Development of High Performance Aerogel Concrete (HPAC) and statistical evaluation of compressive strength for practical use in construction

The Institute for Structural Concrete (ISC) at the University of Duisburg-Essen and the Institute of Materials Research of the German Aerospace Center (DLR) developed a new lightweight concrete, called "High Performance Aerogel Concrete" (HPAC). HPAC is made by embedding of silica aerogel granules in a high strength cement matrix. It exhibits a remarkable relation between compressive strength and thermal conductivity. HPAC for the load bearing layer of double-leaf external walls contains approx. 50 vol% aerogel and has a compressive strength in the range of normal concrete (20 MPa – 30 MPa). Up to now, the compressive strength of each mixture was determined on three to six cubes or cylinders. The scattering of the results has not been investigated yet. For this reason, 30 test specimens of a 50 vol%-mixture have been produced in two batches. The results of the compressive strength tests were then statistically evaluated. The underlying statistical distribution was determined by the Anderson-Darling-Test. Subsequently the 5 % fractile values of the mixtures, which represent the characteristic concrete compressive strength, were determined.