Lu Lingchao

Study of Ba-bearing calcium sulphoaluminate minerals and cement

Abstract In this paper, we synthesized a series of new cement minerals, Ba-bearing calcium sulphoaluminates, by the substitution of Ba2+ for Ca2+ ions of C4A3S (3CaO · 3Al2O3 · CaSO4). The strength development was studied. The results show that the strength of Ba-bearing calcium sulphoaluminates is higher than that of C4A3S, and the optimal composition has been found. Based on this conclusion, Ba-bearing calcium sulphoaluminte cement has been burned with Ba-bearing industrial wastes. In addition, the hydration mechanism of the cement was analyzed by X-ray diffraction, scanning electron microscopy, and infrared spectrophotometry.

Influence of Ceramic Particle Size on Piezoelectric Properties of Cement-Based Piezoelectric Composites

Cement-based piezoelectric composites with 0–3 connectivity pattern were fabricated from lead lithium niobate-lead zirconate-lead titanate (PLN) and sulphoaluminate cement. The influences of PLN particle size on the electromechanical coupling and piezoelectric properties of composites were discussed in detail. The results show that under the conditions of the same PLN content and fabrication technique, the piezoelectric strain factor d 33 and piezoelectric voltage factor g 33 increase with increasing the PLN particle size. When the PLN particle size is larger than 100 μ m, d33 and g 33 are hardly influenced by the PLN particle size. Electromechanical coupling coefficient K p and K t are shown to be independent of the PLN particle size, while mechanical quality factor Q m decreases with increasing the PLN particle size.

Smart Properties of Carbon Fiber Reinforced Cement-based Composites

In this study carbon fiber reinforced cement-based composites (CFRC) are fabricated by compressing, and the smart properties of the composites are studied. The results show that there exists a remarkable negative temperature coefficient (NTC) and a positive temperature coefficient (PTC) in the composite. The resistivities of the composites formed under 10 MPa are more sensitive to temperature than that of the composites formed under 2 MPa, and the critical temperature zone of the composites formed under 10 MPa (100-130°C) is narrower than that of the composites formed under 2 MPa (50-100°C). The fractional change in resistance of CFRC shows obvious one-to-one correspondence with cyclic load. The amplitude of the fractional change in resistance of the composites formed under 10 MPa is obviously larger than that of the composites formed under 2 MPa, which is more suitable for the application of important buildings such as bridges, dams, and so on to realize the real-time, dynamic and health monitoring, and damnification evaluation.

High Water Content Material Based on Ba-Bearing Sulphoaluminate Cement

A new type of high water content material which is made up of two pastes is prepared, one is made from line and gypsum, and another is based on Ba-bearing sulphoaluminate cement. It has excellent properties such as slow single paste solidifing, fast double pates solidifing, fast coagulating and hardening, high early strength, good suspension property at high WIC ratio and low cost. Meanwhile, the properties and hydration mechanism of the material were analyzed by using XRD, DTA-TG and SEM. The hydrated products of new type of high water content material are Ba-bearing ettringite, BaSO4, aluminum gel and C-S-H gel.