The Degradation Mechanism And Protection Of The Han Dynasty Brick

The Han Dynasty brick is a precious cultural heritage of the world. But after has been buried for about two thousand years in the ground, it was destroyed by the humid environment in the cemetery, such as groundwater, and the chemical constituents of soil. The brick has been seriously damaged in essence.At present, the methods to protect the brick were limit to clean and desalinate, study rarely on the degradation mechanism in-depth. Some bricks become loose and fragile during keep in the museum, lost its heritage value. So study from the microscopic to learn the degradation mechanism, and made a reasonable measure of protection is very importance.In this thesis, we use the discarded pieces as the object, XRD, scanning electron microscope, energy spectrum analysis methods had been used to analyze the Han Dynasty brick's microstructure and mineralogical properties. We used some our country's clay brick standardization measures to analyze the hydraulics, anti-salt capability, anti-freeze capability, and contrasted with the modern black and red bricks performance. We studied the mechanism of damage from the microcosmic of the bricks.The Experiments results show that, the Han Dynasty brick after more than two thousand years burial experience, it was destroyed by the humid environment in the cemetery, micro-organisms and some other factors. On the surface of the brick there is much gypsum, this is the most important reason of the brick's degradation. In addition the destruction of micro-organisms and the migration of soluble salts within the pore size, made the water absorption increase, its resistance, salt resistance, anti-freeze turned to more poor than before.So we use a new protecting material of organ silicon, which has many advantages on protect the loose, porous objects. On the base of some related references and the work of my colleague, we improve the process of synthetic organic silicon paint, leave the y -glycidoxypropyltrimeth-oxysilane (KH560) and the γ-methylacryl-oxypropyltrimethoxysilane (KH550) react at the room temperature. We get the best experiment condition via judging of the organ silicon film performance. The results show that the best condition is KH560:KH550:H2O=10:1:2.4(volume ratio), using thick hydrochloric acid as catalyst, the dosage is 1-2 % of all the reactants.We use the protective agent to protect the Han Dynasty bricks. The study shows that: the Han Dynasty brick still has good air permeability performance, and its strength, salt resistance, anti-water capability, anti-freeze capability are increase deeply.The experiment also studied the reciprocity between the protective agent and the brick material.