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Xu S.,Beijing University of Chemical Technology | Wang J.,Beijing University of Chemical Technology | Ma Q.,Chinese Academy of Cultural Heritage | Zhao X.,China National Petroleum Corporation | Zhang T.,Beijing Institute of Ancient Architecture
Construction and Building Materials | Year: 2014

In order to increase energy and resources utilization efficiency, and to find hydraulic mortars with improved properties, in this paper we employed diatomite as partial replacement of natural hydraulic lime NHL2 (NHL) and masonry waste powder (MWP) as aggregate in the preparation of mortars. Diatomite was used at 0%, 10% and 20% replacement by weight for NHL2 and the mortars were designed with different water binder ratios (w/b). The physical, mechanical, and anti-aggressive properties such as freeze and thaw, and acid and sulfate resistance properties of mortars were tested after 14, 28 and 90 days of curing. The introduction of diatomite reduced the density of mortars, and it also reduced the total amount of raw materials, especially the amount of NHL, to prepare same volume of mortars. Diatomite replacement generally enhanced the compressive and flexural strength of hydraulic mortars. The enhancement mainly happened after 14 days of curing when pozzolanic effect was noticeable. Diatomite replacement percentage and w/b influenced porosity, compactness and strength of mortars. There existed optimal diatomite replacement percentage and w/b for mortars to attain largest strength. The introduction of diatomite improved acid and sulfate resistance of mortars greatly. All the hydraulic mortars studied in this paper can still well develop strength under freeze and thaw condition. © 2014 Elsevier Ltd. All rights reserved. Source

Zhan G.,Iicc omos International Conservation Center Xian | Jin Z.,Chinese Academy of Cultural Heritage
Landscape Research | Year: 2015

Abstract: The Honghe Hani Rice Terraces, set in the mountainous slopes that flow to the valleys of the Hong River in the southern Yunnan Province, is a cultural product of rice farming. The rice terraces were created by a particular ethnic group that utilised the water and vegetation resources of their unique geography and climate. Today, after hundreds of years of cumulative effort, the terraces constitute a breathtaking cultural landscape. The rice production technology interwoven with the local people’s cultural spirituality and governance is a unique way of living that has been developing over a thousand years, creating and maintaining a spectacular landscape. The Hani Rice Terraces in the Honghe region of China’s Yunnan province was inscribed as a cultural landscape on the World Heritage List in 2013 for bearing a unique testimony to a cultural tradition and as an outstanding example of traditional human land-use. This study describes the unique property with its spatial structure of forest water and village terrace systems and discusses the physical factors that sustain this landscape. Indivisible from the landscape is the culture of the local Hani people, their land-use and management, along with their traditional practices and spiritual values that sustain the landscape. In recent years, this extraordinary, expansive region has become a popular destination for photographers, anthropologists, folklorists, ethnologists and scholars studying traditional villages. The study also raises issues on how the landscape can be maintained in contemporary times with tourism and modern living aspirations. © 2015 Landscape Research Group Ltd. Source

Li Z.,Lanzhou University | Li Z.,National Research Center for Conservation of Ancient Wall Paintings | Zhao L.,Lanzhou University | Zhao L.,National Research Center for Conservation of Ancient Wall Paintings | Li L.,Chinese Academy of Cultural Heritage
Science China Technological Sciences | Year: 2012

During 1970s, the residential remains of the Yangshao Period were discovered at the Dadiwan site in Qin'an County, Gansu Province, China. With carbon-14 dating, scanning electron microscope (SEM), thermal expansion analyzer, polarizing microscope (PLM), and X ray diffraction (XRD), the microstructures and chemical compositions of the pottery shard, floor materials of the housing site, kunkur, calcined kunkur, ginger nut (calcium concretion) from the Dadiwan site were analyzed and researched. Analysis and simulation tests were also carried out to study the hydratability of calcined ginger nut and calcined kunkur, and the manufacturing process of the residential floors. The research shows that the floor was made of a light concrete formed by the mixture of aggregate of calcinated ginger nut (locally deposited), red clay and kunkur. The dicalcium silicate (C 2S) from the floor material of the housing site is one of the main constituents of modern cement, and the floor is also similar to modern concrete in nature. Therefore, the floor material of the housing site at the Dadiwan site was the earliest man-made concrete in the world ever discovered. © Science China Press and Springer-Verlag Berlin Heidelberg 2012. Source

Yang F.,Zhejiang University | Yang F.,Tianshui Normal University | Zhang B.,Zhejiang University | Ma Q.,Chinese Academy of Cultural Heritage
Accounts of Chemical Research | Year: 2010

Replacing or repairing masonry mortar is usually necessary in the restoration of historical constructions, but the selection of a proper mortar is often problematic. An inappropriate choice can lead to failure of the restoration work, and perhaps even further damage. Thus, a thorough understanding of the original mortar technology and the fabrication of appropriate replacement materials are important research goals. Many kinds of materials have been used over the years in masonry mortars, and the technology has gradually evolved from the single-component mortar of ancient times to hybrid versions containing several ingredients. Beginning in 2450 BCE, lime was used as masonry mortar in Europe. In the Roman era, ground volcanic ash, brick powder, and ceramic chip were added to lime mortar, greatly improving performance. Because of its superior properties, the use of this hydraulic (that is, capable of setting underwater) mortar spread, and it was adopted throughout Europe and western Asia. Perhaps because of the absence of natural materials such as volcanic ash, hydraulic mortar technology was not developed in ancient China. However, a special inorganic-organic composite building material, sticky rice-lime mortar, was developed. This technology was extensively used in important buildings, such as tombs, in urban constructions, and even in water conservancy facilities. It may be the first widespread inorganic-organic composite mortar technology in China, or even in the world. In this Account, we discuss the origins, analysis, performance, and utility in historic preservation of sticky rice-lime mortar. Mortar samples from ancient constructions were analyzed by both chemical methods (including the iodine starch test and the acid attack experiment) and instrumental methods (including thermogravimetric differential scanning calorimetry, X-ray diffraction, Fourier transform infrared, and scanning electron microscopy). These analytical results show that the ancient masonry mortar is a special organic-inorganic composite material. The inorganic component is calcium carbonate, and the organic component is amylopectin, which is presumably derived from the sticky rice soup added to the mortar. A systematic study of sticky rice-lime mortar technology was conducted to help determine the proper courses of action in restoring ancient buildings. Lime mortars with varying sticky rice content were prepared and tested. The physical properties, mechanical strength, and compatibility of lime mortar were found to be significantly improved by the introduction of sticky rice, suggesting that sticky rice-lime mortar is a suitable material for repairing mortar in ancient masonry. Moreover, the amylopectin in the lime mortar was found to act as an inhibitor; the growth of the calcium carbonate crystals is controlled by its presence, and a compact structure results, which may explain the enhanced performance of this organic-inorganic composite compared to single-component lime mortar. © 2010 American Chemical Society. Source

Xu S.,Beijing University of Chemical Technology | Wang J.,Beijing University of Chemical Technology | Sun Y.,Chinese Academy of Cultural Heritage
Materials and Structures/Materiaux et Constructions | Year: 2015

In order to study the effect of the water binder ratio (w/b) on the early hydration of natural hydraulic lime (noted NHL), NHL pastes with 0.3, 0.5, 0.7 w/b were prepared and cured at 25 °C and 70 % RH. The composition, the structure, the morphology and the porosity of each sample at 1 h, 10 h and 3 days curing ages were studied by X-ray diffraction, thermogravimetry, infrared spectroscopy, scanning electron microscopy with EDS and mercury intrusion porosimetry. The results show that, at early hydration within 3 days, calcium silicate hydrates (CSH) appear in all the pastes, the w/b affects the hydration rate and the hydration of three kinds of w/b pastes mainly occurs within the first hour of curing. The carbonation rates of Ca(OH)2 and CSH in lime pastes both exhibit downward trend with an increase in the w/b. The morphologies of hydration products (CSH) differ with the w/b of the lime pastes and there exists a growth process for CSH when the curing period increases. To conclude, the w/b has a big influence on hydration of NHL and the chemical analysis on grouts may give a basis for the optimization of the grouting parameters. © 2014, RILEM. Source

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