shows the failure modes
of the concrete after impact strength test. The ordinary concrete
suffered a great crushing degree under external impact. The concrete
was brittle and the concrete structure was completely
destroyed. The toughness of the concrete is obviously improved
by adding crumb rubber, because more intense external impact
only produced much narrower cracks. The reason for the improvement
of the impact strength in the rubber concrete is that the elastic
rubber particles can disperse local stress. The modified crumb
rubber has stronger interfacial chemistry reaction with cement
and better stress dispersion effect, resulting in less and narrower
cracks and higher impact toughness of the concrete.