Effect of different types of biopolymers on mechanical and durability properties of cement mortar

Studies have been developed due to biopolymer usage in civil engineering in recent years. While biopolymers are frequently used in industry and medicine fields they are rarely used in construction materials. In the scope of this study, effect of cement mortars incorporating with biopolymers with different concentrations on mechanical properties as flow, strength and durability properties as freeze-thaw and acid resistance were investigated. Cement mortars were prepared by using three different types of biopolymers such as xanthan gum, chitosan and chitin according to different cement weight ratios (%0,2, %0,3 ve %1,0). Effects on fresh and hardened state were investigated by adding %0,2, %0,3 and %1,0 biopolymers into cement mortars. Flow test is performed to determine the effects on fresh state. As a result, flow value of chitosan additive with 0,2 dosage is bigger than reference value. On the other hand, flow values of xanthan gum and chitin are lower than reference sample. Flow area ratios are determined by using all flow values in order to understand the admixture effect. Behavior of cement mortars in fresh directly affects the strength and durability properties which are gained afterwards. Intended properties of hardened cementitious construction materials are obtained by taking control of fresh state properties. 5x5x5 cm and 4x4x16 cm sized cubic samples are produced to determine the properties of hardened cement mortars. These samples are tested to obtain the strength and durability properties on the 1st, 2nd, 7th and 28th days. Compressive and bending strength tests are performed to determine the strength properties. Compressive tests of 5x5x5 cm sized cubic samples were performed on the 1st, 2nd, 7th and 28th days. Similarly, compressive strength after bending and bending tests were performed for prismatic samples having 4x4x16 cm sizes at the same ages. Strength and flow test results are presented in the study. While strength values of %0,2 and %0,3 dosage chitosan are lower than values of control samples on the 1st and 2nd days, these values are higher than values of control samples on the 7th and 28th days. However, strength values of cement mortars incorporating with chitin by %1 dosage are lower than control samples tested at the end of 1st, 2nd, 7th and 28th days. Compressive and bending strengths are higher than control samples for %0,2 dosage chitin mixed cement mortar samples after 28 days. Strength and flow values of all series prepared with xanthan gum are lower than control samples. Acid resistances and freeze-thawing tests are performed to determine the durability properties after obtaining strength values. For this purpose, cubic samples having 5 cm side lengths were weighed after taking out from curing pool and kept waiting in %3, %5 and %7 HCl acid solution for 7 days. These samples were weighed at the end of 7th day. Mass losses of samples were determined in consideration of experimental results. Moreover, prismatic samples were kept waiting in air conditioner after 28 days. Bending and compressive tests are performed at the end of 50th and 100th cycles. Suitable biopolymers and optimum additive dosages were determined after analyses and ultimate properties of early aged concrete were tried to enhanced.