1 Characteristics of antique bricks based on silica aerogel preparation technology

First, the antique brick material that incorporates the properties of silica aerogel has obtained higher characteristic upgrades on the basis of traditional antique brick materials, such as better waterproof and breathable, lighter, stronger, chemical resistance, Cold resistance, shock resistance, crack resistance, etc. Second, the transportation safety performance is greatly improved. The antique brick is different from other ancient building repair materials. The texture of the antique brick is stronger, and the material damage caused by road bumps is avoided during transportation. Third, the silica aerogel antique brick can change its shape at will, which can play a better material advantage at the restoration site, and can also be quickly cloned according to the texture characteristics of the original material of the ancient building, so as to show the same texture and color as the ancient building. . Fourth, the antique brick material can be constructed quickly, and the material can be covered and pasted more conveniently on the premise of ensuring that the wall structure is not damaged. Fifth, the production process of silica aerogel antique bricks all use clean energy and will not produce any pollution emissions. Sixth, the radioactivity and soluble lead and cadmium content of silica aerogel antique bricks are far below the national standard.

2 Silica aerogel antique brick production and preparation process

2.1 Silica aerogel antique brick production formula

10-20 parts of silica aerogel powder, 10-15 parts of magnesium silicate, 10-15 parts of calcium silicate, 25-35 parts of silicone-acrylic emulsion, 10-25 parts of magnesium hydroxide, 0.5-2 parts of inorganic pigment , 20 to 35 parts of sulfoaluminate cement, mesh cloth woven from polyester containing silica aerogel (hereinafter referred to as mesh cloth), 15 to 30 parts of quartz sand, 2 to 5 parts of coupling agent, waterproof dose 0.5 to 1 serving.

2.2 Silica aerogel antique brick production process

Mix the silicone-acrylic emulsion, inorganic pigment, coupling agent and water repellant fully to obtain mixed solution A; in terms of color ratio, the selection of inorganic pigment is based on the color of the original wall, and the silica aerogel powder is mixed. , calcium silicate, magnesium hydroxide, sulfoaluminate cement, quartz sand and magnesium silicate are fully mixed to obtain solid mixture B; mixture B is poured into mixture A and fully mixed, and mixture C is obtained after mixing evenly.

Put the mixture C in the mold, the depth is 1-10mm, the mesh size is 20-40 mesh, and then add the mixture C, the thickness is 1-3mm, and the thickness is required to be uniform. After that, it is sent to the drying room. The temperature of the drying room is 40-60 °C and the time is 4-10 hours. If there are picture bricks (picture stones) on the ancient wall that need to be copied, rubbing moulding, clay rubbing moulding and other methods can be used to make moulds. If the original image brick (image stone) is damaged, the incomplete part can be composed according to the cultural relic restoration method to make a mold; while the antique brick is not solidified, it is pressed, copied into image brick (image stone), and then put into steam curing equipment for further curing , the temperature is 120 ~ 200 ℃, the time is 1 ~ 2h, and then the temperature is lowered for steam curing, the temperature is 70 ~ 100 ℃, and the time is 4 ~ 6h.

experiment one:

① Mix 25 parts of silicone-acrylic emulsion, 0.7 parts of inorganic pigments (0.1 parts of Fe3O4, 0.6 parts of TiO2), 3.5 parts of coupling agent, and 0.6 parts of waterproofing agent, and fully stir and mix to obtain mixed solution A.

② Fully mix 12 parts of silica aerogel powder, 10 parts of calcium silicate, 10 parts of magnesium hydroxide, 20 parts of sulfoaluminate cement, 16 parts of quartz sand, and 10 parts of magnesium silicate to obtain B , and poured into the mixture A for stirring to form a homogeneous mixture C.

③ Arrange the grid in the mold, pour the mixture C and tamp it, the thickness is 3mm, and the thickness is uniform.

④ Send it to the drying room, the temperature of the drying room is 40 °C, the time is 6 hours, then put into the steam curing equipment for further curing, the temperature is 180 °C, the time is 1 hour, the temperature is adjusted to 90 ° C, and the steam curing equipment is removed after steam curing for 5 hours. , the finished product is obtained.

Experiment 2:

① Mix 30 parts of silicone-acrylic emulsion, 1.5 parts of inorganic pigments (Fe2O3, H2O), 3 parts of coupling agent, and 0.8 part of water repellant, and fully stir and mix to obtain mixed solution A.

② Mix 18 parts of silica aerogel powder, 12 parts of calcium silicate, 10 parts of magnesium hydroxide, 25 parts of sulfoaluminate cement, 16 parts of quartz sand, and 12 parts of magnesium silicate to obtain B, And poured into the mixed solution A for stirring to form a homogeneous mixture B.

③Pour the mesh into the mold and tamp the mixture, the thickness is 5mm, and the thickness is uniform.

④ Send it to the drying room, the temperature of the drying room is 40 °C, and the time is 4 hours. After that, it is pressed into the desired pattern with a prefabricated mold, and then put into the steam curing equipment for further curing. The temperature is 160 °C and the time is 1.5 hours. Adjust the temperature. To 70 ℃, after steaming for 6 hours, remove the steaming equipment to obtain the finished product.

3 Technical parameters of silica aerogel antique brick

The product is composed of inorganic powders such as soil, stone powder, sand, and cement waste blocks and modifiers, and the product density is 2327kg/m3. After inspection, the combustion performance of the product meets the requirements of class A, and the additional classification meets the requirements of class s2, d0, and t0. According to GB 8624-2006, the combustion performance of this product reaches A2-s2, d0, t0 grades (Table 2).

Summarize

At this stage, a variety of silica aerogel products have entered the market one after another, and the application of silica aerogel is becoming more and more mature. However, it is necessary to continue to explore the integration of silica aerogel materials in the protection of ancient buildings. , and the entire industry needs to work together to perfect the silica aerogel protective material based on the characteristics of ancient buildings. In addition, in addition to the research on its own characteristics, the research on silica aerogel materials must further reduce the cost and improve the cost performance of the material, so as to effectively promote its market development, which is also more conducive to the application in the field of ancient wall protection. and research.