Uncompacted Void Research Articles

Performance Assessment of Basic Oxygen Furnace Slag (BOFS) as an Ice-Melting Abrasive Material

Abrasives play a crucial role in surface blasting, especially in cold climates, where snow and ice significantly challenge transportation infrastructure and road safety. The main purpose of this research is to address the critical need for effective and sustainable winter maintenance techniques. This study examined the possibilities of Basic Oxygen Furnace Slag (BOFS) as a substitute (an abrasive substance) for conventional aggregates in ice-melting applications. Thus, this research assessed the physical properties of BOFS, such as absorption capacity, tested at -5°C, and aggregate angularity test, and designed for evaluation of the surface texture, friction, and percentage of fractured faces in uncompacted voids (SSD%) of the aggregates. Moreover, the potential use of a blend of BOFS with de-icing salts, specifically sodium chloride (NaCl) and calcium chloride (CaCl2), was investigated as an effective ice-melting agent. For this purpose, three tests were carried out: the petri dish test according to SHRP H-205.1, the polishing ice melting test using a modified ASTM C 944 (rotational cutter), and the surface temperature measurement test. By assessing the performance of BOFS, our goal was to justify its efficacy, offering a practical alternative for regions experiencing severe winter conditions. Eventually, the findings from this study assert that BOFS can be used for surface blasting, indicating its potential as a substitute for traditional abrasives.

Examining the Influence of Aggregate Shape Properties Measured Using Imaging Technique on the Flexural Strength of Concrete

It is known that aggregate shape properties influence the quality and performance of pavement materials. Yet, there is little information available on the effect of aggregate shape properties on the flexural strength of concrete, which is the main topic of the present study. Aggregate Image Measurement System (AIMS) was used to analyze three sizes of coarse aggregate and three sizes of fine aggregate obtained from three different sources. Portland cement concrete beams were prepared and tested for flexural strength using Universal Testing Machine (UTM) according to ASTM standards. A positive relationship with a high correlation was found between some aggregate shape properties (angularity and texture) and the flexural strength of the concrete. At the same time, an inverse relation with weak correlation was noticed between flexural strength and sphericity of coarse aggregates. Meanwhile, the 2-D form of fine aggregate showed a positive relationship with a weak correlation with flexural strength. Despite showing a similar trend of effects that shape properties have on flexural strength, the shape indices showed a better correlation with flexural strength than uncompacted void content, which is used as a measure of combined shape properties in the conventional indirect test methods. Results also suggested that the shape indices measured using the imaging technique can be a good alternative for the conventional methods.

Increasing sustainable aggregate usage in concrete by quantifying the shape and gradation of manufactured sand

Sustainable fine aggregates are becoming an area of greater discussion. Manufactured sands are materials created by crushing larger aggregates that are not widely used. Interest is growing in the use of manufactured sand in concrete because it provides a way to improve the sustainability of concrete with a decrease in cost. However, manufactured sands typically have different shapes, gradations, and mineralogy in comparison to natural sand. There is concern that these differences can impact the performance of concrete that uses manufactured sands. This work quantifies the shape properties of manufactured sands and natural sands using the AIMS II, microscopic inspection, and the Uncompacted Voids Content (ASTM C1257 -Method A). Next, concrete mixtures are created with different proportions of manufactured sand and the workability is measured. This work provides a correlation between different methods to measure the shape and then relates these measurements to the impact of the workability and finishability of concrete. Adjustments to the Tarantula Curve are also suggested.

Characteristics of crushed and alternative fine aggregates based on flow, shear and impact behaviour

Crushed sand has been found to be an excellent replacement for river sand as the latter is not readily available. As a part of sustainable construction methods and practices, industrial by- products such as copper slag, cinder etc., can be used as alternative sands. In this work, an attempt has been made to study the performance of crushed stone sand for its flow properties based on large sample analysis. For this, 30 samples of crushed sand were procured from different sources. In addition, few alternative sands were also considered for the analysis which included copper slag, Ennore sand and two types of cinders. The parameters tested are flow time based on New Zealand flow cone, loose bulk density, uncompacted voids and specific gravity. In order to enhance the performance of the poor crushed sand, different samples of crushed sands were blended which results in acceptable flow characteristics. Similar exercise was done for alternative sands by considering double or triple blending which finally resulted in good flow properties for possible use in concrete. In addition, few samples were also tested and evaluated for their shear and impact behaviour. Conclusions are drawn based on the results obtained.

Quantification of Shape Properties and Their Effects on Particle Packing of Coarse-Grain Soil

Particle shape is known for its significant influence on the engineering properties of coarse grain soil. But it remains difficult to quantify how the different scales of shape properties will affect the macroscopic soil behavior individually. This study aims to select independent shape descriptors at different geometrical scales and evaluate the influence of particle shape irregularities on the particle packing of coarse-grain soil. With the aid of the digital image technique for 2D image acquisition of coarse grain soil particles, the shape properties were firstly quantified by the presented shape descriptors. Statistical analysis was performed to evaluate the independence of each shape descriptor and the most common independent descriptors; elongation, roundness, and texture signature were put forward. The proposed shape descriptors were then used to classify the collected particles and establish the particle shape library. The influence of each scale shape property on particle packing was systematically investigated using discrete element method (DEM) simulations of uncompacted void content test with predefined particles selected from the shape library. The simulated particles with specified shape properties were selected from the corresponding shape library. The numerical simulation results indicated that elongation and roundness significantly contribute to particle packing, while the influence of texture signature can be neglected due to its small variation in nature. The larger elongation and smaller roundness values were proved to increase the uncompacted porosity of coarse grain soil.

Interrelationship between uncompacted void content of aggregates and asphalt concrete properties

ABSTRACTIt is a well known fact that morphological characteristics of aggregates influence the mechanical response of asphalt concrete (AC). Uncompacted void content (UVC) of aggregate is often related to their morphological characteristics. A detailed experimental study was performed to explore relationship between UVC and mechanical response of AC. Initially, aggregates were artificially smoothened using Los Angles abrasion testing machine. UVC was then evaluated using blended aggregates at five levels of smoothness/texture. Increasing aggregate smoothness resulted in decreased UVC values. Higher UVC was obtained with a finer gradation compared to coarse gradation. Three AC mixtures prepared using these smoothened aggregates were tested for their strength and flow properties. A linear, strong positive correlation was found between UVC and Marshall parameters (stability, Marshall quotient). This can be attributed to interparticle resistance developed during mechanical loading. Parabolic relations were found between UVC and retained Marshall parameters. The retained Marshall parameters was found to be a function of UVC. It is concluded that UVC can be effectively used to capture changes in aggregate morphology and AC response.

Evaluation of morphological characteristics of fine aggregate in asphalt pavement

Aggregate makes up a high mass fraction in asphalt pavements. The morphological characteristics of aggregate (i.e., shape factors, angularity, and surface texture) significantly affect the mechanical performance of asphalt pavement. Extensive investigations of aggregate morphology have been conducted on coarse aggregate in recent years; however the analysis of fine aggregate has not been carried out up to date. Commonly used methods to extrapolate information on the morphology of fine aggregate such as sand flow test (SFT) and Uncompacted Void Content Test (UVCT) give a general characterization of the aggregate morphology without allowing for differentiated conclusions regarding the respective morphological factors. In this study digital image processing (DIP) is used to determine morphological index values of fine aggregate. Data from DIP is compared with results from UVCT and SFT by means of correlation analyses to investigate the applicability and precision of the respective methods. UVCT and SFT are found to be strongly reliable on the absolute grain size rendering the methods less resilient. DIP is very well suited to determine specific morphological indices of fine aggregates and is a useful tool for the design of asphalt mixtures.

Quantification of aggregate morphologic characteristics with the correlation to uncompacted void content of coarse aggregates in Virginia

A three-dimensional (3-D) high-resolution image analysis system for aggregate morphologies characterization, the Improved Fourier Transform Interferometry (FTI) system, is presented. The following aggregate morphological characteristics were measured: sphericity, flatness ratio, elongation ratio, angularity and surface texture. Compared to the FTI system, the improved FTI system improves usability and data collection speed and provides a more user-friendly graphical interface. The objective of this paper is to investigate the correlation between morphological characteristics and uncompacted void content of coarse aggregates. Sixteen types of coarse aggregates from different quarries in Virginia were analyzed using the improved FTI system. It was found that aggregates’ morphological characteristics can be affected by the material type, size, origin and crushing technique. The shape results from the improved FTI system showed a good agreement with the manual measurements via a caliper, demonstrating the accuracy of this image analysis system. The relationship between the void contents of different sizes of coarse aggregates and morphological characteristics was examined. Regression analysis indicated that void content was significantly influenced by the morphological characteristics.

Modeling the triaxial behavior of riverbed and blasted quarried rockfill materials using hardening soil model

Riverbed modeled rockfill material from Noa Dehing dam project, Arunachal Pradesh, India and blasted quarried modeled rockfill material from Kol dam project, Himachal Pradesh, India were considered for this research. Riverbed rockfill material is rounded to sub-rounded and quarried rockfill material is angular to sub-angular in shape. Prototype rockfill materials were modeled into maximum particle size (dmax) of 4.75 mm, 10 mm, 19 mm, 25 mm, 50 mm and 80 mm for testing in the laboratory. Consolidated drained triaxial tests were conducted on modeled rockfill materials with a specimen size of 381 mm in diameter and 813 mm in height to study the stress–strain–volume change behavior for both rockfill materials. Index properties, i.e. uncompacted void content (UVC) and uniaxial compressive strength (UCS), were determined for both rockfill materials in association with material parameters. An elastoplastic hardening soil (HS) constitutive model was used to predict the behavior of modeled rockfill materials. Comparing the predicted and observed stress–strain–volume change behavior, it is found that both observed and predicted behaviors match closely. The procedures were developed to predict the shear strength and elastic parameters of rockfill materials using the index properties, i.e. UCS, UVC and relative density (RD), and predictions were made satisfactorily. Comparing the predicted and experimentally determined shear strengths and elastic parameters, it is observed that both values match closely. Then these procedures were used to predict the elastic and shear strength parameters of large-size prototype rockfill materials. Correlations were also developed between index properties and material strength parameters (dilatancy angle, ψ, and initial void ratio, einit, required for HS model) of modeled rockfill materials and the same correlations were used to predict the strength parameters for the prototype rockfill materials. Using the predicted material parameters, the stress–strain–volume change behavior of prototype rockfill material was predicted using elastoplastic HS constitutive model. The advantage of the proposed methods is that only index properties, i.e. UCS, UVC, RD, modulus of elasticity of intact rock, Eir, and Poisson's ratio of intact rock, νir, are required to determine the angle of shearing resistance, ϕ, modulus of elasticity, E50ref, and Poisson's ratio, ν, of rockfill materials, and there is no need of triaxial testing. It is believed that the proposed methods are more realistic, economical, and can be used where large-size triaxial testing facilities are not available.

PZT-Based Detection of Compactness of Concrete in Concrete Filled Steel Tube Using Time Reversal Method

A smart aggregate-based approach is proposed for the concrete compactness detection of concrete filled steel tube (CFST) columns. The piezoceramic-based smart aggregates (SAs) were embedded in the predetermined locations prior to the casting of concrete columns to establish a wave-based smart sensing system for the concrete compactness detection purpose. To evaluate the efficiency of the developed approach, six specimens of the CFST columns with the rectangular cross-section were produced by placing some artificial defects during casting of concrete for simulating various uncompacted voids such as cavities, cracks, and debond. During the test, the time reversal technology was applied to rebuild the received signals and launch the reversed signals again by SAs, to overcome the issue of the lack of the prototype. Based on the proposed nonprototype, two indices of time reversibility (TR) and symmetry (SYM) were applied to relatively evaluate the level of concrete compactness in the range of the two SAs. The experimental results show that the developed method can effectively detect the compactness of concrete in CFST columns.

Testing and Modeling the Behavior of Riverbed and Blasted Quarried Rockfill Materials

AbstractModeled rockfill materials were obtained from nine sites (two riverbed and seven quarried) from different projects in India and Nepal, and drained triaxial tests were conducted with specimens that were 381 mm in diameter and 813 mm high. Index properties of the rockfill materials, namely, unconfined compressive strength (UCS) and uncompacted void content (UVC), were determined. An elastoplastic hierarchical singe-surface (HISS) constitutive model was used to characterize the behavior of modeled rockfill materials. The predicted stress-strain-volume change behavior was compared with the observed behavior, and it was found that both observed and predicted behavior matched closely. Procedures have been developed to predict the shear strength and elastic parameters of rockfill materials using the index properties, namely, UCS, UVC, and relative density (RD), and predictions were made satisfactorily. Predicted shear strength and elastic parameters were compared with the experimental values, and it was ...

2011 AEG Outstanding Student Professional Paper: Comparison of Colluvium, Debris-Flow, and Glacial Deposits Using Sedimentological, Geotechnical, and Geological Properties, Durango, Colorado

Colluvium and debris-flow deposits differ from each other and from glacial till and glacial outwash deposits in Durango, CO, in terms of sedimentological properties evaluated using laboratory testing. Testing included grain-size analysis, Atterberg limits, specific gravity, visual angularity, and uncompacted void content (UVC). Grain-size analysis showed that colluvium, glacial deposits, and debris-flow deposits had different grain-size distributions (GSDs) that occupied fields on a GSD graph with some overlap. Debris-flow deposits had the most gravel-sized grains, and colluvium had the most silt- and clay-sized grains, while glacial till and glacial outwash had very similar GSDs between colluvium and debris-flow deposits. Comparisons of angularity to gravel-to-fines (G/F) ratio provided a second graphical method for discriminating between debris-flow, colluvium, and glacial deposits. Generally, colluvium and debris-flow deposits were more angular than glacial till and outwash. Additionally, several linear correlations were recognized between lithology of grains and sedimentological and geotechnical properties, the most significant of which were: (1) The angularity of gravel in glacial till and outwash was positively correlated to sandstone gravel content, (2) the plasticity index of outwash fines was positively correlated to the metamorphic gravel content, (3) the amount of outwash fines was positively correlated to sandstone and metamorphic gravel content, while it was negatively correlated to carbonate gravel content, and (4) rounded and sub-rounded gravel content in outwash was positively correlated to carbonate and extrusive igneous gravel content. This study provides insight into the geomechanical differences between depositional mechanisms in similar semiarid environments.

Effect of size and type of fine aggregates on flowability of mortar

The present study investigated how the aggregate characteristics namely individual size, grade and type affects flowability of mortar mixes. Two types, river sand and crusher dust four single sizes namely 1.18 mm, 0.600 mm, 0.300 mm, 0.150 mm and for single gradation of each fine aggregate were considered in the present research work. In total, 103 mortar batches was made with three different sand to cement ratios [s/c] and two different water to cement ratios [w/c] to find out the flowability of mortar and tested using standard flow table. Out of 103 mortar batches, 52 were with river sand and 51 were with crusher dust. Tests were performed as per ASTM 109 standards. S/c ratio varied from 1 to 3 with an increment of one and w/c ratio was chosen in such a way that all the mixes to give measurable flow. The influence of particle shape and surface texture of aggregate were characterized with an angularity test based on ASTM C1252 in terms of percent of air voids in a loosely compacted fine aggregate. The results indicate that the size of aggregate and uncompacted void content have greater impact flowability of mortar. Mortar made with river sand has got better flowability than that of mortar made with crusher dust due to its higher degree of irregularities. Mortar with higher aggregate content has low percentage of spread compared to mortar with low aggregate content. Similarly, graded aggregate has lesser percentage of spread due to its proper packing compared to single sized aggregates.

Evaluation of ASTM G65 abrasive —Spanning 13 years of sand

Abstract Standardized testing requires consistency of all testing parameters including consumables. One of the more common American Society for Testing and Materials (ASTM) tests to evaluate abrasive wear resistance is the ASTM G65-04 Standard Test Method for Measuring Abrasion Using the Dry Sand/Rubber Wheel Apparatus. The specified abrasive is nominally 100% silica (SiO 2 ), sieved to 50/70 mesh. To quantify the consistency of the commercially available silica abrasive used in the ASTM G65-04, five lots of the abrasive were compared using five material characterization tests. The five lots of the abrasive, purchased from U.S. Silica Co., were manufactured in March 1997, July 2007, August 2008, June 2009 and October 2009. The five tests used to compare the different lots of abrasive were the ASTM G65-04 wear test, Uncompacted Void Content (ASTM C1252), chemical composition, size (sieved size distribution) and particle shape (visual). It was found that there was only one instance of significant difference in the characterization tests among the five lots of abrasive. One lot had a significantly different amount of void content among the individual particles but demonstrated similar results to the other lots in wear rate, chemical composition, size distribution and particle shape.

Coarse Aggregate Angularity and Its Relationship to Permanent Deformation of Gravel-Aggregate Hot-Mix Asphalt in New York State

This study evaluated the asphalt mixture performance of various gravel and crushed stone sources with different levels of crushed face counts as determined by ASTM D5821. Coarse aggregate angularity and texture were also evaluated with AASHTO T326 and aggregate imaging system testing. Each of the asphalt mixtures designed and tested used three asphalt binders: (a) neat PG 64-22, (b) polymer-modified PG 64-22 meeting New York State Department of Transportation (New York State DOT) elastic recovery specifications, and (c) polymer-modified PG 76-22. The permanent deformation properties of the different asphalt mixtures were measured with the asphalt pavement analyzer (AASHTO TP63) and the asphalt mixture performance tester (AASHTO TP79) with confining pressure applied to the specimens. Aggregate testing showed that ASTM D5821 correlated poorly with both AASHTO T326 and the aggregate imaging system. Situations also occurred in which aggregates had identical crushed counts but different levels of uncompacted void contents. The asphalt mixture performance tester that used confining pressure correlated well with the uncompacted voids content results of AASHTO T326. However, stresses applied in the asphalt pavement analyzer did not sufficiently mobilize the asphalt mixtures to allow differences in aggregate angularity to be clearly noted. Both asphalt tests were sensitive to asphalt binder high-temperature stiffness as determined by AASHTO TP70. Statistical analysis of the data resulted in a table that allows the New York State DOT to use aggregate angularity (as determined by AASHTO T326) and nonrecoverable creep compliance (as determined by AASHTO TP70) interchangeably to ensure that hot-mix asphalt (HMA) blends containing gravel aggregate perform as well as HMA blends containing crushed-stone aggregate.

Effect of coarse aggregate characteristics on concrete rheology

In the present study, concrete was considered as a two-phase material, consisting of coarse aggregate (CA) and mortar. Coarse aggregate properties were characterized by fineness, uncompacted void and friction angle. The combined effects of CA characteristics and mix design on the rheological properties of the corresponding concrete were investigated using a portable IBB concrete rheometer. Experimental results indicated that a higher CA and fine aggregate content normally result in higher concrete rheological parameters (yield stress and viscosity). For a given type and amount of mortar, concrete yield stress and viscosity generally increase with the uncompacted void content and friction angle but decreased with the size (or fineness) of CA. Well graded CA, generally having low uncompacted void content, provides concrete with considerably reduced yield stress and viscosity when compared with single-sized CA. In addition, a multiple-parameter linear regression analysis was conducted to evaluate how different CA characteristics (fineness, uncompacted void and friction angle) and mix design parameters (mortar composition, and CA volume fraction) affect concrete rheological behavior.

Effects of coarse aggregate angularity and asphalt binder on laboratory-measured permanent deformation properties of HMA

Rutting has been identified as one of the primary distresses in asphalt pavements. Rutting in hot-mix asphalt (HMA) mixtures can be attributed to either the lack of interlocking of aggregate structure or insufficient bonding between aggregate and asphalt binder, or both. In the present study, efforts have been made to identify the contributions of aggregate structure and asphalt binder to the rutting characteristics of a dense-graded surface HMA mixture. Coarse gravels at five different angularity levels (100, 85, 70, 50 and 35% of aggregate with two or more fractured surfaces) were used to produce mixtures with similar aggregate gradations. Three different asphalt binders (PG 64-22, PG 76-22 and PG 82-22) were used to make mixtures for laboratory rut evaluations. The aggregate imaging system (AIMS), uncompacted voids in coarse aggregate (VCA) and tri-axial shear tests were conducted to evaluate the coarse aggregate angularity (CAA). The US Army Corps of Engineers' gyratory testing machine (GTM), creep and the asphalt pavement analyser (APA) tests were selected to characterise the rut resistance of asphalt mixtures. The results from this study indicated that coarse aggregate AIMS, VCA and tri-axial tests were related to the CAA and laboratory-measured rutting indices. At temperatures close to the binder's upper grade limit, aggregate structures played a critical role in the rut resistance of HMA mixtures; whereas, at temperatures below the binder's upper grade limit, the stiffness of the asphalt binder played a more important role in the rut resistance of asphalt mixtures evaluated in this study.

Effects of Size and Uncompacted Voids of Aggregate on Mortar Flow Ability

The effects of aggregate characteristics on the flow ability of mortar mixtures were investigated. Two types, five single-sized and three graded fine aggregate were considered. Uncompacted voids of the aggregates were measured. Flow properties of 166 mortar batches made with different aggregates, sand-to-cement ratios (s/c) and water-to-cement ratios (w/c), were evaluated using the modified ASTM C109 flow table test method. The results indicated that in addition to w/c, the content, uncompacted voids, and size of aggregate all significantly affect mortar flow ability. Generally, aggregate having higher uncompacted void content provides its mortar with a lower flow. When aggregate content was low (s/c = 1), aggregate size had little effect on the flow ability of the mortar; when aggregate content was high (s/c = 3), aggregate size significantly influenced the mortar flow ability. The mortar with graded aggregate has better flow ability than the mortar with single-sized particles. River sand provides a mortar with better flow ability when compared to limestone. A statistical model was developed to predict the flow ability of mortar. The model can also be used to study the effect of different parameters on mortar flow properties.

The Role of Nature of Particles on the Behaviour of Rockfill Materials

The nature of the particles of seven alluvial rockfill materials and three quarried rockfill materials are expressed in terms of uncompacted void content and unconfined compressive strength of each of the rockfill materials. Drained triaxial tests are conducted on modeled rockfill materials. The behaviour of the rockfill materials is related to the uncompacted void content and unconfined compressive strength of the rockfill materials. A prediction procedure is proposed to determine the angle of shearing resistance of the rockfill materials using uncompacted void content and unconfined compressive strength of these materials.

Technical and Computational Aspects of the Measurement of Aggregate Shape by Digital Image Analysis

Aggregates need to pass numerous tests to ensure the performance of asphalt and concrete structures and pavements. Some of these tests are fairly onerous, requiring manual, labor intensive, cost ineffective measurements that do not provide significant statistical validity, and are prone to errors through ignorance, negligence, or even in some cases through deliberate misrepresentation. This paper presents a vision based alternative to measure the shape of aggregate particles. The system, although requiring increased capital investment, will result in objective, cost effective, and timely testing of aggregate shape. The system uses dual, synchronized, double speed progressive scan cameras to image the aggregate piece from two directions. A dual image acquisition card simultaneously digitizes both images and does real-time thresholding to create a binary image, which is ported to the host computer. A software trigger determines the presence of an aggregate piece in the image, and the boundaries of the piece are delineated by a perimeter-walking routine. Measurements of aspect ratio and minimum curve radius are made on the perimeter array, and are compared to flat and elongated tests, coarse aggregate angularity (uncompacted voids), compacted voids, and fractured face counts.