Papers by Author: Lu Qian Weng

Abstract: There are shown studies on development of the alkali-activated slag cements and concretes using Chinese raw materials. Such cements and concretes are able to provide high performance characteristics of materials and constructions under exposure of sea climate. The tests had been done for compliance with the requirements set in the national standards of P.R.China and were determined characteristics of strength, wet conditions shrinkage, freeze-thaw resistance, corrosion and weather resistance, biodegradability, water permeability, bond strength between concrete and reinforcement. The obtained positive results of tests allowed to recommend them for a pilot-scale production of the developed materials in sea construction for protection of the sea coastal line in the P.R.China.

Abstract: In order to improve the mechanical properties of HA/PEEK composite, the surface modification of nanosized hydroxyapatite (n-HA) was carried out with silane coupling agent (SCA).The modified particles were produced using different contents of SCA (KH560) and characterized by virtue of Fourier Transform Infrared (FT-IR) spectroscopy. The polyetheretherketone (PEEK) nanocomposite materials reinforced by surface-modified n-HA were successfully prepared and their microstructure and mechanical properties were examined by scanning electron microscopy (SEM), Instron IX Material Testing System and Vickers micro-hardness tester. The result of FT-IR indicated that the nanosized HA was coupled with the SCA by a chemical bonding. SEM observation showed that SCA-HA was well-dispersed in PEEK matrix. The results incicated that mechanical strength of SCA-HA/PEEK composite was improved and best at 5 vol.% HA, 3wt.% SCA.Keywords: nanosized hydroxyapatite; Silane couping agent; Polyetheretherketone; Biocomposite; Mechanical propertity

Abstract: Less than half a century ago just an idea of presence of free alkalis in a ceramic matrix was considered by ordinary Portland cement people as an absurd one and this was a basic postulate accepted in chemistry of cements. In 1957 a scientist from Ukraine (USSR) Viktor Glukhovsky put forward an assumption which was taken as a base for development and bringing into practice of construction a principally new class of cementitious materials which first appeared in the field under a name of alkaline (now also known under a general name of alkali-activated) cementitious materials. A validity of these ideas was confirmed by more than 50 years of evolutional development and vast experience collected on practical use of new materials in different applications. The paper covers theoretical views on role played by alkali in the formation of an alkali-activated cement matrix with high durability. Examples of compositional build-up of the alkali-activated cementitious materials vs. quantity of added alkali and type of aluminosilicate component are reported together with results of 50-year experience obtained from observation of concrete structures made from these cements.

Abstract: The paper covers the results of studies of the alkali activated slag cement concretes from the cements prepared under all-in-one technology to meet the requirements for concretes for marine engineering application. The compressive strength, weather resistance, biodegradability, bonding strength with steel reinforcement bar, steel reinforcement bar protection, chlorine ions diffusion parameters and resistance to corrosive exposure of 5% Na₂SO₄ solution were tested, which exhibit that alkali activated slag cement and concretes are very suitable for marine engineering applications.