The removal of azo dyes is a critical issue in current textile industry wastewater treatment. In contemporary wastewater management, many structures that are in direct contact with wastewater are constructed with concrete. In this contribution, the removal of Congo red from aqueous solutions by the material in the surface of hardened binder paste was studied in multiple exposure experiments. Flat prisms made with ordinary Portland cement and ground granulated blast-furnace slag were stored in different aqueous solutions. The powdered surface material of these flat prisms was used as a substrate for the removal of Congo red from aqueous solutions. Storage in sodium sulfate solution lead to the formation of hydrotalcite nanosheets on the surfaces of hardened binder pastes rich in magnesium provided by the granulated blast-furnace slag. These nanosheets resulted in a large specific surface area and increased the discoloration capacity with respect to binder mass. The results also suggest that the carbonation of C-S-H can provide fresh calcite that can act as a secondary adsorbent. The results of this study suggest that cementitious binders with high magnesium contents could contribute to the removal of azo dyes from industrial wastewater by providing economically attractive treatment materials.

The hollow cylinder method was used to estimate the expansion stress that can occur in concrete due to the crystallisation pressure caused by the formation of ettringite and/or gypsum during external sulphate attack. Hardened cement paste hollow cylinders prepared with Portland cement were mounted in stress cells and exposed to sodium sulphate solutions with two different concentrations (3.0 g L SO₄²⁻ and 30.0 g L SO₄²⁻). Microstructural analysis and finite element modelling was used to evaluate the experimental observations. The expansion stress calculation was verified for a range of diameter/length ratios (0.43–0.60). Thermodynamically predicted maximum expansion stresses are larger than expansion stresses observed in experiments because the latter are affected by the sample geometry, degree of restraint, pore size distribution and relaxation processes. The results indicate that differences in self-constraint at the concave inner and convex outer surfaces of the hollow cylinder lead to an asymmetric expansion stress when ettringite is formed. This leads to macroscopic longitudinal cracks and ultimately failure. Heavy structural components made of concrete are likely to support larger maximum expansion stresses than observed by the hollow cylinder method due to their self-constraint.

A novel uncooled long-wave infrared imaging technology with optical readout is proposed and developed targeted for low cost thermal imaging applications. This technology uses the thermo-optic effect in a semiconductor to detect infrared signals rather than the thermal-resistance effect used in traditional microbolometers. The key component of the imager, the focal plane array, is made up of thermally tunable thin film filter membrane pixels. Each thermal pixel acts as a wavelength translator, converting far infrared radiation signals into near infrared signals which are then detectable by off-the-shelf CCD or CMOS cameras. This approach utilizes optical filter and MEMS technologies, to build a low-cost passive long wavelength infrared focal plane array without electrical leads or active cooling. Within one year since the commencement, NETD values of 0.28K in a 160x120 array operating at 22Hz video frame rate have been achieved without temperature control.