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Autoclaved aerated concrete (AAC) panels have ultra-light weight, excellent thermal insulation and energy absorption, so it is an ideal building material for protective structures. To improve the blast resistance of the AAC panels, three schemes are applied to strengthen the AAC panels through spraying 4 mm thick polyurea coating from top, bottom and double-sides. In three-point bending tests, the polyurea-coated AAC panels have much higher ultimate loads than the un-coated panels, but slightly lower than those strengthened by the carbon fiber reinforced plastics (CFRPs). Close-in explosion experiments reveal the dynamic strengthening effect of the polyurea coating. Critical scaled distances of the strengthened AAC panels are acquired, which are valuable for the engineering application of the AAC panels in the extreme loading conditions. Polyurea coatings efficiently enhance the blast resistance of the bottom and double-sided polyurea-coated AAC panels. It is interesting that the polyurea-coated AAC panels have much more excellent blast resistance than the CFRP reinforced AAC panels, although the latter have better static mechanical properties.

Autoclaved aerated concrete (AAC) is a lightweight cellular building material and can be applied as sacrificial claddings in protective structures to absorb impact energy. Low-velocity impact tests were performed to reveal the strain-rate effect and specific energy absorption (SEA) of the AACs. Three damage patterns, including shear failure, splitting failure, and compressive failure were revealed. Normal AAC cylinders were crushed at shear failure and splitting failure successively with increased impact speed. Crushed at shear failure mode, the AACs have greater dynamic strength, which increases with the impact velocity. Short AAC cylinders are crushed at compressive failure mode and dissipate more impact energies. Through the experiments, strain rate sensitivity of the dynamic strength is revealed and it is concluded that only compressive mode can make full use of the energy absorbing ability of the AAC.

To enhance their static and dynamic structural performances, autoclaved aerated concrete (AAC) panels were strengthened by carbon fibre reinforced polymer (CFRP) sheets. Five kinds of specimens were investigated: (a) reinforced AAC panels (RAPs), (b) RAPs strengthened by externally bonded unidirectional CFRPs (UCRAPs), (c) RAPs strengthened by bidirectional CFRPs (BCRAPs), (d) plain AAC panels (PAPs) and (e) PAPs strengthened by unidirectional CFRPs (UCPAPs). CFRP reinforcement changes the failure style of PAPs from tensile failure to shear failure while enhance the shear resistance and ductility of RAPs under static bending. According to the explosion experiments and structural damage evaluations, CFRP strengthened AAC panels have excellent anti-blast resistance. UCPAPs even have comparable blast-resistant ability to RAPs. Encased by CFRPs, UCRAPs and BCRAPs restrict the crack development and have excellent damage tolerance in explosion. Critical scaled distance of BCPAPs in this research is reduced to 0.684 m/kg 1/3 , while for RAPs this value is 1.506 m/kg 1/3 . BCPAPs even have comparable blast-resistant ability to steel reinforced concrete slabs.