In our country, the demand for building materials has increased speedily within 5 years: from 10% to 12% on average. According to the development program for non-baked building materials, period 2008 – 2020, from 2011, all skyscrapers having more than 9 floors must use at least 30% light non-baked materials.  

According to the Master plan for Vietnam building material development to 2020, demands for building materials in 2010, 2015, 2020 are correspondingly 25, 32, 42 billion brick equivalent units, in which, the proportions of non-baked material are 10%, 15 – 20% and 30 – 40%, respectively.

According to  Pham Van Bac, Deputy director of Building Material Department, Ministry of Construction, the Master plan for Vietnam building material development to 2010 set a target that total amount of non-baked material would reach 20% and 30% in 2005 and 2010 respectively. However, the figure was just 8% - 8.5% in 2008.     

Building materials from …waste

 According to Mr. Bac, 32 billion bricks will be used in 2015 and 42 billion bricks in 2020; that will be equal to 60-64 million m3 of clay and 3,200ha of agricultural land. It requires six million tons of coal to bake these bricks which emits 23 million tons of carbon dioxide.

Non-baked brick is made from industrial waste such as ash and cinder of thermal power stations and metallurgy factories, quarry fines in building stone exploiting mines and red mud from bauxite factories. Statistics shows that from 2015 to 2020, 50-60 million tons of waste matter is discharged which can cause serious harm to the environment. However, with this amount of waste matter, 40 billion bricks could be produced.

In addition, non-baked building materials are much slighter than other kinds of materials that can help reduce base expenditure. Therefore, non-baked materials are very suitable for construction works in weak land areas.

Materials used in producing light materials are various, from simple things like ash, cinder, gypsum refuse, industrial “mud”  to toxic things like emissions from metallurgy and electric industry.  Scientists could make use of them all to create “green” building materials.

Dr. Nguyen Hong Binh, HCMC Institute for construction Science and technology claimed that using “mud” – toxic emission from industry to create concrete is a significant achievement in recycling technology. Economic “mud” including toxins (lead, mercury, cadmium, …)  after being deodorized would be mixed into powdered stone accompanied with solidification substances. This process would create a type of concrete which has similar toughness as the normal concrete; moreover it is “greener” and not harmful to people. 

Various benefits
Development in production and consumption of non-baked building material to replace traditional baked bricks would save agriculture land and coal, bring economical benefit to society and reduce polluted emissions. Especially, this process would take part in reducing processing cost by consuming a large amount of junk from thermo-electricity, metallurgy …

According to Mr. Bac, in 2020 the total amount of waste (including ash and cinder) of electricity industry and metallurgy is predicted to be 45 million tons. This huge mass would take away 1,100 hectare to contain. Using light building material would free these occupations and also reduce construction load, hence save materials on foundation and load bearing frame. This action also quickly speeds up the industrialization progress.

Recently, the use of non-baked materials in construction has become a global trend. For example, in the UK and China, the percentage of non-baked materials in building material accounts for 55-60 percent of construction. However, in Vietnam, this figure is only 8-8.5 percent.

According Decision No. 121/2008/QĐ-TTg on the development program for non-baked building materials by the Prime Minister, Vietnam is striving to use 23-25 percent of non-baked materials in 2015 and 30-40 percent in 2020. From 2011, construction works which have more than nine floors must use at least 30 percent of slight non-baked materials and amount of non-baked material must be below 1,000kg/m3.

Trong Nhan