Grinys Audrius, Balamurugan Muthaiah, Augonis Algirdas, Ivanauskas Ernestas
Faculty of Civil Engineering and Architecture, Kaunas University of Technology, Studentų Str. 48, LT-51367 Kaunas, Lithuania.
Materials (Basel). 2021 Apr 29;14(9):2321. doi: 10.3390/ma14092321.
This paper analyzes concrete fine aggregate (sand) modification by scrap tire rubber particles-fine crumb rubber (FCR) and coarse crumb rubber (CCR) of fraction 0/1 mm. Such rubberized concrete to get better bonding properties were modified by car-boxylated styrene butadiene rubber (SBR) latex and to gain the strength were modified by glass waste. The following tests-slump test, fresh concrete density, fresh concrete air content, compressive strength, flexural strength, fracture energy, freezing-thawing, porosity parameter, and scanning electron microscope-were conducted for rubberized concretes. From experiments, we can see that fresh concrete properties decreased when crumb rubber content has increased. Mostly it is related to crumb rubber (CR) lower specific gravity nature and higher fineness compared with changed fine aggregate-sand. In this research, we obtained a slight loss of compressive strength when CR was used in concrete However, these rubberized concretes with a small amount of rubber provided sufficient compressive strength results (greater than 50 MPa). Due to the pozzolanic reaction, we see that compressive strength results after 56 days in glass powder modified samples increased by 11-13% than 28 days com-pressive strengths, while at the same period control samples increased its compressive strength about 2.5%. Experiments have shown that the flexural strength of rubberized concrete with small amounts of CR increased by 3.4-15.8% compared to control mix, due the fact that rubber is an elastic material and it will absorb high energy and perform positive bending toughness. The test results indicated that CR can intercept the tensile stress in concrete and make the deformation more plastic. Fracturing of such conglomerate concrete is not brittle, there is no abrupt post-peak load drop and gradually continues after the maximum load is exceeded. Such concrete requires much higher fracture energy. It was obtained that FCR particles (lower than A300) will entrap more micropores content than coarse rubbers because due to their high specific area. Freezing-thawing results have confirmed that Kf values can be conveniently used to predict freeze-thaw resistance and durability of concrete. The test has shown that modification of concrete with 10 kg fine rubber waste will lead to similar mechanical and durability properties of concrete as was obtained in control concrete with 2 kg of prefabricated air bubbles.
本文分析了用废旧轮胎橡胶颗粒——0/1毫米级的细粒橡胶（FCR）和粗粒橡胶（CCR）对混凝土细集料（砂）进行的改性。为使这种橡胶混凝土获得更好的粘结性能，用羧基化丁苯橡胶（SBR）胶乳进行改性；为提高强度，用玻璃废料进行改性。对橡胶混凝土进行了如下试验：坍落度试验、新拌混凝土密度、新拌混凝土含气量、抗压强度、抗折强度、断裂能、冻融试验、孔隙率参数以及扫描电子显微镜试验。从试验中可以看出，当橡胶颗粒含量增加时，新拌混凝土性能下降。这主要与橡胶颗粒（CR）比重较低且与被替代的细集料——砂相比细度较高有关。在本研究中，当在混凝土中使用CR时，抗压强度略有损失。然而，这些含有少量橡胶的橡胶混凝土提供了足够的抗压强度结果（大于50兆帕）。由于火山灰反应，我们发现玻璃粉改性样品56天后的抗压强度结果比28天抗压强度提高了11% - 13%，而同期对照样品的抗压强度提高了约2.5%。试验表明，与对照混合料相比，含有少量CR的橡胶混凝土的抗折强度提高了3.4% - 15.8%，这是因为橡胶是一种弹性材料，它会吸收高能量并表现出良好的弯曲韧性。试验结果表明，CR可以拦截混凝土中的拉应力并使变形更具塑性。这种团聚混凝土的断裂不脆，峰值后荷载不会突然下降，超过最大荷载后仍会逐渐持续。这种混凝土需要更高的断裂能。结果表明，FCR颗粒（低于A300）由于其高比表面积，会比粗橡胶截留更多的微孔含量。冻融试验结果证实，Kf值可方便地用于预测混凝土的抗冻性和耐久性。试验表明，用10千克细橡胶废料改性混凝土将导致混凝土具有与用2千克预制气泡的对照混凝土相似的力学性能和耐久性。
