I know geopolymer such as slag and fly ash are used to reduced shrinkage in OPC, instead of using these 2 materials, any other options from geopolymer materials??
Blending of ground granulated blast furnace slag (GGBFS) with low-calcium fly ash can have significant effects on the setting and early strength development of geopolymers cured at room temperature. If class F fly ash is replaced with 10% or 20% GGBFS and the sodium silicate to sodium hydroxide (SS/SH) ratio is kept between 1.5 to 2.5. Shrinkage of geopolymer and ordinary Portland cement (OPC) concrete mixtures cured at room temperature are studied and comparisons made between the shrinkage behaviours of geopolymer concretes with different mixture proportions and those of the OPC concrete. It can be found that shrinkage decreases with the increase of slag content and decrease of SS/SH ratio in geopolymer concrete cured at room temperature. The shrinkage of geopolymer concrete up to the age of 180 days is found to be comparable to that of OPC concrete of similar compressive strength.
Adding some finer such as CFRP GDP could aid the durability feature of the concerts.
Debasish Mondal thanks for your answer. The activator i used was sodium carbonate and sodium silicate. and i have silica fume. The slag content i used was optimize until i get the optimum strength, so it is difficult for me to reduce the slag content. I worry the strength would be affected.
Hello Tan Leng Ee @ . There are a few ways. 1) You can use other sources of aluminosilicates, such as fly ash or metakaolin, along with slag. 2) In the alkaline solution, the ratio of sodium silicate to sodium hydroxide should close to 1 or 1.5, although it leads to a decrease in mechanical properties. 3) Another way is to use polypropylene fibers, glass and carbon. 4) You can use 10 to 20 percent microsilica. If the shrinkage is still visible, use 6% gypsum. 5) The use of bubble wrappers and water reducing agents can also be effective. 6) The treatment(curing) of samples within the autoclave is effective in reducing the shrinkage for 360 minutes. 7) Although the optimum ratio of alkaline solution to the slag powder is 0.45, it is better to reduce dry shrinkage this number increase up to 0.6
water-repellent additives highly effective in reducing drying shrinkage
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