Clean sand paradox

The washed sand selected for construction has shown outstanding advantages over unwashed sand.
The durable buildings built in the early 19th century with a lifespan of over 100 years are all contributed by the use of hand-washed sand as one of the materials to help ensure the quality of the works. , the use time of the work contributes to a great reduction in construction costs instead of using it for 30-40 years to rebuild.

Contribute to protect the environment On August 18, 2020, the Prime Minister signed and promulgated Decision No. 1266 approving the strategy for development of building materials in Vietnam in the 2021-2030 period, with a vision to 2050. Accordingly, provinces and cities must minimize the impact on the environment in the process of mining and processing minerals for building materials (building materials) and production of building materials. Using advanced mining technology combined with washing and removing impurities to improve sand quality Promote and encourage all economic sectors to invest in and develop the building materials industry; the fastest access and application of scientific and technological achievements; to develop an efficient and sustainable building materials industry to basically meet domestic demand, step by step increase exports; to encourage investment in research and transfer of production technology for processing lines of crushed sand, sea sand, salt water sand, brackish water sand, fine sand into sand qualified for use in concrete and mortar. “Do not use river sand that meets technical standards for concrete as a leveling material; do not export construction sand extracted from nature; promote the production and use of brackish water, fine sand, and sea sand. together with technical solutions; using advanced mining technology in combination with washing and removing impurities to improve sand quality; waste generated during sand treatment must be collected and stored properly. techniques or reuse; sand mining and processing establishments must meet standards and technical regulations on environmental protection; must carry out environmental rehabilitation and restoration in accordance with the law on mining. , sand processing…”, Decision 1266 stated. Increase project life The Ministry of Construction has submitted to the Government for issuance of Decision 1266, in which Appendix X on sand of the decision states: “For natural sand: Using advanced mining technology combined with washing and removing impurities. to improve the quality of sand,…”. Using clean sand contributes to environmental protection, limiting riverbank and coastal erosion Natural sand sources include hill sand, river and stream sand, estuary sand, dirty fine sand, etc., which have not been washed, so there is still a lot of dust, mud, clay, organic impurities, etc., which are harmful substances to the calf. cardboard and mortar, so often used for leveling is very wasteful. In particular, estuarine sand and sea sand with Cl- ion salt content in the sand > 0.05% cannot be used for leveling and must be discarded, causing waste. Currently, there are enterprises in the country that have successfully researched, manufactured and applied the technology of washing hill sand, river sand, sea sand, dirty sand to produce clean sand for concrete and mortar that meets TCVN 7570 standards: 2006, when applying technology, will make full use of special sand resources, contributing to rational use of sand resources and overcoming sand scarcity. Talking to the press, architect Tran Thanh Tong – Director of Tran Giang Planning and Architectural Design Consulting Co., Ltd (Can Tho City) – said that over the past 10 years, the company has always used clean sand in accordance with the law. Phan Thanh technology for all construction works. Works using clean sand have a slight increase in cost compared to dirty sand, unwashed sand, but in return, works using clean sand are very durable, beautiful, and have a much longer life than using dirty sand. , sand is not ready to wash. According to Mr. Vo Tan Dung, the inventor of the sand washing technology of Phan Thanh Can Tho Company, in fact, when exploiting sand from Tien and Hau rivers in combination with a cleaning factory in the spirit of Appendix X of Decision No. 1266/QD-TTg dated August 18, 2020 of the Prime Minister will help the cost of sand in construction to be converted lower than the cost of using unfiltered sand about 115,000 VND/m3 of sand (cost of The cost of selecting and washing sand at the mine and loading and unloading the sand onto the barge costs at most: 50,000 VND/m3; meanwhile, the cost of sieving through manual nets but not clean: 60,000 VND/m3, 10% impurities including sand and transportation loading and unloading to the construction site but cannot be used, the minimum cost is: 25,000 VND/m3, over 10% of the cement cost, equivalent to about: 80,000 VND when using 1m3 of sand for concrete and mortar). People are used to using unfiltered sand to clean it is paradoxical because in concrete and mortar, there is still too much dust, mud, clay, organic impurities, harmful to the house, and using clean sand when re-cleaning is less expensive and reduces costs. construction cost compared to using unwashed sand. For example, converting sand containing 10.5% impurities, concrete grade 250 will be mixed with 9.06 kg of impurities/bag of cement 50 kg and if sand with 5% impurities, concrete grade 250 will be mixed 4.2 kg. impurities/bag of cement; mortar grade 100 if the sand 10.5% impurities are mixed 17.47 kg of impurities/1 bag of cement and mortar grade 100 if the sand 5% impurities in the sand are mixed 8.32 kg of impurities/bag cement. In addition, using clean sand contributes to quality assurance, so you don’t have to spend too much money on painting many times to waterproof, reduce maintenance costs, etc. In particular, the lifespan is hundreds of years compared to using sand without passing. After a few decades, the construction must be demolished and rebuilt, causing damage of several tens of % of the total value of the work. Therefore, the promulgation of Decision 1266/QD-TTg dated August 18, 2020 of the Prime Minister is practical, especially sand resources will be improved in quality by removing harmful impurities when being washed. clean, contributing to the rational use of sand resources, overcoming the scarcity of sand and ensuring sustainable construction quality for the entire population.