travertine

One of the criterions for evaluating the cutting of building stone using the diamond wire cutting system is the energy consumption of the cutting wire machine. In this study, in order to evaluate the amount of energy consumed in the cutting process, a laboratory diamond cutting wire system was designed and built with the ability to change and stabilize the operational and tooling parameters of cutting, including linear velocity, backward pulling speed and angle of impact of diamond wire. In order to determine the relationship between the physical and mechanical properties of the stone with the energy consumption of the cutting machine, 6 different samples of travertine were prepared from the mines of East and West Azerbaijan, Isfahan, Yazd and Markazi provinces and The values of physical and mechanical properties including density, porosity, water absorption, uniaxial compressive strength, tensile strength and the speed of ultrasonic waves passed through them were measured in the laboratory. Then, by cutting cubic blocks of the samples with the laboratory diamond cutting wire system, the energy consumption of the device in different situations of the angle of the wire with the sample was recorded. Using regression and univariate fitting, the relationship between each of the rock properties and the specific cutting energy with respect to linear, logarithmic, power and exponential functions was investigated. The results showed that the best value for the angle at which the wire hits the specimen, at which the lowest specific energy consumption is recorded, was 15 degrees.

One of the problems caused by air pollution is acid rain. The development of urban communities and subsequent use of air polluting vehicles on the one hand and the widespread use of travertine in building facades in Iran on the other hand have doubled the study of the effect of acid rain on the properties of travertine. In this study, three types of travertine (Travertine B, Travertine D and Travertine R) were studied. This paper investigates the effect of the rain at four pH (2.5, 4, 5.5 and 7) on its physical properties including effective porosity, longitudinal wave velocity and permeability, and its mechanical properties including tensile strength and uniaxial compressive strength. The results showed that as the pH decreases, the effective porosity increased and the longitudinal wave velocity, tensile strength and uniaxial compressive strength decreased. The highest increase in effective porosity due to decreasing pH was related to travertine B and the lowest increase was related to travertine R. The highest decrease in longitudinal wave velocity, tensile strength, and uniaxial compressive strength due to decreasing pH was related to travertine B and the lowest decrease was related to travertine R.

In the case of explosions and fires, the rocks undergo cycles of heating and cooling, that is, they are exposed to considerable heat first and then cooled after extinguishing the fire. The purpose of this paper is to study how the temperature in a heating-cooling cycle can affect the physical and mechanical properties of travertine. In Iran, travertine stone is widely used for building facades, so travertine was chosen as the material of study. In this study, three types of travertine (Travertine B, Travertine D and Travertine R) were studied. The effective porosity and permeability at 25 °C for Travertine B is greater than Travertine D and Travertine D is greater than Travertine R. Also, the longitudinal wave velocity, tensile strength and uniaxial compressive strength at 25 °C for Travertine B are lower than Travertine D and Travertine D is lower than Travertine R. During the heating phase in a heating-cooling cycle, experiments were performed on specimens that were initially exposed to temperatures of 150, 300, 500 and 800 °C and then cooled gradually to ambient temperature. A series of experiments were performed on specimens that were not exposed to a heating-cooling cycle. This paper investigates the effect of the heating-cooling process on its physical properties including effective porosity, longitudinal wave velocity and permeability, and its mechanical properties including tensile strength and uniaxial compressive strength. The results showed that as the temperature increases, the effective porosity and permeability increased and the longitudinal wave velocity, tensile strength and uniaxial compressive strength decreased. The highest increase in effective porosity and permeability due to increasing temperature was related to travertine B and the lowest increase was related to travertine R. The highest decrease in longitudinal wave velocity, tensile strength, and uniaxial compressive strength due to increasing temperature was related to travertine B and the lowest decrease was related to travertine R.

The purpose of improvement of building stone industry is to re-engineer the chain of stone production. Re-engineering the chain of stone production encompasses a significant increase in production quantity and an improvement in efficiency. This is performed by supplying high quality final product, and by minimizing the amount of wastes abandoned at environment as well as producing byproducts using rubble stones. In current research, strategies to improve all stages of building stone production chain containing exploration, quarry and processing have been presented mainly focusing on stone type, quarry methods, equipment and quarry machines, processing (cutting and polishing) methods and the machinery, personnels and investement. As a case study, travertine quarries and stone cutting and processing units in Mahallat district located at Markazi province have also been studied. The study of 29 travertine quarries and 18 stone cutting and processing units in this region was done through field visits. It reveals that the chain of the stone production need to be improved in general. Although all quarries in the region are mined by the novel method (wire cutting method), awfull amount of rubble stone is inappropriately produced, so the quarry operation needs improvement on all accounts. Also a large number of stone cutting and processing units in the region (about 65 percent) yet works traditionally which should be equipped with new machinery and optimized. Finally some needed strategies to improve the stone industry which should be done by the government were presented.

Salt crystallization is one of the important factors on durability and deterioration of building stones. Magnesium sulphate is a common salt that can lead to deterioration, thus it is necessary to consider this subject before select the stones as building facade. In this research, alteration index and alteration velocity were be used to evaluate the durability of travertine against Magnesium sulphate that can be used as criterion in salt crystallization test. For this purpose, fifteen travertine were sampled from different areas in Iran then petrologic, some chemical (density, porosity and water adsorption) and mechanical properties (uniaxial compressive strength and tensile strength) were obtained for samples. Salt crystallization test were carried out 60 cycles and alteration index, alteration velocity were calculated for samples based on the weight loss and appearance variation of samples then relationship between alteration index and alteration velocity with effective porosity, tensile strength and weight was analyzed with regression analysis. The results show that alteration velocity has higher correlation with tensile strength, effective porosity and weight loss whereas the alteration index of the travertine is not. Also the results show that fabric, effective porosity and tensile strength are important factors that controll durability of samples in salt crystallization test.