Effects of superplasticizer on the physical and mechanical properties of concrete with paper mill sludge as fine aggregates

• Main Authors: Nogoy, Juan Angelo M., Tan, Jefferson James F., Uy, Vicky L.
• Format: text
• Language: English
• Published: Animo Repository 2006
• Subjects: Plasticizers; Concrete > Additives
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/9646
• Institution: De La Salle University

The main problem regarding the use of paper mill sludge as fine aggregates is the decrease in workability of the concrete mix. Additional water is the common solution to this kind of problem. However, higher water content decreases the strength of concrete. In this study, an ASTM Type-D/G superplasticizer was introduced in the concrete with paper mill sludge as fine aggregates to alleviate the problems in using paper sludge as an ingredient in concrete. Concrete with 0% (control), 5%, 10%, and 15% sludge replacement were supplemented with superplasticizer. Samples without superplasticizer were also cast for comparison. The workability of the mixes was maintained to fall within the slump range of 75 to 100mm (3 to 4 in.). The dosage of superplasticizer was also constant at 1L per 100kg of cement. The findings obtained from the study showed that the addition of the superplasticizer decreased the water content of all the specimens but still attained the desired workability. The superplasticizer also caused an increase in the density of concrete with paper mill sludge compared to those without superplasticizer. Conversely, a decrease in compressive and splitting-tensile strength generally occurred for the concrete with paper mill sludge supplemented with superplasticizer. However, contrary to what is expected, an increase in strength was observed on the concrete without superplasticizer as the sludge replacement increased but only up to a certain ratio between 5% and 10%. Generally, the use of the superplasticizer was only beneficial to the water content and density of concrete with paper mill sludge as fine aggregates.