Dissolution capacity of orange and eucalyptus oils versus endodontic types of cement (in vitro study)

Introduction: Endodontic retreatment seeks reentry to the root canal system to remove all filling material, identification and correction of pathological or iatrogenic defects. Objective: This study aimed to compare the dissolving capacity of eucalyptus oil, orange oil, and distilled water versus three types of endodontic cements. Materials and methods: Two hundred and four stainless steel molds were fabricated, where each cement sample was placed to the edge and left to set in the incubator, simulating normal oral conditions for 7 days. Subsequently, the solubility of each cement was analysed by immersing the samples in eucalyptus and orange oil for ten minutes in a static and ultrasonic environment. The solubility of the cement was evidenced by the difference between the weight before and after contact with the oils, data were statistically analysed with the ANOVA test and the post hoc Tukey bootstrap means test with 1,000 repetitions. Results: The control group and eucalyptus oil having no significant effect (p>0.05), the ultrasonic environment was found to be effective (p<0.05), whereas orange oil had better dissolution effects (p=0.004). Conclusions: The most susceptible cement was Sealapex, while the least soluble was MTA-Fillapex in all the solvents studied.

Use of Modified Palm Kernel Shell Particles Composite Blend with Cement or Clay as Alternative Material for Block Production

This study presents the potential of modified Palm Kernel Shell (MPKS) particles in the production of blocks as an alternative building material using cement or clay as binders. Several studies on Palm Kernel Shell (PKS) as a blend with other natural fibres/fillers found that due to its hydrophilic nature, it has low physical and mechanical capabilities in comparison to MPKS, making it less compatible with any polymeric matrix. Experimental tests were conducted to determine the physicomechanical attributes of MPKS/Cement and MPKS/Clay blocks, including characterization of the cement and clay using Atomic Absorption Spectroscopy (AAS), as well as moisture content, water absorption, hardness, apparent porosity, bulk density, compressive strength, and flake. The morphology of the samples was determined using Scanning Electron Microscope (SEM). Results show that MPKS/Cement block samples exhibit superior physicomechanical and morphological properties compared to MPKS/Clay. The MPKS/Cement block sample moisture content ranged between 4.76 – 9.94%. The 80/20 MPKS/Cement sample recorded the most water absorption at 49.5%, and a microhardness value of 82.3 Hv for the 20/80 sample. The MPKS/Clay samples showed higher values of apparent porosity but recorded the least bulk density in the 80/20 samples. The 20/80 MPKS/Cement and MPKS/Clay samples showed the best compressive strength at 63.72 and 50.3 N/mm2 respectively, while 80/20 for both cement and clay displayed very weak compressive strengths. The ratio 20/80 of MPKS/Cement is observed to be the optimum ratio where better properties of the composites were obtained. For the structure industry's long-term viability, MPKS' superior mechanical properties as an aggregate in block manufacturing make it an asset material as an alternative for some high-cost construction resources such as sand.

Application of Tire Waste Material to Enhance the Properties of Saudi Class G Oil Well Cement

Cementing is an important operation for the integrity of the wellbore due to its role in providing several functions. To perform these functions, a high performance cement is required. Different types of additives and materials have been added to the cement slurry to improve its performance. Tire waste material is considered one of the greatest wastes globally. It is a dangerous material to the environment and human. Subsequently, it has been included in many industrial processes to reduce its hazards. This work evaluated the application of tire waste material in oil and gas industry to improve the properties of Saudi class G oil well cement. Two cement slurries were formulated under high pressure and high temperature of 3000 psi and 292 °F, respectively. The first slurry was the base cement without tire waste and the second slurry contained the tire waste. The effect of using the two slurries on the cement properties such as density variation, compressive strength plastic viscosity, Poisson's ratio and porosity was evaluated. The results showed that, when tire waste material was used, lower density variation was accomplished. Using tire waste was efficient to decrease the density variation to an extremely low proportion of 0.5%. Adding tire waste to the cement composition decreased its plastic viscosity by 53.1%. The tire waste cement sample had a higher Poisson's ratio than the base cement sample by 14.3%. Utilizing the tire waste improved the cement's compressive strength by 48.3%. The cement porosity was declined by 23.1% after adding the tire waste. Beside the property's enhancement in the cement, the application of tire waste has also an economical advantage, since it is inexpensive material which is influential in our daily life.

Freeze–Thaw Damage Model of Polypropylene Fiber Reinforced Cement Stabilized Waste Construction Slurry under Uniaxial Action

In order to apply the fiber reinforced cement stabilized waste construction slurry more widely, it is crucial to evaluate its mechanical behavior under freeze and thaw (F–T) cycles. The mechanical properties of fiber cement-modified waste construction slurry (FCMS) under five different F–T cycles were studied using unconfined compressive strength tests. One fixed cement sample with five different types of polypropylene fiber was used in the FCMS. Using the meso random damage model, the two-stage damage stress–strain relationship of FCMS was established using particle swarm optimization (PSO). The results were as follows: (1) The mechanical properties of FCMS at room temperature and in an F–T environment were significantly improved by fiber; (2) The elastic modulus of FCMS decreased in the form of a power function with the increase of F–T cycles; (3) The fitting results of the two-stage F–T damage model based on meso random damage theory were in agreement with the measured data.

Simulation of the cement measurement based on the pulse DT neutron generator: A Monte Carlo study

The PGNAA system for the cement measurement was simulated based on Monte Carlo method. The sizes of the moderator and reflector for the 14 MeV DT neutron generator were optimized for fast and thermal neutron outputs. The DT neutron generator was simulated at the pulse mode, and the gamma-ray detector was set as LaBr3(Ce) scintillator. The characteristic peaks of the major elements (Ca, Si, Al, Fe) can be identified from the gamma-ray spectra which induced at the different time intervals of the neutron radiation. For the different thicknesses of the cement sample the ratios of the gamma-ray peaks were observed, and the result showed that when the thickness was between 20 to 30 cm, the ratios became stable. With the ratios, we can calculate the iron modulus, silica modulus and lime saturation factor.

Pengaruh Thermal Shock dan Komposisi Evaporation Boats, Semen Tahan Api, dan Pasir Silika terhadap Kekuatan Impact dan Foto Makro Lining Refractory

<p>The thermal shock behavior of ceramic refractory materials is of particular interest. Refractory materials are submitted to local temperature gradients in service that originate thermal stresses and thermal shock damage to the material. However, thermal shock treatment on the refractory made from evaporation boat waste is not well documented. The purpose of this study is to determine the effect of thermal shock on the strength of refractory with various compositions. In this study, the refractory was made using 100% refractory cement (sample 1). For Sample 2, the refractory was made from a mixture of refactory cement and evaporation boats waste, each of 50%: 50%. Meanwhile, specimen 3 of the refractory is made from a mixture of refactory cement, evaporation boat waste, and silica sand of 40%: 50%: 10%, respectively. The Thermal shock treatment is carried out at a temperature range of 100 – 700^oC for each specimen. The effect of thermal shock treatment on the mechanical properties of each refractory specimen was investigated using the impact and macrography test. Temperature variations in thermal shock have different effects on the level of impact strength on impact test specimens. The lowest strength was 0,012297735 J/mm²at thermal shock 700⁰C in sample 3, and the highest impact strength was 0,03928934 J/mm² at 400^oC thermal shock temperature in sample 2. The macrographic examination shows the higher the thermal shock temperature, the greater the fracture produced when the impact test is carried out. This is because the hardness of the refractory material increases.</p>

Bacillus Subtilis as Self-Healing Agent in Cement Mortar: Combined and the Separate Effect of Bacteria and Calcium Lactate on Self-Healing Behavior in Cement Mortar

Cement mortar, which is one of the most useful materials for construction applications, can deteriorate its performance by developing cracks. In order to cope with this issue, the materials’ scientist came forward with a unique biogeochemical phenomenon in which cement mortar can selfheal its crack autonomously using calcium carbonate precipitating bacteria and their feed. In this research, it was intended to study the separate and combined effect of Bacillus Subtilis (bacteria) and Calcium Lactate (feed) on the properties of conventional mortar. Cement mortars were made using conventional method and cast in the form of cylinders. Four types of samples were taken. Sample-N contains only cement and sand, Sample-B was made by addition of bacteria Bacillus Subtilis with sand and cement, Sample-C contains Calcium Lactate which is usually used as feed for Bacteria while the last sample ‘BC’ have both Bacteria as well as Calcium Lactate. The samples were observed up to 44 days for their surface characteristics and compressive strength. The Sample-N and B did not show any remarkable change in their surface appearance with respect to curing time. Sample-C and BC did show the precipitation of CaCO3 but the Sample-C precipitation was stopped soon while for Sample-BC, the precipitation was continued for a longer time. The Sample-BC showed the highest compressive strength (approximately 17.57 MPa), followed by Sample-N (approximately 13.32 MPa), Sample-B (approximately 11.04 MPa) while Sample-C displayed lowest strength (approximately 2.75 MPa). This gives an idea that Calcium Lactate which acts as feed for bacteria has the negative effect on the strength if not consumed and converted into CaCO3.

An Experimental Assessment of Iraqi Local Cement and Cement Slurry Design for Iraqi Oil Wells Using Cemcade

This effort is related to describe and assess the performance of the Iraqi cement sample planned for oil well-cementing jobs in Iraq. In this paper, major cementing properties which are thickening time, compressive strength, and free water in addition to the rheological properties and filtration of cement slurry underneath definite circumstances are experimentally tested. The consequences point to that the Iraqi cement after special additives encounter the requests of the API standards and can consequently is used in cementing jobs for oil wells. At this research, there is a comparative investigation established on experimental work on the effectiveness of some additives that considered as waste materials which are silica fume, bauxite, and glass powder, and other conventional additives which are: (SCR -100 Retarder, HR-5, FWCA, Hollow Glass Spheres (HGS) and Halad-9) that currently used in our fields on local Iraqi cement and putting foreign cement results as a governor. Chemical analysis for Iraqi cement, imported cement, and waste materials samples was determined using the X-ray fluorescence (XRF) technique and found minor differences in composition between those samples and depending on the results of X-ray, we selecting the appropriate additives to prepare cement slurry samples. The X-ray fluorescence (XRF) results show that Iraqi Cement has a low value of silica which is about 18.63% while Omani cement about 37.58%. This research examined the potential of micro silica, bauxite, and waste glass powder to produce sustainable cement slurry. The results showed that adding micro silica and bauxite enhances the performance of Iraqi cement but also leads to a slight decrease in thickening time. To avoid this problem, Superplasticizer is used to make the process of cement pumping more easily, in other words, increase thickening time and increase compressive strength. Furthermore, adding glass powder increase the value of compressive strength. Both additives (waste and conventional) are used for the slurry design for achieving better slurry properties, but waste additives increase and enhance Iraqi cement performance than conventional additives, in other words, making it more effective than commercial cement. Depending on the results of the compressive strength test, the optimal concentration of the waste materials used in this research was found, and then the optimal concentration was used to prepare cement samples. The results showed that the use of waste materials to prepare cement slurry is a promising way to improve the efficiency of cement work and to reduce the negative environmental impact resulting from the industry. The results of the program CemCADE proved to be the sample A and C showed good performance through high cement bonding and ideal distribution of fluids designed to accomplish the cementing process.

The cement-bone bond is weaker than cement-cement bond in cement-in-cement revision arthroplasty. A comparative biomechanical study

This study compares the strength of the native bone-cement bond and the old-new cement bond under cyclic loading, using third generation cementing technique, rasping and contamination of the surface of the old cement with biological tissue. The possible advantages of additional drilling of the cement surface is also taken into account. Femoral heads from 21 patients who underwent a total hip arthroplasty performed for hip arthritis were used to prepare bone-cement samples. The following groups of samples were prepared. A bone—cement sample and a composite sample of a 6 weeks old cement part attached to new cement were tested 24 hours after preparation to avoid bone decay. Additionally, a uniform cement sample was prepared as control (6 weeks polymerization time) and 2 groups of cement-cement samples with and without anchoring drill hole on its surface, where the old cement polymerized for 6 weeks before preparing composite samples and then another 6 weeks after preparation. The uniaxial cyclic tension-compression tests were carried out using the Zwick-Roell Z020 testing machine. The uniform cement sample had the highest ultimate force of all specimens (n = 15; Rm = 3149 N). The composite cement sample (n = 15; Rm = 902 N) had higher ultimate force as the bone-cement sample (n = 31; Rm = 284 N; p <0.001). There were no significant differences between composite samples with 24 hours (n = 15; Rm = 902 N) and 6 weeks polymerization periods (n = 22; Rm = 890 N; p = 0.93). The composite cement samples with drill hole (n = 16; Rm = 607 N) were weaker than those without it (n = 22; Rm = 890 N; p < 0.001). This study shows that the bond between the old and new cement was stronger than the bond between cement and bone. This suggests that it is better to leave the cement that is not loosened from the bone and perform cement in cement revision, than compromising bone stock by removal of the old cement with the resulting weaker cement-bone interface. The results support performing cement-in-cement revision arthroplasty The drill holes in the old cement mantle decrease cement binding strength and are not recommended in this type of surgery.