions namely 50-50%, 60-40%, 70-30%, 80-20% and 90-10% were considered. The tests on Geopolymer concrete reveal that the compressive strength increases as the percentage of GGBS increases up to 30%. Hence the combination of 70% fly ash and 30% GGBS was considered as a base material. …

Mathematical Modeling Of The Structure Cellular Concrete, Anvar Ishanovich Adilkhodjayev, E.V. Shipacheva, S.S. Shaumarov

Journal of Tashkent Institute of Railway Engineers

The article presents the developed mathematical model of the structure of cellular concrete, which allows one to establish pore sizes and characteristics of inter-pore walls corresponding to the required thermal conductivity and strength of the material, and the results of its numerical implementation are presented

Research Of System Conditions For Formation Of Failure On Mathematical Models By The Results Of The Research Of Reinforced Concrete Bridges, E.T. Yaxshiev, F.Z. Zokirov, A.B. Karimova

Journal of Tashkent Institute of Railway Engineers

Based on the data of field surveys, the results of assessing the state of reinforced concrete span structures of bridges and characteristic defects that occur in the structure during operation are presented. An analysis of the results of inspections and periodic inspections responsible for the operation of artificial structures shows that a significant part of reinforced concrete spans has various types of defects and damage to load-bearing structures. Studies show that defects have a significant impact on the operational properties of reinforced concrete spans, leading both to a limitation of the speed regime of train movements and to the emergence …

Investigated The Strength Of Rolling Stock As A Fuzzy Function, M.L. Waail, R.V. Rahimov

Journal of Tashkent Institute of Railway Engineers

In this paper we use Fuzzy Set Theory to solve one of the essential problems in Railway Engineering: estimate the strength of rolling stock. As known, the strength of, any, rolling stock depends upon several factors that cannot determine them accurately. Therefore, we can consider them as fuzzy factors. The strength of any rolling stock can be changed depending on its operating conditions and the intensive of operation, that can consider as fuzzy factors too. A new proposal method developed depending on Fuzzy Set Theory to estimate the strength of mobile equipment or to compare between several rolling stocks for …

Long-Term Performance Of Sustainable Pavements Using Ternary Blended Concrete With Recycled Aggregates, Seth M. Wagner

Theses and Dissertations

The purposes of this study were to (a) design concrete pavement mixtures with recycled concrete aggregates using ternary blends of cementitious materials and a low water-to-binder ratio, (b) measure the fresh and hardened properties of the proposed concrete mixtures and (c) assess the long-term performance of the concrete implementing the use of recycled coarse aggregates. Preliminary investigation into ternary blend combinations via the compressive testing of mortar cubes and isothermal calorimetry was used to predict an optimal blend of cementitious material. Mixes using recycled concrete aggregates at varying replacement rates were tested for fresh and hardened properties using the proposed …

Theoretical Aspects Of Structural And Simulation Modeling Of The Macrostructure Of Composite Building Materials, Anvar Ishanovich Adilkhodjayev, I.M. Mahamataliev, S.S. Shaumarov

Journal of Tashkent Institute of Railway Engineers

At the present time, the description of the joint work of multi-component, high-quality concretes in the framework of the structural and simulation modeling of cement composites is a very topical task of building materials science. In the context of the solution of the above problems, theoretical aspects of structural and simulation modeling are presented on the example of the developed program "Concrete-technology", which allows to predict the strength properties of multicomponent high-quality concrete at the macro structural level.

Ductile Corrosion-Free Self-Centering Concrete Elements, Maged Youssef, Mohamed E. Meshaly, Ahmed Elansary

Civil and Environmental Engineering Publications

Corrosion is a major factor in the deterioration of reinforced concrete (RC) structures. To mitigate this problem, steel bars can be replaced with glass-fiber-reinforced-polymer (GFRP) bars. However, the lack of ductility of GFRP-RC elements has prevented their use in many structural applications, especially in seismic areas. Superelastic shape memory alloy (SMA) bars have been proposed to be used in seismic areas because of their self-centering characteristics. Also, they have the added advantage of being corrosion resistant. This paper examines the combined use of SMA and GFRP bars to achieve ductile self-centering and corrosion-free elements. The first challenge for such a …

Flexural Behaviour Of Superelastic Shape Memory Alloy Reinforced Concrete Beams During Loading And Unloading Stages, Yamen Ibrahim Elbahy, Maged Youssef

Civil and Environmental Engineering Publications

Trend of using smart structures, which can adjust when exposed to severe unexpected loading, is increasing. One of the methods to achieve such structures relies on smart materials. For example, replacing conventional steel reinforcing bars in Reinforced Concrete (RC) structures with superelastic Shape Memory Alloy (SMA) bars significantly reduces the residual deformations caused by post-yielding behaviour. This paper provides in-depth understanding of the flexural behaviour of SMA RC beams. A sectional analysis method, which predicts the flexural behaviour of SMA RC beams during both loading and unloading stages, is adopted and validated using available experimental data. An extensive parametric study …

Effect Of Volcanic Ash Pozzolan Or Limestone Replacement On Hydration Of Portland Cement, Kemal Celik, Craig W. Hargis, Rotana Hay, Juhyuk Moon

Craig Hargis