Experimental Study on Restoration Materials of Newly Earthen Ruins under Different Slaking Times
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Abstract:
The newly repaired Kaifeng City Wall has serious cracks, shedding and other issues on the surface, which constitute a significant problem. It is of great significance for the restoration of Kaifeng City Wall to explore the repair materials and techniques suitable for Kaifeng City Wall. The pH, particle gradation, compressive strength and SEM were tested on soil samples with different lime and MgO contents under different slaking times. With the increase of slaking time, the pH value first increased and then decreased. The relationship between pH value and strength showed three stages. The strength of lime-containing soil samples increased first, then decreased and then increased. The MgO content of soil samples showed an opposite trend. The particle gradation was significantly improved with increasing aging time. The main reason for the reduction of soil strength is the calcium carbonate crystals and magnesite microcracks produced by lime and MgO in the later stage of slaking.Keywords:
Gradation
Particle (ecology)
Magnesite
Magnesite is a very important non-metallic mineral.And it is widely applied in metallurgic,building materials,chemical industry and so on.Low grade magnesite can't be used directly as material of refractory,and as the continuously mining,the reserves of high grade magnesite becomes less and less.Therefore,for better utilization the resources,it is necessary to find a purification method,which is suitable for low grade magnesite.The research used the kind of low grade magnesite as the material.The high grade magnesite obtained contains more than 47% of MgO and less than 0.2% of SiO2 by flotation,the recovery ratio of magnesium oxide of concentrate is 76.25%.The results show the flotation flowsheet is applicable for the purification of the magnesite in Dashiqiao areas.
Magnesite
Refractory (planetary science)
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The physical characteristics of conventional lime mud from straw pulping process,the refined lime mud and the commercial precipitated calcium carbonate were investigated,and the potential of applying these mineral materials as filler was also studied.The results showed the refined lime mud with an average particle size of 6.36 μm,and about 82% particles less than 10 μm,which were similar to commercial precipitated calcium carbonate.However,the conventional lime mud had a wide size distribution,with an average particle size of 12.78 μm,and 66% particles above 10 μm.The refined lime mud had higher oil absorption and lower sedimentation volume.The effect of conventional lime mud and refined lime mud loading on paper properties were also investigated and compared with that of commercial precipitated calcium carbonate loading.The results showed that loading with refined lime mud and commercial precipitated calcium carbonate could increase paper whiteness,on the contrary,loading with conventional lime mud decreased the paper whiteness.The refined lime mud was found to impart good opacity,and the commercial precipitated calcium carbonate took the second place for improving opacity.The paper loaded with refined lime mud improved apparently in sizing effect and strength properties compared with conventional lime mud.Thus it can be concluded that the refined lime mud can take place of commercial precipitated calcium carbonate as filler,while conventional lime mud cannot be accepted as filler.
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Magnesite
Periclase
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Gradation
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Gradation
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In this paper, the influence of RAP state on warm recycled mixture gradation design was experimentally studied. Different kinds of mixture gradations with different content and state of RAP were synthesized. The concept of “variation degree of gradation” was proposed to quantify the uncertainty of the recycled mixture gradation. It was described as the different passing rate at each sieve size between the two kinds of gradations that respectively synthesized by using the RAP screening result of pre-extracting and post-extracting. Their properties were then tested and compared with each other. The results show that, when the variation degree of gradation is bigger, the state of RAP should be simplified to complete mixing state, that is to say, the recycling mixture gradation should be synthesized by using the RAP post-extracting screening result; but when it is smaller, the state of RAP could also be simplified to black aggregate state, i.e., using the RAP pre-extracting screening result to synthesize gradation is also feasible.
Gradation
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In the published article, there was an error in Figure 4 as published. The caption of Figure 4 in the published article is "Discrete model of 4 types of sands: (A) Gradation A; (B) Gradation A; (C) Gradation A; (D) Gradation (A)." The corrected caption of Figure 4 is "Discrete model of 4 types of sands: (A) Gradation A; (B) Gradation B; (C) Gradation C; (D) Gradation D."
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Two sections of pavement were built with different specifications for the gradation of the aggregates, one with the standard WSDOT specification and one with a combined gradation, to determine if the use of the combined gradation would result in a pavement more resistant to studded tire wear. The standard gradation can result in a gap-graded aggregate whereas the combined gradation produces a more uniform gradation. Wear rates calculated for the most recent data set collected in the fall of 2006 reveals no difference in wear rates between the pavements paved with the standard gradation versus those paved with the combined gradation.
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Gradation
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Gradation
Asphalt pavement
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