2013 Session: 288

• Evaluation of Microencapsulation of Dicyclopentadine and Sodium Silicate for Self-Healing Concrete
  Abstract: Considerable interests have been given in recent years to utilize self-healing materials in concrete. The concept of microcapsule healing is based on a healing agent being encapsulated and embedded in the concrete. The objective of this study was to evaluate the effects of preparation parameters, namely, temperature, agitation rate, and pH on the shell thickness and size (diameter) of the microcapsules. Two healing agents were evaluated in this study, dicyclopentadiene (DCDP) and sodium silicate. Based on the results of the experimental program, it was determined that as the pH was reduced, the shell thickness increased for sodium silicate. Unlike DCDP, sodium silicate shell thickness was almost twice the amount of DCDP. The more uniform and coherent microcapsules were produced at a temperature of 55°C. For the DCDP microcapsules and at 49°C, the solution remained an emulsion and no encapsulation took place. The increase in agitation rate resulted in a decrease in the average diameter of the microcapsules for DCDP. This is due to the large microcapsules being broken up into smaller ones when high shear is applied. On the other hand, the diameter of the microcapsules remained constant for sodium silicate microencapsulation as the agitation rate increased. Testing of concrete specimens modified with the two healing agents showed that DCDP-based microcapsules were effective in enhancing the modulus of elasticity of un-cracked concrete and increasing its modulus of elasticity after healing. For sodium silicate, an optimum pH value should be identified in order to produce microcapsules that enhance the modulus of elasticity of concrete before and after healing.
  Authors: Gilford III, James; Hassan, Marwa M.; Rupnow, Tyson; Barbato, Michele; Okeil, Ayman M.
  Authors: Gilford III, James; Hassan, Marwa M.; Rupnow, Tyson; Barbato, Michele; Okeil, Ayman M.
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 288
  Paper Number: 13-1172
• Identifying Improved Standardized Tests for Measuring Cement Particle Size and Surface Area
  Abstract: The Blaine fineness (Blaine) of a cement powder is a single parameter that is meant to characterize the specific surface area of a cement, and is assumed to be linked to physical and mechanical properties of the hydrated cement such as strength, setting time, and rheology. A single parameter cannot characterize the particle size distribution of a cement particle size distribution, upon which the hydration kinetics and solid properties depend. And as the cement industry continues to develop more sophisticated blended cements, it will be even more clearly seen that a single parameter fails to capture the true complexity of the cement. The laser diffraction (LD) measurement of the entire particle size distribution is currently being used by cement producers for quality control of their cements while still measuring the Blaine, which is based on surface area measurement. Despite its wide use by the cement industry, LD is not a standardized test. This project’s goal is to examine various tests, such as laser diffraction and Blaine, which measure the particle size distribution and total surface area of cement powder, and then determine the most appropriate test based on correlation with macro-properties of the cement paste or mortar. In addition, the shape of the cement particles, for a partial particle size range, was determined using X-ray computed micro-tomography (X-Ray CT) and the relationship between X-ray CT, the Brunauer-Emmett-Teller surface area method (BET) (surface area), laser diffraction, and Blaine measurements was explored. The more fundamental and sophisticated experiments, nitrogen BET and X-ray CT, were used as “ground truth” to critically evaluate the laser particle size distribution and Blaine fineness measurements. The standardization of the laser diffraction test method is proposed.
  Authors: Ferraris, Chiara F.; Garboczi, Edward J.
  Authors: Ferraris, Chiara F.; Garboczi, Edward J.
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 288
  Paper Number: 13-2578
• Performance of Pore-Lining Impregnants in Concrete Protection by Unidirectional Salt-Ponding Test
  Abstract: Until recently, solvent based forms of monomeric alkyl (isobutyl)-trialkoxy silane, produced under various trade names, were exclusively used in the UK for concrete protection of transportation structures and other structures subject to surface salt contamination. Reflecting the move toward more sustainable construction, with increasing demand for less hazardous materials, alternative protective treatments have emerged, these based on various aqueous formulations. These include dual purpose materials for protection and concrete colouration. At the same time, developments in nano materials has resulted in the availability of a low hazards, pure silane that is neither water nor solvent based. This investigation evaluates the performance of this material together with three water based materials in respect to their resistance to water and salt solution absorption, and chloride ion penetration. A comparative investigation is included to assess the possibility of using convenient concrete cubes rather than larger scale slabs for chloride contamination testing by the salt ponding method. The results of the study are particularly relevant to older reinforced concrete structures, ones that frequently suffer low concrete cover to their steel reinforcing bars.
  Authors: Rahman, Mujib; Chamberlain, Denis; Balakhrishna, M; Kipling, Judith
  Authors: Rahman, Mujib; Chamberlain, Denis; Balakhrishna, M; Kipling, Judith
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 288
  Paper Number: 13-2677
• Fatigue Simulation of Cement Concrete Bridge Pavement Using Dissipated Energy Approach
  Abstract: One of the best methods for analyzing the fatigue properties, the dissipated energy (DE) approach was used to investigate the fatigue properties of the cement concrete bridge pavement in this paper. Based on the DE concept for asphalt mixture, the fatigue life equation is derived for cement concrete bridge pavement sustaining repeated cyclic load. The composite beam fatigue tests were conducted using a third-point flexural bending test to determine the dissipated energy parameters and the relevant regression coefficients, and then the fatigue lives of pavement under different axle loads can be predicted. On the basis of these works, the fatigue life predictive formula of pavement using DE approach is expressed as a relationship between the initial dissipated energy (W0) and the fatigue life (Nf). The results of this paper have strong theoretical and practical value in establishing the fatigue design theory and method for cement concrete bridge pavement and estimating effectively the service life of concrete bridge pavement.
  Authors: Qian, Zhendong; Wang, Jiangyang; chen, Leilei; Peng, Guangyin
  Authors: Qian, Zhendong; Wang, Jiangyang; chen, Leilei; Peng, Guangyin
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 288
  Paper Number: 13-3278
• Improving Concrete Sustainability and Performance UsingPortland-Limestone Cement Synergies
  Abstract: Increased use of portland-limestone cements (PLC’s) in the US is anticipated, as a new provision for PLC’s containing up to 15% limestone has been added to blended cement specifications. Published research has documented performance synergies of cementitious mixtures with finely ground limestone (particle sizes generally smaller than for cement), especially in combination with certain sup¬plementary cementitious materials (SCM’s). Time of setting and strength development bene¬fits are reported, generally in proportion to limestone fineness. It appears possible to fully develop poten¬tial for these performance synergies in mill-ground PLC’s, in which lime¬stone comprises the majority of the finest particles. In this paper, performance trends observed in concrete with PLC have been further investigated using separately propor¬tioned ground limestone and ordi¬nary portland cement (OPC) as well as mill-ground PLC samples. Influ¬ences of variables such as SCM type and lime¬stone fineness were evalu¬ated using laboratory paste mixtures. Set acceleration increased with limestone fineness for all combinations in¬cluding mix¬tures without SCM’s. Strength synergies were clearly evi¬dent with all SCM’s, more signifi-cantly with Class C ash and slag cement than with Class F ash. All strength trends improved as lime¬stone fineness was increased. Consistent synergies that enhance setting and strength performance appear achieva¬ble with PLC’s. Optimizing particle fineness will be a key factor in achieving these benefits. Performance contributions of SCM’s in combinations with PLC’s may exceed those of similar mixtures with traditional OPC’s, thus SCM use can be maximized and related sustainability impacts further extended.
  Authors: Cost, Tim; Howard, Isaac L.; Shannon, Jay
  Authors: Cost, Tim; Howard, Isaac L.; Shannon, Jay
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 288
  Paper Number: 13-4429
• Temperature Prediction for Mass Concrete Using Finite Element Method
  Abstract: In this research, large concrete cubes were constructed to study the early temperature distribution inside the concrete. Finite element model was created using ABAQUS to simulate the heat transfer process. To account for the variation of concrete properties during hydration and the fact that heat generation not being uniform inside concrete, user subroutines were developed and incorporated in the model to enable solution dependent material properties and thermal loading function. In this study, there are three major improvements of the finite element method: 1. Material properties are now dependent on degree of hydration and temperature. 2. Thermal loading function is also degree of hydration dependent. 3. Degree of hydration varies at different locations in concrete depending on their unique temperature histories. The method developed in this study is applicable to predict temperature history for mass concrete with better accuracy. Simulation results of temperature field fit well with data collected from the experiments.
  Authors: Lin, Yun; Chen, Roger H. L.
  Authors: Lin, Yun; Chen, Roger H. L.
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 288
  Paper Number: 13-4904
• Investigation of Internal Frost Damage in Cementitious Materials with Micromechanic Analysis, Scanning Electron Microscope Imaging, and Ultrasonic Wave Scattering Techniques
  Abstract: This study investigates the internal-frost damage due to ice crystallization pressure in capillary pores of concrete. The SEM imaging analysis, micro-damage modeling and ultrasonic wave scattering techniques were developed to study the internal-frost damage in cementitious material samples. The pore structures have significant impact on freeze-thaw durability of cement/concrete samples. The scanning electron microscope (SEM) techniques were applied to characterize freeze-thaw damage within pore structure. The digital sample was generated from SEM imaging processing. In the microscale pore system, the crystallization pressures at subcooling temperatures were calculated using interface energy balance with thermodynamic analysis. The largest crystallization pressure on the pore wall was input for the fracture simulation with the developed Extended Finite Element Model (XFEM). One comparison study between model simulation and test results indicates that internal-frost damage model can reasonably predict the crack nucleation and propagation within multiphase cement microstructure. In addition, the ultrasonic wave scattering technique was developed for rapid measurement of pore size distribution and volume fraction in cementitious concrete. The inverse analysis results show the promising measurements of size distribution of pores in concrete samples. Future study will link the micromechanics analysis and the ultrasonic wave scattering techniques to study the internal-frost damage evolution.
  Authors: Dai, Qingli; Ng, Kenny; Yu, Xiong
  Authors: Dai, Qingli; Ng, Kenny; Yu, Xiong
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 288
  Paper Number: 13-4966
• Bond Characteristics of Engineered Cementitious Composite Overlays
  Abstract: Rigid concrete overlays have been used for smoothing a damaged surface and/or restoring or improving the mechanical capacity of bridge-decks for many years. The superior ductility with high strength and improved durability characteristics suggest that Engineered Cementitious Composites (ECC) could be used as an attractive alternative to conventional overlay materials, and solutions if a strong mechanical bond is formed between the overlay and the substrate material. An experimental study was performed to evaluate the bond strength between ECC overlay and an ordinary concrete substrate with different types of surface textures including, smooth and rough. Micro-silica concrete (MSC), generally used as an overlay material, were also prepared as a control mixture. ECC and MSC overlay mixtures were cast over the concrete substrate to determine bonding performances. Two test methods; slant shear and splitting prism tests with MSC and two ECC mixtures were used. The experimental results show that when ECC is used as an overlay material, bond strength is significantly increased compared to those of MSC. Under compression loading (slant shear test), the bond strength properties of layered ECC-substrate concrete cylinder specimens is greater than the strength of substrate concrete with compressive strength of around 30 MPa. However, in the case of layered MSC-substrate concrete cylinder specimen, failure consistently occurs at the interface.
  Authors: Sahmaran, Mustafa; Yucel, Hasan Erhan; Al-Emam, Muhannad; Yaman, Ismail Ozgur; Guler, Murat
  Authors: Sahmaran, Mustafa; Yucel, Hasan Erhan; Al-Emam, Muhannad; Yaman, Ismail Ozgur; Guler, Murat
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 288
  Paper Number: 13-1578
  Practice-Ready: Yes
• Evaluation of Microencapsulation of Dicyclopentadine and Sodium Silicate for Self-Healing Concrete
  Authors: Hassan, Marwa
  Authors: Hassan, Marwa
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 288
  Paper Number: 13-1172
• Bond Characteristics of Engineered Cementitious Composite Overlays
  Authors: Sahmaran, Mustafa
  Authors: Sahmaran, Mustafa
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 288
  Paper Number: 13-1578
• Effect of High-Volume Fly Ash on Shear Strength of Concrete Beams
  Authors: Arezoumandi, Mahdi
  Authors: Arezoumandi, Mahdi
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 288
  Paper Number: 13-2080
• Fatigue Simulation of Cement Concrete Bridge Pavement Using Dissipated Energy Approach
  Authors: Wang, Jiangyang
  Authors: Wang, Jiangyang
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 288
  Paper Number: 13-3278
• Improving Concrete Sustainability and Performance Using Portland-Limestone Cement Synergies
  Authors: Cost, Tim
  Authors: Cost, Tim
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 288
  Paper Number: 13-4429
• Improving Concrete Sustainability and Performance Using Portland-Limestone Cement Synergies
  Authors: Howard, Isaac
  Authors: Howard, Isaac
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 288
  Paper Number: 13-4429
• Temperature Prediction for Mass Concrete Using Finite Element Method
  Authors: Chen, Roger
  Authors: Chen, Roger
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Materials
  Session: 288
  Paper Number: 13-4904
• Effect of High-Volume Fly Ash on Shear Strength of Concrete Beams
  Abstract:

  The production of Portland cement – the key ingredient in concrete – generates a significant amount of carbon dioxide. However, due to its incredible versatility, availability, and relatively low cost, concrete is the most consumed manmade material on the planet. One method of reducing concrete’s contribution to greenhouse gas emissions is the use of fly ash to replace a significant amount of the cement. An experimental investigation was conducted to study the shear strength of full-scale beams constructed with both high-volume fly ash concrete (HVFAC) – concrete with at least 50% of the cement replaced with fly ash –and conventional concrete (CC). This experimental program consisted of 16 beams (12 without shear reinforcing and four with shear reinforcing in the form of stirrups). Additionally, three different longitudinal reinforcement ratios were evaluated within the test matrix. The beams were tested under a simply supported four-point loading condition. The experimental shear strengths of the beams were compared with the shear provisions of both U.S. and international design codes (U.S. [ACI-318 and AASHTO LRFD], Australia, Canada, Europe, and Japan) as well as a shear database of CC specimens. Furthermore, statistical data analyses (both parametric and non-parametric) were performed to evaluate whether or not there is any statistically significant difference between the shear strength of the HVFAC and the CC beams. Results of these statistical tests show the HVFAC beams had higher shear strength than the CC beams tested in this investigation.

  Authors: Arezoumandi, Mahdi; Volz, Jeffrey; Myers, John J.
  Authors: Arezoumandi, Mahdi; Volz, Jeffrey; Myers, John J.
  Year: 2013
  Document Type: Paper
  Subject: Materials
  Session: 288
  Paper Number: 13-2080