Resistance to acid degradation,sorptivity,and setting time of geopolymer mortars  

作　　者：Osama A MOHAMED Rania AL-KHATTAB Waddah AL-HAWAT 

机构地区：[1]College of Engineering,Abu Dhabi University,Abu Dhabi,United Arab Emirates

出　　处：《Frontiers of Structural and Civil Engineering》2022年第6期781-791,共11页结构与土木工程前沿（英文版）

基　　金：This project was funded by the Office of Research and Sponsored Programs at Abu Dhabi University(Nos.19300460 and 19300643);The project is also funded by ASPIRE Award for Research Excellence(AARE),Abu Dhabi,UAE。

摘　　要：Experimental evaluations were conducted to determine the water sorptivity,setting time,and resistance to a highly acidic environment,of mortar with alkali-activated ground granulated blast furnace slag(GBS)binder and also of combinations of fly ash and GBS binders.Binders were activated using mixtures of NaOH and Na_(2)SiO_(3)solutions.The molarity of NaOH in the mixtures ranged from 10 mol·L^(−1)to 16 mol·L^(−1),and the Na_(2)SiO_(3)/NaOH ratio was varied from 1.5 to 2.5.Mortar samples were produced using three binder combinations:1)GBS as the only binder;2)blended binder with a slag-to-fly ash ratio of 3:1;and 3)mixed binder with 1:1 ratio of slag to fly ash.Mortar samples were mixed and cured at(22±2)°C till the day of the test.The impact of activator solution alkalinity,activator ratio Na_(2)SiO_(3)/NaOH,GBS content on the rate of water absorption were evaluated.After 7,28,and 90 d of immersion in a 10%sulfuric acid solution,the resistance of a geopolymer matrix to degradation was assessed by measuring the change in sample weight.The influence of solution alkalinity and relative fly ash content on setting times was investigated.Alkali-activated mortar with a slag-to-fly ash ratio of 3:1 had the least sorptivity compared to the two other binder combinations,at each curing age,and for mortars made with each of the NaOH alkaline activator concentrations.Mortar sorptivity decreased with age and sodium hydroxide concentrations,suggesting the production of geopolymerization products.No reduction in weight of sample occurred after immersion in the strong acid H_(2)SO_(4)solution for three months,regardless of binder combination.This was due to the synthesis of hydration and geopolymerization products in the presence of curing water,which outweighed the degradation of the geopolymer matrix caused by sulfuric acid.

关 键 词：alkali-activated materials fly ash SORPTIVITY durability of concrete sodium hydroxide sodium silicates reduction in CO_(2)emissions sulfuric acid 

分 类 号：TU578.1[建筑科学—建筑技术科学]