Shoude Wang

Dielectric and piezoelectric properties of piezoelectric ceramic–sulphoaluminate cement composites

Using cement as the matrix of piezoelectric smart composites can solve the problem of mismatch of smart composites and concrete structure in civil engineering. 0–3 cement based piezoelectric composites were fabricated by a compression technique using PMN and sulphoaluminate cement as raw materials. The influence of the PMN content on the dielectric and piezoelectric properties of the composites was investigated. The temperature dependence of the dielectric properties of the composites was discussed in detail. The results indicate that the dielectric constants are almost constant in the temperature range from −30 to 50 °C, which shows excellent dielectric–temperature stability. With increasing PMN content, the piezoelectric and dielectric properties of the composites increase. The theoretical values of the dielectric constants show good agreement with the experimental values for the composites.

Effect of aggregate gradation with fuller distribution on properties of sulphoaluminate cement concrete

Experimental investigations on mechanical property and durability of sulphoaluminate cement concrete with aggregate gradations according to Fuller distribution are presented in this paper. Compressive strength, water impermeability and resistance capability to sulfate attack of SACC have the same trend of concrete with fine aggregates of Fuller distribution gradation<concrete with coarse aggregates of Fuller distribution gradation<concrete with total aggregates of Fuller distribution gradation. The relationship between bulk density of aggregate and water penetration depth obeyed the second-order polynomial y=0.002x2-6.863 8x +5 862.3, and had a notable correlation R2=0.979 9. The sulphoaluminate cement concrete with total aggregate gradation with Fuller distribution for h=0.50 had the best resistance capability to sulfate attack. It was a second-order polynomial relationship between bulk density of aggregates and water penetration depth of y=0.002x2-6.863 8x+5 862.3 with R2=0.979 9, which indicated notable correlation. The fitting formula between bulk density of aggregates and sulfate resistance coefficient of SACC was y=0.000 5x+0.370 4 with R2=0.958 5.

Effect of natural zeolite on performance of sulfoaluminate cement-based planting cementitious material

This paper aimed to improve the water-retention performance and basic physical properties of sulfoaluminate cement (SAC)-based planting cementitious material. The effect of natural zeolite on the performance of SAC-based planting material was investigated. The water-retention performance, porosity, compressive strength, and alkalinity had been tested and TG-DSC analysis had been adopted in this paper. Experimental results showed that zeolite was effective to improve the water-retention capacity and 10%, 20% and 30% natural zeolite increased the pore volume of the hardened pastes by 10.6%, 26.0%, and 38.6%, especially pore size below 0.1 μm was increased by 9.7%, 26.2% and 17.5%. And 10% zeolite was beneficial to the compressive strengths of cementitious material and 1, 3, and 28 d compressive strength reached up to 35.9, 55.0, 80.3 MPa. Furthermore zeolite decreased the alkalinity of pore fluid of hardened cementitious material, while the addition of zeolite reached up to 30%, the alkalinity of pore fluid of hardened cementitious material decreased by 8.9%. Therefore zeolite was suitable for improving the performance of SAC-based planting cementitious material.

Effect of early-strength-enhancing agents on setting time and early mechanical strength of belite–barium calcium sulfoaluminate cement

Belite–barium calcium sulfoaluminate (C2.75B1.25A3

Effect of Aggregate Gradation with Fuller Distribution on Properties of Sulfoaluminate Cement Concrete

) cement is a new type of belite-rich cement with great long-term mechanical performance and good durability. Its early-age mechanical property was found to be comparable to that of Grade 32.5 ordinary Portland cement. In order to further improve its early hydration activity, the effect of two known early-strength agents on the performance of the belite–barium calcium sulfoaluminate cement was investigated by means of XRD, pore structure and TGA. It was found that Na2SO4 and Ca(HCOO)2 can be used as an early-strength-enhancing agents for this type of cement with the best dosage of 0.5 and 2.0% by weight, respectively. Ca(HCOO)2 was preferable to this type of cement from the durability point of view.

Effect of matrix components with low thermal conductivity and density on performances of cement-EPS/VM insulation mortar

Aggregate, the main ingredient of concrete, has a great effect on mechanical property and durability of concrete. Sulfoaluminate cement has lots of special properties such as high early-age compressive strength, fast hydration and setting rate, and hydration with slight swelling. But effect of aggregate gradation with Fuller distribution on properties of sulfoaluminate cement concrete was seldom studied. Hence, in this paper, experimental investigations on mechanical property and durability of sulfoaluminate cement concrete with aggregate gradations according to Fuller distribution were presented. Fuller distribution of aggregates was beneficial to the close packing of aggregates, and the packing density was changed by adjusting the aggregate gradations. Compressive strength, water impermeability, and resistance capability to sulfate attack of SACC have the same trend of concrete with fine aggregates of Fuller distribution gradation < concrete with fine aggregates of Fuller distribution gradation < concrete with fine aggregates of Fuller distribution gradation. The relationship between packing density of aggregate and water penetration depth obeyed the second-order polynomial y = 0.002x2 – 6.8638x + 5862.3 and had a notable correlation R2 = 0.9799. The sulfoaluminate cement concrete with total aggregate gradation with Fuller distribution for h = 0.50 had the best resistance capability to sulfate attack. It was a second-order polynomial relationship between packing density of aggregates and water penetration depth of y = 0.002x2 – 6.8638x + 5862.3 with R2 = 0.9799, which indicated notable correlation. The fitting formula between packing density of aggregates and sulfate resistance coefficient of SACC was y = 0.0.0005x + 0.3704 with R2 = 0.9585.