I.Stone and stone waste
Stone has been used as a building material for thousands of years. It has long been recognised as a material of great durability and low maintenance with high thermal mass. It is versatile, available in many shapes, sizes, colours and textures, and can be used for floors, walls, arches and roofs.
As a high-grade architectural decoration material, stone materials are widely used in indoor and outdoor decoration design, curtain wall decoration and public facilities construction. At present, the common stone is mainly divided into natural stone and man-made stone, marble. Natural stone is divided into two kinds of slate and granite according to the quality of physicochemical properties. Man-made stones are divided into terrazzo and synthetic stones by operation. Terrazzo is made of cement, concrete and other raw materials forging; Synthetic stones are made from crushed stones of natural stone as raw material and adhesive, etc. Since the latter two are man-made, the strength is not as high as the value of natural stones.
II.Multipurpose use of stone waste
In the past ten years, construction stone processing industry has developed rapidly, however，most of the waste through landfill and waste to the local water are contaminated, and occupy a lot of land, how to effectively use these stone wastes has become an urgent problem.
In view of the high silica content in the wastes of stone (granite and basalt), it can be used as the main siliceous material for the preparation of autoclaved aerated concrete blocks. Marble waste is not suitable for preparation because of its low silicon content.
The preparation of B06 grade autoclaved aerated concrete block with basalt waste is economical and applicable. The formulation and result of batch production are as follows:
table 1:
formulation | basalt | lime | cement | Gypsum | aluminite powder | ratio of water to material | Compression strength Mpa | dry density kg/m3 |
1 | 65% | 17.2% | 12.8% | 5% | 0.06% | 0.41 | 5.9 | 715 |
2 | 70% | 18% | 7% | 5% | 0.08% | 0.42 | 4 | 606 |
B05 grade autoclaved aerated concrete blocks are prepared from granite waste. The main design formulas are as follows:
table 2:
formulation | granite | cement | lime | Gypsum | aluminite powder | ratio of water to material | compression strength Mpa | dry density kg/m3 |
1 | 64% | 11% | 23% | 2% | 0.09% | 0.6 | 3.9 | 495 |
III.Project Application
With the development of waste stone material, the technology of autoclaved aerated concrete is becoming more and more mature, and mass production has achieved good economic and social benefits. Many enterprises aimed at the market, seize the opportunity of development, which have carried out the two processing and reuse of stone waste.
1. In May 2013, Yunfu City Beijiang Building Materials Co., Ltd. and KEDA SUREMAKER reached an agreement with an annual output of 300,000 m³ AAC and panel production line;
2. In March 2017, Ningbo Heiner Energy-saving Wall Materials Co., Ltd. and KEDA SUREMAKER reached an agreement with an annual output of 300,000 m³ AAC block and panel production line
IV．Appendix
1. Guangdong province Yunfu Pui Rong Building Materials Co., Ltd. (hereinafter referred to as "PUI-Rong Building Materials Company") is a subsidiary of Jiangxi Pui-Rong Building materials group, which is a professional company that engaged in AAC blocks and panels, commercial concrete, pre-mixed mortar and other new types of environmental protection building materials development, production and sales. PUI-Rong Building Materials Company covers an area of about 102 acres is located in Yunan, GuangDong Privince, with a total investment of 150 million RNB with an annual output of 300,000 m3 AAC blocks and plate production. The first phase of project investment is about 102 million RNB. Company uses granite scrap as the main raw materials, plus some accessories processing, fully automated production lines.
2. Ningbo Haina Energy-saving wall material co., Ltd. (Hereinafter referred to as "Haina Company") is a subsidiary of Deli Group. Haina company is located in Ningbo， ZheJiang Province, which was founded in February 9, 2017 with a registered capital of 40 million RNB. The company is mainly engaged in autoclaved aerated concrete block and panel business activities, which is expected to reach annual output of 300,000 m3. The establishment of Haina Company marks the Deli Group with the policy support formally entered the field of wall materials to achieve diversified development of the group business.
