Investigation of mixing ratio and restraint condition effects on alkali–silica gel pressure in mortar by using a uniaxial alkali–silica gel pressure measuring device (ASGPM-D)

A pressure of alkali silica gel which is the product of alkali–silica reaction causes pattern crack development and ultimately failure in cement based materials. This paper examines the measurement of alkali–silica gel pressure in cylindrical mortar specimen by a new test device (alkali–silica gel pressure measuring device, ASGPM-D) and investigates also the effects of the test medium on test results. Specimens of various sizes and geometries were tested to develop standard specimen size for ASGPM test method. The most suitable specimen with diameter of 35 mm and 250 mm in length was selected by optimizing the experimental results. Furthermore, the highest alkali–silica pressure value was recorded on a specimen which has 0.45 w/c and 74–150 μm grain size in an 80 °C 1 N NaOH solution. Also, swelling pressures of four reactive aggregates (opal, chert, basalt and chalcedony) were determined under two distinct restraint stages (1.5 kN and 3 kN).