Your article is protected by copyright and all rights are held exclusively by Shiraz University. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com". AbstractGeopolymer is synthesized by mixing material rich in alumina and silica, such as fly ash, with a highly alkaline solution to form a hardened matrix. However, when using high calcium fly ash as a precursor, a flash set frequently occurs, i.e., the mixture hardens very rapidly before casting can be completed. The use of borax as an additive has been reported due to its potential to prolong the setting time. In this study, the use of a significantly higher dosage of borax is explored. The results show that the addition of borax up to 20% of fly ash, by mass, into the alkaline solution prolongs the setting time by up to 90 min. Conversely, the addition of higher amounts of borax tends to decrease the compressive strength of the geopolymer, whereas adding a small amount of calcium oxide into the mixture increases the strength marginally, especially when the borax content is small. However, the amount of calcium oxide should be limited because at higher content, the effectiveness of borax to prolong the setting time is reduced.

The steady increase of human population and the limited living space encourages developers to make vertical residential namely apartments. The developers certainly need the right marketing strategy, one of them is determining the target age of the buyer. In this study, age is categorized into several generations, which is Gen X and Gen Y. Gen X and Gen Y have different characters and mindsets. This also makes a difference in consideration of buying an apartment. This research examines about the differences in the consideration of external factors and internal factors between Gen X and Gen Y in purchasing an apartment. External factors consist of physical condition of the apartment, location, environmental and financial factors. Meanwhile, internal factors consist of psychological, emotional, and intuition factors. The results stated that there were only differences in external environmental factors. Although there are no difference on other external and internal factors, Gen X tends to consider physical and location factors more, while Gen Y considers financial factors more. Meanwhile, all internal factors are considered more by Gen X than Gen Y.