Drilling Resistance Measurement Research Articles

Profiling Novel, Multifunctional Silane-Phosphonate Consolidants for the Mitigation of Gypsum Stone Deterioration via Concerted Autocondensation/Surface Complexation Processes.

Mineral gypsum (selenite) stones have been used extensively by ancient Cretans in the Minoan Palace of Knossos (Crete, Greece), mostly for building and ornamental purposes. Exposure of mineral gypsum to environmental stresses (temperature fluctuations, rain, air-borne pollutants, soluble salts, etc.) causes solubility-driven degradation, and loss of cohesion of the crystal aggregates, with ensuing aesthetic degradation. In this work, the efficiency of four consolidants for artificial gypsum specimens is presented and evaluated based on drilling resistance measurements [drilling resistance measuring system (DRMS)]. Two of them (commercial names RC-70 and RC-90, RC = Rhodorsil Consolidante) are alkoxysilane-based and they are considered as benchmark consolidants. The other two [3-(trihydroxysilyl)propyl methylphosphonate monosodium salt, TRIMEPHONA, and 3-(trihydroxysilyl)propylamino-diphosphonate, TRIPADIPHOS] are multifunctional consolidants because they possess a self-condensable (after hydrolysis) trihydroxysilyl [-Si(OH)3] moiety and phosphonate groups (one in the former, two in the latter). Consolidants RC-70 and RC-90 exhibit rather low consolidation effectiveness. This is not unexpected, as these are alkoxysilane-based and act simply as "fillers" for the pores of the gypsum. Consolidant TRIMEPHONA demonstrates an enhanced level of consolidation action. This is due to its double functionality, i.e., the presence of an anionic phosphorus-based moiety that anchors onto the gypsum surface, and a condensable silane triol [-Si(OH)3] unit. Consolidant TRIPADIPHOS shows excellent gypsum consolidation features and is much more efficient (per unit concentration) than all other tested consolidants. This is assigned to its better gypsum anchoring ability via surface Ca-complexation. Selected compressive strength studies were performed on gypsum samples treated with the phosphorus-based consolidants, and corroborate the findings from DRMS. To shed further light on possible binding modes of the phosphonate moiety on surface Ca2+ sites in gypsum, two model compounds were synthesized and structurally characterized, Ca-C2D and Ca-C3D (C2D = ethylamino-di(methylenephosphonic acid) and C3D = propylamino-di(methylenephosphonic acid).

The effect of temperature and moisture content on drilling resistance measurements in wood (Pinus sylvestris L.)

ABSTRACT Drilling resistance (DR) measurements is widely used for nondestructive testing and evaluation of wood in growing trees and timber structures. A DR method can be applied in the regions with a cold climate and in wood with temperatures below zero degrees Celsius and varied moisture content (MC), which raises a question of correct interpretation of DR profiles and prediction of wood properties. Laboratory tests were conducted on Scots pine specimens with four levels of MC (7.4%, 11.0%, 23.5%, 147.9%) and temperature (+20°С, +2°С, −2°С, −10°С) variations. In-field tests were made on 33 growing trees at +18°С and −15°С. An IML-RESI PD 400 tool with a fixed rotational frequency of 2500 rpm and a feed rate of 1.5 m·min−1 was used. In most cases, wood temperature and MC had a significant influence on DR, but differences in an absolute value could be slight. A drastic increase in DR and feeding resistance was observed for water-saturated specimens tested at −10°C. For structural health assessment of timber structures at temperatures below 0°C, it is recommended to control wood MС. The effect of MC on DR was pronounced for groups of specimens with temperatures below and above the fibre saturation point. The in-field tests confirmed an increase in DR for frozen wood that can be used for studying water-conducting layers in growing trees.

Reliability of Noninvasive Sonic Tomography for Detection and Quantification of Internal Defects in Yoshino Cherry

Abstract Preventive maintenance through monitoring and early detection is important for trees that are structurally weak due to internal decay. Once internal decay has occurred, recovery of lost strength is irreversible. The decaying tree becomes vulnerable to external impacts, which may lead to breakage or windthrow. The Yoshino cherry (Cerasus×yedoensis (Matsum.) “Somei-yoshino”) accounts for a high proportion of landscape trees in Asia. Testing the reliability of noninvasive sonic tomography (SoT) to estimate internal defects could facilitate structural stability evaluation and proactive preventive management. We performed noninvasive SoT and invasive resistance microdrilling to detect and quantify internal defects in old and large Yoshino cherry trees. Generally, SoT reflected the areas and location of severe structural defects, showing a correlation with the resistance microdrilling results (R² = 0.542, p < .001). However, when cracks were present in disks, the SoT overestimated defects and errors mainly observed in the transition zone (green). Based on these findings, when evaluating the SoT, careful decisions are needed to distinguish between actual defects and broad sonic shadows. Furthermore, additional evidence from drilling resistance is required to differentiate between incipient decay and cracks. The results of this study provide valuable insights for enhancing the interpretation of sonic tomograms. Study Implications: We suggest defect boundaries in sonic tomograms should be redefined to improve the accuracy of interpretation for any new species being studied. Careful drilling resistance measurements should be taken, especially in transition zones (green areas in tomogram) and incipient decay zone (light brown areas). Noninvasive sonic tomograms only reflect acoustic properties of the tested cross-section of a tree and cannot be considered an actual representation of the internal conditions until the readings are calibrated to destructive sampling results.

Determination on the thickness of superficially weathered layer of historical stones from Guanzhong area in China

Superficial weathering in the form of granular disaggregation, powdering and flaking on stone surface is one of the most serious damages to stone heritages, since the surface carries most of the artistic, historical information. The determination of the thickness of the superficially weathered layer of historical stones is critical to their conservation. However, the methodology for quantitative analyses of such thickness remains very limited. In this study, we carefully study the vapor absorption and pore structure evolution of historical sandstones from Guanzhong area with respect to their weathering. We find out that the thickness of superficial weathered layer of Guanzhong sandstones can be derived by following the changes in vapor absorption or pore structure. Such data achieved from various methods developed in this work are consistent with each other and in good agreement with the results obtained by using current techniques such as drilling resistance measurement, the Ruxton method and ultrasonic testing. Among all methods used, pore size distribution analysis requires less sample preparation and measures the thickness of superficial weathered layer of Guanzhong sandstones around 7 mm.

Effect of drilling resistance measurement on residual load capacity of Scots pine (Pinus sylvestris L.)

Effect of drilling resistance measurement on residual load capacity of Scots pine (Pinus sylvestris L.)

Оценка точности метода измерения сопротивления сверлению древесины в дендрохронологических исследованиях

One of the promising methods for determining physical and mechanical properties and structure of wood is the method based on the measurement of drilling resistance. Limitations of application of the method of measuring drilling resistance in dendrochronological studies are related to a number of factors that have a significant impact on the accuracy of determining the variation of physical and mechanical properties of wood within annual layers: the depth of drilling, its direction relative to the fibers, and the speed parameters of the drilling process. In order to assess the accuracy of measuring the radial growth of pine wood (Pinus sylvestris L.) with moisture content of 6–8 %, the ResistYX device and standard thin drill bits were used. On the basis of comparative analysis of radial wood growth determined by the optical method and the method of measuring resistance to drilling, it was found that in order to obtain accurate data on growth with a correlation coefficient greater than 0.7, it is recommended to measure no more than 17 annual layers on one sample, which corresponds to an average total width of annual layers of 36.6 mm. The influence of the main reasons for the decrease in the accuracy of radial growth determination by the drilling resistance measurement method was studied: geometrical parameters of the cutting part of a thin drill bit, deviation of the drilling direction from the specified one, impossibility of precise determination of the strictly radial drilling direction, wood flaws, as well as friction of the drill shank when the drilling depth increases. To increase the accuracy of the method of measuring drilling resistance in dendrochronological studies it is proposed to develop a method including the use of a special or newly developed tool for more accurate determination of the core and radial drilling of wood or round timber; to increase the rigidity of the thin drill bit; to provide the required fixation of the thin drill bit during its initial contact with wood and inside the device. Further studies in this direction will be associated with the assessment of measuring accuracy for the radial growth of coniferous wood by the feeding force for drill bit penetration. For citation: Chernov V.Yu., Sharapov E.S., Gaisin I.G. Evaluation of the Accuracy of Wood Drilling Resistance Measurement Method in Dendrochronological Studies. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 5, pp. 135–150. (In Russ.). https://doi.org/10.37482/0536-1036-2023-5-135-150

Bioconsolidation of Damaged Construction Calcarenites and Evaluation of the Improvement in Their Petrophysical and Mechanical Properties.

Bioconsolidation treatment using bacterial carbonatogenesis has been proposed as an environmentally friendly strategy for the efficient preservation of damaged stones, particularly suitable for carbonate stones. The study presented here deals with the evaluation of the performance of this treatment, applied to damaged carbonate stones in two historical buildings in Spain. The methodology applied in this research serves as a reference for future similar studies. Results showed significant improvement in the petrophysical and mechanical properties of the damaged stone following the treatment through the production of calcite and vaterite by the abundant carbonatogenic bacteria inhabiting the stone. These bacteria were able to effectively consolidate weathered areas if an adequate nutritional solution was employed, thereby augmenting the stone's resistance, as evidenced by the Drilling Resistance Measurement System (DRMS). FESEM images showed calcified bacteria and calcified exopolymeric substances (EPS) consolidating stone minerals without blocking their pores. In addition to consolidation, this biotreatment improves the stone's behavior against water absorption and increases the contact angle of water droplets without significant modifications in the pore size or diminishing vapor permeability. No color changes are observed. Overall, these results show that the application of the nutritional solution (M-3P) for in situ consolidation of different types of porous carbonate building stones is a highly effective conservation method, with no modification of the chemical composition of the treated materials.

Density Estimation by Drilling Resistance Technique to Determine the Dynamic Modulus of Elasticity of Wooden Members in Historic Structures

(1) The assessment of the mechanical properties of old timber is essential for the proper maintenance of wooden structures. (2) Among the non-destructive properties, the dynamic modulus of elasticity is one of the best predictors of the mechanical characteristics of the members, but it requires the determination of wood density to be determined. (3) Thus, wood density was estimated by drilling resistance measurements, developing species-specific prediction equations for silver fir, chestnut and poplar. (4) The estimated density was combined with the stress wave velocity propagating longitudinally through the wooden piece, and the dynamic modulus of elasticity was calculated. (5) Medium-high coefficient determinations (R2 from 0.79 to 0.94) were found for density estimation, and medium coefficient determinations (R2 from 0.53 to 0.60) were found for the estimation of the static modulus of elasticity using the dynamic modulus.

Automatic assessment of insect degradation depth in structural solid wood elements by drilling resistance measurements

The assessment of insect degradation on the surface of timber elements is a key point in evaluating the safety of wooden buildings. The depth and the degree of the insect attack are necessary data to determine the resistant section of the load-bearing elements.To the aim, the resistance drilling is applied as non-destructive technique in the on-site inspection. Here, a routine is proposed and verified to automatically process the resistance data and to identify the presence of insect decay.Twelve wooden beams disassembled from an old timber structure were used as experimental material: five to optimize the routine and seven to verify the output after the optimization. In total, 78 % of the measurements showed an error of less than 5 mm and 86 % less than 10 mm when compared to the determination made by an expert operator on the same drilling profiles. Comparing the non-destructive measurements with the cross-sections cut from the beams, the profiles seemed very informative when the degradation was caused by cerambycids, but less so with anobiid attacks.

The influence of using wet cellulose poultice on nanolime consolidation treatments applied on a limestone

Consolidation treatment with nanolime is a common conservation intervention which needs more research to enhance penetration and mechanical properties while also minimizing the undesired white veil on the surface which significantly alters the surface appearance. In this light, the application of a cellulose poultice soaked in distilled water over the treated surface with nanolime tries to prevent the formation of white hazes and to favour nanolime carbonation and penetration in the pore structure. However, the real influence of this practice on the consolidation effectiveness has never been studied yet and is not yet well understood. In order to provide more insights about its most suitable application method, in this study, we investigated the effectiveness of a wet cellulose poultice for two different nanolime consolidation treatments on a weathered limestone. Nanolime has been synthetized by anion exchange processes and dispersed in two mediums: i) water and ii) 50% v/v of water and alcohol. The influence of the poultice on the penetration and aesthetic properties has been studied by drilling resistance measurement, ultrasounds test, stereomicroscopy, measurements of roughness and static contact angle, spectrophotometry and scanning electron microscopy (superficial and cross sectioned samples). Additionally, consolidation effectiveness has been evaluated through the changes in apparent density, open porosity, porosity network in the outer 5 mm of the surface by mercury intrusion porosimetry and surface cohesion by the peeling test. Results show that, contrary to what is usually assumed, samples where a wet cellulose poultice was applied after the consolidant reached the lowest penetration levels and retained lower dry matter in comparison to their counterparts without poultice. A consolidation treatment with nanolime is more complex that it is generally considered, and the application of poultices is not always enhancing consolidation level; the most suitable application procedure must be chosen with regards to the nanolime and substrate specific characteristics.

Evaluation of white rot decay in phenol-formaldehyde resin treated European beech (Fagus sylvatica L.) LVL by drilling resistance measurements

Evaluation of white rot decay in phenol-formaldehyde resin treated European beech (Fagus sylvatica L.) LVL by drilling resistance measurements

ПРИМЕНЕНИЕ ИНСТРУМЕНТАЛЬНЫХ МЕТОДОВ ПРИ ОЦЕНКЕ СОСТОЯНИЯ СТВОЛОВ PINUS SYLVESTRIS L.

Assessment of stem wood quality in urban environment is relevant due to the fact that trees felled under increased wind load cause enormous damage to the city economy and lead to human losses. The aim of the study was to assess the viability of growing Scotch pine (Pinus sylvestris L.) trees using pulsed tomography and drilling resistance measurements. Research in coniferous forest plots included the development during the construction of the city. Arbotom® equipment of the German company RINNTECH was used to study the trunk by pulsed tomography. Drilling method was used (Resistograph® 4450 device) to estimate the relative density of the stem wood. A total of 20 model trees were examined: 10 trees each on 2 test plots. An instrumental-visual description was compiled for each tree: height and diameter, girth of the trunk at the root neck and at breast height, the shape and length of the crown, the shape of the trunk, the presence of visible defects in the trunk were visually determined. It was found that the average speed of sound pulse in the wood of the studied model trees fluctuates in the range of 1003-1349 m/s. The research based on the data of instrumental study of the quality of stem wood (Scots pine) at the age of 60-70 under the conditions of intense exposure to industrial emissions and recreational load. Zones of local wood destruction have been clearly defined in the structure of the density distribution. Comparison of the results (obtained by two different assessment methods of wood state at the same object) shows high degree of comparability. The parallel use of two measuring instruments in assessing the growing tree state increases the accuracy of the obtained data and enables more reliable determination of emergency trees, areas of their maximum destruction and, as a consequence, the most probable direction of tree fall.

Distribution depth of stone consolidants applied on-site: Analytical modelling with field and lab cross-validation

An analytical model was applied in order to understand the distribution depth of cured stone consolidants. The model is grounded on a case study of Vienna’s St. Stephen’s Cathedral and was verified against drilled cores examined by SEM and image analysis, on-site drilling resistance measurements and laboratory-based mechanical tests. The results reveal that the variation of the concentration gradient with penetration depth resembles an exponential decline. The deposition of the cured consolidant is governed by capillary forces upon drying within water-based nano-zirconia dispersions and water/alcohol-based colloidal silica. This effect is less pronounced within reactive consolidants, which undergo polycondensation reactions, as with alkoxysilanes.

Effect of Grain Direction on Drilling Resistance Measurements in Wood

ABSTRACT An IML-Resi PD-400 drilling tool with two types of spade drill bits (IML System GmbH, Wiesloch, Germany) was used to study the influence of the drilling direction in relation to wood grain orientation on drilling resistance (DR) and feeding resistance (FR) measurements. The drilling tests were performed on Scots pine, European beech, English oak and Silver poplar conditioned in a standard climate. The differences in DR between radial and tangential drilling direction were negligibly small or minor for both drill bit types. In contrast, the difference between longitudinal and tangential drilling direction was more pronounced but differed between wood species and drill bit types. FR was the most sensitive parameter to changes in the wood grain orientation when using a drill bit with a single major cutting edge. The mean FR decreased by approximately 27% for Scots pine, 33% for Beech, 37% for Oak and 40% for Poplar when changing the drilling direction from longitudinal to tangential. It was concluded that the drilling direction between longitudinal and transversal drillings needs to be considered for the prediction of wood properties based on DR measurements. Potential applications of drill bits with a single major cutting edge can be the object of further studies.

Assessment of Preservative-Treated Wooden Poles Using Drilling-Resistance Measurements

An IML-Resi PD-400 drilling tool with two types of spade drill bits (IML System GmbH, Wiesloch, Germany) was used to evaluate the internal conditions of 3 m wooden poles made from Scots pine (Pinus sylvestris L.). Drilling tests were performed on poles that were industrially vacuum-pressure-impregnated with a copper-based preservative (Korasit KS-M) and untreated reference poles. Both types of poles were subject to 10.5 years of in-ground exposure. Wood moisture content (MC) was measured using a resistance-type moisture meter. MC varied between 15% and 60% in the radial and axial directions in both treated and untreated poles. A higher MC was detected in the underground, top, and outer (sapwood) parts of the poles. Typical drilling-resistance (DR) profiles of poles with internal defects were analyzed. Preservative treatment had a significant influence on wood durability in the underground part of the poles. Based on DR measurements, we found that untreated wood that was in contact with soil was severely degraded by insects and wood-destroying fungi. Conversely, treated wood generally showed no reduction in DR or feeding resistance (FR). DR profiling is a potential method for the in-situ or in vitro assessment and quality monitoring of preservative treatments and wood durability. The technological benefits of using drill bits with one major cutting edge, instead of standard drill bits with center-spiked tips and two major cutting edges, were not evident. A new graphical method was applied to present DR data and their spatial distribution in the poles. Future studies should focus on the impact of preservative treatments, thermal modification, and chemical modification on the DR and FR of wood. This may further elucidate the predictive value of DR and FR for wood properties.

Potential of Advanced Consolidants for the Application on Sandstone

Alkoxy-based consolidants are widely used for conservation of cultural heritage objects made from sandstones. Even if such consolidants were introduced into practice already in the 19th century, their performance has been enhanced by several modifications to their composition only recently. To obtain a relevant comparison of their application potential, both commercial (Remmers KSE OH and SurfaPore FX SB) and a self-developed particle-modified ethyl silicate consolidant supplemented with two phosphate-based ones, were assessed. Importantly, the potential toxicity of our novel consolidants was considered. Since the stone substrate should mimic the properties of naturally weathered stone, sandstone from the Msene quarry in Central Bohemia, characterized by a high porosity and relatively low mechanical strength, is selected. From practical point of view, the long-term durability of the consolidation effect is crucial compared to the initial level of consolidation. Regarding the determination of durability of the sandstone consolidation according to an American Society for Testing and Materials (ASTM) accelerated weathering test, we performed mechanical tests in micro- (nanoindentation) and macroscale (drilling resistance measurements). The cohesion of the consolidant xerogels in the pores were determined by sorption experiments in gas phase. The durability of our TiO2 and ZnO particle-modified consolidants is superior to that of the commercial products. The aqueous diammonium hydrogen phosphate-based consolidant, which also shows exceptional durability, reveals itself to be a promising product for not only carbonate but also sandstone materials.

Impact of drill bit feed rate and rotational frequency on the evaluation of wood properties by drilling resistance measurements

ABSTRACTIML-Resi PD-400 drilling tools (IML System GmbH, Wiesloch, Germany) were used to study the influence of the feed rate and the rotational frequency of the drill bit on the drilling resistance (DR) measurements. The study presents theoretical aspects concerning chip formation, kinematics (speeds, cutting angles, chip thickness) and cutting forces distribution during the drilling process. Drill bit rotational frequency and feed rate have an impact on nominal chip thickness or a feed rate per major cutting edge of the drill bit, and were correlated to DR measurements. Varied rotational frequency and feed rate had a significant impact on DR and feeding resistance (FR). Positive correlations between feed rate per major cutting edge and DR (FR) for the individually tested wood species can be described by allometric functions (R2 = 0.93–0.99). Wood density had a partial impact on correlations between feed rate per major cutting edge and DR (FR).

Prediction of modulus of elasticity in static bending and density of wood at different moisture contents and feed rates by drilling resistance measurements

An IML-RESI PD 400 drilling tool and a standard spade drill bit were used to find the correlations of drilling and feeding resistance with the modulus of elasticity in static bending and density of wood. In total, 1575 drillings at 0.5, 1.0 and 1.5 m/min feed rates were made in specimens of Scots pine (Pinus sylvestris L.), European beech (Fagus sylvatica L.), English oak (Quercus robur L.) and common lime (Tilia europaea L.), which were oven-dried, conditioned at 20 °C/65% RH and 20 °C/95% RH and vacuum-impregnated with water. The feed rate (feed rate per major cutting edge or uncut chip thickness) had a significant impact on the prediction of density and modulus of elasticity through drilling resistance measurements and should be considered for comparison of properties and internal conditions of wood. Because of stronger correlation between drilling resistance and tested wood properties compared to feeding resistance, drilling resistance is recommended for density and MOE prediction of sound wood. Moisture content had no significant impact on the modulus of elasticity prediction by the drilling resistance measurements, while density can be predicted by linear models for two stages of moisture content variation, below and above fibre saturation.

Calcium Ethoxide as Consolidant for Porous Limestones: Influence of the Solvent

Calcium ethoxide nanosuspension, a consolidating product developed during the European Nanomatch project, is here modified by adding two different solvents, 2-butanol and n-butylacetate, chosen for their different boiling points with respect to ethanol, the solvent employed in a previous work to dilute the original product. Fourier transform infrared spectroscopy (µFT-IR) was used to understand how the presence of these new solvents can influence the kinetics of the carbonation process and the pathway reaction. Furthermore, coatings derived from nanosuspensions were maintained for specific time intervals at controlled relative humidity conditions (RH = 50% and RH = 90%); the formed mineralogical phases were characterized by µFT-IR and X-ray diffraction (XRD). Results indicate that the used solvents can influence the kinetic and reaction pathways, while the phases formed at the end of the carbonation process are influenced by both solvents and RH conditions. The effectiveness of calcium ethoxide based product diluted in 2-butanol and n-butylacetate as limestone consolidants was evaluated with drilling resistance measurement system (DRMS) and ultrasound pulse velocity (UPV). The impact on color coordinates was also assessed. The results were compared with those obtained with the same product diluted in ethanol and a commercial nanolime. The use of these solvents gave different and better results in terms of efficacy.

Combined effect of wood moisture content, drill bit rotational speed and feed rate on drilling resistance measurements in Norway spruce (Picea abies (L.) Karst.)

ABSTRACT An IML-RESI PD 400 drilling tool and a standard spade drill bit (IML System GmbH, Wiesloch, Germany) were used to study the combined effect of wood moisture content (MC), drill bit rotational speed and feed rate on drilling resistance (DR) and feeding force (FF). Tests were made with Norway spruce (Picea abies (L.) Karst.) conditioned in a normal climate (20°C/65% RH), at 20°C/95% RH, vacuum-pressure impregnated in water, and oven-dried. Rotational speeds and feed rates had an impact on feed rate per cutting edge for the major cutting edge of the drill bit which was used for correlation with DR and FF for various MC. Impact of MC on DR and FF depended on rotational speeds and feed rates of the drill bit. For feed rates per cutting edge less than 0.09 mm, DR was higher for water saturated (WS) specimens. Negligible differences between DR for various MC were found for feed rates per cutting edge between 0.09 and 0.15 mm. DR was higher at low MC for feed rates per cutting edge which were higher than 0.15 mm. FF extremely increased in conditioned (20°C/95% RH) and WS specimens at feed rates per cutting edge less than 0.1 mm.