This paper reports on an experimental program investigating the durability and mechanical properties of alkali activated slag concrete (AASC). The AASC was prepared using ground granulated blast furnace slag activated by high concentration alkali solution. The mechanical properties were determined by compressive strength and elastic modulus. The durability characteristics of AASC were measured using Ultrasonic Pulse Velocity (UPV) and permeable voids tests. The result showed that AASC developed a comparable strength to Portland Cement (PC) concrete over the short term. However, the material displayed an increase in voids, as well as a reduction of velocity over time. This could lead to the material displaying inferior performance over longer periods of time.
The use of geopolymer binder as cement replacement material can reduce the amount of carbon dioxide gas produced during the Portland Cement manufacturing process. However, the main issue of geopolymer binder is in the mixing process of sodium silicate and NaOH which requires specialized knowledge and strict supervision. This paper reports the effect of water binder ratio on strength development of fly ash geopolymer mortar using dry geopolymer powder. Fly ash with high calcium content was used as primary material. The dry geopolymer powder was prepared by wet mixing method which was made by drying a mixture of NaOH solution and limestone for 24 hours. The variations of water to binder ratio were 0.30, 0.35, 0.40, 0.45, and 0.50. Strength properties were measured by compressive strength at the age of 7, 14 and 28 days. The results showed that the water binder ratio significantly affect the strength development of geopolymer mortar prepared by dry geopolymer powder. The water binder ratio of 0.40 gives the highest compressive strength of 10.3 MPa at 28 days. This suggests that the use of dry geopolymer powder on geopolymer mortar production can overcome the difficulties of geopolymer mortar mixing on site.
This study aims to determine differences (1) curriculum structure; (2) industrial work practices; (3) graduate work readiness; and (4) the absorption of graduates between 3-year Vocational Schools and 4-year Vocational School building engineering expertise programs. The research method used was descriptive research with ex post facto approach and survey. Data collection techniques in this study used documentation, interviews and online questionnaires. The results of this study are as follows: (1) the learning burden on 3-year Vocational High Schools is 5016 JP and 413 KD while the 4-year Vocational School is 6648 JP and 443 KD; (2) apprenticeship implemented at 3 Years Vocational School for 3 months and 4 Year Vocational School for 6-8 months; (3) 3-year SMK graduates 60% of whom are declared ready for work, while 4-year SMK graduates 71.80% of whom are declared more ready to work; and (4) 70% of 3-year vocational school graduates work in a field, while 92% of 4-year SMK graduates work in a field. This can explain that it will be more effective if the Vocational School is held with a 4-year SMK pattern.
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