Background and Aim: ZOE has been used in different fields of dentistry for many years. A locally produced component (Zoliran) has been recently introduced to the marketwith similar characteristic to the original Zonalin. Because of a lower cost involved to use Zoliran cement and its availability, confirm reliability of its physical properties. This investigation was designed to assess the Compressive strength of Zoliran cement in comparison to Zonalin cement as the standard material. Materials and Methods: Five samples with dimension of 4mmx6mm of each cement were provided and stored in distilled water in 370C±10C for a period of 24 hours. The lowest load of force was registered as the reference to which the sample could be broken by(according to the criteria No: 30 of ANSIIADA). The value of compressive strength was then calculated using the following formula (K =4F/πD2 ). Results: The mean compressive strength of five samples was measuredas: 14.33 Mpa for Zoliran cement and 31.83 Mpa for Zonalin cement. The mean compressive strength of Zonalincement was significantly higher than the mean suggested in ANSl/ADA Specification No.30. The mean compressivestrength of Zoliran cement was also lower than the mean value registered in ANSI/ADA SpecificationNo.30. Conclusion: Compressive strength of Zoliran cement was significantlylower than that of Zonalin cement. Further tests are required to compare the other physical properties of this material before it can be clinically recommended.

Use of scrap tire rubber particles as aggregate in Portland-cement concrete is a suitable solution for the environmental hazards of waste tires being produced on a large scale. Tire rubber particles also reduce the brittle behavior of concrete due to their elasticity and plasticity. The effect of tire rubber particles on the mechanical properties of concrete is investigated in this study. Tire rubber particles were used in three (coarse, fine, and combined) groups to replace 12.5, 25, 37.5, and 50% of total aggregate volume in concrete. Cylindrical concrete specimens (15cm across and 30 cm high) were fabricated and cured. A compressive strain-control test was performed on the specimens until failure occurred in large deformations. Results show lower strength and more ductile behavior for rubberized concrete compared to plain concrete specimens. Unlike in plain concrete, the failure state in rubberized concrete occurred gently and uniformly and did not cause any separation in the specimen. The crack width and its propagation velocity in rubberized concrete were lower than those in plain concrete.

This study was conducted to analyze factors influencing the compressive strength test. The purpose is to introduce various factors affecting the accuracy of the compressive strength test in accordance with current standards and evaluate the effect of some effective parameters such as equipment (loading rate of automatic compression machine, jolting or vibrating), mortar preparation, sample preparation, etc. To check the reproducibility of the compressive strength test a program was developed to assess the possible modes through changes in loading rate, standard sand, sample preparation, and operator. The changes of each parameter were measured within 2, 7 and 28-day interval, while other conditions were considered as constant based on the EN 196-1 and ISIRI 393 standards. According to the test results, the most important factors in creating the difference in results are the type of the sand and loading rate. The changes in the reproducibility percentage using different sands with softer grains increases the coefficient of variation and reduced performance of the test. Also in some cases, with increasing the loading rate up to 40%, the compressive strength of 28 days is increased by 13%.

Measuring of uniaxial compressive strength (UCS) of intact rocks is necessary in many engineering projects. In deep well drilling for petroleum production or exploration drilling in deep tunnels, because depth wells, obtain suitable core samples for UCS test is too extensive and sometimes impossible. Therefore indirect method for UCS determine (for example using rock particles) is common. One of these methods is known as indentation test. In this test an indenter that is hard penetrate in to rock particle which surrounded by resin is used. In this paper, 11 microcrystalline limestone block samples from carbonate Zagros formation outcrops is prepared and UCS test in laboratory is performed. Then cores are crushed and 720 rock particle samples with 2, 3 and 4 millimeters size is prepared. Indentation test with indenter 0.6, 0.8 and 1 millimeters diameter is done and critical transitional force (CTF) for each particles is determined. Empirical equation between UCS and CFT for different samples and indenter with R2³0.78 is suggested. Using multiple regression general equation between UCS, CFT, particle size (D) indenter diameter (I) with R2=0.85 is proposed. Verification of the proposed equations with 135 indentation tests on 3 microcrystalline limestone samples and comparing measuring UCS in laboratory with estimate UCS are evaluated. This comparison showed that 88% they are similar.

In this paper based on the plastic stress wave propagation theory, a new analytical model is presented for impact of the cylindrical projectiles on the rigid surface. In this analytical model, Johnson-Cook material behavior equation, Mie–Grueneisen equation of state, Johnson-Cook strain at fracture equation and kinematics equations of motion, are used. Also, the conservation equations of mass, momentum and energy in front of plastic stress wave are determined.For solving the governing equations, a computer program is developed. The values of stress, strain, strain rate, velocity and length and radius of rigid and deformed region of projectile were determined. Using new model proposed in this paper, the compressive stress at different plastic strain and strain rates were determined. The results of the new model have been compared with ABAQUS finite element simulations and available experimental results.It shows that the length and radius of deformed region of projectile predicted by the new model have good agreements with experimental results and ABAQUS FE simulations. Furthermore, the compressive dynamic stress is determined as a function of the final projectile dimensions and material behavior coefficients.

Determination of uniaxial compressive strength (UCS) of intact rock is an important mechanical parameter required for many engineering projects. In some engineering projects for example well drilling for production petroleum because of more deep well exist limitation for obtain rock core sample and determination UCS. On the other hand determination this parameter is essential in order to analysis well wall stability and wells development program. Because of this, the idea of using drilling cuttings is proposed for determination UCS. In this paper in order to develop relationship between UCS and single compressive strength (SCS) were used from 7 block sample microcrystalline limestone from Asmari formation outcrops. Then UCS test was performed and was determined uniaxial compressive strength. Next these samples were crushed and were prepared 420 single particles. Then SCS for each particle is determined. Since shape of particles effect on particle strength therefore shape of particles has been modified and total particles that used for determination SCS was spherical. In order to study effect size of particle, particles with diameters 2, 3 and 4 millimeter is prepared and determined SCS for each particles. With increase diameter of particle, increase SCS. In order to eliminate effect of size particles is defined variable size and strength and is proposed chart between them. Coefficient of correlation between SCS and UCS is more than 0.91 that present exist good correlation between them.

Piles are relatively long structural foundation members that are used to transmit loads from soil layers with low bearing capacity (or high settlement) to deep soil layers with high bearing capacity. In foundation design, determination of pile bearing capacity is considered as a complex issue. In this paper, the bearing capacity of steel pipe piles in sandy soil is studied using the results of static compressive load test. Piles were installed in soil using the jacking method. In this method, at first, a hydraulic jack was applied for installing piles and then, it was used for applying the compressive load required in the static load test. After recording data, the values of bearing capacity of the piles were compared with the values calculated from analytical methods. Then, the values of friction capacity of piles were evaluated using the results of tension test. The results showed that due to the effects of soil plug on the bearing capacity of piles and installing piles using the jacking method, the obtained values of bearing capacity of the piles are much than their analytical ones. Moreover, the results indicate the effect of frictional resistance on the ultimate bearing capacity of the piles.

The use of lightweight structural concreteto reduce the weight of earthquake resistant buildings is very useful, and utilizing non-destructive tests for determining the concrete strength of these structures is essential. Ultrasonic pulse velocity test is one of the main methods of non-destructive testing in the assessment of compressive strength of concrete in the service area. The aim of this study is estimation of the compressive strength of lightweight aggregate concrete by offering suitable mathematical formulations. For this purpose, many samples of three different types of lightweight aggregate concrete are made and tested by concrete breaking machine and Ultrasonic pulse velocity instrument. Then some relationships for prediction of the compressive strength of the concrete by using ultrasonic test results are presented. Two different methods of fitting exponential function and Gene Expression Programming (GEP) are utilized to find the proper relationships. The results show that the exponential function has high accuracy in estimating the compressive strength of lightweight aggregate concrete made with natural pumices. But it doesn’t have good results for concrete made of expanded clay. However the GEP has high accuracy for all the materials and the experimental results are perfectly compatible with the test results.

Uniaxial Compressive Strength (UCS) of rock material is one of the most important and effective parameters in geotechnical and mining projects. Direct evaluation of UCS is expensive and time-consuming, therefore indirect tests such as point load, Schmidt hammer and sound wave velocity tests have been developed, among which the point load test is very commonly used, simple and economic. However, this method has limitations such as the effect of loading direction, the application of load to a small part of the rock and the high dependency of the results on the dimensions of the sample. In 2009, the Core Strangle Test (CST) was developed, which has the advantage of applying load through a circle perpendicular to the core axis. In this paper, the results of designing and manufacturing a CST machine, which has been performed for the first time in Iran, are described in order to estimate the UCS of rocks with high accuracy and low cost. The design and construction of the machine were done in the rock mechanics laboratory of Yazd University. In order to calibrate the machine, 70 standard rock and concrete samples with lengths of 20, 10 and 5 cm and a diameter of 54 mm were prepared. In addition to CST, point load and direct UCS tests were performed on these 70 specimens. Then, the relationship between UCS obtained by direct, CST and point load methods was investigated. Calculations showed that the relationship between UCS and machine oil pressure at the moment of failure in the CST method is a linear relationship with a correlation coefficient of 0.78 and the relationship between UCS and point load index is also linear with a correlation coefficient of 0.63.