Penetration Resistance Test Research Articles

Using ultrasonic wave reflection to monitor false set of cement paste

The standard mechanical penetration approach for monitoring cement paste stiffening (Vicat needle method, ASTM C191) does not distinguish responses associated with false set of cement paste caused by secondary gypsum formation. The objective of this research is to determine whether ultrasonic wave reflection, using a testing set up with high measurement sensitivity, could be used to monitor false set of cement paste. Penetration resistance, P-wave, and S-wave reflection coefficients were measured on cement pastes with water-to-cement ratio 0.5. The S-wave reflection coefficient showed a sharp and abrupt linear drop associated with secondary gypsum formation, thereby indicating that S-wave ultrasonic wave reflection can be used to monitor false set of cement pastes. False set could not be distinguished in penetration resistance or P-wave UWR test data.

Evaluation of Early-Age Concrete Compressive Strength with Ultrasonic Sensors.

Surface wave velocity measurement of concrete using ultrasonic sensors requires testing on only one side of a member. Thus, it is applicable to concrete cast inside a form and is often used to detect flaws and evaluate the compressive strength of hardened concrete. Predicting the in situ concrete strength at a very early stage inside the form helps with determining the appropriate form removal time and reducing construction time and costs. In this paper, the feasibility of using surface wave velocities to predict the strength of in situ concrete inside the form at a very early stage was evaluated. Ultrasonic sensors were used to measure a series of surface waves for concrete inside a form in the first 24 h after placement. A continuous wavelet transform was used to compute the travel time of the propagating surface waves. The cylindrical compressive strength and penetration resistance tests were also performed during the test period. Four mixtures and five curing temperatures were used for the specimens. The surface wave velocity was confirmed to be applicable to estimating the concrete strength at a very early age in wall-like elements. An empirical formula is proposed for evaluating the early-age compressive strength of concrete considering the 95% prediction intervals.

Using Modified ASTM C403 Test Procedure to Evaluate Set Time and Admixture Compatibility of Shotcrete Mortar

Abstract Set time of shotcrete is mainly driven by the use of a highly reactive set accelerator. The control of set time is very important for providing successful application of shotcrete in the construction site, because it determines key parameters such as capability to increase layer thickness and loss of the material caused by rebound of shotcrete. However, there is no standard test procedure available to determine the set and stiffening process of shotcrete. In this research, the stiffening process of shotcrete mortar was measured using the penetration resistance test in the American Society for Testing and Materials (ASTM) C403, Standard Test Method for Time of Setting of Concrete Mixtures by Penetration Resistance. Various types of shotcrete accelerators and three different sources of portland cement have been used to investigate the set and stiffening process of shotcrete mortar. According to the experimental results, calcium aluminate type accelerators worked most effectively in controlling set and stiffening of shotcrete mortar. It was found that the penetration resistance test can be used to evaluate compatibility issues between the cement and the shotcrete accelerator. The set time of shotcrete can be determined using best fitted function using current set time criteria of 3.5 and 27.6 MPa for initial and final set.

GRAZING CHANGES THE SOIL-PLANT RELATIONSHIP IN THE TREE-REGENERATION STRATUM IN THE PAMPA OF SOUHTERN BRAZIL

ABSTRACT Despite being prominent in flora, the region of the Parque Estadual do Espinilho located in the Pampas of southern Brazil, where dense herbaceous stratum and isolated trees make this region suitable for livestock farming, has received little attention. The objective of the study was to analyze floristic and edaphic changes imposed by livestock farming in two areas of the park, the first under livestock grazing and the second protected from grazing (livestock-excluded) for five years. We evaluated soil physical properties of and the herbaceous aboveground biomass in order to investigate relationships with key regenerating tree species. A sampling unit of 2ha was installed in both areas, each composed of 200 subunits. Inventory of regenerating trees and herbaceous aboveground biomass, soil sampling, and soil penetration resistance tests were done in 50 subunits. The results, which were evaluated by Student’s t-test, exhibited variations between the two areas in regards to floristic and environmental factors. The abundance of the P. affinis and V. caven species and the variables of soil penetration resistance, soil bulk density, gravimetric moisture and herbaceous aboveground biomass differ significantly between the two areas. Principal coordinates analysis (PCoA) allows to infer that variables such as soil bulk density, penetration resistance and the abundance of V. caven species exhibit higher values in the area under gazing, while gravimetric moisture, aboveground biomass and abundance of P. affinis are higher in the area under livestock-excluded, showing that significant changes occur over just five years of livestock-excluded from the area.

Rheological and fresh properties of reduced fine content self-compacting concretes produced with different particle sizes of nano SiO2

In this study, colloidal nano SiO2 (CNS), which can be assumed as a multi-functional nano-technological material in cement-based systems, was utilized in an effort to reduce the total fine material content in self-compacting concrete (SCC) designs. The influence of CNS addition on flow properties and rheological parameters has been investigated. Three different average particle diameter of CNS which was used to modify the SCC mixtures are 35nm, 17nm and 5nm. CNSs were used at different amounts and total fly ash amount in the mix design was decreased step by step from 160kg/m3 down to 0kg/m3. The volumetric emptiness occurred by the reduction of fine materials was filled by aggregates. On fresh state, T500 slump flow time, slump flow diameter, V-funnel time, static penetration resistance, sieve segregation and visual stability index tests were performed. Moreover, rheological parameters such as static yield stress, dynamic yield stress and plastic viscosity were obtained by using a concrete rheometer. In this way, it was aimed to design SCC mixtures with reduced fine material content by benefiting of the viscosity modifying effect of CNSs with various sizes. Results have shown that the effectiveness of CNS, in an effort to reduce the fine material content in SCC design is very significant.

Setting and nanostructural evolution of metakaolin geopolymer

AbstractThe nanostructural evolution during formation of geopolymers and its correlation with setting have not been well understood. In this study, penetration resistance and ultrasonic wave reflection tests were conducted to measure setting, and solid‐state27AlNMRand liquid‐state29SiNMRwere used to examine nanostructural changes in a metakaolin geopolymer as a function of time. Aluminum was released rapidly during the first 10 hour after mixing and immediately condensed with silicate species in solution to form larger sized aluminosilicate oligomers, which then condensed to form large structural units. Our evidence suggests these units form near metakaolin particle surface. Smaller sized silicate ions in the sol phase then attach to these units to form a gel with a more interconnected network structure. The initial stage of this attaching process was seen to be associated with set, which in this mixture occurred at 15 hour.

Testing the Setting and Hardening of Concrete Using the Prism Technique

In non-destructive testing of concrete, the ultrasonic pulse-echo technique has proven to be a reliable method for locating cracks and other internal defects. An electro-mechanical transducer is used to generate a short pulse of ultrasonic stress waves that propagate into the object being inspected. Reflection of the stress pulse occurs at boundaries separating materials with different densities and elastic properties. The reflected pulse travels back to the transducer that also acts as a receiver. The received signal can give many insights to the properties of materials under test.The question arises how the setting and hardening of cement paste, mortar, and concrete can be measured continuously. Continuous measurement ask sfor non destructive methods. The current testing method such as the vicat needle for cement paste and penetration resistance test for concrete methods measure at intervals.These methods can be applied before the end of setting. All these methods do not allow continuous measurements and are partly destructive. In this paper a special pulse-echo technique called prism technique is used to evaluate the evolution of proprieties of concrete over time. For that, an automatic system has been developed with labview program in order to monitor the time of flight of the reflected p-wave. Two mixtures of mortar are made using different proportions, of water, cement, and sand. The mortar is poured into a mould that has a form of a prism. Measurements are taken every 10 minutes over a period of 24 hours. This enabled us to plot the evolution of p-wave velocities over time for the samples and compare the results.

Ultrasonic Monitoring of Setting and Strength Development of Ultra-High-Performance Concrete.

In this study, the setting and tensile strength development of ultra-high-performance concrete (UHPC) at a very early age was investigated by performing the penetration resistance test (ASTM C403), as well as the direct tensile test using the newly developed test apparatus, and taking ultrasonic pulse velocity (UPV) measurements. In order to determine the optimum surface treatment method for preventing rapid surface drying of UHPC, four different methods were examined: plastic sheet, curing cover, membrane-forming compound, and paraffin oil. Based on the test results, the use of paraffin oil was found to be the best choice for measuring the penetration resistance and the UPV, and attaching the plastic sheet to the exposed surface was considered to be a simple method for preventing the rapid surface drying of UHPC elements. An S-shaped tensile strength development at a very early age (before 24 h) was experimentally obtained, and it was predicted by a power function of UPV. Lastly, the addition of shrinkage-reducing and expansive admixtures resulted in more rapid development of penetration resistance and UPV of UHPC.

Experimental study on strength and durability of lightweight aggregate concrete containing silica fume

In this study, the mechanical property and durability performance of high strength lightweight aggregate concrete (LWAC) with silica fume for 91days were presented. LWACs were designed to have the design compressive strength of 60MPa at 28days and the oven-dry density below 1900kg/m3. Nine mixtures with three aggregate types and silica fume replacement ratio of 0%, 3.5% and 7.0% by cement weight were prepared. The splitting tensile strength, the compressive strength and the modulus of elasticity tests were conducted at 7days, 28days, 56days and 91days. The chloride penetration resistance tests were done at 28days, 56days and 91days. The chloride diffusion coefficient based on the measurement of chloride penetration depth was also measured at 7days, 14days, 28days, 56days and 91days. The rapid freeze-thaw cycling tests were conducted and the relative dynamic modulus was evaluated up to 300 cycles. The results indicate that the durability against chemical deterioration for LWAC incorporated to silica fume depends on the compositions of hardened cement pastes in concretes, while the durability against physical attack depends on the types of aggregates.

Installation of an environmental monitoring system in the Chapel of Our Lady of Guia, Macau

Built in the early seventeenth century, the Chapel of Our Lady of Guia is one of the most important heritage sites in the historic centre of Macau. Its architectural features and wall paintings with Chinese and Western characteristics reflect the historical status of Macau as a hub for cultural exchange between China and the West. Since signs of deterioration have been observed on the wall paintings in recent years, it is very urgent and necessary to conserve them. In this paper, we will introduce the modern diagnostic techniques applied in the course of their conservation, including 3D laser scanning, high-definition digital photography, environmental monitoring, thermal infrared imaging, microwave scanning and penetration resistance tests. Comprehensive information on the current state of the wall paintings is collected, providing a solid foundation for their scientific preservation.

Effect of M-Sand on Setting Time of High Performance Concrete

The setting time of concrete has more practical significance to Engineers and Contractors, than the setting time of cement. The present study seeks to gauge The efficacy manufactured sand or M-sand a fine aggregate in the place of natural river sand. The effect of M-sand on the setting time of high performance concrete is studied on an experimental basis under laboratory conditions. It is proved using three series of HPC with different compositions, through penetration resistance tests on the parameters of workability, setting time and compressive strength. On grounds of sustainable development and environment preservation, M-sand is seen as a viable substitute for river sand.

Long-term impacts of season of grazing on soil carbon sequestration and selected soil properties in the arid Eastern Cape, South Africa

The Karoo biomes of South Africa are major feed resources for livestock farming, yet soil nutrient depletion and degradation is a major problem. The objective of this study was to assess impacts of long-term (>75 years) grazing during spring (SPG), summer (SUG), winter (WG) and exclosure (non-grazed control) treatments on soil nutrients, penetration resistance and infiltration tests. A soil sampling campaign was carried out to collect soil to a depth of 60 cm to analyse bulk density, soil physical and chemical parameters as well as soil compaction and infiltration. Generally, grazing treatments reduced soil organic C (SOC) stocks and C:N ratios, and modified soil properties. There was higher SOC stock (0.128 Mg ha−1 yr−1) in the exclosure than in the SPG (0.096 Mg ha−1 yr−1), SUG (0.099 Mg ha−1 yr−1) and WG (0.105 Mg ha−1 yr−1). The C:N ratios exhibited similar pattern to that of C. From the grazing treatments, the WG demonstrated 7 to 10 % additional SOC stock over the SPG and SUG, respectively. Short period animal exclusion could be an option to be considered to improve plant nutrients in sandy soils of South Africa. However, this may require a policy environment which supports stock exclusion from such areas vulnerable to land degradation, nutrient and C losses by grazing-induced vegetation and landscape changes.

광물성 혼화재료의 종류 및 혼입율에 따른 숏크리트의 역학적 특성 및 염해 저항성

In this study to improve the chloride durability of the shotcrete structure depending on types and contents of mineral admixture chloride resistance was evaluated by NT BUILD 492 of european test standards. It was also evaluated with the mechanical properties such as static strength and chloride penetration resistance. For shotcrete mixed crushed stone aggregate of the maximum size 10mm of coarse aggregates was produced. Based on 28days compression strength the variable mixed with 15% silica fume showed the highest strength in 67.55MPa. As the content of fly ash and blast furnace slag increased, the strength lowered. In the chloride penetration resistance test, OPC showed high grade and In the case of admixture, the penetration resistance tended to increase in all variables except the fly ash. In order to evaluate the service life, the accelerated chloride penetration test was conducted by the standards of KCL, ACI, FIB. Test results were obtained with the lowest spreading factor in a variable mixed with silica fume of 15%. At the KCI standards, It was found to have a service life of about 65 years and at the FIB standards, It was found to have a service life of 131 years. Among standards, the service life of KCI standard in all of the variables was evaluated as the lowest.

Prediction Equations for Estimating Shear‐Wave Velocity from Combined Geotechnical and Geomorphic Indexes Based on Japanese Data Set

© 2015, Seismological Society of America. All rights reserved. We develop empirical predictive equations for shear-wave velocity (V S ) conditional on standard penetration test resistance (N-value) and other explanatory variables using data sets from Japan. The V S and N data sets are from the Kyoshin network (K-NET), which include 16,845 collocated measurements of V S and N at 1102 sites. We begin with baseline equations considering soil type and overburden pressure in addition to N. For coarse-grained soils, V S is more sensitive to overburden pressure than to N, whereas for fine-grained soils, V S is more sensitive to N. We find that residuals (difference between data and model) for a given borehole tend to be correlated (e.g., samples within a boring are consistently high or low); hence, we use mixed-effects regression to compute a quantity akin to an average borehole residual referred to as the between-boring residual. Sites associated with older (pre-Holocene, >10,000 yrs) geology tend to have null to slightly positive between-boring residuals, whereas these residuals are negative for more recent materials. Accordingly, we provide adjustments to the baseline equations conditional on geologic condition. Between-boring residuals exhibit spatial correlations; however, due to lack of knowledge as to the cause of these correlations, we do not recommend such effects for inclusion in the model. When applied to predict the time-averaged V S in the upper 30 m (V S30 ) in the absence of direct measurement, the proposed equations provide significantly better accuracy than widely used local geomorphology-based proxies (0.26 versus 0.42 of standard deviation of the natural log of residuals). This suggests that penetration resistance data can improve predictions of V S30 compared with geomorphology- based proxies alone, when site-specific V S measurements are unavailable.

Research on Infiltration Rate of Topsoil in Combination with Steady Infiltration Model and Penetration Resistance Test

In this study, infiltration experiment and survey on specific penetration resistance for the topsoil were conducted for five land use patterns at the Liudaogou Catchment on the northern Loess Plateau. A simple infiltration model has been developed based on water balance principle combined with theory of steady infiltration. The mean unsaturated infiltration rate of topsoil was estimated based on the results of infiltration experiment and survey on specific penetration resistance combined with model calculation. The results indicated that determination coefficient of relation curve between mean unsaturated infiltration rate and the topsoil specific penetration resistance is higher than 0.93; order of the mean unsaturated infiltration rate of topsoil was 10-5 m/s during the research period; sequence of the mean unsaturated infiltration rate of the five land use patterns is Alfalfa (on slope land) < Grassland (on slope land) < Grassland (on alluvial plain) < Farmland (on alluvial plain) < Sandy loess (bare land); mean unsaturated infiltration rate of alfalfa (on slope land) and grassland (on slope land) was obviously lower than that of the mean of the five land use patterns, and mean unsaturated infiltration rate of sandy loess (bare land) was significantly higher than that of the mean of the five land use patterns.

COMPRESSIBLITY AND PENETRABILITY OF LATOSSOLO VERMELHO-AMARELO DISTRÓFICO (OXISOL) UNDER VARIED MANAGEMENT SYSTEMS AND LAND USES

Soil compaction is one of the main degradation causes, provoked by inappropriate agricultural practices that override the limitations of the soil physical properties. Preconsolidation pressure and penetration resistance have proved effective as alternative to assess and identify soil compaction. Based on the interpretation of these physico-mechanical parameters, compaction can be prevented with a better adjusted soil management. This study was performed to generate preconsolidation pressure and penetration resistance models for Latososlo Vermelho-Amarelo distrófico (Oxisol) under various managements and uses; and evaluate which of these would lead to degradation or degradation susceptibility. The study was carried out in Curvelo, MG. Two managements and one land use were evaluated: no-tillage, sheep grazing and natural forest. Undisturbed soil samples collected from the 0-5 cm layer were subjected to uniaxial compression and penetration resistance tests. Preconsolidation pressure models for forest and no-tillage soils were not statistically different, demonstrating a low degradation potential in no-tillage systems. Preconsolidation pressure was higher in soil under sheep grazing at all water retention tensions and penetration resistance values were higher than under native forest indicating animal trampling as a potential degradation factor. Neither management presented penetration resistance values above 2 MPa at field capacity moisture. Only under sheep grazing the soil penetrability was near 2 MPa at field capacity and values greater than 2 MPa at 0.2 kg kg-1.

Durability performance of concrete with recycled aggregates from construction and demolition waste plants

This research intends to analyse the durability performance of concrete with recycled aggregates (RA) from construction and demolition waste (CDW) from various locations in Portugal. To that effect water absorption by immersion and capillarity, carbonation resistance and chloride ion penetration resistance tests were performed.To better understand the experimental results, the characteristics of the various aggregates (natural and recycled) used in the production of concrete were analysed in detail. The composition of the RA was determined and various physical tests of the aggregates were performed. 33 concrete mixes with RA from different CDW recycling plants were evaluated in order to understand the influence that the RA’s collection point, and therefore their composition, has on the characteristics of the concrete mixes produced. Both coarse and fine RA were used to determine the influence of their size on concrete’s performance.The analysis of the durability performance allowed concluding that the use of RA is highly detrimental. This is mostly true when fine RA are used. The carbonation resistance is the property most affected by the use of RA, leading to increases in the carbonation depth between 22.2% and 182.4% for the various RA types. However, the most influencing factor is by far the RA’s composition.

Influence of Recycled Aggregate Defects on the Durability of Recycled Aggregate Concrete

An experimental investigation was conducted on the durability of recycled aggregate concretes with the water to binder ratios of 0.26 and 0.60, including chloride ion penetration resistance test, freezing-thawing resistance test and water penetration resistance. Natural aggregate, recycled aggregate untreated and recycled aggregate treated by sulfuric acid solution, were employed. Results indicated that, 3 mol/L acid concentration and the 7 days soaking duration was the optimum to remove the attached mortars in recycled aggregate, and its removal rate could reach to 90.8%. Water penetration resistance, chloride ion penetration resistance and freezing-thawing resistance of concrete with 0.26 W/B was superior to that of concrete with 0.60 W/B. The more pores in the internal of concrete with 0.60 W/B could be attributed to that. Durability of recycled aggregate concrete, incorporating recycled aggregate treated by sulfuric acid solution, was improved. In particular, the improvement in recycled high strength concrete was significant.

Set Time Measurements of Self-Compacting Pastes and Concretes Using Ultrasonic Wave Reflection

The ultrasonic shear-wave reflection coefficient at the interface between a hydrating material and a buffer material was monitored immediately after mixing as a function of time to study setting behavior of self-compacting pastes and concretes. High-impact polystyrene was used as the buffer material because it is very sensitive to early changes. Self-compacting pastes were produced using fly ash and superplasticizer. Initial and final set times were measured and compared with those obtained from the standard penetration resistance test. Both methods showed reproducible results with self-compacting pastes and were able to distinguish fairly small changes in composition. A good correlation was found between set times obtained from the two methods. The self-compacting pastes were seen to have a substantially delayed set as compared with plain pastes. In addition, self-compacting concretes were made and their set times were measured using ultrasonic wave reflection. The method was seen to be quite reproducible for concrete, and concrete set times matched those of the corresponding pastes reasonably well.

Characterization of Cross-Sections from Old Chestnut Beams Weakened by Decay

This work aims to experimentally assess the material properties of old chestnut (Castanea sativa Mill.) cross-sections weakened by decay. Specimens were taken from critical zones of twenty floor beams, mostly corresponding to their ending parts, in contact with granite masonry walls. These specimens were compared with clear wood specimens taken from non-decayed parts. The experimental campaign comprised of visual inspection, non-destructive testing (ultrasound, impact penetration and drilling resistance tests) and uniaxial compression tests, parallel to the grain. Pin penetration test evidenced a depth of penetration 36% higher for decayed specimens compared to non-decayed specimens, proving the loss of capacity in the superficial decayed layer. The results of decayed specimens exhibited a decrease of approximately 30% in the compressive strength parallel to the grain. A reduction of approximately 5% was found for the dynamic and elastic moduli. The coefficients of variation for decayed specimens are significantly higher than for sound specimens. Different decay models are considered and compared aiming at analyzing decay evolution along time and determining the decrease of load bearing cross-section. Finally, the results were used to calibrate a bi-parametrical decay model for above ground timber structures, considering a linear relation between time and decay depth.