Optimum superplasticizer contents of ready mixed concretemade with blended portland cement

ABSTRACT OPTIMUM SUPERPLASTICIZER CONTENTS OF READY MIXED CONCRETE MADE WITH BLENDED PORTLAND CEMENT DEMIREL, Ergin Oral M. S. in Civil Eng. Supervisor: Assoc. Prof. Abdurrahman GÜNER September 1995, 271 pages Using the Gaziantep blended port land cement and locally commercially available sieved and washed river bed aggregate of three different size fractions and a fine sand of silt size to obtain pumpable mixes with slumps around 60-80 mm to 150-200 mm concretes of classes C14, C16, C20, C25 and C30 were produced. The superplasticizing admixture of modified sodium and calcium lignosulphonate type with some additions of mel amine formaldehyde and naphthalene formaldehyde sulphonate condensates contents were 0.0, 0.25. 0.5, 1.0, 1.5, 2.0 and 5.09s by weight of cement. The effects of superplasticizer on fresh and hardened concrete were investigated. In the optimization computer program, the simplex linear formulation was used as the core. To determine, the optimum composition, the objective function was chosen as the total investment, operating and maintenance cost related to constituent materials, quality control, transportation, placing and compaction, formwork and scaffolding per cubic metre of concrete in- place. The relative total costs up to and including compaction of concretes show a general trend of increase with increasing slump and concrete class. Minimum costs however, are obtained progressively at higher superplasticizer contents up to about 1.25% at higher s 1 umps. Key words: Blended cement, superplasticizer, entrained air, pumpability, ready-mixed concrete, optimization a a n.