Field to laboratory shear strength ratio for clays stabilized with low-carbon binders

The rise in global temperatures, driven in part by significant transportation carbon emissions, necessitate sustainable solutions for infrastructure. Traditional asphalt binders and lime additives significantly contribute to carbon emissions, and conventional liquid amine-based antistrip agents, which are used to reduce moisture damage, lose efficacy over time. This study evaluates the performance of PG 64-16 Low Carbon binder, incorporating 10% post-consumer plastic and amine-impregnated zeolite (AIMZ) as a protective carrier for liquid amines. Researchers compare this low-carbon binder to conventional PG 64-16 binder and evaluate AIMZ against amine and zeolite separately (AZ) and a commercial liquid antistrip (LAS). The study tests three aging levels (3, 5, and 7 days), simulating 4, 8, and 10 years, respectively, of field aging in Southern California. The evaluation of moisture-induced damage uses the Tensile Strength Ratio (TSR), while the Hamburg Wheel Tracking (HWT) test assesses rutting resistance (the wear from tires and loads that occurs on roads). The IDEAL Cracking Test measures cracking resistance, Hello, We have a new project that needs to be published to ScholarWorks and registered with DOI. Attached are the report and RB PDFs. Thank you in advance, and the Moisture-Induced Shear-Thinning Index (MISTI) and Multiple-Stress Creep Recovery (MSCR) tests analyze moisture susceptibility and rheological properties, all of which are important factors to consider in long-term efficacy. AIMZ demonstrated higher TSR values compared to those with AZ and LAS at both 5 days and 7 days of aging levels for both binders. Rutting resistance is comparable between binders, and low-carbon binder mixtures show improved cracking resistance over time. MISTI values suggest lower moisture susceptibility for the low-carbon binder, though MSCR results suggest it is best suited for low-traffic volumes. This study indicates that AIMZ effectively prolongs liquid amine efficacy and that low-carbon binders, despite some limitations, offer environmental and performance benefits. These findings support the potential for incorporating post-consumer plastics in asphalt pavements, promoting sustainability in infrastructure.

Alkali-activated slag is a widely used low-carbon binder. Incorporation of textile can mitigate the brittle weakness of alkali-activated composites. The bonding between fibers and matrix is critical for the performance of textile reinforced mortar. This paper is focused on the effect of different treatment methods on the bonding properties of carbon fiber in alkali-activated slag. The interfacial shear strength of fiber bundles in matrix was determined by the pull-out test. The flexural strength of the reinforced mortar was evaluated by a repeated bending. A scanning electron microscopy test was performed to characterize the interfacial properties of the fiber bundles. The results show that the interfacial shear strength of carbon fibers in matrix is improved by the electroplating with calcium silica slurry (CSS), impregnation in different solutions, and plasma treatments. An electroplating in CSS has the best improvement in the bonding strength with an increase by 620%. The CSS treatment increases the maximum flexural strength of CFT reinforced mortar with 22.5% and 30% at 7 and 28 d respectively, and it significantly inhibits the crack growth under the cyclic loading. This effect becomes more significant after a longer curing age. The electroplating treatment eliminates the cracks in the interface of fiber yarns. Slag reacts with the plated portlandite to strengthen the bonding between mortar and fiber bundles, so it has a better inhibiting effect on the crack growth after a longer curing.

Large scale direct shear tests of soil/PET-yarn geogrid interfaces

Soil reinforcement is a reliable and effective technique for enhancing soil resistance. The present study aims to investigate the impact of water content on the mechanical behavior of a fiber-reinforced clay. To this end, clay specimens were prepared with three water contents (15%, 17.5%, and 20% by clay weight) and three contents of fiber (0.1%, 0.2%, and 0.3% referred to clay weight). Next direct shear and unconfined compressive strength tests were performed to study the effect of water content on the modulus of elasticity, compressive strength, strain energy, shear strength, shear strength ratio, stress–strain behavior, internal friction angle and cohesion coefficient of the prepared clay. The results indicate when the water content is lower than the optimum moisture content (OMC), fiber decreases modulus of elasticity and increases ductile behavior, compressive and shear strength, strain energy, shear strength ratio and cohesion coefficient but when the water content is more than the OMC, fiber increases brittle behavior, compressive and shear strength, strain energy, shear strength ratio and friction angle.

Collapse indicators for existing nonductile concrete frame buildings with varying column and frame characteristics

Keywords: embankments ; landslides ; limit state design analysis ; numerical modelling and analysis ; plasticity ; slopes ... Show All

The paper deals with an analysis of the shear strength behaviour of coarse-grained materials using large-sized direct shear apparatus. The shear strength curve of compacted coarse-grained material allows for determining the three typical shear strengths, i.e. the shear strength for a maximum density of the sample tested (shear strength at point A), the peak shear strength (shear strength at point P), and the critical shear strength achieved for a large horizontal movement (shear strength at point C). Professional laboratories usually apply for determining the critical shear strength two different methods. The first method considers the critical shear strength at point A and the second method considers the critical shear strength at point C. The aim of the article is not to critically evaluate both methods, but to analyze the results of shear tests of gravels. The results of a large series of tests showed that these stresses may differ from each other in some cases, especially for poorly graded materials. In the case of sandy soil, the shear strength at point A and at point C is equal. However, in the case of poorly graded gravel, the shear strength at point C is greater than the shear strength at point A. The greatest difference between these shear strengths was measured in the case of poorly graded medium gravels. The results showed that the ratio of shear strength at point C to the shear strength at point A increases with increasing the grain size of the material tested. The peak as well as the critical shear strength parameters of poorly graded gravels is better represented by a multi-linear or a nonlinear failure line.

The ratio of frame strength and stiffness to masonry infill are major parameters that influence the seismic capacity of masonry infill. The influence of such parameters to seismic capacity in terms of strength, stiffness and deformation has significant variations between different design codes and past literature on the topic. This study focused on the in-plane behaviour of unreinforced masonry infill walls installed in reinforced concrete (RC) frames with different strengths. In the first part of this study, two ½ scale specimens with different RC frames and identical masonry infill walls were tested using a static cyclic loading protocol. The main objective was investigating the influence of changing frame strength to seismic capacity in terms of: strength, stiffness and deformation. Results of the presented experiment showed that as the ratio of frame shear strength to masonry shear strength increased, there was great improvement of the masonry infill walls in terms of strength and avoidance of sudden brittle behaviour of the masonry infill. However, varying frame strength did not significantly influence the initial stiffness and story drift at maximum strength. In the second part of this study, an investigation was conducted on the deformation limits of masonry infilled RC frames and the influence of various parameters, based on data collected from many recent experimental tests. Based on these experimental results, the deformation limits of masonry infill were found to be directly proportional to both the compressive prism strength of the masonry infill and the ratio of shear strength of frame to that of the masonry infill. The influence of aspect ratio showed large variation and it is difficult to conclude its level of influence on deformation. A simplified procedure based on experimental data was proposed that can estimate the backbone curve and gave good estimation of the post-peak lateral strength degradation slope based on the ratio of frame strength with simple hand calculation. Such a method is useful in the preliminary design process to help practicing engineers understand the general behaviour expected by infilled RC frames.

One of the widely used parameters in evaluating moisture susceptibility of asphalt mixtures is tensile strength ratio (TSR). From a mechanical point of view, TSR is only appropriate at the bottom of asphalt concrete (AC) layer where tensile stress is predominant since near the surface or in the middle of AC layer shear stress is the major driving force to create moisture damage. Therefore, a better parameter that can describe moisture susceptibility for the entire AC layer is needed. In this study, the potential of shear strength ratio (SSR) in evaluating moisture susceptibility at different AC depths is attempted. The mechanical relationship among the SSR, TSR, cohesion and indirect tensile (IDT) strength has been studied wherein it was found that the SSR can be mechanically represented by the TSR and cohesion. In addition, the SSR values are determined from mechanistic analyses using the shear properties obtained from laboratory tests conducted for three types of asphalt mixtures. The results show that the SSR values are significantly varying along the depth of AC layer, while the TSR values are constant. Therefore, SSR could be a good alternative parameter in evaluating the moisture susceptibility of asphalt mixtures at different AC depths.

In this study, the use of shear strength ratio (SSR) in analysing asphalt mixture’s susceptibility to moisture was investigated and verified. Three surface and two base mixtures were considered for the asphalt mixture to be tested. Indirect tensile and uniaxial compressive strength tests were conducted in the laboratory to obtain the mixtures’ shear properties. The SSR in the asphalt concrete (AC) layer was determined for six types of pavement structure with varying asphalt thicknesses. Even though the results of SSR agree with the result of tensile strength ratio (TSR) for the two base mixtures, the SSR values of the three surface mixtures are significantly different while the TSR values are similar, thus, SSR is more sensitive to moisture effect than TSR. Furthermore, the Model Mobile Load Simulator (MMLS3) was conducted on different types of compacted slabs. It was found that the results of MMLS3 and SSR show a good correlation for both surface and base mixtures. This proves the effectiveness of SSR as an indicator for evaluating the moisture susceptibility of asphalt mixtures for the entire AC layer.

The authors examined the results of 172 CKoU direct simple shear (DSS) tests. Their research has led to four important conclusions. Firstly, the test results confirm observations by other investigators that an acceptable correlation does not exist between the shear strength ratio, cu/?'v, and plasticity index, Ip. Secondly, consolidation pressure has a greater effect on cu/?'v than Ip and should be considered when evaluating DSS test results for use in a normalized soil parameter (NSP) procedure such as SHANSEP (stress history and normalized soil engineering properties). Thirdly, correlating cu/?'v results from DSS tests with only Ip could lead to either overestimating or underestimating in-situ undrained shear strength when employing an NSP procedure. Lastly, the authors demonstrate that correlations of DSS measured soil undrained shear strength, consolidation pressure and water content can provide a useful tool for evaluating in-situ undrained shear strength. Introduction Over the past thirty years, the DSS test has become widely used in geotechnical investigations, particularly in deepwater regions. The results of these tests are typically employed in some type of NSP procedure to evaluate in-situ undrained shear strength of clay deposits. The NSP procedure known as SHANSEP1 is a common method employed to perform this task. However, because of the expense and the considerable duration of testing associated with the SHANSEP procedure, laboratory testing is typically limited to a few tests within soil units defining the soil stratigraphy being evaluated. Subsequently, the results are often correlated with Ip To interpolate between SHANSEP test intervals to define the interpreted shear strength profile. A common correlation used to interpolate data between SHANSEP test intervals is that of the strength ratio, cu/?'v, and Ip. However, the authors' experience has been that a very poor correlation exists between cu/?'v and Ip when evaluated over a wide range of Ip common to offshore soils. This same opinion has been expressed by other investigators.2,3 To assess the reliability of the cu/?'v and Ip correlation, the authors examined the results of 172 DSS specimens tested in a normally consolidated state (OCR = 1). These tests were performed by five different geotechnical laboratories with extensive experience in performing SHANSEP-type testing. The soil specimens are from geotechnical site investigations conducted in six different offshore regions of the world. The plasticity characteristics of the 172 specimens examined in this study are presented in Fig. 1. This plasticity chart reveals that most of the specimens are highly plastic (CH) clays with liquid limits as high as 143 percent and Ip values as high as 101 percent. There are also several lower plasticity (CL) clays with Ip values ranging from 14 to 29 percent as well as some elastic silts (MH) and organic (OH) clays that fall below the A-line. The database does not include highly sensitive, cemented, or highly structured samples. Prevailing Strength Ratio - Ip Correlation In 1957, Skempton4 proposed the following correlation for normally consolidated clays based on field vane test results: (Mathematical equation available in full paper)

Shear strength distribution of district heating pipe under accelerated aging condition with respect to PU foam density

Effect of polypropylene and steel fibers on web-shear resistance of deep concrete hollow-core slabs

Proposal of a complete seismic shear strength model for circular concrete columns

Undrained shear strength of saturated clays is a vital property in geotechnical engineering practice. If any relationship between shear strength of soil and index properties of soil is developed, it would be exceptionally alluring. A few endeavors have been made in the past to associate shear strength with Liquidity Index. The Liquidity Index requires the estimation of plastic limit calculated by Casagrande [1] thread rolling method which does not provide the correct assurance of plastic limit of the soil particularly in less plastic soils. Shear strength variation with water content does not follow a regular trend, which makes the analysis difficult. It has been observed in the past researches that shear strength of soil correlates very well with the consistency limits of soils. The present paper develops the correlation between shear strength and Water Content Ratio (wX) and between shear strength and Liquidity Index, to find out the better parameter to evaluate shear strength between Water Content Ratio (wX) and Liquidity Index. The experimental results on three different highly compressible soils having water content ranging from 5% to 25% showed that the regression coefficient value of relation between undrained shear strength with Water Content Ratio came out to be closer to one compared with Regression coefficient value of relation between undrained shear strength with Liquidity Index, for the soils of same geological origin. Liquidity Index variation with Water Content Ratio suggests that there is a definite relation between Liquidity Index and Water Content Ratio and Liquidity Index can be substituted by Water Content Ratio. However, the results obtained from both are more or less same for the soils irrespective of their origin.KeywordsShear strengthWater content ratioLiquidity indexPlastic limit