Effect of high dosage lignosulphonate and naphthalene sulphonate based plasticizer usage on micro concrete properties

• Overdose usage of lignosulphonate (LS) and naphthalene sulphonate (NS) based admixtures were observed.
• Optimum dosage of LS and NS improved mortars’ physical properties.
• Overdose usage of LS and NS has negative effect on mortar.
• SEM analysis proved porous structure of overdosed LS and NS mixtures.
• Pore volume decreased with optimum dosage, while it is increasing with over dosage.

In concrete production, because of plasticizers are used for a small percentage by weight of cement (in the range from 0.3% to 1.5%), there is a possible risk adding more admixture in concrete than calculated from personnel or equipments sensitivity errors. In this situation concrete’s strength and durability performances are diminishing. In this work, it is investigated the effect of high dosage lignosulphonate based water-reducing admixture and naphthalene sulphonate based high-range water-reducing admixture usage on mortar properties. It was carried out unit weight, flowability, setting time, air content, compressive strength, flexural strength, ultrasonic pulse velocity tests and microstrucural inspections on specimens which were produced with 5 different dosages for each admixture. As a result of experiments, in case of using admixtures with overdose, there would be loss of quality of physical and mechanical properties of concrete, for this reason it is concluded that, there must be some legal regulations using chemical admixtures sensitively.