Penetration Resistance Test Research Articles

Effects of repeated cycles of sterilisation on the mechanical characteristics of titanium miniplates for osteosynthesis

Aim This study investigates the changes occurring in the mechanical characteristics of osteosynthesis titanium miniplates when exposed to repeated sterilization cycles. Methods For this study Medicon © titanium miniplates were used. The characteristics of miniplates were evaluated using the Penetration Resistance test, MSC/Pal2 Software, and the Finite Elements Method (F.E.M.). Surface roughness measurements were also carried out. Statistical analysis was conducted using the One way ANOVA model. The significance level was set at >0.05. Results The one way ANOVA analysis between HV value and increased sterilization cycles showed P > 0.029; between the Ra value and increased sterilization cycles it was P > 0.325; between the Rq value and increased sterilization cycles it was P > 0.703. The Finite Element Model shows an amplified deformed shape of the miniplate at a load of 196 [N]. At this load value the equivalent ‘von Mises stress’ reaches the value of σ P0.2, shown by the ASTM F 67–95 standard. Stress distribution comparison between the six-holed plate and the equivalent straight miniplate shows more consistent behaviour for the Medicon © miniplate. The rigidity of the Medicon © miniplate is 14.46, lower than that for the equivalent straight miniplate ( R = 23.4). The ANOVA analysis between the break load and increased sterilization cycles showed P > 0.175; between the break position and increased sterilization cycles it showed P > 0.016. Conclusions Experimental static tests have shown that all tested miniplates did not have notable differences and this suggests that sterilization cycles do not affect mechanical characteristics.

옥상 및 인공지반녹화용 방근재의 성능기준 설정을 위한 방근성 시험방법에 관한 연구

Selection of proper root barrier as destination part of greening is very important in Root penetration resistance plan. To select proper root barrier, it need to understand composition of greening part, size, kind of plant, connection with waterproofing layer. In this point of view, we have establish greening on the roof or concrete structure, not been understand the structural mechanism. It means that we misunderstood about purpose of greening and using it. So, chosen materials and construction method was not proper for greening, it caused water leakage and decrease performance of concrete structure. Therefore, we would suggest 5 items of test methods considering environmental condition for green roof. Watertightness by water of greening part, root penetration resistance test by root penetration, bacteria resistance by must or bacteria in soil, chemical resistance by rain and chemical agent of fertilizer, and load resistance by soil depth, size of plant. These suggested test methods could be referred as guideline to test in green roof system because of not exist any performance appraisal guideline or standard. Consequently, it should be analysis as technical and institutional subdividing test methods and it need to study constantly as varied angles.

복합양생에 의한 폴리머 시멘트 모르타르의 성질

Concrete is much more easily damaged by various parameters than by the only one and performance reducing mechanism grows more complicated in that condition. In addition, the factors which really act in concrete structure tend to be activated in turn and the degradation of concrete is very rapidly progressed. The purpose of this study is to evaluate the properties of polymer cement mortars under combined cures. The polymer cement mortars are prepared with various polymer types, polymer-cement ratios and cement-fine aggregate ratio, and tested for compressive and flexural strengths, accelerated carbonation, chloride ion penetration and acid resistance test, and freezing-thawing test. The properties of polymer cement mortars under combined cures is discussed. From the test results, polymer cement mortars have superior strengths compared with plain cement mortar under combined cures. The strengths of polymer cement mortars are markedly increased at curing condition II and V, however strengths are not improved at curing condition I and IV irregardless of polymer types. The carbonation and chloride ion penetration depths of polymer cement mortars tend to decrease in curing conditions, III-C, IV-B, V-A order, and decrease with increasing polymer cement ratios. It is concluded that polymer cement ratio of 10 to 15% are considered optimum for the preparation of such polymer cement mortars.

Ultrasonic in-situ monitoring of setting process of high-performance concrete

The present standard test for the setting times of concrete is the penetration resistance test specified by ASTM C403. This test, while good for standard concrete mixtures, may not be appropriate for high-performance concrete (HPC) because of the high viscosity of the mortar. To address this issue, the ultrasonic pulse velocities (UPV) were measured using an ultrasonic monitoring system during the first 24 h of age for mortar and concrete specimens having various water-to-cementitious materials (w/cm) ratios and with and without fly ash (FA). Various characteristics observed from the measured UPV agreed with the previous theory of cement hydration, which describes the mixture as viscous suspension transforming into saturated porous solid phase. It was also found that the development of UPV in concretes, particularly without FA, was faster than that of mortars with the same w/cm. The values of concrete UPV corresponding to the initial and final setting (ASTM C403) did not show a trend consistent with those of mortar UPV. Two alternative criteria were applied to determine the setting characteristics from the UPV evolution curves. They were found to better represent the microstructural changes than the penetration method, as suggested by the consistent trend with decreasing w/cm among various mortars and concretes. Thus, the potential use of these alternative methods is suggested by specifying, at each w/cm, general target UPVs that are valid for both mortar and concrete with or without FA. It was concluded that the methods and monitoring device used in this research were useful for the in-situ monitoring of the setting of concrete, particularly in HPC.

Hardening process of cement-based materials monitored by the instrumented penetration test: Part 1: Neat cement paste and mortar

Little fundamental understanding of hardening of cement-based materials can be derived from the standard tests, such as the Vicat needle (ASTM C191-82) and penetration resistance (ASTM 403) tests. A new instrumented penetration test has been developed which continuously monitors the hardness development during early hydration and enables greater understanding of details of the hardening process. The test was designed to measure hardening in situ under ambient temperature or during microwave heating. Descriptive models of the hardening response to selected processing variables for paste as well as mortar were established using statistical experimental designs. The water/cement (w/c) ratio and temperature significantly influenced hardening, while the effect of the amount of sand on hardening was negligible. Several interactions among processing variables were observed to affect hardening. Rheological as well as chemical effects were observed.

The effects of permeable formworks with sucker liners on the physical properties of concrete surfaces

In this study, the effects of formwork, with drainage holes that are attached with different liners, on the physical properties of concrete surfaces are investigated. Nine formworks, three of them normal (reference) and six of them with drainage holes, were prepared. The three formworks, which had drainage holes, were attached with type I geotextile+hessian and the remaining three were attached with type II geotextile. Blow hole ratio, surface hardness by using the rebound hammer test, pull-off strength, carbonation, chloride penetration, sorptivity and abrasion resistance tests were measured on concrete blocks which were cast with the three types of formwork. It was observed that the concrete that was made with formwork attached with type II geotextile had better surface properties than that made with the reference formwork and formwork attached with type I geotextile+hessian.

Contact force calculations with a simple spring-mass model for hard impact: A case study using polystyrene aggregate concrete

A simple spring-mass model is used to calculate the contact force-time relationship during hard impact. The non-linear spring stiffness in the contact zone is estimated from static penetration resistance tests, and the differential equation of equilibrium is solved numerically for an initial impact velocity. The model is validated with experimental results for polystyrene aggregate concrete at relatively low impact velocities (0–8 m/s). Penetration depths, also, can be obtained with this method.

A Liquefaction Susceptibility Map for Peninsular Charleston, South Carolina

A map depicting the liquefaction susceptibility of the near surface soils in Charleston, South Carolina, is presented in this paper. The map shows five zones of different susceptibility. Susceptibility was defined as the critical ground acceleration required to cause liquefaction of the soil. Critical acceleration was obtained using the simplified method developed by Seed and Idriss (1981), Seed and others (1983 (1985), and Seed and DeAlba (1986). This method relates Standard Penetration Test resistance and the cyclic shear stress required to cause liquefaction at sites that have experienced shaking in the past to liquefaction susceptibility. Typical soil profiles of peninsular Charleston are presented to show the wide variability of the subsoil conditions in the area. This variability is due to the large amount of filling that took place over 300 yr to reclaim land from the sea and from the swamps and creeks that covered much of the original peninsula.

施工管理特性値としてのコンクリートの凝結時間に関する研究

Although the consistency of concrete can be increased by adding vibration, the effect of vibration is continually lowering in the setting process of concrete, and the rate increase rapidly according as the hydration of cement actively. The hydration process of cement is divided into dormant period and acceleratory period according to its characteristics. In this paper we have discussed that the expiration of dormant period can be clearly specified by the characteristics of the change with time of the dynamic shear modulus of cement paste and mortar, and that the properties of revibrated concrete show the remarkable change according to the time when the vibration is added;that is dormant period or acceleratory period. Thus the boundary time was defined as the initial set. It is cleared that the initial set is affected by a water-cement ratio of mixtures;i. e. the lower the water-cement ratio, the later the time of initial set, and that the initial set is independent of the content of aggregate. Furthermore we have discussed on the standard method of test for the time of setting of concrete mixtures by penetration resistance, then following were cleared. The penetration resistance is insensible to hydration of cement (as is estimated from the fact that the penetration resistance is independent of water-cement ratio of mixtures). Therefore the progress schedule of concrete works may not be controlled well by a fixed value of penetration resistance. To provide a practical usage for penetration resistance test method, the penetration resistance for initial set must be classified according to the mix of concrete.

The Official Head‐Hardness Certification Program

In an effort to emphasize the importance of wearing hard hats, Frank M. Graham of Western Paving Construction Company in Denver, Colorado has developed a Head‐Hardness Certification Program. He suggests performing penetration, absorption, heat and chemical resistance, electrical, and impact tests on the head of those who dislike wearing hard hats.

Structural Verification of a Fiberglass/Polyimide Acoustic Inlet for the DC-10

A program was undertaken to determine the structural suitability of a composite acoustic inlet for the DC-10 wing engine. Air frame and mission structural requirements for the inlet were determined. A flightworthy prototype panel was designed, fabricated, and tested. Mechanical properties were determined in the laboratory. The general durability and resistance to sonic fatigue were determined by over 250 hr of combined ground and flight testing in front of a CF6 engine. Blade fragment penetration resistance tests were conducted. CDONNELL Douglas has accumulated considerable background in the development and use of the concept, a fiberglass/polyimide sandwich structure in which the webs are woven integrally with the face sheets, eliminating unreinforced bondlines. The concept presently is employed in DC-10 airplanes as an acoustic inlet duct structure for the auxiliary power units (APU). The approach appears to be applicable as well to nacelle acoustic panels with potential for substantial reduction in cost and some reduction in weight. However, to assure that such a concept can be used to reduce cost or weight of an existing component, it must be shown that it can perform the same structural job as the existing component. The purpose of the program described here is to subject a composite nacelle component to the real-life service en- vironment of commercial airplane nacelles in a program leading to certification, and verify that the expected structural adequacy is indeed achievable for future production ap- plication. The component selected was an acoustic panel in the inlet nose cowl of a DC-10 wing engine. The present acoustic inner barrel of the DC-10 wing engine nose cowl is composed of three 120° panels made of perforated aluminum sheet on the inside and solid aluminum sheet on the outside, both bonded to an aluminum honeycomb core, to form an acoustic sandwich. Figure 1 shows the location selected for the prototype composite panel. The lower panel position was selected because it presented the most severe problem from the standpoint of exposure to the environment and to service maintenance conditions. It is subjected to sunlight, settling dust and moisture, and service personnel walking on it, as discussed in the following.

Methods for investigating the strength characteristics of a lunar soil simulant : MELZER, KJ ARMY WATERWAYS EXPT. STAT. VICKSBURG, USA 7F, 1T, 11R. GEOTECHNIQUE, V24, N1, MAR. 1974, P13–20

A lunar soil simulant was used in research on predicting the performance of the Lunar Roving Vehicle (LRV) on the moon. The simulant was prepared from ground basaltic rock whose grain size distribution was matched to the lunar soil samples collected by Apollo 11 and 12. The strength characteristics of the simulant, i.e., internal friction angle, cohesion, and cone penetration resistance, were tested in triaxial tests, trenching tests, and cone penetration resistance tests. Subsequent soil tests and LRV performance on the moon proved that the lunar soil strength characteristics could be successfully simulated.-

Chemical Vapor Deposition of Silicate Glasses for Use with Silicon Devices: II . Film Properties

Chemical, dielectric, thermal, and optical properties of glass films synthesized by chemical vapor reactions from the hydrides are discussed. The binary borosilicate glasses deposited at low temperature from silane, diborane, and oxygen require a thermal densification to approach bulk glass properties. The rate of densification in the temperature range of 770°–800°C is very rapid but water vapor has an accelerating influence, allowing densification at reasonable rates at temperatures as low as 450°C. The thermal expansion match with silicon was sufficiently close to allow the crack‐free coating of wafers with 12µ of glass. Borosilicate films of 5µ thickness on silicon withstood severe thermal shock, temperature cycling, moisture penetration, and corrosion resistance tests. Densified borosilicate of typical compositions had a dielectric constant of 3.8–4.1 and a dissipation factor at 103 Hz of 0.10–0.15. The d‐c dielectric field strength sustained by MIS capacitors made from 1µ thick densified films measured before and after a 1‐yr exposure to room air, was . The properties of vapor‐deposited phosphosilicate glasses and of glasses containing the oxides of aluminum and zinc are briefly described.

Settlement of Spread Footings on Sand

Settlement measurements for a large number of footings supported on dune sand are compared to settlement predictions based on standard penetration tests, plate load tests, oedometer tests and triaxial stress path tests. The sand considered in this study has been preloaded by dunes or compacted by vibratory rollers. Good agreement between measurement and prediction is obtained using the procedure suggested by Meyerhof, a modification of the Terzaghi and Peck method, provided that the blow-count is corrected for overburden pressure. Good agreement is also obtained with oedometer and stress path test predictions. Predictions based on plate load tests underestimated measured settlements whereas the conventional correlations between settlement and standard penetration test resistance overestimated measured settlements.

レデーミクストコンクリートによるコールドジョイントの性質

The state of appearance, strength, water-permeability and carbonation of the concrete including cold joint which caused by ready-mixed concrete were investigated experimentally, and the following results were obtained. 1. The occurrence and properties of cold joint are affected by mixing time, time interval between layers, method of compaction when upper layer was placed, temperature and admixture (retarder). 2. The properties of cold joint are correlative to the proctor penetration resistance test value which was measured on under layer of concrete at the time when upper layer was placed. This value is advisable not to exceed 50g/(mm)^2 generally, and 10g/(mm)^2 for special case. 3. Judging from the above mentioned points of view, the haul time of ready-mixed concrete should be controlled strictly as a important factor which not only affects the concrete properties but also determines the concrete placing programme.