Search

This article presents a laboratory and field investigation of pull-out resistance of wood bolts in rammed earth heritages. The laboratory testing involved axial tensile tests of four grout specimens prepared in specially designed moulds using PS-F (Potassium Silicate solution-Fly ash) slurry to investigate the performance of anchors. The field testing involved pull-out tests of three wood anchors installed in rammed earth heritages by gravity grouting. Experiments reveal that the failure mode is the pull-out of bolt from grout and average skin friction resistance of bolt–grout interface is approximately 0.34MPa. Load–displacement curves and elastic–residual displacement derived from cyclic loading indicate such anchor system has strong ductility with small elastic deformation and large residual deformation. Bond collapse firstly occurs at the loaded end and then propagates towards the full bonded length. Bond stress distribution is not uniform along the bonded length. Maximum bond stress distributes at the range from 0.3 m to 0.4 m. Emergence of compressive strain in the interface reveals such anchor system enjoys the advantages of both tensile and compressive anchor types, which significantly differs from results from other regular bolts. The research conclusion makes scientific senses to traditional material and craft in rammed earth heritages. [ABSTRACT FROM PUBLISHER]

The work reported here is a systematic study to evaluate the compatibility of using PS-F (potassium silicate with high modulus – fly ash) slurry in the conservation of adobe structures. Firstly, the optimum mixing proportion (0.47) was determined by flow meter. Then the experimental program was divided into two parts: one part studied changes in physical and mechanical properties with increase in setting time by means of the measurement of moisture content, compressive and flexural strength, elastic-wave velocity, density, and porosity; the other part studied the durability of PS-F slurry through temperature and humidity cycles, freeze–thaw cycles, water stability, tensile testing, and alkali resistivity tests. The results show that the consolidation process with the slurry can meet the requirements of conservation applications and provide a timely anchoring force, and the slurry and soil mass of adobe-based structures have good compatibility in physical and mechanical properties. In addition, the slurry can strongly resist freeze–thaw cycles, temperature-moisture cycles, and tensile stress and has a relatively weak resistance to alkali solutions and water immersion. In conclusion, PS-F with a mixing ratio of 0.47 is a suitable slurry for conservation of adobe structures. [ABSTRACT FROM PUBLISHER]

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 (C2S) 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. [ABSTRACT FROM AUTHOR]

The Silk Road played an important role in the economic and cultural exchanges between central China, Europe and Central Asia. A number of heritage sites with significant values still remain throughout the Gobi Desert and other desert regions in Northwest China. Most of the heritage sites composed of adobeern materials and the earthen structures have been impacted by adverse environmental conditions for thousands of years causing severe damage with only a small proportion of the structures left surviving to the present day. Analysis of the main environmental factors affecting the heritage sites such as temperature difference, wind storms, rain storms, and the freeze-thaw process and a study of the mechanism of the deterioration are the main topics presented in this paper. The authors have concluded that a Potassium-Silica solution PS invented by one of the authors has been effective in improving the intrinsic properties of heritage site earthen structures with regard to reducing the impact of environmental damage. The results of comparative tests show that samples treated by using the PS solution have performed well, particularly in protecting structures from aeolian erosion and heavy rainfall. Some findings on the effect of PS treatment on earthen structures at heritage sites are discussed in detail in the present paper. [ABSTRACT FROM AUTHOR]

Mogao Grottos are located at the eastern foot of the Mingsha Mountain, 25 km southeast of Dunhuang City. The caves were excavated into the cliff on the west bank of the Daquan River. The wall paintings in the caves are subject to the severe deterioration generated by recrystallization of salt. It relates with the movement of water/moisture in rock formation. Through the satellite image analysis and geological survey, it has been clarified that the movement of ground water is governed by the fault system. The geographical nature is specified by the aggressive tectonic movement from the south. [ABSTRACT FROM AUTHOR]