Two types of slump‐retention polycarboxylate superplasticizers (PC‐M and PC‐S) were synthesized by using 3‐mercaptopropionic acid or sodium hypophosphite as chain transfer agents, the effects of polycarboxylate superplasticizers on slump‐retention of cement and concrete were investigated, and the mechanism of action and the structure of polycarboxylate superplasticizers were investigated by using conductivity, complexing Ca2+ concentration, gel permeation chromatography (GPC), nuclear magnetic resonance hydrogen spectroscopy (1H‐NMR), and nuclear magnetic resonance phosphorus spectroscopy (31P‐NMR). The results indicated that the slump flow of cement paste mixed with PC‐M was increased quickly within 60 min and then lost gradually, while PC‐S increased slowly and evenly within 240 min. The slump flow of concrete mixed with PC‐S reached 405 mm after 150 min, but the concrete mixed with PC‐M was almost no fluidity after 150 min. The conductivity of the PC‐M aqueous solution decreased quickly within 45 min, then slowly decreased, while the conductivity of the PC‐S aqueous solution decreased slowly within 180 min. PC‐M had a much greater complexation ability of Ca2+ than PC‐S. The composition and structure of the two slump‐retention polycarboxylate superplasticizers were altered by different chain transfer agents, and the hydrolysis‐adsorption capacity of each component was different. The rate of hydrolyzation‐adsorption of each component was PC‐M3 ≈ PC‐S3>PC‐M1>PC‐M2 ≈ PC‐S1>PC‐S2. The faster the adsorption rate, the faster the slump flow loss of concrete.

In this work, we have investigated effects of calcium on the atomic and electronic structures of CdSe QDs by ab initio molecular dynamics. The increase of CaO content in glass is found to break the linkage between Na and O atoms, while interactions between Cd atoms and non-bridging oxygens are not disrupted. The presence of the CdSe QD promotes the migration of Na atoms from the glass matrix to the interface, and even the interior of CdSe QD, while Ca atoms are only found to be present at the QD/glass interface and in glass matrices far from QD. However, on the basis of radial concentration distribution, the CdSe QD only impacts the structure of glass at short-range near the interface. The increase in CaO content is also shown to increase the HOMO-LUMO gap of CdSe QDs embedded glasses. Our findings can extend understanding of the effect of calcium on the structural and luminescence properties of CdSe QDs embedded glasses.