Polimer modifiye harçların özellikleri ve uçucu kül ve cüruf katkısının etkisi

In this study, polymer modified mortars, which are composites of portland cement, aggregate and polymer admixture, are described and change of properties of polymer modified mortars with respect to curing conditions, type of polymer admixture and supplementary cementing material incorporation is investigated. Matrix phase of polymer modified mortars consists of cement hydrates and polymer film formation intermingled with each other. Properties of cement mortars could be improved by incorporation of polymer admixtures. However, properties of polymer modified mortars depend on various parameters such as type of polymer, polymer/cement ratio, water/cement ratio and curing conditions. The study is divided into two phases as preliminary and comparative. In the preliminary phase, the objective is to determine favorable curing condition for polymer modified mortar. In the comparative phase of the study, effects of polymer type on properties of polymer modified mortars and optimum polymer content was investigated. Three different brands and two different types of polymers were used. Polymers were labelled as Polymer-A (SBR), Polymer-B (SBR) and Polymer-C (EVA) respectively. Hardened and durability properties of polymer modified specimens become different with respect to curing conditions. Polymer modified mortars require water during curing for hydration of cement and air for polymer film formation. For this reason, the favorable curing regime for polymer modified mortars should be consisted of both curing regimes. In order to determine the favorable curing conditions for polymer modified mortars, specimens with SBR polymer admixture (Polymer A) were prepared with 5%, 15%, 25% polymer / binder ratios and five different curing regimens were applied for a total of 28 days. Curing regimes were numbered from #0 to #4. Curing regimes were grouped as water curing (#0), air curing (#1), water and high humidity curing (#2), high humidity and air curing (#3) and water and air curing (#4). Preliminary strength tests were performed related specimens after 28 days of curing. According to results of preliminary tests, favorable curing condition for polymer modified mortars was selected and comparative tests were carried out using SBR (Polymer B) and EVA (Polymer C) polymer admixture. In addition, effects of fly ash and ground granulated blast furnace slag incorporation to properties of polymer modified mortars were also studied. For this purpose, fly ash and slag was incorporated to mixtures separately or together with 10%, 30% and 50% of cement amount of unmodified specimens. Properties of supplementary cementing material (SCM) incorporated specimens were compared to those of polymer modified specimens under same curing conditions. Workability of polymer modified mortars were determined by flow test. Hardened properties after 28 days curing were evaluated by flexural and compressive strength tests. For each label 3 rectangular blocks of mortar with dimension of 40x40x160mm were prepared. 3 ea flexural strength tests were performed on specimens. As a result of flexural strength tests, specimens were divided in two parts and a total of 6 pieces were obtained. Compressive tests were performed on divided pieces. In total 4 ea compressive strength tests were performed. Sorptivity tests were performed on remaining two pieces. Results of preliminary tests showed that workability of mortars are increased with respect to polymer admixtures addition. For this reason, change of properties of specimens for similar workability as polymer modified specimens was added to study. Water/binder ratios of several specimens were changed in order to obtain similar workability as polymer modified mortar. These specimens were labelled as "W". Favorable curing conditions for polymer modified mortars was chosen as curing regime #4 (3 days immersed in water + 25 days curing at room environment), which allowed cement hydration and polymer film formation. Strength and sorptivity of specimens differed with respect to type of polymer and curing condition. It was observed that polymer admixture incorporation increased flexural strength values, but mainly decreased compressive strength values. The decrease in compressive strength has been attributed to void-like behavior of soft polymer inside matrix. In addition, lower sorptivity values could be obtained with polymer incorporation. Overall, EVA polymer showed higher strength values, whereas SBR polymer showed lower sorptivity values.