بررسي آزمايشگاهي خصوصيات فيزيكي و رفتار مكانيكي بتن‌هاي حاوي نانو ذرات اكسيد تنگستن در پوشش‌ تقويتي تيرهاي بتني

Experimental study of physical characteristics and mechanical behavior of concrete containing Tungsten Oxide (WO3) Nanoparticles in RC beam retrofitting

با بررسي‌هاي انجام شده در خصوص تأثير نانوذرات بر بتن مشخص شده كه نانوذرات با يك فرآيند فيزيكي، شيميايي و مكانيكي بتن را متراكم ساخته و در مقاومت بتن تأثير مطلوبي مي‌گذارند. ازاينرو در پژوهش حاضر رفتار بتن‌هاي درشت‌دانه و ريزدانه (بتن اوليه و ملات بتني) حاوي نانواكسيد تنگستن و نيز عملكرد تيرهاي ترميم شده با ملات بتني حاوي نانواكسيد تنگستن مورد بررسي قرار مي‌گيرد. براي اين منظور جهت آزمايش مقاومت فشاري از نمونه‌هاي استوانه‌اي با ابعاد mm75×mm150 و مكعبي با ابعاد mm50×mm50×mm50، جهت آزمايش مقاومت كششي از نمونه‌هاي استوانه‌اي با ابعاد mm75×mm150 و براي تيرهاي خمشي ساده و ترميم شده از نمونه‌هاي به ابعاد mm76×mm76×mm305 استفاده گرديد. در اين پژوهش، تعداد 115 نمونه استوانه‌اي، 100 نمونه مكعبي و 70 نمونه تير خمشي ساده و ترميم شده (تير مركب) ساخته و مورد آزمايش قرار گرفتند. نتايج نشان داد كه با افزايش حضور نانوذرات در بتن اوليه و ملات بتني، مقاومت فشاري، كششي و خمشي نسبت به نمونه شاهد روند صعودي داشته است.

The present study examines the behavior of concrete coarse-grained and fine-grained (raw concrete and concrete mortar) containing tungsten oxide Nanoparticles as well as the performance of concrete beams repaired with concrete mortar containing tungsten oxide Nanoparticles. For this purpose, two types of designs, including primary concrete and concrete mortar containing 0.5, 1.5 and 2.5 weight percent of cement were used. The compressive and tensile strength tests 0f 3, 7, 28 and 63 days specimens and 1 , 3, 7 and 28 days specimens were carried out on the primary and mortar concrete, respectively. Four-point bending strength tests on the primary concrete by 28 and 63-day duration and concrete mortar was performed on 28 day. For the repair of concrete beams, the contact surface of concrete and concrete mortar were prepared in a smooth and coarse manner and subjected to a four-point bending test in order to evaluate compatibility between the repair materials and the primary concrete. To examine the compressive strength, the cylindrical specimens with dimensions 150mm × 300mm and cube specimens with dimensions 150mm × 150mm × 150 mm were used. For evaluating the tensile strength, cylindrical samples with dimensions 150 × 300mm and simple repairing beams with 150mm × 150mm × 700mm dimensions were utilized. In this study, 130 cylindrical samples, 115 and 85 cubic specimens and repairing beams were constructed. The results showed that with the increasing presence of nanoparticles in raw concrete and mortar, increase compressive strength, flexural tensile, by compared to the control samples and about the repairing beams with rough surface samples have a flexural strength more than the sampler with a smooth surface that part of this increase in flexural strength can be used to increase the compressive and tensile strength of mortar and other restorative effect of tungsten oxide nanoparticles to The link of location between mortar and concrete repair. and about broken mood items in the type of sample with a smooth surface has been dominant second failure (half of the healing substance is completely isolated from the raw concrete) and for sample rough surface in first failure mood has been dominant (failure in the middle of a third span without detachment in the article restoration).