An experimental investigation was conducted to study the performance of fly ash based geopolymer mortar specimens in Magnesium Sulphate solution. Specimens were manufactured from low calcium fly ash by activation with a mixture of Sodium Hydroxide and Sodium Silicate solution and cured thermally. 10% by weight Magnesium Sulphate solution was used to soak the specimen up to 24 weeks. Performance of the specimens was evaluated in terms of visual appearance, variation of pH of solution, change in weight, and change in compressive strength over the exposure period. White deposits occurred on the surface of specimen which was initially soft but later converted to hard crystals. pH of solution increased noticeably during the initial weeks which indicate migration of alkalis from mortar specimens. At the end of 24 weeks samples experienced very little weight gain and recorded a loss of compressive strength by up to 56%.Keywords: Fly ash, geopolymer, durability, pH value, weight change, compressive strength. Bonen and Cohen [6] investigated the response of Portland cement pastes on magnesium sulphate and suggested that the attack by magnesium ions primarily leads to formation of a layer of brucite on the exposed surfaces. Journal of EngineeringGeopolymers are a class of new binder generally manufactured by activating an aluminosilicate source material in a highly alkaline medium. Davidovits [7] reported that geopolymers possess high early strength, better durability and has no dangerous alkali-aggregate reaction. So far investigations in geopolymers mostly deal with the manufacturing processes and effects of synthesizing parameters on physical and mechanical properties. Very few studies had been carried out with regard to durability of geopolymer materials. Geopolymers manufactured from fly ash have shown excellent performance when exposed to different acids with varying concentrations and exposure durations. [7] -[11].Wallah and Rangan [12] reported that geopolymer concrete specimens exhibit extremely small changes in length and also shows very little increase in mass after one year of exposure in sulphate solution. In another study by Bakharev [13] the author used various concentrations of sulphate solution to immerse the geopolymer materials prepared using different types of activating solutions.The objective of present experimental program was to evaluate the performance of fly ash based geopolymer mortar specimens in Magnesium sulphate solution. The geopolymer mortars manufactured with varying contents of alkali were immersed in Magnesium sulphate solution and its performance was evaluated on the basis of appearance, changes in weight, pH and compressive strength at regular intervals over the exposure duration.

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Durability of fly ash based geopolymer mortar specimens in Nitric acid solution was investigated on three different series of specimens manufactured by activating fly ash with a mixture of sodium hydroxide and sodium silicate solution containing Na2O ranging from 5% to 8% of fly ash. Specimens were exposed in 10% by weight Nitric acid solution up to 24 weeks. The effect of alkali (%Na2O) content on durability of geopolymer mortar specimens were studied in terms of visual appearance, change in weight and change in compressive strength. Mineralogical and microstructure changes due to nitric acid attack were also investigated. Geopolymer mortar specimens showed excellent durability in terms of extremely less weight loss as well as high retention of compressive strength. Specimens with higher alkali content exhibited better durability in nitric acid. Santrauka Buvo tiriamas geopolimerinio skiedinio bandinių, pagamintu naudojant lakiuosius pelenus, ilgaamžiškumas azoto rūgšties tirpale. Buvo tiriami trijų skirtingų partijų bandiniai, pagaminti pridėjus lakiųjų pelenų, kurie turi natrio hidroksido ir natrio silikato mišinį, jo sudėtyje Na2O svyruoja 5–8% nuo lakiųjų pelenų kiekio. Bandiniai 24 savaites buvo veikiami 10% (pagal masę) azoto rūgšties tirpalu. Šarmų (% Na2O) kiekio poveikis geopolimerinio skiedinio bandinių ilgaamžiškumui buvo tiriamas įvertinant išvaizdą, nustatant masės ir gniuždomojo stiprio pokytį. Taip pat buvo nustatyti mineraloginiai ir mikrostruktūriniai pokyčiai veikiant azoto rūgštimi. Geopolimerinio skiedinio bandinių ilgaamžiškumas buvo labai didelis, masės nuostoliai nedideli ir didelis gniuždomasis stipris. Bandiniai su didesniu šarmų kiekiu buvo ilgaamžiškesni azoto rūgštyje.

Bamboo is considered one of the most versatile, sustainable and environment friendly building material. They grow naturally all over the globe but are more abundantly found in the tropical and sub-tropical regions such as Asia, Africa and some parts of America. The social and economic benefits granted by bamboo and its product to the society has been high since time immemorial. On account of this fact, it is widely recognized as one of the most important forest resources. Its compressive strength is higher than that of concrete, brick or wood and its tensile strength is comparable to that of steel. The over consumption of conventional construction material such as steel, bricks has posed serious depletion issues of raw materials. Also, with the global increase in population, it has become a challenge to provide proper housing which is both economical and safe for the common people. In addition, in view of the current tectonic activities around the different parts of the world, Bamboo can serve as an alternative building material to steel reinforcement. This paper studies the results of bamboo reinforced concrete and the performance of housing system where bamboo is used as a chief construction member.

This paper reports the results of an experimental program performed to study the effect of incorporation of sugarcane bagasse ash (SCBA) in Ground granulated blast furnace slag (GGBS) based geopolymer composites by performing various destructive and non-destructive tests. GGBS was replaced by SCBA in dosages of 5%, 10%, 15% and 20% by weight and activated by a solution of sodium hydroxide and sodium silicate. Some of the test performed during the experimental investigation were compressive strength, water absorption, bulk density, rebound hammer test, ultrasonic pulse velocity etc. It is observed that compressive strength and bulk density decreases with increase in the dosage of SCBA. The results of the present study indicates suitability of replacing SCBA in the GGBS based geopolymer composites.