Feasibility Study on Fabrication of Geopolymer Bricks by Wasted Grinding Wheel at Room Temperature

In this study,the feasibility of producing eco-friendly bricks by using geopolymer technology and a waste grinding wheel(WGW)from the grinding wheel industries was investigated.Nowadays,in order to meet industrial needs,for instance,in Taiwan,approximately 500,000 grinding wheels are used annually.That is,a large number of“waste”grinding wheels are produced.Furthermore,few studies have been conducted on the use of WGWs as raw materials in geopolymer applications.The use of geopolymer technology to form bricks can avoid the utilization of clay and cement and even prevent the use of a high-temperature process in kilns.Moreover,it can decrease CO_(2) emission and energy consumption and thus,protect the environment.In this study,the following three major factors were considered:press-forming pressure(70 and 100 kgf/cm2),NaOH molar concentration(2 and 4M),and the ratio of binder fineaggregate(1:3,1:4,and 1:5).Under these conditions,the specimens were tested using the compressive strength test,water absorption test,microstructure analysis,a freezing–thawing test and toxicity characteristic leaching procedure test.The optimal formulation was composed of 1:4 binder fine-aggregate ratio,4M NaOH concentration,and 100-kgf/cm2 pressure.Furthermore,we used a WGW and achieved a compressive strength of 50.6 MPa after 28 days,which was greater than 32 MPa and conformed to the Grade A brick standard of National Standards of the Republic of China(13295).In conclusion,this brick fabrication method based on geopolymer technology was not only beneficial to the environment but also improved the efficiency of reutilizing WGW.

Recycling Bayer and sintering red muds in brick production:a review

Red mud(RM)is a solid waste generated from the extraction of alumina from bauxite.It is estimated that more than1.5 billion tonnes of RM are produced annually worldwide.Stockpiling and landfilling of RM is toxic for the environment due to the presence of high quantities of alkali-generating minerals and metal ions.The high cost of RM treatment and limited land availability encourage the recycling and reuse of RM as construction materials.In many developing countries,brick remains the ubiquitous building material.Thus,it is reasonable to use brick as a medium to accommodate a large amount of RM.In this review,the properties of RM are analyzed and their applications in bricks are discussed.Two common types of RM,namely Bayer red mud(BRM)and sintering red mud(SRM),are introduced along with the methods to produce bricks from them through firing,cementing,and geopolymerization.High alkaline-based BRM is particularly useful as a raw material to produce fired brick and geopolymer brick,whereas SRM,which contains more dicalcium silicate(C_(2)S)and some cementitious phases,can be favorably used to produce cementing brick.RM geopolymer brick normally has more strength(up to 51 MPa)than fired and cementing bricks,and good durability(no efflorescence)with low energy consumption and CO_(2)emissions.Finally,several solutions have been suggested to resolve the issue of the radioactivity of RM brick,and strict regulation of its application has been imposed in some countries,such as China.