scholarly journals Developing Laboratory Performance Models for Thin Asphalt Overlay Mixtures

2019 ◽  
Vol 27 (1) ◽  
pp. 382-395
Author(s):  
Mousa Zeki ◽  
Shakir Al-Busaltan
Keyword(s):  
Tensile Strength ◽  
Statistical Modeling ◽  
Statistical Models ◽  
Performance Enhancement ◽  
Aggregate Size ◽  
Experimental Program ◽  
Maximum Aggregate Size ◽  
Durability Properties ◽  
Asphalt Overlay ◽  
Asphalt Content

Statistical modeling is utilized effectively to development relation/s between the dependent variables and independent variables. In other words, it describes how one or more random variables are related to one more other variables. Building verified models can help in predicting performance characteristics, and saving time and money. This study aims to present a statistical models which help to understand the significance of the different parameters in characterizing the performance of the Thin Asphalt Overlay (TAO). The experimental program included: design the thin asphalt overlay mixtures using one gradation type (9.5 Nominal Maximum Aggregate Size NMAS), three filler types (conventional mineral filler, Ordinary Portland Cement, and Quick lime), and five percentages of asphalt content to identify the optimum asphalt content. Then, Styrene Butadiene Styrene (SBS) modified polymer binder was introduced for performance enhancement. Performance tests were used to evaluate TAO mixture in term of some main namely, volumetric, mechanical, and durability properties are (bulk density, indirect tensile strength and tensile strength ratio). Statistical Product and Service Solutions (SPSS) software (Version 24) was used as a tool for models building. To find the most accurate statistical models, linear and nonlinear regression was achieved. This study demonstrates that the using statistical modeling is achievable and offer a vital tool to describe the characteristics and performance of the TAO mixture in term volumetric, mechanical and durability properties.

scholarly journals Enhancing the Flexural Strength of Concrete using Recycled Iron and Steel Slag Aggregate

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
A. A Raheem
Keyword(s):  
Tensile Strength ◽  
Flexural Strength ◽  
Concrete Beams ◽  
Steel Slag ◽  
Aggregate Size ◽  
Mineralogical Composition ◽  
Maximum Aggregate Size ◽  
Considerable Effort ◽  
Iron And Steel ◽  
Coefficient Of Uniformity

Concrete is strong in compression but weak in tension hence, considerable effort is required to improve concrete’s tensile strength by the use of pre-stressed concrete and addition of admixtures or additives. In this study, the use of recycled iron and steel slag (RISS) aggregate to improve the tensile strength of concrete was considered. The paper assessed the mineralogical composition of RISS and granite aggregates, and gradation. It also determines the effects of RISS aggregate on the flexural strength of concrete beams of 150 × 150 × 600 mm containing 0, 10, 20, 40 and 60% RISS aggregate replacement in mix ratios 1:1½:3, 1:2:4 and 1:3:6 with water cement ratios 0.65,0.60 and 0.55 respectively. Diffractograph of RISS and granite aggregate showed that RISS contains Magnetite, Ilmenite and Quartz, while granite contains Quartz, Annite, Microcline and Albite as the predominant minerals. The coefficient of uniformity and concavity of RISS and granite aggregate for maximum aggregate size of 37.5 mm are 4.35 and 1.33; and 4.64 and 1.76 respectively. Both aggregates contain quartz as the predominant mineral and are well graded. The result of the Flexural strength at 28 days curing is within 0.135 – 0.250 MPa specified byBS8500 – 2:2015. Flexural strength of concrete beams cast with RISS aggregate is relatively higher than concrete cast with granite aggregate. Flexural strength, a measure of tensile strength of concrete is improved as percentage RISS aggregate increased.

Refinement of the Hot-Mix Asphalt Ignition Method for High-Loss Aggregates

2005 ◽  
Vol 1907 (1) ◽  
pp. 128-134
Author(s):  
Graham C. Hurley ◽  
Brian D. Prowell
Keyword(s):  
Standard Deviation ◽  
Standard Method ◽  
Aggregate Size ◽  
Maximum Aggregate Size ◽  
High Loss ◽  
Ignition Furnace ◽  
Aggregate Breakdown ◽  
Furnace Control ◽  
Asphalt Content ◽  
Glass Cleaning

Four methodologies for determining the asphalt content of mixtures containing high-loss aggregates in the ignition furnace were evaluated: the standard method using the Thermolyne furnace (control), the Troxler NTO infrared furnace, the Ontario method, and a Tempyrox glass-cleaning oven. Six aggregate sources with high ignition furnace aggregate corrections were obtained from around the country: four dolomites, a basalt, and a serpentine/chlorite. Calibration factors were determined for each method at optimum asphalt content. Additional samples were then tested at optimum plus 0.5% asphalt content, and the measured asphalt content was calculated by using the correction factor determined for that method and aggregate source. The Tempyrox Pyro-Clean furnace, commonly used for cleaning laboratory glassware, produced the lowest aggregate correction factors. The standard method and the Ontario method, both using the Thermolyne ignition furnace, produced the smallest bias or error in measured asphalt content. The standard deviation of the corrected asphalt contents for these high-loss sources was higher than the within-laboratory standard deviation reported for AASHTO T308. The only exception was the Alabama source using the standard method. The Ontario method and Tempyrox oven generally reduced the variability of asphalt content measurements for high-loss aggregates. None of the methods evaluated statistically reduced aggregate breakdown on the nominal maximum aggregate size and 4.75-mm sieves. The Ontario method significantly reduced, but did not eliminate, aggregate breakdown on the 0.075-mm sieve. The Ontario method is the best method for immediate implementation for determining the asphalt content by the ignition method for high-loss aggregates.

Evaluation of Infrared Ignition Furnace for Determination of Asphalt Content

2003 ◽  
Vol 1861 (1) ◽  
pp. 44-50 ◽  
Author(s):  
Graham C. Hurley ◽  
Brian D. Prowell
Keyword(s):  
Aggregate Size ◽  
Maximum Aggregate Size ◽  
Correction Factors ◽  
Ignition Furnace ◽  
Aggregate Breakdown ◽  
Significant Difference ◽  
Asphalt Content ◽  
Aggregate Loss ◽  
Separate Calibration

The Troxler Model 4730 infrared ignition furnace was compared with a standard Thermolyne ignition furnace. Comparisons conducted with a single unit of each furnace type were based on the correction factor for aggregate loss during ignition, accuracy, and the variability of the measured asphalt content and aggregate degradation during ignition. Forty-eight samples representing two nominal maximum aggregate sizes (9.5 and 19.0 mm), four aggregate types (granite, crushed gravel, limestone, and dolomite), and two asphalt contents (optimum and optimum plus 0.5% asphalt content) were tested in each furnace. The results indicated that the correction factors for aggregate loss during ignition were significantly different for each type of furnace, thus requiring a separate calibration for each type of furnace. In practical terms, the differences for all but the 9.5-mm nominal maximum aggregate size (NMAS) limestone and both dolomite mixtures were less than 0.1%. The samples with the optimum plus 0.5% asphalt content were tested by using the calibration factors developed for a particular mix–furnace combination. The results were analyzed in terms of accuracy (bias) and variability (standard deviation). Neither the measured biases nor the standard deviations for the two types of furnaces were significantly different. The results obtained with four sieve sizes (NMAS and 4.75, 2.36, and 0.075 mm) were evaluated for aggregate breakdown. A comparison of the aggregate gradations recovered from both furnaces indicated no significant difference in the degree of aggregate degradation. A round-robin investigation should be conducted to confirm that the precision of the infrared furnace is similar to the precision of the standard furnace.

scholarly journals The Effects of Maximum Attapulgite Aggregate Size and Steel Fibers Content on Fresh and Some Mechanical Properties of Lightweight Self Compacting Concrete

2020 ◽  
Vol 26 (5) ◽  
pp. 172-190
Author(s):  
Shubbar Jawad Al-obaidey
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Aggregate Size ◽  
Steel Fibers ◽  
Maximum Aggregate Size ◽  
Marginal Effect ◽  
Fresh Properties ◽  
Self Compacting Concrete ◽  
Flexural Tensile Strength

The main objectives of this study were investigating the effects of the maximum size of coarse Attapulgite aggregate and micro steel fiber content on fresh and some mechanical properties of steel fibers reinforced lightweight self-compacting concrete (SFLWSCC). Two series of mixes were used depending on maximum aggregate size (12.5 and 19) mm, for each series three different steel fibers content were used (0.5 %, 1%, and 1.5%). To evaluate the fresh properties, tests of slump flow, T500 mm, V funnel time, and J ring were carried out. Tests of compressive strength, splitting tensile strength, flexural tensile strength, and calculated equilibrium density were done to evaluate mechanical properties. For reference mixes, the results showed that mixes with a larger maximum aggregate size of 19 mm exhibited better fresh properties, while mechanical properties negatively affected by using a larger maximum aggregate size. The results also showed that using steel fibers led to negative effects on fresh properties, especially with higher steel fibers content and larger maximum aggregate size. The marginal effect of steel fibers on compressive strength was noticed, while for both splitting and flexural tensile strength, significant increase was obtained with increasing of steel fibers content. The properties of SFLWSCC in the fresh state had a considerable effect on mechanical properties, whereas with the best fresh properties, the best mechanical properties can be obtained.

Effect of Asphalt Mixture Components on the Uncertainty in Dynamic Modulus Mastercurves

2020 ◽  
Vol 2674 (5) ◽  
pp. 135-148
Author(s):  
Hussein Kassem ◽  
Ghassan Chehab ◽  
Shadi Najjar
Keyword(s):  
Dynamic Modulus ◽  
Asphalt Mixture ◽  
Fundamental Property ◽  
Aggregate Size ◽  
Pavement Design ◽  
Experimental Program ◽  
Maximum Aggregate Size ◽  
Pavement Materials ◽  
Material Sources ◽  
Key Factor

Practitioners and researchers in the paving industry have highlighted the importance of the adoption of reliability-based pavement design. The goal of developing reliable pavements with optimum performance over their design life has become a key factor to be considered during both pavement design and construction processes. This requires the adoption of statistical and probabilistic-based analyses for the formulation of the properties and behavior of pavement materials. Thus, many researchers worked on the quantification and modeling of the uncertainty caused by the inherent variability in pavement materials in general and that of asphalt concrete (AC) in particular. The dynamic modulus (| E*|), a fundamental property for mechanistic-empirical and purely mechanistic pavement designs, has been proven to have a significant level of uncertainty that is dependent on climatic and traffic loading conditions. The main objective of this study is to investigate the effect of the AC mixture properties and components on the uncertainty in the | E*| mastercurve. This objective is achieved by conducting an experimental program incorporating four different mixtures having the same material sources but different binder types and gradations. Monte Carlo simulations are used to model the uncertainty of | E*| for each of these mixtures. The paper shows that the uncertainty is dependent on mixture type, as the presence of larger nominal maximum aggregate size, modified binder, or additive can increase the uncertainty in the | E*| mastercurve, especially at high temperatures or slow loading rates. The uncertainty is proven to be material related and not imposed by the testing instrumentation.

Analysis of Quality Control and Quality Assurance Data for Superpave Mixes

2000 ◽  
Vol 1712 (1) ◽  
pp. 25-34 ◽  
Author(s):  
Frazier Parker ◽  
M. Shabbir Hossain ◽  
Jiansheng Song
Keyword(s):  
Quality Control ◽  
Quality Assurance ◽  
Aggregate Size ◽  
Mix Design ◽  
Maximum Aggregate Size ◽  
Air Voids ◽  
Density Measurements ◽  
Control Quality ◽  
Asphalt Content ◽  
Mat Density

Asphalt content, voids, and mat density quality control–quality assurance data were collected for selected Marshall and Superpave mixes during 1997 and for selected Superpave mixes during 1998 and 1999. Analyses indicate that the accuracies and variabilities of asphalt content measurements for Marshall and Superpave mixes are comparable. However, analyses also indicate that the accuracies and variabilities of voids and mat density measurements are not comparable. Moreover, variabilities for Superpave mixes are much higher, and measurements for Superpave mixes are more off target than those for Marshall mixes. The effects of gyratory compactor use, mix design range for an equivalent single-axle load, and maximum aggregate size were investigated to explain the observed differences. Although few consistent trends were observed, all these factors seem to affect the variabilities and accuracies of air voids and mat densities of Superpave mixes.

scholarly journals Correlations between compressive strength and tensile strength of concrete for two-layers pavement with exposed aggregate

2014 ◽  
Vol 13 (4) ◽  
pp. 137-144
Author(s):  
Małgorzata Konopska-Piechurska ◽  
Wioletta Jackiewicz-Rek ◽  
Paweł Łukowski
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Aggregate Size ◽  
Bottom Layer ◽  
Concrete Pavement ◽  
Maximum Aggregate Size ◽  
Splitting Strength ◽  
Tensile Splitting Strength ◽  
Cylindrical Samples

In the paper the results of experiments on concrete pavement with exposed aggregate technology placed in two technological layers were presented. The following properties were measured: compressive strength, flexural strength by two methods: two-point loading and centre-point loading, tensile splitting strength of cubic and cylindrical samples. The study was performed for two type of concrete with a maximum aggregate size Dmax 8 mm (concrete applied to the upper layer of concrete pavement - GWB) and Dmax 22 mm (concrete used for the bottom layer - DWB). After the analysis of the tests, the correlations between compressive strength and tensile strength, measured by flexural strength and tensile splitting strength, were determined for the used two-layers concrete pavement with exposed aggregate depending on applied Dmax.

scholarly journals Effect of Maximum Aggregate Size on the Bond Strength of Reinforcements in Concrete

2018 ◽  
Vol 8 (3) ◽  
pp. 2892-2896
Author(s):  
S. Iqbal ◽  
N. Ullah ◽  
A. Ali
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Bond Strength ◽  
Aggregate Size ◽  
Splitting Tensile Strength ◽  
Strength Calculation ◽  
Maximum Aggregate Size ◽  
Test Results ◽  
Tensile Stresses ◽  
Concrete Mix

The bond between reinforcements and concrete is the only mechanism that transfers the tensile stresses from concrete to reinforcements. Several factors including chemical adhesion, roughness and reinforcement interface and bar bearing affect the bond strength of reinforcements with concrete. This work was carried out considering another varying factor which is maximum aggregate size. Four mixes of concrete with similar compressive strengths but different maximum aggregate sizes of 25.4mm, 19.05mm, 12.7mm and 9.53mm were used with the same bar size of 16mm. Compressive strength, splitting tensile strength and bond strength for each concrete mix were studied. Test results depict a slight increase in compressive and splitting tensile strength with decrease in maximum aggregate size. The bond strength remained at the same level with decrease in maximum aggregate size except at maximum aggregate size of 9.53mm when there was a drop in bond strength, despite better compressive and splitting tensile strengths. ACI-318 and FIB-2010 codes equation for bond strength calculation work well only when the maximum aggregate size is 12.7mm and above. Therefore, maximum aggregate size is critical for bond strength when smaller size aggregates are used.

Effect of Aging on Resilient Modulus of Hot Mix Asphalt Mixtures

2013 ◽  
Vol 723 ◽  
pp. 291-297 ◽  
Author(s):  
Mohd Khairul Idham ◽  
Hainin Mohd Rosli ◽  
Haryati Yaacob ◽  
M. Naqiuddin M. Warid ◽  
Mohd Ezree Abdullah
Keyword(s):  
Aging Process ◽  
Hot Mix Asphalt ◽  
Resilient Modulus ◽  
Aggregate Size ◽  
Asphalt Mixtures ◽  
Maximum Aggregate Size ◽  
Porous Asphalt ◽  
Asphalt Content ◽  
The Difference ◽  
Air Void

Asphalt hardens as a result of an aging process. This study was undertaken to determine the effect of field aging simulated by laboratory aging method of different hot mix asphalt (HMA) mixture. Three types HMA mixtures were used for this study namely Asphaltic Concrete with 10 mm nominal maximum aggregate size (AC 10), Aspaltic Concrete 28 mm (AC 28) and Porous Asphalt 10 mm (PA 10). The resilient modulus test was carried out as an indicator of the performance at a 25 °C and 40 °C. Generally, all samples show similar trend which aged mixture produced slightly higher resilient modulus compared to unaged mixture while an increase in temperature from 25 °C to 40 °C might reduced the resilient modulus up to 88%. This study also found that the difference increment of resilient modulus after the aging process attributed by asphalt content, air void and gradation of respective mixtures.

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