Disintegration Ratio Research Articles

Elevation-related variations of soil disintegration and its driving forces in the water level fluctuation zone of the Three Gorges Reservoir, China

Soil disintegration is a key process of the early stages of soil erosion. The water level fluctuation zone (WLFZ) in reservoirs undergoes seasonal changes involving periodic alternations in inundation and exposure that can affect soil disintegration. In this study, we conducted experiments on pre-wetted undisturbed soil samples obtained from different elevations ranging from 155 to 180 m a.s.l. and different soil depths (0–10 and 10–20 cm) in the WLFZ of the Three Gorges Reservoir (TGR), upper Yangtze River, China. We investigated how soil disintegration varies depending on elevation within the WLFZ and used principal component analysis (PCA) and stepwise regression to identify the dominant variables affecting soil disintegration. Results show the following: (1) The disintegration ratio, which is a measure of the amount of soil disintegration that occurs during experiments, varied in the range of 0.45 %–4.79 % over 60 min, with 79 %–100 % of the disintegration occurring within the first 30 min. The disintegration ratio increases with decreasing elevation in the WLFZ. Soil samples from a depth of 0–10 cm disintegrated 0.43 % less on average than those from a depth of 10–20 cm. The relationship between disintegration rate and elevation can be expressed using an exponential function with R2 > 0.80. (2) The main variables loading onto the first three principal components (explain 91.4 % of the variation in all variables) identified by PCA were those involving soil aggregates, the plant root system, and soil particle-size, respectively. (3) Stepwise regression identified >0.25 mm water-stable aggregate content (Ws0.25) and root mean diameter (Droot) as the strongest predictors of soil disintegration and yielded a linear regression equation with R2 = 0.88. Ws0.25 and Droot were the most influential variables on the elevation-dependent occurrence/degree of disintegration. Such information is essential for understanding the occurrence and prevention of bank erosion in reservoir areas.

Effect of different buried depth on the disintegration characteristic of red-bed soft rock and the evolution model of disintegration breakage under cyclic drying-wetting

The disintegration of red-bed soft rock exhibits a strong correlation with various geological disasters. However, the investigation into the evolutionary mechanisms underlying disintegration breakage has not yet received extensive exploration. In order to comprehensively examine the disintegration characteristics of red-bed soft rock, the slake durability tests were conducted to red-bed soft rocks of varying burial depths. Subsequently, an investigation was carried out to examine the disintegration characteristics and the evolution of disintegration parameters, including the coefficient of uniformity (Cu), coefficient of curvature (Cc), disintegration rate (DRE), disintegration ratio (Dr), and fractal dimension (D), throughout the disintegration process. Finally, employing the energy dissipation theory, an energy dissipation model was developed to predicate the disintegration process of samples at various burial depths. The findings demonstrate a decrease in the abundance of large particles and a concurrent increase in the abundance of small particles as the number of drying-wetting cycles increases. Furthermore, as the number of drying-wetting cycles increases, a significant alteration is observed in the content of particles larger than 10 mm, whereas the content of particles smaller than 10 mm undergoes only minor changes. The disintegration parameters, including the curvature coefficient, non-uniformity coefficient, disintegration rate, and fractal dimension, exhibit a positive correlation with the number of drying-wetting cycles. Conversely, the disintegration index demonstrates a decreasing trend with the increasing number of cycles. Nevertheless, as the burial depth increases, a notable trend emerges in the disintegration process, characterized by a gradual increase in the content of large particles alongside a progressive decrease in the content of small particles. Concurrently, the curvature coefficient, non-uniformity coefficient, disintegration rate, and fractal dimension exhibit a gradual decline, while the durability index experiences a gradual increase. In addition, based on the principle of energy dissipation, it is revealed that the surface energy increment of red-bed soft rock increases with the increase of the number of drying-wetting cycles, but decreases with the increase of burial depth. Ultimately, by leveraging the outcomes of energy dissipation analyses, a theoretical model is constructed to elucidate the correlation between surface energy and both the number of drying-wetting cycles and burial depth. This model serves as a theoretical reference for predicting the disintegration behavior of samples, offering valuable insights for future research endeavors.

Assessment of Engineering Behavior and Water Resistance of Stabilized Waste Soils Used as Subgrade Filling Materials

Urban construction has generated substantial amounts of waste soils, impeding urban ecological development. With the aim of promoting waste recycling, waste soils possess a high potential for sustainable utilization in subgrade construction. However, these waste materials exhibit inadequate engineering properties and necessitate stabilization for an investigation into their long-term performance as subgrade filling materials. Initially, a thorough assessment and comparison were conducted to examine the key mechanical properties of lime- and cement-stabilized soils with mixed ratios (total stabilizer contents ranging from 2% to 8%). The results indicated that these soils met the requirements of subgrade materials except for the 2% lime-treated soil. Subsequently, to reveal the improvement in water resistance of stabilized waste soil (e.g., under conditions of rainfall or elevated groundwater table), the effects of soil densities and stabilizer contents on the disintegration characteristics were investigated using a range of disintegration tests. An evolutionary model for the disintegration ratio of stabilized soils was then developed to predict the process of disintegration breakage. This model facilitates the quantification of the lower disintegration rates and elevated disintegration time attributed to higher levels of compactness and stabilizer contents during a three-stage disintegration process. This enhances the understanding and evaluation of sustainable applications in stabilized waste soils used as subgrade filling materials.

Disintegration behavior and its grading entropy characterization of polyurea modified graded carbonaceous mudstone under loading and drying-wetting cycles

To study the disintegration behavior and characterization indexes of Modified Graded Carbonaceous Mudstone (MGCM), soaking disintegration tests of MGCM under vertical loading and cyclic drying-wetting were carried out with a disintegration test instrument which self-designed by our team. The grain size distribution of MGCM during drying-wetting cycles was analysed. Standard basal entropy, as an important parameter of grading entropy that quantitatively characterizes distribution curves, was introduced to characterize the disintegration behavior of MGCM and correlated with the comprehensive evaluation index, namely, disintegration ratio. The results show that as the number of drying-wetting cycles increases, the Graded Carbonaceous Mudstone (GCM) blocks disintegrate rapidly and the fine-grain content increases. With an increase in vertical load, the particles disintegrate more completely. The contents of each particle group in the GCM test groups stabilize after 9, 7, and 4 drying-wetting cycles under vertical loads of 0, 100, and 200 kPa, respectively. Under the same vertical load of 200 kPa, the contents of each particle group in MGCM test groups with Polyurea (PU) content 0, 5, and 10 wt% stabilize after 4, 6, and 8 drying-wetting cycles, respectively. The inclusion of PU can effectively retard the disintegration of GCM, and the effect is more pronounced with 5 wt% PU content compared to 10 wt%. However, it is also susceptible to the deterioration of PU layer caused by mechanical screen. The grading entropy model of MGCM under loading and cyclic drying-wetting is established. There is a significant positive, linear correlation between the standard basal entropy and the disintegration ratio. A smaller standard basal entropy to a smaller disintegration ratio, indicating a greater degree of particle disintegration and fragmentation. The standard basal entropy can characterize the disintegrated particles of MGCM with different PU content under vertical loading and drying-wetting cycles. The standard basal entropy of GCM decreases rapidly initially and then stabilizes as the number of drying-wetting cycles increases. The standard basal entropy decreases exponentially as the vertical load increases. The results provide a new quantitative index for analyzing the grading characteristics of MGCM following disintegration, which are valuable for engineering construction and disaster prevention in carbonaceous mudstone areas.

Experimental study on the disintegration characteristics of undisturbed loess under rainfall-induced leaching

Loess is prone to collapse as the soil approaches saturation, leading to severe geological hazards. However, how the undisturbed loess microstructure evolves due to rainfall-induced leaching is poorly understood and a detailed assessment of the corresponding disintegration characteristics is lacking. In this study, we conducted a series of leaching and disintegration tests on undisturbed Q3 loess from Yan’an, China. Loess disintegration on a macroscopic level were characterized using a self-developed disintegration apparatus, and the relationship with influencing factors such as moisture content, temperature, and salinity were explored. At the microscopic scale, scanning electron microscopy (SEM) was performed to qualitatively probe the underlying mechanisms of loess disintegration under varied leaching conditions. The microstructure properties of the loess samples revealed in the SEM images were examined using Image-Pro Plus (IPP) software. A quantitative relationship between the microstructural parameters of the pores and particles with disintegration was established based on the grey correlation theory. The results show that the disintegration process of undisturbed loess under the action of leaching can be divided into three stages: soaking, softening, and collapsing. Compared with samples without leaching, the study demonstrates that leaching can facilitate the loess disintegration. Under otherwise similar conditions, loess disintegration ratio decreases with increasing moisture content and salinity, whereas it increases with water temperature. In addition, microstructural observation shows that the undisturbed loess microstructure changed from interlocking to overhead with increased leaching, inducing favorable conditions for loess disintegration. Moreover, grey correlation analysis shows that the particle size distribution and macropore content of undisturbed Q3 loess yields a satisfactory correlation with the loess disintegration ratio. In general, rainfall-induced leaching effect is conducive to the disintegration of loess by degrading its internal structure.

The hydro-mechanical characteristics and micro-structure of loess enhanced by microbially induced carbonate precipitation

Microbially induced calcite precipitation (MICP) is an emerging biological method for soil improvement which has been applied to several soil types. However, only very limited research is conducted on the effectiveness of MICP treatment on loess, especially its hydro-mechanical characteristics. A set of unconfined compression, disintegration and scanning electron microscopy tests under various conditions were performed to quantify the mechanical and water stability of MICP solidified loess, including the cement reagent concentration (CRC = 0.5, 0.75, 1.0, 1.5 M) and curing age (CA = 0, 7, 14, and 28 days). Results indicate that MICP is a promising method for improving the mechanical property and water stability of loess under the present scenario of sustainable development worldwide. The uniaxial compressive strength (UCS) of MICP treated loess under CRC of 1.0 M curing for 14 days can be increased by 260%. The observed maximum performance of disintegration ratio of MICP treated loess is reduced by 68% through the self-designed disintegration instrument. Considering different CRCs, the empirical equation of UCS and deformation modulus of MICP-treated loess is proposed by regression analysis. In addition, with the aid of the scanning electron microscope, it is found that: (i) the precipitated CaCO3 crystals bridge and bind the loess particles together which can effectively increase the shearing resistance of loess skeletons; (ii) the CaCO3 aggregates filling in the pores between the loess particles could prevent the water molecules from damaging the original loess structures, and effectively reduce the disintegration of loess.

Permeability and Disintegration Characteristics of Composite Improved Phyllite Soil by Red Clay and Cement

The bearing capacity of the phyllite soil subgrade can be greatly improved by red clay, but the water stability of the modified soil is still poor. Hence, the blended soil has been found to be unsuitable for the construction of high-speed railways. This paper proposes an innovative scheme, by adding appropriate amounts of cement and red clay concurrently, to improve phyllite soil, which achieves a higher bearing capacity of the subgrade immediately after compaction, while also solving the problem of insufficient water stability. Laboratory tests of the permeability and disintegration characteristics of phyllite soils improved by cement, red clay, and both were carried out. The test results show that the permeability coefficient and maximum disintegration rate of soil can be improved effectively by using both red clay and cement. It was found that the optimal combination scheme is to add 3% cement and 40% red clay to phyllite soil by mass. Under the optimal scheme, the permeability coefficient, maximum disintegration rate, and disintegration rate of the improved soil decreased by 90.02%, 90.30%, and 99.02%, respectively, compared with the phyllite soil. The microscopic study shows that the mechanism of red clay blending with phyllite is that the finer particles of red clay infill the pores among the phyllite particles, thus reducing its permeability coefficient. The mechanism of adding cement to the blending soil mainly results from the production of hard-setting new materials and the formation of a cementation network among the soil particles, which not only increases the shear strength of the soil, but also reduces the permeability coefficient and the maximum disintegration ratio of the soil. This work makes full use of the complementary characteristics of red clay and phyllite soil and the advantages of hard-setting new materials, which will provide a new idea for soil improvement of the phyllite soil in the future.

Characteristics of biocrusts in croplands and their effects on surface soil disintegration in the black soil region of Northeast China

We selected typical croplands in the black soil region of Northeast China to analyze the characteristics of biocrusts during the growing season, including species composition, thickness, coverage, and biomass (chlorophyll content). We collected bareground soil and biocrusts samples with chlorophyll content of 5-15, 15-25, 25-35, and 35-50 mg·g-1, and measured the soil disintegration rate and soil maximum disintegration ratio of each sample using a force gauge in the laboratory. The results showed that: 1) biocrusts dominated by algae and moss were frequently developed in the croplands, with Stigeoclonium and Bryum capillare as the most common species, respectively. The thickness and biomass of algal crusts were significantly lower than moss crusts, with a successional trend from algal crusts to moss crusts. 2) The coverage, thickness, and biomass of biocrusts in croplands were negatively correlated with the frequency and intensity of tillage disturbance. For instance, the values of those characterisitics were only 27.8%, 1.52 mm, and 6.49 mg·g-1 on average, respectively, in traditional tillage croplands, and increased to 83.5%, 2.74 mm, and 34.16 mg·g-1, respectively, in the croplands with conservational tillage. 3) Biocrusts considerably reduced the disintegration of surface soil, particularly in the layer of biocrusts. Compared to the bareground soil, the soil disintegration rate of biocrusts, with four levels of biomass (with chlorophyll content of 5-15, 15-25, 25-35, and 35-50 mg·g-1), was reduced by 43.1%, 50.1%, 55.5%, and 59.8%, respectively, while the soil maximum disintegration ratios were reduced by 11.4%, 17.7%, 33.2%, and 36.6%, respectively. 4) Soil disintegration rate and maximum disintegration ratio were significantly and negatively correlated with the biomass and thickness of biocrusts, indicating that the impacts of biocrusts on soil disintegration were primarily caused by the improvements in physical properties of surface soil. In conclusion, biocrusts were frequently deve-loped in croplands in the black soil region of Northeast China, owing to less disturbance following the conversion from traditional tillage to conservational tillage. They had the potential to protect surface soil against disintegration and improve soil anti-scourability, which was critical for soil conservation in croplands in this region.

Disintegration of granite residual soils with varying degrees of weathering

Although rock disintegration has been well studied, much less is known for the residual soils decomposed from the parent rocks. Weathering affects every aspect of residual soil properties; however, how it controls soil disintegration behavior is yet to be established. In this study, laboratory disintegration tests were performed using a self-developed device on natural granite residual soil (GRS) collected at various depths (3.5–17.5 m). The remolded soil was also tested to investigate the effects of the soil structure. The disintegration process was quantitatively traced through several parameters that reflected soil disintegration degree and rate. A new classification system for soil disintegration behavior was proposed accordingly. It was found that the weathering degree (WD) significantly affected the disintegration behavior of GRS, with more weathered GRS being more susceptible to disintegration. The time required to initiate complete soil disintegration increased from 1.9 min (3.5 m deep soil) to 140 min (12.5 m deep soil), and the GRS at the depth of 17.5 m exhibited incomplete disintegration behavior, with an ultimate disintegration ratio of 62%. The disintegration rates v10, v30, and v50 for 17.5-m-deep GRS were ~97% lower than the values for soil at the depth of 3.5 m. In addition, the variations in particle composition caused by the degree of weathering did not control soil disintegration while cementation played a critical role. Soil disintegration was likely triggered by cementation damage upon soaking which broke up the soil aggregates and reduced soil stability. This study not only establishes a framework for studying the disintegration behavior of residual soils as affected by weathering but also provides a comprehensive dataset of GRS.

Formation mechanism of collapsing gully in southern China and the relationship with granite residual soil: A geotechnical perspective

Recently, there has been an increase in collapsing gullies in the south of China as one of the most destructive types of soil erosion. Most collapsing gullies are formed on a well-developed granite crust; thus, granite residual soil plays a critical role. However, the extent to which the geotechnical features of residual soil, especially soil disintegration, affects collapsing gully formation is poorly understood. This study performed laboratory disintegration tests on granite residual soil taken from the red soil, sandy soil, and detritus layers of a collapsing gully. The disintegration behaviour was quantified by defining the disintegration ratio, Rd, and three equivalent disintegration rates, vI, vII, and vIII, corresponding to Rd = 10%, 30%, and 50%, respectively. The results revealed that the red soil layer (depth < 1.3 m) and the soil at the shallower depth of the sandy soil layer (depth < 3.0 m) showed similar disintegration behaviours, which were complete (Rd = 100%) and rapid, with vI values in the range of 66.7–266.7%/min. The soil disintegration in the sandy soil layer was characterised by an incremental increase in Rd to 100% within 100 min. The residual soil at the bottom of the sandy soil layer and the top of the detritus layer (depths of 4.0–8.0 m) disintegrated consistently at the first, after which the disintegration rate gradually decreased with vIII lower than 1%/min. The detritus layer soil at a depth greater than 10.0 m showed incomplete disintegration, and the ultimate Rd was approximately 60%. The formation mechanism for the soil disintegration and gully collapse was also proposed. The weakening of cementation triggered the breakup of soil aggregates and led to soil disintegration and the occurrence of a gully collapse. This study provided new insights on gully erosion.

Enhancement of isopropanol removal with concomitant power generation by microbial fuel cells: Optimization of deoxidizing composite anodes using response surface methodology

This study used a response surface method to develop a deoxidizing anode, which was introduced into microbial fuel cells (MFCs) to treat isopropanol (IPA) wastewater and waste gas. By embedding a deoxidizing agent (DA) into the anode of MFCs, a hypoxic environment can be created to enable anaerobic electrogens to be effectively attached to the anode surface and grow. Consequently, MFC power generation performance can be enhanced. The optimal coke and conductive carbon black ratio of an anode and percentage of DA added were 3.61 g/g and 3.15 %, respectively. The research design concurrently achieved the maximum deoxygenation efficiency (0.86 mg O2/bead), minimum disintegration ratio (3.51 %), and minimum resistance (30.2 Ω). The regression model had high prediction power (R2 > 0.93) for anode performance. As determined through multi-objective optimization, the results highly satisfied the target expectation (desirability = 0.82). The optimized deoxidizing anode was filled into an air-cathode MFC, which had a higher IPA removal efficiency (1.15-fold) and voltage output (1.24-fold) than an MFC filled with coke. The results for the trickling-bed MFC filled with a deoxidizing anode revealed that when the inlet concentration was 0.74 g/m3, the voltage output and power density were highest at 416.3 mV and 486.6 mW/m3, respectively. The deoxidizing anode developed has the potential to increase the MFC voltage output and the pollutant removal.

Investigation of Disintegration Behaviors of Clay-Bearing Rocks by a New Methodology

Abstract Disintegration behaviors of clay-bearing rocks are special engineering problems. Samples are isolated and unconstrained in previous disintegrating-durability tests, unlike clay-bearing rocks under the natural controlled condition in the field. Then, a methodology of disintegration testing regarding natural controlled conditions was evaluated to study the disintegration behaviors of clay-bearing rocks. The study results indicated that the fissure area ratio (FAR) increases rapidly before the seventh wetting-drying cycle and then begins a stable trend. The fragment size distribution characteristics show that the proportion of small fragments gradually increases and that the proportion of large fragments gradually decreases with the increase in the number of wetting-drying cycles. Clay-bearing rock fragments larger than 2 mm disappear after seven wetting-drying cycles. The change characteristics of the disintegration resistance of the disintegrating clay-bearing rock are that, regardless of the critical fragment size diameter (Dcr) of complete disintegration, the slake durability index (I(D)) and disintegration ratio (DR) are reduced. The disintegration degree of aggregate fragments is further reflected by the DR, which corresponds with the FAR. A trend of the maximum shear stress related to the number of wetting-drying cycles has two stages: the first significant and then insignificant decrease. The critical number of wetting-drying cycles is seven, after which point the disintegrating clay-bearing rock fragments with a size coarser than 2 mm disappeared. The results indicate the highly positive correlation between strength and the DR of the disintegrating clay-bearing rock.

Investigation of the slaking behavior of weak geological units in terms of undercutting rate

It is aimed in this study to measure the undercutting rate of weak geological units under field conditions and to determine the relationship between this parameter and other indexes and physical properties of related rocks. Thus, 11 different locations in which weak materials were found and undercutting problems were observed in the road slopes were selected. In these road cuts, the undercutting depths in many locations were obtained by measurements taken at different dates from the pins installed in the fresh surface of weak units. In addition, undercutting depth was directly taken by using the amount of erosion between durable and weak rock units in the road slopes with a known date of the excavation. Samples having suitable amounts and sizes were collected at the measured locations to be used in physical and durability tests. In the analyses, the applicability of the results of slake index and durability tests, as well as the disintegration ratio in the determination of the disintegration behavior of these geological units, was investigated, and statistically significant empirical equations were obtained. Considering the results obtained from different weak geological units, it was determined that the depth of undercutting values change approximately between 10.1 and 45.8 mm.

Effect of different test methods on the disintegration behaviour of soft rock and the evolution model of disintegration breakage under cyclic wetting and drying

Red-bed soft rock covers a large area in China and is often used as filling materials for highway roadbed and embankment, while the disintegration of red-bed soft rock often causes serious settlement of the roadbed and decreased stability. To thoroughly study the disintegration properties of red-bed soft rock, a series of slake durability tests were performed using different test methods. First, the gradation of disintegrated red-bed soft rock was investigated, and the shape of the gradation curve mainly presented as reverse sigmoidal and hyperbolic. Moreover, the evolution model of the disintegration breakage of red-bed soft rock using the Morgan-Mercer-Florin (MMF) model was derived, and the model parameters were analysed. Based on the test results, the disintegration behaviours of red-bed soft rock were measured by the disintegration ratio; then, the new formula to calculate the disintegration ratio based on the concept of the traditional disintegration ratio was derived using the established model. Finally, the effect of different test methods, i.e., different test devices, drying temperatures and sizes, on disintegration breakage under cyclic wetting and drying was analysed, and the test results showed that the rate of disintegration was accelerated by the slake durability apparatus, a higher drying temperature and a larger size.

Evolution of the disintegration breakage of red-bed soft rock using a logistic regression model

Abstract The disintegration of red-bed soft rock is closely associated with a series of geological disasters. However, research on the evolution of the disintegration breakage has not yet been sufficiently executed. To compensate for this insufficiency, slake durability tests are carried out by three widely used experimental methods to explore the disintegration of red-bed soft rock. Then, based on the logistic regression model, the evolution model of disintegration breakage is derived, and the mathematical meaning of the model parameters (i.e., β 0 and β 1 ) is analysed. The results show that the variation in model parameters corresponds to the process of disintegration breakage. Moreover, the new formulas based on the established evolution model to calculate the disintegration index (including the slake durability index and the disintegration ratio) are presented to replace the traditional expression. Finally, the effects of the test device, drying temperature, and disintegration index on the disintegration breakage of soft rock are studied and discussed. Compared with the slake durability index, the disintegration ratio considering all mesh sizes is a more reasonable index to quantify the disintegration characteristics. The results of the present study are helpful for understanding the evolutionary process of disintegration breakage.

Impact of slaking shale behaviour on damage of engineering structures, Saudi Arabia

Shale slaking has caused problems on infrastructure and buildings in Tabuk City, Saudi Arabia. Most of these problems occur in the form of subsidence, cracking and loss of bearing capacity related to the slaking more than the expansion of clay minerals in shale. The aim of this research is to study the possible causes of such problems in Tabuk districts. The geotechnical properties of Tabuk shale indicate that the shale has a low degree of expansion. X-ray diffraction analysis confirms that kaolinite is the predominant clay mineral, while expansive clay minerals are not present. Based on slake durability index, disintegration ratio and shale rating system, the shale is classified as soil-like with low to medium durability. Scanning electron microscopy results indicate that the development of gypsum crystals could be a crucial factor in the degradation. Pore-air compression and crystal growth or the dissolution of gypsum and halite minerals are significant slaking mechanisms in triggering the disintegration of shale because they disturb the structure and destroy the diagenetic bonds of shale, which reduces the strength. The damage is not related to the expansion of clay minerals within the shale but is significantly influenced by the slaking of shale and its transition from rock-like to soil-like material.

Experimental characterization and quantitative evaluation of slaking for strongly weathered mudstone under cyclic wetting-drying condition

The fragmental disintegration processes of strongly weathered mudstone subjected to periodic changes in wet-dry state detrimentally affect numerous slope stability. To quantitatively study the disintegrating characteristics, laboratory-based eleven-cycle’s disintegration tests were performed on the mudstone samples taken from Guandukou area in Three Gorges region. Under the periodic action of wet-dry cycle, the tested mudstone samples continuously disintegrate, with bigger pieces with various sizes broken down into smaller fragments of different sizes. The fragmental disintegration process of the tested mudstone is relatively strong, but which cannot be indicated only by the content variation of small particles with some sizes (< 2 mm). To better characterize the slaking behavior, a quantitative measure based on the particle grading characteristics was proposed, with its effectiveness and reliability demonstrated by sensitive analysis. When the number of wet-dry cycles rises, the proposed slaking durability parameter decreases linearly while disintegration ratio shows slowly increasing tendency, indicating non-stop of mudstone disintegration subjected to cyclic changes in wet-dry state.

The Use of Disintegration Ratio in Evaluating Rock Durability in Selected Mudrock Samples in Indonesia

Characterization of durability of mudrocks is important regarding its slaking behaviour within a short time when exposed to and or interact with water. Some relevant cases that occurred due to slaking are damage to roads and slope failures along the Cipularang and Cipali Toll Road. Current engineering activities related to the presence of mudrocks are being and will be held in several locations in Indonesia such as the construction of the Cisumdawu Toll Road in Ujungjaya District, Sumedang and building the National Observatory in Timau District, Kupang. This research is useful for providing engineering considerations related to those activities.&#x0D; The methods used in this research included X-ray diffraction to obtain mineralogy of mudrock, laboratory testing of physical properties of rocks such as dry density, water content, porosity, absorption and mudrocks durability tests. Durability of rocks was determined by disintegration index test. Testing was carried out by wetting and drying of rock samples.&#x0D; Test results showed that the average disintegration ratio of claystones, shales, mudstones and siltstones are 0.1035, 0.2183, 0.4942 and 0.9900. Slaking mode occurs to claystones, mudstones and shales is body slaking while dispersion slaking occurs to siltstones. Evaluation of the durability of mudrocks in this research indicates that siltstones have the highest durability characterized by very slow disintegration, followed by mudstones, shales and claystones at the lowest with very quick disintegration. Disintegration ratio from the disintegration index test characterizes the durability of mudrocks in more details. It can be concluded that porosity and absorption are incorporated into the main factors affecting the durability of mudrocks.

Durability classification of red beds rocks in central Yunnan based on particle size distribution and slaking procedure

Moisture induced disintegration of soft rock in Red Beds is common all over the world. The slake durability index test is most useful to quantify durability of the soft rocks. Based on a series of slaking test, this article aims to develop a durability classification involving particle size and slaking procedure. To describe the slaking procedure in detail, the Relative Slake Durability Index (Idi) is proposed. The Idi is the percentage ratio of the ith weight of oven-dry retained portion to the (i-1)th weight of ovendry retained portion. Results show that the Idi of samples have a large difference in certain slaking procedure, whereas the traditional Durability Slake Index (Id) is almost constant. Considering this limitation of Id in durability classification, an advanced classification by applying the Idi and disintegration ratio (DR) is further established in this article. Compared to the durability classification based on Slake Durability Index (Id), the new classification accounts for the particle size of the slaked material and the slaking procedure, so it provides a better measure of the degree of slaking. The classification recommended in this article divide the slake durability into three classes (i.e., low, medium and high class). Furthermore, it divides both the low class and the medium class into 3 subclasses.

Re-weathering of stabilized clay shale with Portland cement behavior

Clay shale is a claystone which in fresh condition has a very high shear strength. When it reacts with the atmosphere or hydrosphere it will weather so that the shear strength of clay shale will drop drastically. The weathering potential of clay shale is generally done by the slake durability test and the weathering process is measured by disintegration ratio test (DR). The strength of clay shale that has fully weathered will increase again when it is stabilized with a minimum of 6% PC (Portland Cement). It was found from the wetting drying cycle process testing that durability of re-weathering of stabilized clay shale with PC is increased compared to natural clay shale. Disintegration ratio of natural clay shale DR was smaller than stabilized clay shale with 6% PC. Additionally, more than 6% PC increased the durability of re-weathering of clay shale.