Geometric quality assessment of in situ blocks in dimension stone quarries

The profitability of stone quarries depends on the appearance (color and texture) and, more importantly, on the size of the blocks, which is determined by the three-dimensional discontinuity pattern of the rock mass. However, to date there is no comprehensive criterion by which to assess the size of blocks in quarries. The aim of the study reported here is to identify factors that facilitate decision-making on the desirability of an individual block and ultimately on all blocks for extraction as a dimension stone. To this end, we first developed a novel algorithm to calculate the largest rectangular parallelepiped that can be placed inside a block and then defined a regularity factor (α) and a quarry block shape factor (q) that enable the geometric quality of the block to be assessed more accurately than currently possible. The sensitivity analysis of these factors showed that the change in angle relative to the change in spacing has the greater effect on the geometric quality. The proposed factors displayed a good performance in a comparison analysis of four sites of the Dareh Bokhari travertine quarry complex located in Mahallat, Markazi province, Iran. Based on the results, blocks at sites 2 and 4 have the lowest and the highest geometric quality, respectively, which is in accordance with the operational conditions at the respective sites. Moreover, comparison of the values of factor q obtained from applying various cutting planes indicated that to maximally increase block production capacity, the current cutting direction at site 4 should be adjusted 33° eastward.

     

Mesozoic carbonate rocks in Serbia used as dimension stone

The building industry in Serbia uses, to a great extent, imported natural stone for architectural purposes. The significance of local deposits, particularly limestones, is not adequately perceived despite the country’s abundance of these valuable resources. Therefore, this study focuses on Serbia’s Mesozoic carbonate rocks, specifically on the deposits of four selected quarries: Klisura, Skrzut, Struganik, and Tisnica. The quality and prospects of the application of these limestones has not yet been the subject of a detailed, comprehensive investigation. Therefore, this research is primarily concerned with the examination of their petrological and physico-mechanical properties in order to propose their scope of application further as dimension stone. According to the petrological features, different carbonate microfacies are observed: biolithites, pure orthochemical micrites, allochemmicrites, and allochemsparites. Physico-mechanical characteristics confirmed that the investigated carbonate rocks are of high bulk density, compact or of low porosity, of very low water absorption, hard, and with high to moderately high values of compressive strength. The scope of use is established according to a comparison of statically analysed engineering properties with the technical requirements necessary for a suitable reference of natural stone products. The results demonstrate that the examined rocks are suitable for use as slabs for architectural cladding and paving, whereas the occurrence of bedding and occasional tectonic fissures (fractures) is considered to be a limiting factor of exploitation.     

The basalt stone quarries of eastern India

Quarrying of basalt stone in the Early Cretaceous Rajmahal Trap region of eastern India is increasing at an alarming pace. The quarries have created an extensive ugly landscape of pits and overburden dumps. The stone workshops continuously emit dust. These quarries generate year‐round employment in an impoverished terrain. The workforce mostly comprises the socio‐economically deprived indigenous tribal population. They are an important source of income to the State Governments of Jharkhand and West Bengal. While the need for building stone cannot be denied in a region that is rapidly industrialising and urbanising, issues of land degradation and health cannot be ignored. The paper offers measures to contain environmental degradation and generate alternative sources of income with bio‐fuel crops such as Jatropha curcas.     

General material properties of Denizli (SW Turkey) travertines as a building stone

The quality and material properties of Denizli travertine as a natural building stone have been investigated. The Denizli region is one of the world’s major travertine deposits and production basins. Travertine blocks are extracted from over fifty quarries in the region. In this study, investigations and evaluations of experimental test results of travertine samples from six areas (Kakl?k–Kocaba?, Honaz–Emirazizli, A?a??da?dere, Akköy, Karaçay and Çivril), which represent the entire Denizli basin, are presented. Kakl?k–Kocaba? is the biggest production area in the region, and therefore most of the quarries are located in this area. Physical, mechanical, micro-structural and macro-structural properties of the travertine samples are evaluated within the scope of stone quality assessment. Variations of test results by area are presented, and correlations between them are proposed. Test results are also compared with the results of various studies from Turkey and other parts of the world.     

Sawing of blocks of siliceous dimension stone: influence of texture and mineralogy

The sawing of granite blocks using multi-blade gangsaws and an abrasive mixture is one of the most complex operations in the rock transformation industry. The surface quality of the finished slabs is the major determinant of the volume of material to be removed in subsequent polishing operations, thus influencing the final cost of the product. To determine this quality, a portable piece of equipment which records direct measurements of the roughness of the slab surface was developed. The measurements were carried out on two types of granite slabs of high commercial value. These granites showed mineralogical similarities, but great differences in cutting speed and the cost of the industrial process. The paper discusses the results in relation to Knoop hardness, Amsler wear, deep abrasion and petrography and concludes that the texture of the rock has the most important influence on the cost of production of polished slabs.      

采用VC＋＋编程对石材大板表面轮廓提取的研究

本文采用CCD摄像机、图像采集卡和计算机来实现非接触测量系统的硬件搭建,构成了基于CCD技术的石材大板在线测量系统,解决了天然石材传统接触式尺寸测量方法的缺陷。由CCD采集的彩色石材大板图像通过图像处理技术并结合vc＋＋编程实现了图像灰度变换、平滑处理、图像分割和数学形态学处理过程,快速完成了石材大板表面轮廓提取,为进一步对石材大板表面尺寸在线测量提供了理论和实践基础。     

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.     

基于不规则块体几何指标的藏式毛石墙体抗震性能研究

为量化不规则毛石墙体几何指标(块体形状、块体尺寸、水平和竖向接缝)对其抗震性能的影响,对3片1/2缩尺的传统藏式毛石墙体进行低周往复荷载试验,获得其典型破坏形态、滞回曲线、骨架曲线等抗震性能参数。基于藏式毛石墙体的不规则构造特征和块体形状,结合灰色理论建立不规则块体面积、周长等9个形状参数与墙体地震响应特征的关联度。研究结果表明：低周往复荷载下块材几何尺寸对墙体抗震性能的影响最大;大块石组砌的墙体抗剪刚度和承载力均较大,且墙体规则性和质量等级较好、抗震性能更优。确定了量化藏式毛石墙体抗震性能的几何指标的方法,可用于评价藏式毛石墙体的基本受力性能。     

Seismic performance analysis of Tibetan rubble stone walls based on irregular block geometry indexes

为量化不规则毛石墙体几何指标(块体形状、块体尺寸、水平和竖向接缝)对其抗震性能的影响，对3片1/2缩尺的传统藏式毛石墙体进行低周往复荷载试验，获得其典型破坏形态、滞回曲线、骨架曲线等抗震性能参数。基于藏式毛石墙体的不规则构造特征和块体形状，结合灰色理论建立不规则块体面积、周长等9个形状参数与墙体地震响应特征的关联度。研究结果表明：低周往复荷载下块材几何尺寸对墙体抗震性能的影响最大；大块石组砌的墙体抗剪刚度和承载力均较大，且墙体规则性和质量等级较好、抗震性能更优。确定了量化藏式毛石墙体抗震性能的几何指标的方法，可用于评价藏式毛石墙体的基本受力性能。     

Characteristics and the environmental acceptability of the natural stone quarrying waste rocks

The paper summarises the results of a study by the Geological Survey of Finland on the potential use of waste rocks from natural stone quarry production. Petrographic, chemical, mechanical and physical tests were undertaken on granite, rapakivi granite, migmatite, syenite, diorite, gabbro, anorthosite gabbro, schist and soapstone from 33 dimension stone quarries in Finland. The results indicate the waste rocks of Finnish natural stone quarries can generally be considered environmentally sound with potential uses in other industries.     

Architectural vanguard stone

The modern and updated use of traditional materials in the building industry often proves to improve the performance of the buildings through the economy of management, duration, conditions of comfort and safety, appearance and shelf life. Within this problem a search has allowed us to verify a new building procedure based on the use of reinforced masonry with blocks of natural stone and steel bars and mortar. Then a new phase of research has defined the building procedure of prestressed reinforced masonry with dry-assembled blocks of natural stone. This paper reports the results from a test phase of the research relating to the execution of a full-scale prototype of a panel, with a curved shape, called “stone sail”. This testing allows us to verify the real feasibility of the new building procedure.     

Investigating on possible use of Diyarbakir basalt waste in Stone Mastic Asphalt

Stone Mastic Asphalt (SMA) improved for road construction which has been utilized in Europe and America for 40 years is a rather new process in Turkey. SMA basically consists of 93–94% aggregate and mineral fillers, 6–7% bitumen and additives. Road and construction industry consume stone in large amounts. Stone used are obtained from nearby quarries and carried to the location where they are to be used, destroying the nature and causing large costs. The constantly increasing demand on quarries harms the general structure of the earth thus causing the emergence of large scale environmental problems. The use of basalt waste from stone processing plants as aggregates and mineral filler in SMA might help to meet this increasing demand thus solving environmental problems. In this study, primarily some important material properties of fine and coarse basalt waste, taken from basalt processing plants in Diyarbakir, such as sieve analysis, chemical analysis, specific gravity, water absorption, Los Angeles abrasion loss value, soundness of aggregate by Na₂SO₄, flakiness index and stripping strength were determined. Then by using this waste material, a SMA was designed according to Turkish Highway Technical Specifications. Marshall stability and flow tests have been carried out on designed SMA specimens. Test results indicate that properties of the basalt waste and the SMA produced were within the specified limits and that these waste materials can be used as aggregates and mineral filler in SMA.     

某电站淤泥质壤土与含块碎石土振冲施工对比

针对仁宗海水库电站坝基采用振冲碎石桩进行处理，在施工中出现了参数特征变化较大等情况，通过现场试验，对第⑦层淤泥质壤土与第⑥层含块碎（卵）石土施工特征进行对比，对施工质量进行了定性评价，以指导现场施工。     

钢筋网改性砂浆加固石楼板受弯性能试验研究

由于石楼板受弯承载力低且常存在天然裂隙,极易脆断,存在安全隐患,应对其开展加固技术研究.提出采用钢筋网改性砂浆加固石楼板受弯承载力计算方法,开展了5个钢筋网改性砂浆加固石楼板试件和1个未加固的对比试件的受弯性能试验.研究了加固砂浆种类、钢筋类别和配筋率对加固效果的影响.试验结果表明:复合加固石板的破坏类似适筋梁的延性弯...     

石材加工过程中的磨轮磨损研究

高档装修对石材制品的形状和尺寸精度要求愈来愈高，一些数控和自动化的设备进入石材加工业。磨削是石材加工中保证产品形状和尺寸精度的主要因素，也是制约加工效率的关键工艺。本文通过实验，找出刀具磨损的原因，并给出磨轮在花岗石磨削过程中的半径补偿值，以指导实际生产，提高生产效率和加工精度。     

石屑代砂混凝土配制技术探讨

本文根据石屑的颗粒形态和级配情况。提出在配合比设计过程中采用细砂与石屑相掺,调整砂的细度模数。针对石屑中粗颗粒较多的特点。采用简单的数学公式。对砂率进行调整．使配制的混凝土具有良好的工作性能。     

振冲碎石桩施工质量控制

就振冲碎石桩施工质量中的水、电、石料等三要素的控制提出了建议，指出振冲碎石桩施工的全过程自动控制监测装置对保证施工质量，减少人为因素，实现振冲碎石桩施工的质量控制监测自动化具有重要意义。     

石材旋转楼梯栏河的加工

本文针对现阶段各大宾馆运用石材旋转楼梯进行装饰越来越广的现象，介绍了一种旋转楼梯栏河的加工工艺流程，指出了其中螺旋面加工时存在一些误差，导出了系列用数控串珠绳锯近似加工螺旋面的方便、实用的计算公式，并用实例计算说明这种新方法的应用。     

Factors affecting slab surface roughness of siliceous dimension stones

The sawing of granite blocks using multi-blade gangsaws and an abrasive mixture is one of the most complex operations in the rock transformation industry. The surface quality of the finished slabs is the main determinant of the volume of material to be removed in subsequent polishing operations, thus affecting the product’s final cost. Measurements carried out on five types of siliceous dimension stone slabs showed differences in sawing speed and industrial process costs. The roughness values obtained, together with the test results for the uniaxial compressive strength, Amsler wear, sawability, coefficient of dynamic friction and petrographic analysis, showed that the rock texture has the most important influence on the production cost of polished slabs.     

斜石拱桥拱轴线公式的推导及其应用

针对石拱桥拱圈在设计施工中出现的技术问题,研究了石拱桥质量通病的各种诱发因素,主要通过对道路石拱桥质量通病的成因及防治措施进行分析,得出石拱桥工程病害的四种破坏机理与模式,最后主要针对斜石拱桥拱轴线公式应用数学知识归纳推导和论证,为设计和施工提供了技术保障。