Stone Loss Research Articles

Robot-assisted laparoscopic Anderson–Hynes pyeloplasty for ureteropelvic junction obstruction

ObjectivesTo explore surgical, functional, and symptomatic outcomes in a series of patients who underwent robot-assisted laparoscopic Anderson–Hynes pyeloplasty (RALP) for ureteropelvic junction obstruction using the DaVinci Si surgical robotic system.MethodsRetrospective study including patients aged 16 years or older who underwent RALP from June 2016 to December2021. The following outcomes were recorded: operative outcome and complications [classified according to the Clavien–Dindo Classification (CD)] within 30 days of the procedure as well as 1 year success rate and restenosis during follow-up.ResultsIn total, 194 patients were available for analyses with a median follow-up of 4.5 (IQR 3.0-6.0) years. The primary indications were loss of kidney function (45%), pain (36%), infection (11%), kidney stone (6%), and others (2%). The median operation time was 134 min (IQR 112-159), the median length of stay was 2 days (IQR 2-2), and the median time with double-j stent postoperatively was 24 days (IQR 22-27). Overall, 65 out of 194 patients (33%) experienced a postoperative complication (12% CD I, 13% CD II, 8% CD IIIa or IIIb). The 1 year success rate was 92% for patients treated because of deteriorating renal function, 78% for patients treated because of symptoms, 82% for patients treated because of infections, and 78% for patients treated because of kidney stones. Seven percent of the patients presented a recurrent ureteropelvic junction stricture during follow-up.ConclusionsIn our experience, robot-assisted laparoscopic Anderson–Hynes pyeloplasty performed with the DaVinci Si system is a safe with a few major complications and acceptable success rate.

One-year results of the first road surface with the addition of sunflower oil porous capsules

This paper presents findings from the first surface course in the UK employing sunflower oil-filled porous capsules as a self-healing additive. The capsules, designed to mitigate ravelling, were tested on a road constructed at an asphalt plant and subjected to a year of traffic in temperatures ranging from below 0°C to 35°C. Spherical in shape with a diameter of about 1.5 mm, the capsules possess a porous structure filled with sunflower oil. Each tonne of asphalt contained 5 kgs of capsules. The material used was Stone Mastic Asphalt (SMA), one of the UK's most utilised surface course materials. Eight sections were built, with four varying binder contents (6.4 %, 5.9 %, 5.5 % and 5.2 %), each with and without capsules. The road performance was evaluated by measuring two indicators: rut depth and surface macrotexture. Results show that the capsules delay fretting progression in wearing courses. Fretting could have resulted from the complex interaction between early life wearing and asphalt compaction by traffic that caused the mastic to move to the road surface. In addition, no considerable difference in rutting was observed between the different materials. Moreover, core samples were extracted from the road before and after traffic and age exposure for further laboratory analysis to assess the long-term performance. Results showed that stone loss resistance in asphalt-containing capsules was 30.02 % lower before ageing and 25.92 % lower after ageing. Furthermore, the stiffness ageing factor was 15–20 % lower in materials with capsules, while the fatigue life remained consistent across all materials.

Assessment of fracturing and blockiness of the Pshenychne gabbro deposit massif

Proper development of the deposit and the choice and use of effective technologies for block stone extraction are impossible without evaluating the structural indicators of the massif. It consists in studying the propagation of cracks in the array, orientation of the main crack systems, studying the anisotropic properties of stone, and predicting the yield of commercial stone blocks in the deposit. This allows both to increase the efficiency of block extraction and to reduce the loss of stone during its extraction, which increases the economic performance of field development. The assessment of fracturing and blockiness of the Pshenychne gabbro deposit was carried out based on the results of studying the core documentation of 11 exploration wells and the documentation of a pilot production quarry. Rose diagrams, pie charts, and fracturing plans were constructed in isolines, and crack systems common in the field were identified.

Analysis of lithotripsy efficiency and stone retropulsion displacement according to pulse characteristics of Ho: YAG laser with Moses effect.

Compared to the conventional Ho: YAG laser, a Ho: YAG laser device has been reported that has a Moses effect to reduce stone retropulsion and increase lithotripsy efficiency. The principle of this equipment is to convert a single laser pulse into two pulses. Most studies on such lasers are limited to lithotripsy efficiency and the prevention of stone retropulsion; studies according to each pulse condition have not been performed. Therefore, the purpose of this study was to quantify the bubble shape, lithotripsy efficiency, and stone retropulsion displacement in a ureteral phantom according to the modulation of the first pulse characteristics of the Moses effect laser under conditions that maintained the total energy and repetition rate. In this study, a Ho: YAG laser system (Holinwon Pro, Wontech Inc., Korea) with an emission wavelength of 2.10 μm and a Moses effect was used. To verify the Moses effect based on the changes in the pulse, a water tank was fabricated, and the ureteral phantom was manufactured in a structure that could be easily installed in the water tank. Additionally, a spherical artificial stone in the ureteral phantom was prepared by mixing calcined gypsum (Cacinated Gypsum) and water at a ratio of 3:1. In the ureteral phantom, a high-speed camera (FASTCAM NOVA S12, Photron Inc.) and visible light were used to record pulse-dependent image analysis of bubbles and stone retropulsion. After mounting the artificial stone in the ureteral phantom, the pulse duration and energy of the first pulse of the Moses effect laser were varied; 30 laser shots for 3 s at a repetition rate of 10 Hz were applied to quantify the lithotripsy efficiency and stone retropulsion displacement, and the experimental values were compared. The fragmentation efficiency was confirmed by measuring the mass before and after the laser pulse application, the original position of the stone retropulsion displacement, and the distance moved. The minimum value of stone retropulsion displacement appeared when the pulse duration of the first pulse was 300 μs, the pulse energy was 100 mJ, and the value was approximately 0.28 mm. The highest fragmentation efficiency was observed under the same conditions, and the mass loss of the artificial stone at that time was approximately 3.7 mg. Quantitative indices, such as lithotripsy efficiency and stone retropulsion displacement, were confirmed using ultrahigh-speed cameras to determine the effect of the first pulse energy and duration of the Ho: YAG laser with the Moses effect on stone removal. It was confirmed that the longer the duration of the primary pulse and the lower the energy, the higher the fragmentation efficiency. In this study, the possibility of manufacturing a laser with an optimal stone-removal effect was confirmed according to the first-pulse condition of the laser with the Moses effect.

HO:YAG LASER VS PNEUMATIC LITHOTRIPSY WITH SEMI RIGID URETEROSCOPE FOR PROXIMAL URETERAL CALCULI : OUR INSTITUTIONAL EXPERIENCE

Introduction & objectives: Different modalities are available for proximal ureteric stone fragmentation. From them pneumatic and holmium: yttrium-aluminum-garnet lithotripsy has favorable outcomes. In our randomized study, we included 100 patients who underwent semi rigid ureteroscopic pneumatic lithotripsy or laser lithotripsy. This study aims to compare the outcome of PL and LL in the management of upper ureteric calculi. 100 patients were a Materials & methods: dmitted in Govt Kilpauk medical college and hospital between January 2021 to June 2022 & randomized 50 cases of URS with pneumatic lithotripter and 50 cases of URS with laser lithotripter were enrolled. Patients with urinary tract infection, radiolucent stones, loss of follow-up, concurrent middle or lower third ureteral stones or acute renal failure were excluded. All patients underwent semi-rigid URS with Ho:YAG laser or pneumatic lithotripsy followed by DJ stenting. The aim of this study to compare the stone-free rate, assess the complications, duration of surgery and assess the need for second procedure , if retropulsion of calculus occurred following PL and LL. Demographically, no s Results: tatistical different in both groups in view of age, gender, mean size of stones (P> 0.05). Retropulsion occurred in 16% of the PL group (P< 0.05) and required auxillary procedure. There was a statistical difference in terms of stone free rate of stone in favor of LL group (p≤0.05) and mean operative time in favor of the PL group (p≤ 0.05). Conclusions: In both techniques, acceptable results were achieved. We found that both the PL and LL approaches were effective and safe for proximal ureteric calculi. LL method had advantages in more stone free rate, lower retropulsion rate but longer procedure duration compare to the PL method

Clinical characteristics and risk factors of patients with eosinophilic fasciitis associated with pleural effusion

To investigate the risk factors of eosinophilic fasciitis (EF) associated with pleural effusion (PE). A retrospective analysis was performed on 22 patients with EF diagnosed by skin biopsy in our hospital, and they were divided into EF-PE and EF according to chest computed tomography examination. The clinical characteristics, clinical manifestations, comorbidities and laboratory test indicators of the two groups were collected and compared, and the risk factors for occurring PE in patients with EF were determined by multivariate logistic regression analysis. Among 22 patients with EF, 8 had PE. The age, course of disease, incidence of fever, weight loss, cough and shortness of breath, pulmonary infection, hypothyroidism, hydronephrosis and kidney stone, swelling rate of small vascular endothelial cells, consolidation shadows, C-reactive protein and thyroid stimulating hormone in EF-PE group were higher than those in EF group, while free triiodothyronine and thyroxine were lower than those in EF group. Age, fever, shortness of breath, C-reactive protein, ESR, thyroid stimulating hormone, pulmonary infection, hypothyroidism, hydronephrosis, kidney stones, swollen small vascular endothelial cells and chest CT consolidation shadows were identified as risk factors for happening PE in patients with EF, while free triiodothyronine and free thyroxine were identified as protective factors against PE in patients with EF. The incidence of EF-PE was 36.36% in this study. Advanced age, high C-reactive protein, ESR, thyroid stimulating hormone, incidence of fever, shortness of breath, pulmonary infection, hydronephrosis, kidney stones, swollen small vascular endothelial cells, chest CT consolidation shadows, and low free triiodothyronine and thyroxine suggest that patients with EF are significantly at increased risk of PE.

Architected cellular particles to mitigate asphalt stone loss

This paper aims to quantify stone loss mitigation due to the action of architected cellular particles that can absorb impact energy. The architected cellular particles presented in this paper are additives for asphalt that have been designed to absorb impact energy through an internal porous structure filled with a bitumen-compatible liquid that controls their strength. The experimental programme is divided into four phases: Cellular particle manufacturing and morphological analysis; optimisation of asphalt mixture performance by selecting the cellular particle content based on mass loss, rutting and skid resistance testing; study of mass loss with varying compaction energy and asphalt gradation and microstructural and energy absorption analysis. It was concluded that (i) the asphalt’s mass loss linearly decreased as the cellular particle content was increased, (ii) up to 1% of architected cellular particle content by total weight of the mixture reduced mass loss without producing adverse effects in the asphalt, (iii) architected cellular particles deformed during testing, absorbing the impact load energy.

Efficacy of extracorporeal shock wave lithotripsy of pancreatic stone in chronic pancreatitis

Background: To study overall outcome of ESWL therapy in large pancreatic duct stone as first line therapy in chronic pancreatitis.Methods: A prospective, observational study which took place in MGM medical college and the patient were admitted in general surgery department. Patients were selected based on the inclusion criteria composed of upper abdominal pain, weight loss, oily stools and presence of pancreatic stones or ductal irregularity/ parenchymal atrophy determined by various radiological investigations.Results: In this study 11 patients with pancreatic stones were recruited in duration of 2 years. Among 11 patients included in this study 63.33% were males and 36.375% were females. The mean age of males and females were 35.57 and 40.50 years respectively. It was observed that all study subjects had abdominal pain and history of pancreatitis. 36% patient had single calculi and 64% patient had multiple calculi. 18% calculi were present in the body of pancreas and 46% calculi in head of pancreas. All these patient had undergone ESWL procedures with minimum number of 400 shocks and maximum number of 4600. Among the patients it was noted that 73% had successful complete clearance of calculi, 18% had partial clearance and 9% had no clearanceConclusions: ESWL is efficient tool for the treatment of pancreatic calculi but can be used alone it is adjunct tool to ERCP. Endoscopy, etc.

Rigid ureteroscopic lithotripsy in the lateral decubitus position for upper urinary tract stones

BackgroundThe current study aimed to assess a novel ureteroscopic technique developed for treating upper urinary calculi based on a specially designed lateral decubitus body position that could avoid stone loss by adjusting to the effects of gravity.MethodsThis retrospective study examined patients with upper urinary calculi who were surgically treated from November 2008 to January 2020, using a new body position and a rigid ureteroscope. Clinical outcomes, stone-free rates, operative times and complications were evaluated, and factors that could influence treatment success were determined.ResultsIn total, 1080 patients were included, and 1145 operations were performed. The maximum calculus diameters were 11.22 ± 5.01 mm. Operative times were 48.60 ± 27.44 min. A total of 1042 cases were successfully treated, with a stone-free rate of 91.00%. Multivariate analysis showed that female sex (OR = 2.135, 95% CI 1.332–3.422, P = 0.002), thin scope standby (OR = 1.643, 95% CI 1.074–2.514, P = 0.022), laser lithotripsy (OR = 5.087, 95% CI 2.400–10.785, P = 0.000) and stone size (OR = 0.946, 95% CI 0.912–0.981, P = 0.003) were independently associated with stone-free outcomes. In total, 2 ureteral perforations, 2 ureteric avulsions and 4 urosepsis cases were observed, but were all cured without sequelae.ConclusionsUreteroscopic lithotripsy in the lateral decubitus position is a safe and effective technique for treating upper urinary tract calculi, especially upper ureteral calculi.

Point Cloud Approach For Modelling The Lost Volume of The Fillaboa Bridge Cutwater

The digitization of heritage is being rapidly realised in many parts of the world, thanks to LiDAR technology. In addition to the simple digital preservation of heritage, 3D acquisition makes it possible to monitor the structural condition and assess possible damage. This paper presents a method for modelling the lost volume of a heritage bridge. The selected case study is the Fillaboa bridge in Salvaterra de Miño, Spain, which has two cutwaters with the same cutting angle, one of which is damaged and has a stone loss. The bridge was acquired with a Terrestrial Laser Scanner. The method consists of the following processes. First, the walls of the whole cutwater are segmented and aligned by the Iterative Closest Point algorithm over the damaged cutwater. Second, the distance between the two point clouds is calculated, and the damaged area is delimited in both point clouds. And third, the alpha-shape algorithm is applied to model the point cloud of the damaged area on a polygon. By searching for the optimal alpha radius, the polygon that best fits the damaged volume is generated. The proposed method also allows digital reconstruction of the damaged area, although it is sensitive to acquisition problems, which require manual interventions in the processing. The accuracy of the method is mainly dependent on the acquired point cloud registration (with an RMS error of 60mm) and the ICP registration error (31mm). Its use is limited to the existence of two geometries that allow superposition: one in good condition and one damaged to compare.

Point Cloud Approach For Modelling The Lost Volume of The Fillaboa Bridge Cutwater

The digitisation of heritage is being rapidly realised in many parts of the world thanks to LiDAR technology. In addition to the simple digital preservation of heritage, 3D acquisition makes it possible to monitor the structural condition and assess possible damage. This paper presents a method for modelling the lost volume of a heritage bridge. The selected case study is the Fillaboa bridge, in Salvaterra de Miño, Spain, which has two cutwaters with the same cutting angle, one of which is damaged and has a stone loss. The bridge was acquired with a Terrestrial Laser Scanner. The method consists of the following processes. First, the walls of the whole cutwater are segmented and aligned by Iterative Closest Point algorithm over the damaged cutwater. Second, the distance between the two point clouds is calculated and the damaged area is delimited in both point clouds. And third, the alpha shape algorithm is applied to model the point cloud of the damaged area to a polygon. By searching for the optimal alpha radius, the polygon that best fits the damaged volume is generated. The proposed method also allows digital reconstruction of the damaged area, although it is sensitive to acquisition problems, which require manual interventions in the processing. The accuracy of the method is mainly dependent on the acquired point cloud registration (with an RMS error of 60mm) and the ICP registration error (31mm). Its use is limited to the existence of two geometries that allow superposition: one in good condition and one damaged to compare.

Factors affecting performance of sprayed seals in rural Victoria

ABSTRACT Factors that significantly affect performance of in-service sprayed seals have been identified through developing comprehensive models using a multilevel analysis approach. Subjective condition data of surface distresses from five rural road networks in Victoria/Australia have been used. They include cracking, deformation, texture loss, stone loss and patching. Evaluations of individual distresses for representative segments are combined into a composite index called Surface Inspection Rating (SIR) which is used to trigger the need for resealing. Contributing factors considered include surface age, traffic volume, aggregate size, subgrade soil type, shoulder seal width, rainfall and temperature. For each network, statistically significant factors for each distress are identified and used in developing their SIR models. An overall SIR model has also been developed using condition data from all five networks. Predictions of this model have been compared with an existing model that has been developed using Markov Chains with surface age as the only predictor. The results show that both models have roughly similar deterioration rates of SIR up to 8 years of seal life, after which deterioration rate of the newly developed model becomes higher.

Comparative Study Between Holmium Laser versus Pneumatic Ureteroscopic Lithotripsy for Proximal Ureteric Stones Close to Pelvi-ureteric Junction (PUJ) -A Prospective Trial

Objective: To compare the outcomes of ureteroscopic lithotripsy with pneumatic lithotripter versus Holium:Yttrium-Aluminum-Garnet (Ho:YAG) laser in the management of upper ureteric stones. Materials and methods: Patients who underwent ureteroscopic lithotripsy with pneumatic lithotripter or Ho:YAG laser for upper ureteric stones were reviewed. Patients with urinary tract infection, ,loss of follow-up, concurrent middle or lower third ureteral stones or acute renall failure were excluded. Patient age, stone size and burden (based on KUB or computerized tomography), stone upward migration, double J stent insertion rate, stone free rate and secondary intervention rate for residual stones were compared in both groups. Results: There were 70 patients with upper ureteric stones (35 in pneumatic group and 35 in laser group) meeting the study criteria. Patients’ age, gender, stone size and burden were similar in both groups. The Ho:YAG laser lithotripsy group had better stone free rate, less double J stent insertion rate and less upward migration and secondary intervention rate, sepsis as compared with pneumatic lithotripsy (94.2% vs. 60%; 85% vs. 100%; 5.7% vs 40%; 5.7% vs 34.2%; 2.8 vs 2.8 respectively, all p < 0.05). In patients with stones sizes 8-10 mm, Ho:YAG laser lithotripsy had significantly lower upward migration rate, lower double J stent insertion rate, higher stone free rate and less secondary intervention rate. Conclusions: Ho:YAG laser lithotripsy is better and much effective than pneumatic lithotripsy in the management of upper ureteric stones in terms of, stone free rate and secondary intervention rate for stones of sizes about 8 to 10 mm.Although the access of upper ureter is difficult but our small calibre (4.5 fr) ureteoscope and gentle manuevre have made the procedures safe and successful. Bangladesh Journal of Urology, Vol. 23, No. 2, July 2020 p.188-192

Modelling long-term performance of asphalt surfaces

ABSTRACT A study has been performed to develop long-term performance models for asphalt surfaces using condition data from two urban road networks. The performance of asphalt surfaces is assessed subjectively every two to three years considering the extent and severity of different distress types. They include cracking, deformation, texture loss, stone loss and patching of potholes and localised depressions. Different ratings are used for each condition then combined into one overall condition index referred to as Surface Inspection Rating (SIR). SIR is used to trigger the need for resurfacing operations. Performance models have been developed for these distresses and SIR considering the following factors; surface age, traffic loading, aggregate size and climatic conditions (rainfall and temperature). Multilevel analysis approach has been used to model the historical time series condition data. The results indicate that surface age, temperature and rainfall affect SIR in both networks and that traffic loading has a significant effect in one network.

Numerical Simulation Study on Root Stones Loss in Dam Buttress Engineering

In order to study the loss of root stones under action of water flow in dam buttress, based on Flow-3D, a mathematical model was established. At first, the physical experiment was carried out about water drag force on a 0.04 m×0.04 m×0.04 m cubic block. And then a numerical flume model about this experiment was established in Flow-3D software. The values of drag force were compared between the numerical and experimental results, and the percentage of error was less than 5%. Thus, the numerical model in Flow-3D was accurate and available. Then, a numerical simulation on root stones loss in an actual dam buttress project was carried out. Since the actual flow is turbulent, the RNGk-εturbulence model was used. And VOF method, FAVOR technology, and GMO model were also used in this simulation. The numerical results showed flow depth, pressure, velocity, turbulent energy, and root stones loss. Because water level of the inflow increased with time continuously, flow depth and velocity also increased, and the root stones would be lost. The increase in flow velocity was the fastest in the dam head, and the start time of root stones loss was also the earliest. The most serious area of root stones loss is the dam head, and the serious second area is the upper cross corner. Those root stones would have the farthest lost distance in the dam head. The root stones loss was also serous in the upstream face. However, the root stones in the upstream face and the down cross corner were less affected by water flow, so there were no root stones loss phenomena. Thus, in the actual project, the dam head, the upper cross corner, and the upstream face should get more attention.

Durability assessment of Gerdoi and red travertines from Azarshahr, East Azerbaijan province, Iran

Durability is the most important characteristic of stones in sustainable architecture. Salt crystallization has been known to damage porous building stones. Gerdoi and red travertines are extensively used in new buildings in East Azerbaijan province. To this end, petrographic and physical properties, dry and saturated P-wave velocity, uniaxial compressive strength and Brazilian tensile strength were obtained for each freshly quarried stone in the laboratory. The samples were subjected to an aging test in order to examine their resistance against sodium chloride crystallization. Water saturated-to-dry strength ratio (a crude immediate estimator) and a decay function model were applied to assess durability of stones. Gerdoi travertine consists of alternation of densely packed layers (laminated fabric) while red travertine exhibits massive fabric. Albeit Gerdoi travertine has laminated fabric, it shows higher initial strength, P-wave velocity and lower effective porosity and water absorption than Gerdoi travertine. The results showed that a crude immediate estimator is not a sensitive indicator for estimating durability of travertine stones. P-wave velocity, uniaxial compressive strength and Brazilian tensile strength decreased with increasing number of salt cycles. A decay function model confirmed that the integrity loss was higher in red travertine in comparison with Gerdoi travertine. It was found that the integrity loss of both stones based on Brazilian tensile strength is highest than those based on uniaxial compressive strength and P-wave velocity.

Comparison of pneumatic and Holmium laser ureteroscopic lithotripsy for upper third ureteral stones

ObjectiveTo evaluate the outcomes of ureteroscopic lithotripsy with pneumatic lithotripter and Holium:Yttrium-Aluminum-Garnet (Ho:YAG) laser in the management of upper third ureteral stones. Materials and methodsPatients who underwent ureteroscopic lithotripsy with pneumatic lithotripter or Ho:YAG laser for upper third ureteral stones were retrospectively reviewed. Patients with urinary tract infection, radiolucent stones, loss of follow-up, concurrent middle or lower third ureteral stones or acute renal failure were excluded. Patient age, stone size and burden (based on KUB or computerized tomography), stone upward migration, double J stent insertion rate, stone free rate and secondary intervention rate for residual stones were compared in both groups. ResultsThere were 158 patients with 178 upper third ureteral stones (135 in pneumatic lithotripsy group and 43 in Ho:YAG laser lithotripsy group) meeting the study criteria. Patients' age, gender, stone laterality, stone size and burden were similar in both groups. The Ho:YAG laser lithotripsy group had better stone free rate, less double J stent insertion rate and less secondary intervention rate as compared with pneumatic lithotripsy (53.4% vs. 40.1%; 72.1% vs. 91.9%; 25% vs. 48.5% respectively, all p < 0.05). In patients with stones larger than 10 mm, Ho:YAG laser lithotripsy had significantly lower upward migration rate, lower double J stent insertion rate, higher stone free rate and less secondary intervention rate. ConclusionsHo:YAG laser lithotripsy is superior to pneumatic lithotripsy in the management of upper third ureteral stones in terms of double J stent insertion rate, stone free rate and secondary intervention rate for stones of all sizes. For stones larger than 10 mm, laser lithotripsy results in less stone upward migration.

Mass loss and flammability of insulation materials used in sandwich panels during the pre‐flashover phase of fire

SummaryNowadays, buildings contain more and more synthetic insulation materials in order to meet the increasing energy‐performance demands. These synthetic insulation materials have a different response to fire. In this study, the mass loss and flammability limits of different sandwich panels and their cores (polyurethane (PUR), polyisocyanurate (PIR) and stone wool) are studied separately by using a specially designed furnace. Expanded polystyrene and extruded polystyrene are tested on their cores only. The research has shown that the actual mass loss of synthetic and stone wool‐based cores is comparable up to 300 °C. From 300 °C onwards, the mass loss of PUR panels is significant higher. The mass losses up to 350 °C are 7%, 29% and 83% for stone wool, PIR and PUR respectively, for the influenced area. Furthermore, delamination can be observed at exposure to temperatures above 250 °C for the synthetic and 350 °C for the mineral wool panels. Delamination occurs due to the degradation of the resin between core and metal panels and the gasification of the (PUR) core. The lower flammability limits have been established experimentally at 9.2% m/m (PUR) and 3.1% m/m (PS). For PUR, an upper limit of 74% was found. For PIR and mineral wool, no flammability limits could be established. Copyright © 2017 John Wiley &amp; Sons, Ltd.

石造物を利用した岩石の風化速度に関する研究動向

It is difficult to estimate weathering rates of rocks based on actual landforms. However, using stone-built architectures, artifacts, and traces of human activity on rock surfaces, weathering rates of rocks under weathering-limited conditions can be obtained easily because stone-built heritages, in general, have a geometrical shape and zero-datum levels. In addition, it is possible to estimate weathering rates of a millennium-scale and changes of rates up to a millennium scale. Many studies on weathering rates of rocks use stone-built heritages. This study reviews recent geomorphological studies that estimate weathering rates, and summarizes their trends. Most of the studies analyze gravestones and churches built since the 19th and 11th centuries, respectively. Such stone-built heritages are more commonly located in humid temperate areas. Weathering rates are estimated mainly from surface recession or surface loss of gravestones and church-building stones. The major three building stones—carbonate rocks (rate: 2-90 mm/ka), sandstone (8-100 mm/ka), and granite (5-65 mm/ka)—have different ranges of weathering rates. Among these stones, the rates for carbonate rocks are sensitive to climatic conditions and atmospheric sulfur dioxide concentrations. The results of the studies reveal that weathering rates show an obvious dependence on aspects. North-facing surfaces tend to have lower rates than surfaces facing other cardinal directions because each surface has different temperature and moisture conditions due to insolation. Moreover, the studies reveal that temporal changes in weathering rates rarely fit a simple linear model. Changes in atmospheric acidity, landform development, and vegetation cover rapidly affect the intensity of weathering processes and cause fluctuations in weathering rates.

The effect of freeze–thaw process on the physical and mechanical properties of tuff

In this study, we used a decay function to predict the long-term durability of tuffs against freeze–thaw (F–T) processes that are responsible of most of damages in natural building stones. The model proposed by Mutluturk et al. (Int J Rock Mech Min 41:237–244, 2004) provides meaningful parameters (including decay constant and half-life) for assessing the integrity loss of stones against freeze–thaw action. After their mineralogical characterization, six different types of tuffs were submitted to freeze–thaw cycles. Their deterioration was investigated by determining the physical (including effective porosity and P-wave velocity) and mechanical properties (including Brazilian tensile strength and uniaxial compressive strength) 10 cycles of F–T up to 70 cycles. Slake durability test was performed after 15, 30 and 60 cycles of F–T action. Results showed that slake durability index cannot be used for assessing the effect of F–T processes on the durability of the samples being studied. The decay model applied to the data indicated that, due to difference of petrographical characteristics of studied samples, decay constant and half-life were different for all types of tuffs. As with increase in lithic fragments and grain size of samples, their decay constant will increase (half-life will decrease) and, consequently, durability will decrease. Furthermore, based on achieved results from values of decay constant and half-life of the different tuff types, the destructive effect of F–T process on tensile strength was higher than on compressive strength. Brazilian tensile strength is a more relevant measurement to assess long-term durability of rocks to F–T.