A Study of nozzle angle in stone surface treatment with water jets

The stone surface treatment with water jet is a recently introduced method. It is used to increase the roughness to improve its antislip properties while preserving esthetic appearance of the stone without having thermal shock, mechanical stress and the production of fumes and dust. Nozzle angle is one of the important parameters affecting treatment of surface. This study is an attempt to assess the effect of nozzle angle on surface treatment quality with water jet and to determine the most suitable nozzle angle value. For this purpose, surfaces of Sardinian Basalt samples are treated with pure water jet in six different nozzle angles (15°, 30°, 45°, 60°, 75° and 90°). The roughness is measured on all the treated surfaces by various roughness parameters. The experimental studies showed that treatment with nozzle angle between 30° and 75° gives the surfaces with similar regular variation.     

A preliminary study on the conservation and polishing performance of Sanliurfa limestones as a traditional building material

Sanliurfa limestones have been used as building materials from antiquity to current day (e.g., Gobeklitepe temple B.P. 14,000, Bazda underground quarries B.P. 3000, Harran castle B.P. 3000, etc.). These antique structures are listed within the United Nations Educational, Scientific and Cultural Organization (UNESCO)’s World Heritage List. However, the stones were used in these structures without any protection, and atmospheric conditions (precipitation, acid rain, temperature changes, etc.) cause damage to these stones over time, such as strength loss, abrasion, and discoloring. The damage can lead to the collapse of precious historical structures, or may require costly restoration. In this study, Sanliurfa limestone was investigated with respect to conservation using polish insulation (polysiloxane, lithium silicate, and varnish), appearance performance by polishing, and potential usage in the marble industry. The results revealed that conservatives could maintain up to 92 % of the unconfined compressive strength (UCS) of the natural stone and reduced acid abrasion to 0.5 % of the original weight. The stone gained a bright appearance after polishing, especially by lithium silicate. Thus, it can be stated that it is possible to recover or prolong the lifetime of the monuments that were constructed using Sanliurfa limestone, and this limestone may have great industrial potential as marble stone.     

Water absorption and dehydration of natural stones versus time

Physical, chemical and mechanical properties of natural stones play an important role on deciding their application area as a building stone. In this study, water absorption and dehydration time of five different types of natural stones (marble, limestone, travertine, onyx and granite) were comparatively examined. Porosity, dry unit weight, wet unit weight, water absorption ratio and chemical analyses of the rock samples were also determined. In the light of the obtained experimental results, it was found that MgO content as the chemical property, and porosity as the physical property played a major role in the water absorption capacity and dehydration time of the studied natural stones. Basing on some observations made in this study, it was also emphasized that common standards involving the determination of water absorption coefficient by the capillarity test in rocks should be re-evaluated.     

Polishing experiments on surface quality of building stone tiles

Polishing experiments were carried out on eight different carbonate stones with a machine designed for simulating industrial scale tile polishing process. Polishing was performed at 0.8, 1.3, 1.8 and 2.3 m/min belt speeds under fixed rotational speed and pressure of a polishing head. During the tests, calibrated stone tiles were sequentially polished with 60, 80, 120, 220, 320, 400 and 600 grit SiC abrasive stones at each belt speed. After polishing of each abrasive size, the quality of surfaces was assessed by measuring the surface roughness and gloss. As abrasive grit size gradually reduced to 320 grit, the roughness on the stone surfaces decreased greatly while gloss readings did not change significantly. But after 320 grit, gloss values increased greatly while change in roughness values was not significant. Reducing the belt speed resulted with a significant decrease in roughness for each grit size of abrasive, but after polishing with abrasive size larger than 320 grit, the influence of belt speed on the reduction in roughness values became less. Among the carbonate stones, micritic limestone tiles, which were homogenous in mineral composition with strong and hard structure, resulted with good surface finish. But clay minerals existing in other limestone and heterogeneous porous structure of travertines had an adverse effect on surface quality of tiles. Results from polishing tests suggest that belt speed value of 1.3 m/min provide optimum polishing quality conditions since optimum consistency in roughness and gloss of tile surfaces was reached at this belt speed. This findings were very valuable information for operating factories in which polishing is carried out. The gloss reading on stone surfaces was found to increase exponentially with decrease in surface roughness. Good correlation was found between surface roughness and gloss quality of micritic limestones and marbles compared to travertines.     

Evaluation of the application conditions of artificial protection treatments on salt-laden limestones and marble

Soluble salts contaminating limestones and marbles used as building and artistic materials play a relevant role in the deterioration processes of the substrates. Although desalination operations are carried out prior to protection and/or consolidation, a certain amount of salt remains inside the stones. When a surface treatment is chosen, the evaluation of its compatibility with the residual saline content is therefore needed. In the present work, specimens of three lithotypes characterized by a very different porosity – Lecce stone and Ançã stone, both highly porous, and the less porous Gioia marble – were contaminated with salt and then treated with two protective products, the organic polydimethylsiloxane and the inorganic ammonium oxalate (NH₄)₂(COO)₂·H₂O. Aim of the research was to select the best application conditions of the two products on salt-laden stone specimens, investigating as well the dependence of the protective action on the procedures adopted to apply the products. The performance of different concentrations and contact times of the products was tested in the laboratory, paying special attention to the possible drawbacks due to the salt. The study was carried out applying different methods: colorimetric measurements before and after the application of the products; water absorption by capillarity to investigate variations in water-interaction features; SEM–EDS analyses to evaluate the distribution of products and salt on the substrates.     

Geomembrane puncture and strains from stones in an underlying clay layer

Results from physical experiments are presented to assess the possible puncture of a 1.5-mm-thick HDPE geomembrane and, if not punctured, the maximum tensile strains in the deformed geomembrane from intentionally placed stone particles in an underlying compacted clay liner when subjected to applied vertical stresses. The influences of applied pressure, clay water content, stone size, stone burial depth and protection layer on the geomembrane tensile strains are reported. Except in one test conducted to a pressure of 2000 kPa, the geomembrane was not punctured in the short-term tests conducted; however, it was subjected to local indentations and tensile strains from the underlying gravel particles that may exceed proposed allowable long-term strain limits. Tensile strains for the specific 35 mm stones tested when initially flush with the clay surface were negligible, even up to pressures of 1000 kPa, provided the initial water content of clay was 12%. Increases in water content or stone size were found to increase the tensile strain. Placing the clay at the lower limit of acceptable water content was found to be beneficial in terms of reducing strains from buried stones; however, this was also found to make the geomembrane more susceptible to stone particles sitting on top of the clay surface and hence careful site inspection is required to remove all visible stones that sit on top of the clay surface.     

大理岩硬性结构面剪切蠕变及粗糙度效应研究

 针对锦屏二级水电站地下洞室富含节理的实际情况,利用双轴蠕变仪对大理岩硬性结构面进行剪切蠕变试验。通过对大理岩硬性结构面表面的量测,采用平均粗糙角描述大理岩硬性结构面表面粗糙度情况;分析不同粗糙度情况下岩样剪切位移与时间的变化规律。结果表明,粗糙角大的岩样瞬时变形要小于粗糙角小的岩样。此外,试验在较低的应力水平下,岩样蠕变变形表现为衰减蠕变和稳态蠕变,但当剪应力水平达到某一应力水平时,岩样在极短时间内迅速破坏,未出现加速破坏阶段,因此,利用大理岩剪切蠕变试验数据对标准线性体剪切蠕变模型进行辩识,得出各岩样的剪切蠕变模型参数,通过由模型参数得出的拟合曲线与试验曲线比较知采用标准线性体模型是合理的。最后分析各大理岩岩样的平均粗糙角与剪切蠕变模型参数的变化规律。     

不同粗细骨料组合下的混凝土耐硫酸腐蚀研究

为比较不同粗细骨料组合对混凝土耐硫酸腐蚀性能的影响,对水灰比为0.45、尺寸为100×200的4种骨料组合（青石+黄砂,青石+大理砂,大理石+黄砂,大理石+大理砂）混凝土试件进行耐硫酸加速腐蚀试验。将混凝土试件浸泡于pH值为0.95左右的硫酸溶液中进行为期194 d的12次跟踪监测,根据检测数据计算得到了混凝土的腐蚀深度,按线性方程斜率从大到小对4种骨料组合混凝土硫酸腐蚀速率进行了排序。结果表明:含有大理石或大理砂骨料的混凝土比含青石和黄砂骨料的混凝土耐硫酸腐蚀性能高;腐蚀层受扰动情况下,腐蚀深度与腐蚀时间呈线性关系;大理石细骨料比大理石粗骨料更有利于减小腐蚀深度。     

海底隧道腐蚀环境下射流风机升压力衰减机理及计算方法研究

海底道路隧道内高湿度、富盐雾和多酸性气体的环境特征会加速腐蚀风机,进而使通风效果无法满足洞内环境控制标准。以厦门翔安海底隧道为依托对隧道内风机升压力展开现场测试,结合理论分析和Fluent滑移网格模型研究风机升压力计算公式和表面粗糙度与风机升压力的衰减关系。研究结果表明：单台射流风机升压力计算公式还应考虑风机自身性能损失折减系数η1;海底隧道腐蚀环境通过积垢沉淀、侵蚀和腐蚀效应增大风机叶片和流通部件的表面粗糙度,进而增大风流阻力,降低风机升压力;通过数值模拟得到基于表面粗糙度的风机升压力计算方法。研究结果揭示海底隧道腐蚀环境下风机升压力衰减机理并建立了计算方法,为同类型海底隧道通风系统设计提供参考。     

立方排列水泥球体通风性能及参数试验研究

 由于块石层具有较好的通风换热特性,使得块石护坡和块石路基在青藏铁路建设中得到广泛的应用,并起到良好的降温效果。块石层中的空气流动规律已成为目前研究的热点问题,但块石的大小、形状和堆砌方式的随机性使得直接进行块石通风试验时,得到的结果具有很大的偶然性和不确定性。为解决这一问题,采用风洞室内模型试验对不同直径立方排列水泥球体层的渗透率及惯性阻力系数进行研究,试验选用的水泥球体直径为0.15,0.20,0.25,0.30 m,立方排列球体的孔隙率均为0.476。风洞试验结果表明：水泥球体层内部压力梯度与渗流速度之间存在良好的二次非线性关系;随着球体直径的增大,渗透率随之增大,而惯性阻力系数随之减小。     

庭园仕女图中植物与石类的美学表现 研究

仕女图始于唐代,通过塑造优美动人的妇女形象来反映当时的社会生活,传达特定的古典艺术趣味和审美模式,研究庭园仕女图对于揭示女性庭园空间的美学特质较为重要。以筛选的庭园仕女图为材料,考察庭园仕女图中植物和石类所呈现的微小空间的显著的美学特点,以此了解古代画家笔下庭园中石类与植物的美学样式,以进一步阐释和揭示古典庭园美学的本质样貌和内涵,为传统历史庭园的保护以及现代庭园的设计传统的传承提供启示。     

CFRP筋增强板加固石梁受弯性能试验研究

为实现在不明显改变被加固构件外观的同时方便现场施工操作,提出了用于既有传统素石梁抗弯加固的预制CFRP筋增强板加固技术。进行了3根采用CFRP筋增强板加固的石梁试件和1根素石梁对比试件的受弯性能试验研究,主要试验参数为CFRP筋配筋率和石梁底面粗糙程度。结果表明：CFRP筋增强板加固技术显著改善了石梁的脆性破坏形态,有效提高了石梁的受弯承载力和变形能力;随着CFRP筋用量的增大,试件受弯承载力提高,加固效果更加显著;石梁底面粗糙度对加固石梁受弯性能的影响较小,机切与凿毛界面均可满足加固需求。试验过程中,CFRP筋增强板与被加固石梁之间的界面黏结性能较好,CFRP筋端部未出现滑移现象,确保了加固试件各部分的共同工作性能。石材的离散性较大,实际工程中应增加对石材材质的检测,避免出现使用较差材质石材产生的安全隐患。     

石渣石粉垫层在室内回填工程中的应用

简述海信集团信息产业园工程概况 通过对该工程软土地基回填处理方案的论证 ,介绍各种回填处理方案的适用性 ,并针对各种方案的优缺点进行综合分析及选择 着重论述换填石渣法加固技术及石粉垫层在本工程中的应用 ,然后以核子密度仪测试的压实系数结果对该方法的运用进行验证 ,证实该方法是一种比较理想的地基处理方法     

Variation on physico-mechanical properties of Kota stone under different watery environments

The physico-mechanical properties of rocks play an important role in planning and designing of civil constructional works. These properties are adversely affected by acidic and alkaline environments, where they are exposed for a longer time. The natural forces and agents of weathering have degrading effect on the appearance and structural soundness of Kota stone. These agents include rain, temperature, wind and atmospheric pollutants. Weathering agents almost never work individually or in isolation, they always act in combination with one another or with other agents of deterioration.

The durability of building stones is primarily judged by its reactivity with acidic and basic water of different pH values. The conditions are very obvious in any of the large scale construction and use of building stone like sandstones and Kota stones. During the mining of carbonate hosted mineral deposits, the interaction of ground water with ore minerals affect the surrounding environment and rock types. This may cause problem in exploitation of minerals and may cause failure of slope or pillars. To avoid such problems, the prior study of effect of ground water charged with ions released from ore minerals on carbonate rock is important.

In this paper, an attempt has been made to see the variation in the physico-mechanical properties of Kota stone under different watery environment. In the present study, the NX size cylindrical cores were prepared with the help of diamond core drilling machine as per ISRM standard. For each mechanical property, eight samples were prepared and tested. The prepared samples were put into the oven for 24 h at 104 °C to eliminate the moisture present and later submerged in to the water having different pH values ranging from nearly 0.89–12 for 24 h under stirring mode till it gets full saturation at room temperature. The study reveals that there is prominent change in strength properties under acidic and alkaline environments. Rock is considered as a neutral substance so at pH 7, Kota stone shows maximum strength due to non-reactive nature of the solution. Majority of rock mass is not neutral but some of the rock mass shows very minor changes in its strength. The chemical composition of the rock mass dominates the reaction process when it is submerged in varying pH solution.     

Characterization of building stones from the ancient Tyana aqueducts,Central Anatolia,Turkey: implications on the factors of deterioration processes

Many archaeological and historical monuments constructed by different civilizations over the last 5500 years can be observed in the Ni?de region located in central Anatolia. The Tyana aqueduct as a continuation of the Roman Pool is one such important historical monument. The aqueducts that carried the water of the Roman Pool to the ancient city of Tyana were constructed during the time of the Roman emperors Trajan, Hadrian and Marcus Aurelius Antoninus. Half of the total length of the aqueducts (3 km) is on the surface and the rest is buried. The engineering properties of the rocks used in such archaeological and historical buildings are very important in terms of conserving these structures for future generations. In this study, the geomechanical and geotechnical features of the Tyana aqueducts were investigated to understand the rock types, deterioration in the stones over time and problems originating from these features. Also, for restoration purposes, the ancient stone quarry areas for the aqueducts were identified, and the chemical, petrographical and geomechanical properties of fresh travertine blocks from these quarries were determined. The main rock type used as building stones in the aqueducts is Mio-Pliocene travertine. Laboratory studies were performed to determine the mineralogical, petrographic and petrophysical properties of the building stone samples. Fresh and used travertine samples were composed exclusively of calcite crystal. The results of chemical analyses were similar for fresh and used travertine samples. To determine the geomechanical properties of the travertines, dry unit weight, water absorption, effective porosity, P-wave velocity, Böhme abrasion test, capillary water absorption and uniaxial compressive strength experiments were conducted. In addition, Schmidt hammer hardness measurements were performed on site for the different levels and different textural characteristics of the belts on the travertines. According to the experimental data obtained, higher strength was displayed by samples with fine grains, massive texture and low porosity. The deterioration effects in most of the travertines used in the original structure are very low. In addition to human effects, the use of small stone dimensions (especially the stones used in belts as keystones) and the use of stone from the same quarry but with features that differ or are inferior are thought to be factors in the destruction of the Tyana aqueducts.     

The effect of using different polymer and cement based materials in pore filling applications on technical parameters of travertine stone

The usage of marbles as a natural building and facing stone shows a gradually rising trend in civil sector all over the world. Due to natural motion, structure of marbles consists of many cracks and holes during formation of rocks. Cracks and holes in the marbles generally increase the wastage ratio and operating costs during production of marbles. Normally, the color consistency, brightness of the colors, hardness, strength, non-porous smooth surface as a hygienic structure are desired properties in the usage of flooring and facing stones.In this study, application of some pore filling methods in travertine and their effects on technical parameters of the rock structure were experimentally investigated. Although travertine has high porosity and is composed of different sizes of pores in its structure, it has a wide usage area in the construction and facing stone industry. Its processing is very easy and is much cheaper than the other marble types. Two different applications were mainly used for the pore filling process. These methods are polyester filling technique and cement filling technique. The use of cement filling method is widely applied in travertine production. The effects of these methods on the rock structure were analyzed and the most suitable filling technique was determined based on the technical data of rock parameters.In this study, in addition to the effective use of cement as a filler material in a travertine stone, different ratios of polymer admixtures as a Stuff (ST) and Poliacrilamid (PA) were used to evaluate the collapse of the filling material through the pores with optimum setting time. These materials were used as a replacement of the cement and calcite with the ratios of 0.1%, 0.5%, 1.0%, 1.5% and 2.0%. Test samples were prepared in the form of 40 cm × 40 cm × 1.2 cm tiles and different ratios of the mixture of cement, calcite and polymer materials were applied on the rock surface. These samples were analyzed in terms of water absorption, point load index and unit volume weight measurements by using appropriate standards, TS 699 and ISRM. According to test results, it was tried to compare the filled and unfilled material properties and to obtain optimum ST–PA and cement usage ratio with respect to improving polishing quality, physical and technical parameters of rock.     

Microscopic and macroscopic characterization of the porosity of marble as a function of temperature and impregnation

Various methods were used in order to study how temperature cycling initiates changes in the porosity of fresh and impregnated marbles. The results indicated that intergranular decohesion was more pronounced in calcitic marble than dolomitic marble. The impregnation agents had a mitigating effect on the intergranular decohesion. Use of fluorescence microscopy, among the other methods, appears to give inexpensive and reliable information about the internal structure of marble. A better understanding of the effect that temperature has on the porosity of marble could be used as a guide for selection of suitable stone material for exterior use as well as an indication for appropriate conditioning of the samples before physical property testing.     

Optimisation of an abrasion resistance test method on natural stones

The determination of abrasion resistance according to EN 14157 “Natural stone test method—determination of abrasion resistance” is required for the CE (European conformity) marking on natural stones. A great deal of abrasive material is necessary for this test, which makes it relatively costly. Furthermore, Boulonnaise marble, the reference stone, is not easily available. The study reports the assessment of Canaloni (Carrara) marble as an alternative reference material using the Capon apparatus, which demonstrates its suitability for this purpose. An evaluation was also made of the effectiveness of the abrasive material (carborundum) after it has been used for the three times stated in the Standard and it was found that its performance remains unchanged, even after a higher number of tests.     

Investigation of meso-failure behaviors of Jinping marble using SEM with bending loading system

In this study, the meso-failure mechanism and fracture surface of Jinping marble were investigated by means of scanning electron microscope(SEM) with bending loading system and laser-scanner equipment. The Yantang and Baishan marbles specimens from Jinping II hydropower station were used. Test results show that the fracture toughness and mechanical behaviors of Yantang marble were basically higher than those of Baishan marble. This is mainly due to the fact that Baishan marble contains a large percentage of dolomite and minor mica. Crack propagation path and fracture morphology indicated that the direction of tensile stress has a significant effect on the mechanical behaviors and fracture toughness of Baishan marble. For Yantang and Baishan marbles, a large number of microcracks around the main crack tip were observed when the direction of tensile stress was parallel to the bedding plane.Conversely, few microcracks occurred when the direction of tensile stress was perpendicular to the bedding plane. The presence of a large number of microcracks at the main crack tip decreased the global fracture toughness of marble. The results of three-point bending tests showed that the average bearing capacity of intact marble is 3.4 times the notched marble, but the ductility property of the defective marble after peak load is better than that of the intact marble. Hence, large deformation may be generated before failure of intact marbles at Jinping II hydropower station. The fractal dimension of fracture surface was also calculated by the cube covering method. Observational result showed that the largest fractal dimension of Yantang marble is captured when the direction of tensile stress is parallel to the bedding plane. However, the fractal dimension of fracture surface of Yantang and Baishan marbles with tensile stress vertical to the bedding plane is relatively small. The fractal dimension can also be used to characterize the roughness of fracture surface of rock materials.     

Some engineering properties of natural building cut stones of Cyprus

Natural building cut (NBC) stones are being used in Cyprus for ages to build masonry structures because of being abundant, relatively easy to cut and shape and good performance in many applications. Almost all of the historical buildings in Cyprus are made of these NBC stones. Although these stones are low cost construction materials, they are not widely used in these days. This is due to lack of knowledge causing incorrect construction methods and highly skilled labour requirement.For this study two quarries are selected and samples obtained were tested for some physical and mechanical properties. Traditional names of these NBC stones are Meluşa Stone and Karpaz Stone (or Bouri Stone). The physical properties such as bulk density, water absorption, specific gravity and porosity were measured. The mechanical properties such as compressive strength, flexural strength, direct tensile strength, splitting tensile strength, point load strength, fire resistance, abrasion resistance and freeze-thaw resistance were measured. From the results obtained it can be said that Meluşa stone behaved better than Karpaz stone. A regression analysis also provided a polynomial relation between compressive strength and burning temperature and flexural strength and burning temperature.