Durability Of Rocks Research Articles

Correlation Between Strength and Durability of Sandstones from the Dumri Formation, Tinau Khola Area, West-Central Nepal

Strength and Durability indices are two significant geotechnical criteria that can describe rock fragments' strength and weathering resistance. The Dumri Formation is the youngest and thickest of the Tansen Group, Lesser Himalaya. A thick succession of medium-grained, bluish-grey quartzose sandstone and red-purple shale represents it. To assess the quality of the sandstones, different laboratory tests and analyses were made to characterize the physical and mechanical properties of the sandstones. Physical properties were greatly influenced by composition and texture. The intact rock strength was figured out by the point load strength index (PLSI) and Aggregate impact value (AIV). Rock durability against slaking was determined using the slake durability index (SDI) test. The strength and durability indices were correlated through regression analysis. Sandstones assessed were classified as lithic and feldspathic wacke. Sandstones exhibited high resistance to slaking and are extremely durable (SDI = 99.53-99.86%) under a two-cycle test. Sandstones are strong to very strong (PLSI = 5.28-8.92 MPa) and possess high impact resistance (AIV = 6-9%). The correlation between PLSI and SDI was found to be high (r=0.86). Similarly, a correlation between AIV and SDI was (r=0.98), and between AIV and PLSI was (r=0.86).

A NOVEL WAY TO CLASSIFY THE SLAKE DURABILITY INDEX OF ROCKS

Slaking, the disintegration of rocks upon exposure to moisture and air, poses significant challenges in engineering applications, such as in slope stability and embankment design. This study improves the slake durability index test by introducing several enhancements to better reflect the field conditions of rocks. A new test methodology is developed which includes a revised slake durability classification table, a novel Discard Method for calculating weight retention in the test drum, and an updated classification chart. The improved methodology considers parameters such as porosity and strength, evaluated through index, Schmidt hammer rebound and point load tests. The new classification table categorizes rocks into durability classes according to the field observations and laboratory test results. The Discard Method improves accuracy by eliminating broken pieces from the durability calculation, addressing the limitations in the suggested method. A Configured Discard Method equation further defines the durability estimation by combining porosity, strength and slake durability data. Field investigations and laboratory tests conducted with various rock types demonstrate that the new classification system provides more accurate and practical assessments of rock durability. This study highlights the importance of effective porosity and strength impact which enhance the reliability of slake durability evaluations, offering a revised classification framework that simplifies field assessments while maintaining the accuracy. Future research should focus on developing these methods and expanding their applicability to diverse geological contexts by including more material to test.

Slake durability and mineralogical characteristic of carbonaceous rocks

Slake durability and mineralogical characteristic of carbonaceous rocks

Determining pore size distribution in rocks using shear‐thinning fluids: Utilisation of the method in geomorphology

AbstractThe pore space characteristics of geological materials are closely related to their mechanical, transport and hydraulic properties. In geomorphology, pore size distribution (PSD) is an important characteristic in rock weathering, evaporation and other studies. In an effort to find novel methods to determine the PSD, perhaps to bypass the disadvantages of the current techniques, there has been a growing interest in the use of non‐Newtonian fluids. In this contribution, we are particularly interested in the method recently introduced by Abou Najm and Atallah (the ANA method), which exploits the way in which the flow of different shear‐thinning fluids distributes differently in the pore space to compute the functional PSD estimation. We performed a set of saturated flow experiments with aqueous xanthan gum solutions of different concentrations, using as simple as possible laboratory settings, and we implemented a modified version of the previously introduced numerical model to obtain the PSDs of four sandstone and one tuff samples. The results are compared with conventional mercury intrusion porosimetry, showing a good agreement regarding the dominant pore size and a notable similarity in the distributions. Several limitations were identified as well, such as the lack of information on relatively small pores (<5–10 μm for the samples studied) and the potential issues in obtaining a more detailed distribution. We conclude that the ANA method is promising for geomorphological evaporation and rock durability studies, particularly for coarser materials such as sandstone, but it also encounters challenges for certain applications, especially for fine‐grained rocks. It must be acknowledged that the ANA method has been tested on a limited range of materials and further investigation is required to fully explore its capabilities and limitations.

Prediction of UCS and BTS under freeze-thaw conditions in the NW himalayan rock mass using petrographic analysis and laboratory testing

Repeated freeze-thaw (F&T) cycles substantially harm the durability of rocks, heightening the potential for landslides, rockslides, and avalanches. The current work investigates the effect of the F&T cycle on rock mass (biotite schist) samples. For this purpose, 32 rock samples were prepared and gathered from eight distinct locations in the northwest Himalayan region. For each sample, petrographical analysis and laboratory testing such as uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) are investigated at repeated (0th, 10th, 20th, and 30th) F&T cycles. Additionally, machine learning (ML) sequential models such as recurrent neural networks (RNN), gated recurrent units (GRU), and bi-directional long short-term memory (Bi-LSTM) are constructed to estimate the UCS and BTS under F&T conditions. Petrographical results show no change in the mineral indices, while there is a noticeable increase in aspect ratio but a significant decline in mean grain size with each successive 10th cycle, suggesting sample damage. The study also provides a comprehensive assessment of the ML models' performance, highlighting the Bi-LSTM model's superior accuracy among all models in terms of R2 (0.9850) and RMSLE (0.0100) during the TR stage and R2 (0.9020) and RMSLE (0.0170) during the TS stage for UCS prediction. Similarly, BTS prediction also shows superior precision, recording an R2 (0.7543) and RMSLE (0.0345) during TR and R2 (0.7404) and RMSLE (0.0213) during TS stages. The present study also explores the heatmap, line diagram, regression analysis, 2D kernel density plot, Taylor diagram, and DDR criterion for evaluating the model performance more clearly.

A rational multiscale nonlinear constitutive model for freeze–thaw rocks under triaxial compression

The stability and durability of rocks in cold regions are significantly impacted by the degradation of mechanical properties caused by freeze–thaw (F–T) environment. In this work, we shall propose a rational multiscale nonlinear constitutive model based on thermodynamics, micromechanics, and fractional calculus theory to describe the complete deformation and failure process of F–T rocks under triaxial compression. The F–T rocks at the mesoscale are regarded as consisting of porous matrix and cracks, while porous matrix is composed of the micropores and elastic solid grains at the microscale. According to experimental observations, we assume the F–T action mainly causes micropores growth and cracks opening, and mechanical damage is resulted from the initiation and propagation of cracks. In this context, the effects of F–T and mechanical damage on effective elastic properties of rocks can be quantitatively analyzed by using the two-step Mori–Tanaka (M-T) homogenization method. After subtly deriving the total free energy function of F–T rocks under compression, we systematically develop specific criteria for describing open cracks closure deformation, mechanical damage evolution and frictional sliding induced plastic distortion. Note that to correctly capture the plastic deformation characteristics, the non-orthogonal flow rule based on fractional differential calculations is employed. Following that, analytical analyses and numerical implementation of the proposed model are conducted. The performance of the model is evaluated by the simulations with experimental data on two kinds of F–T rocks, and discussions on parameters sensitivity and effects of fractional order are followed.

Evaluation of slake durability for carbonaceous rocks exposed to water soaking using electrical resistivity

The present study investigated the electrical conduction and slake durability behaviors of carbonaceous rocks subjected to water soaking. Several series of electrical resistivity and slake durability tests were conducted on carbonaceous rocks with different mineralogical characteristics to explore the intrinsic connection between these two property indexes. Based on the experimental data, a new empirical model was developed to estimate slake durability index of carbonaceous rocks at varied soaking times. The results showed that the clay minerals content of investigated carbonaceous rocks ranged from approximately 20 % to 50 %. The clay minerals are beneficial in enhancing the electrical conduction of carbonaceous rocks, but impose a negative impact on the slake durability, attributing to their superior performance of hydrophilicity and swelling. Electrical resistivity decreased sharply with increasing soaking time within the first 8 days and then it achieved a stable state as soaking time further increased, which was mainly due to the completion of pore saturation and salts/minerals dissolution. The slake durability index exhibited similar evolution characteristics to those of electrical resistivity, which deteriorated sharply to a low or very low level after soaking for 16 days. The clay minerals experienced water absorption and mineral expansion during the first 8 days soaking, leading to the development of micro-cracks that facilitates water intrusion and accelerates the slake durability deterioration. These two processes were essentially complete as the soaking time further increased, and the clay minerals played an insignificant role at this stage. Liner increasing trends were observed in the plot of electrical resistivity decrease versus slake durability index decrease, and the slope values presented a power function relation with the clay minerals content of carbonaceous rocks. The proposed empirical model well captured the trends in the experimental data, with an absolute difference in percentage δ below30 % and a root mean square error RMSE value of 5.613 %. The outcomes of this study provided a viable answer to assess slake durability of carbonaceous rocks exposed to adverse external environments using non-destructive testing techniques.

Stones that stand the test of time: exploring the durability and weathering of metamorphic Rocks of Sri Lanka

Weathering and durability are the key properties of the rock to evaluate the suitability and end-use for different kinds of applications such as building and construction material and engineering structures. Weathering is simply known as the alteration or breaking down of rocks due to air, water, etc. whereas durability of rock can be defined as the ability to resist the weathering to maintain the characteristics of strength under various environmental conditions. To evaluate the strength of rock, the degree of weathering and durability can be used as main indicators[1] as the measure of strength depends on the external force resistance.

On the importance of specimen’s geometric shape effects on the slake-durability index of limestones and grain size distribution of the sediment particles obtained during the test

The slake-durability test is one of vital test method used in engineering geological studies for evaluating resistant of rocks against wetting–drying cycles in humid environments. The result of the test is related to many parameters specially specimen’s geometric shape. In the present research, eight limestone samples used as common building stones in Iran have been selected and their mineralogical and physical properties have been measured in the laboratory. In order to determine the effect of specimen’s shape on the slake-durability index of the stones, laboratory specimens were prepared in seven various shapes including lump, rounded lump, cube, sphere, square prism, square-base plate, and rectangular cube which have different shape parameters. After performing the slake-durability tests, the samples were classified as very durable rocks according to Gamble and Franklin-Chandra classifications. The results indicated that specimen’s shape has essential effects on both rock durability and grain size distribution of the obtained sediment particles, so that the spherical and lump specimens shown the highest and lowest values of the slake-durability index, respectively. This means that more unregular dimensions, nonsphericity, and angularity of the specimens lead to decrease the slake-durability index which is highly correlated to the roundness (Rc) values of the specimens. The granulation parameters (D10, D30, D60, Cu, and Cc) of the obtained sediment particles were different for the tested samples. These parameters were recognized related to the specimen’s shape so that, the D60 and Cu are also highly correlated to the roundness (Rc) values of the specimens used in the slake-durability test.

The Slake Durability of Argillaceous and Non-argillaceous Rocks: Insights From Effects of the Wetting–Drying and Rock Lumps Abrasion

The Slake Durability of Argillaceous and Non-argillaceous Rocks: Insights From Effects of the Wetting–Drying and Rock Lumps Abrasion

Effects of groundwater and distilled water on the durability of evaporitic rocks

Evaporitic rock durability induced by groundwater cause several construction challenges, but representative experimental studies to evaluate such conditions are still missing. Therefore, this study intended to provide better and more realistic degradability features of evaporites with groundwater besides a comparison with distilled water as slaking fluids. Forty-eight evaporitic rock blocks were collected from Abu Dhabi area, United Arab Emirates. 96 slake durability index (SDI) tests were performed, 48 with each of the slaking fluids; groundwater and distilled water, and their textural, mineralogical, and geochemical attributes were also examined before and after the SDI tests. In comparison to mineralogical and textural modifications, slaking fluid had a greater impact on the chemical composition of evaporitic rock. The study shows that the degradability of evaporites with groundwater and distilled water indicates a wide range from very low to high. The mean weight loss values after four cycles with groundwater and distilled water vary from 11 to 77 and from 4 to 81 wt.%, respectively. Consequently, slaking with groundwater illustrates a wide range compared to the slaking with distilled water. This could be due to quick interactions between groundwater and evaporites and fast hydration-dehydration process than distilled water due to the chemical composition of the groundwater. It is recommended to investigate the attributes of evaporitic rocks as well as groundwater geochemistry for safe, cost-effective, and sustainable structures.

An Experimental Investigation on the Durability of Clay-Bearing Rocks in Different pH Conditions

An Experimental Investigation on the Durability of Clay-Bearing Rocks in Different pH Conditions

Effect of pH Condition and Different Solution on the Slake Durability of Granitic Rocks

Effect of pH Condition and Different Solution on the Slake Durability of Granitic Rocks

Quantification and estimation of the durability of stones used as construction material more precisely by modification of static rock durability index

The correct classification of the durability of rocks used as construction material is extremely important, as it directly affects their service life in engineering projects. For this reason, various durability determination methods for stones have been suggested by previous studies. Among them the static rock durability index seems more comprehensive in terms of the input parameters used. However, some studies show that the data obtained from the static rock durability index method may give inconsistent results, especially for moderate- to low-durability rocks like andesite and tuff as indicated by their accelerated weathering test results and long-term field performances. Therefore, to increase the sensitivity of the static rock durability index method and to be able to assess the durability of rocks more precisely, some modifications were carried out on the input parameters of the static rock durability index method and a new durability evaluation method named ‘Modified Static Rock Durability Index’ (MRDIs) was suggested. By using the ratio of wet to dry uniaxial compressive strength, Böhme abrasion value, water absorption by weight, dry surface saturated unit volume, weight loss after salt crystallization and the number of cycles causing total disintegration of sample during the Na2SO4 salt crystallization test as input parameters, the sensitivity of the static rock durability index was increased especially for moderate- and low-durability stones like andesite and tuff.As a result, the durability of six volcanic rocks like andesite and tuff evaluated in this study can be classified precisely with the MRDIs method compatible to the durability properties obtained from the accelerated weathering tests. In addition, the MRDIs method was tested using the data relating to the material properties of andesites and tuffs whose long-term field performances were specified in the literature and compatible results were obtained with their field performances in terms of durability.

The effects of water acidity and engineering properties on rock durability

Fifteen sedimentary rock samples of four rock types including sandstone, limestone, travertine and conglomerate were collected from Damghan area, northern Iran. Mineralogical studies and laboratory experiments were performed to assess physical properties, Schmidt hardness, P-wave velocity, slake-durability index, uniaxial compressive, point load, Brazilian tensile and block punch strengths of the rocks. The studied rock samples are mainly composed of quartz, calcite and dolomite with different textures. The slake-durability test was carried out up to ten cycles in fluids with different pH. The utilized test fluids were natural water with pH of 7 and sulfuric acid solutions with pH of 5.5 and 4. Based on the results, the slake-durability index is affected by pH of the test fluids. Also, the different rock types had distinctive slaking behaviors. Decreasing rate of slake-durability index at initial cycles is higher than the end cycles the same as weight loss rate of the specimens. Regression analyses showed that the evaluated parameters are correlated to the slake-durability index. In other words, the slake-durability index of the studied rock samples is greatly affected by their mineral composition, texture, physical properties such as porosity and closely related to strength parameters of the rocks. This led to extraction of empirical equations for determining essential characteristics of the rocks from the slake-durability index.

Infrared thermography for the investigation of physical–chemical properties and thermal durability of Tunisian limestone rocks

Twenty-one limestone lithotypes from the extreme North of Tunisia (Bizerte region) were characterized in order to investigate their weathering resistance and the resulting damage from thermal shock cycles. An infrared thermography (IRT) monitoring was also conducted to assess the tendencies between the cooling rate index (CRI) and the physical (bulk density, porosity, capillarity and P wave velocity) or the chemical (calcium carbonate, silica and total organic carbon contents) characteristics of the carbonate rocks. Statistical clustering defined four classes in accordance with their different porosity values (1 % < n < 20 %). The obtained CRI within a 10-min of infrared thermography (IRT) survey allowed to forecast not only the total porosity of these rocks but also their major physical properties with a noticeable correlation trends before and even after thermal shock cycles.Similar findings proved the compatibility between the CRI10 and the chemical composition of the limestones due to the different thermal properties of the minerals. The lowest porous samples (n ≤ 5 %) with the highest calcium carbonate content (CaCO3 > 95%) seemed to be the most suitable ones for the infrared thermography (IRT) characterization by its best fitting trends with the CRI10. Thermal shock was very well remarked for all the clusters particularly based on the measures of CRI10 and capillarity, as they are mainly related to surface and subsurface features that are the most affected by the fast cooling process. This study highlighted the validity of the CRI10 as a reliable indirect parameter for the estimation, in laboratory, of low porous stones properties undergoing thermal weathering.

Lichen impact on sandstone hardness is species‐specific

AbstractThe balance between lichen biodeterioration and bioprotection processes on stone surfaces depends on many variables and is crucial to understanding the role of lichens in biogeomorphology and their threat to stone heritage conservation. However, stones colonized by lichens have still been mostly examined in terms of affected volumes and physico‐chemical modes of interactions, overlooking the overall effects on properties related to surface durability. In this study, the impact of lichen colonization patterns on Cortemilia sandstone was examined beneath thalli of three lichen species. Rock hardness, a proxy for rock durability, was measured at different depths from the surface using an Equotip hardness tester and compared to that of freshly cut surfaces and exposed surfaces uncolonized by lichens. Mineralogical analyses were performed by X‐ray powder diffraction on rock beneath lichen colonization, in comparison with unweathered rock. Equotip analyses quantified a differential, species‐specific decrease in stone hardness. This variability was related to differences in hyphal penetration patterns and, possibly, calcite (re‐)precipitation. In particular, in the case of the species most impacting rock hardness, X‐ray diffraction patterns of calcite showed a remarkable stability of crystallographic plane (01–12), known to be enhanced in the presence of organic chelants. These results confirm that decisions on lichen removal from stone surfaces should consider species‐specific behaviour. Moreover, the innovative approach of measuring stone hardness variation in association with the analysis of biomineralization processes contributes to unveil the extension of the sphere of lichen interaction within the stone substrate beyond the limit of the hyphal penetration.

Effects of water intrusion on thermal conductivity and durability of carbonaceous rocks

This study aimed to investigate the role of water intrusion on thermal conduction and durability of three types of carbonaceous rock with different mineralogical components. The soaking method was selected to simulate water intrusion, and the respective evolutions of thermal conductivity k and slake durability index Id2 during soaking period were assessed. Scanning electron microscopy was conducted to explore the mechanism controlling these revolutions. The results revealed that the magnitude of moisture content and density of carbonaceous rocks at their natural state was clearly correlated to the content of illite mineral. Water intrusion was beneficial to the thermal conduction of carbonaceous rocks, where thermal conductivity increased with an increase in soaking time and exhibited a moderate increment after 8 days of soaking. Slake durability index Id2 was sharply decreased as soaking progressed and reached a low level after soaking. This deterioration in durability was mainly attributed to the absorption of free water, which in turn yields the anisotropic expansion of specific minerals. An unstable structure with more pores and new morphology minerals were identified in carbonaceous rocks at the completion of soaking procedure. An empirical relationship was developed successfully for predicting slake durability index using thermal conductivity.

A New Durability Assessment Method for Volcanic Rocks Used as Building Stones; ‘Modified Static Rock Durability Index’

A New Durability Assessment Method for Volcanic Rocks Used as Building Stones; ‘Modified Static Rock Durability Index’

Investigating the durability of weak rocks to forecast their long-term behaviors

Investigating the durability of weak rocks to forecast their long-term behaviors