الفهرس 
Title : Influence of different types of superplasticizer on some physico-mechanical properties of special cement mortar for ductile pipe lining
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Abstract
The present investigation studied the solutions for some problems which have lately appeared in the cement lining of ductile cast iron pipe in EL-Nasr Company. There is a group of deficiency in the lining cement which consists of waves, ripples, knots, strip crack, milky layer, crack network, non-uniform thickness, breakage, and lining too rough. Therefore the present work consists of two parts; the first one involves study the effect of different three types of superplasticizers on some physical properties of cement paste and mortar. The superplasticizers used in this study are Sika Vescocrete - 3425 (polycarboxylate (PC)), plastiment-RX/SR (Modified Lingosulphonate (MLS)), and Sikament-NN (Sulfonate Naphthalene Formaldehyde (SNF)). The physical properties studied here are water reduction, setting times, workability, and compressive strength. The obtained results indicated that the values of such properties increase as the concentration of the used superplasticizers increases. Moreover, the water reduction and compressive strength increase in the order MLS < SNF < PC while the setting times and workability follow the order PC < SNF < MLS. The second part of our work includes the study of the effect of the presence of PC superplasticizer within mortar on reinforcement steel corrosion in a 3.5 % NaCl solution. The results of the polarization and electrochemical impedance revealed that the presence of the superplasticizer within the cement mortar decreases its porosity and consequently decreases the passing of NaCl solution to the steel surface results in decreasing in its corrosion rate. Therefore, the increase of the superplasticizer concentration in cement mortar causes more decrease in the rate of steel corrosion in the test solution