Guo Zhong Li

Study on Paraffin/Expanded Perlite Composite Phase Change Energy-Storage Materials

Paraffin/expanded perlite composite phase change energy-storage material (PPCM) was prepared by vacuum adsorption method with expanded perlite as adsorption material and paraffin as phase change energy-storage material. The diffused-exudative circle method was used to determine that the best adsorption quantity of expanded perlite was 65%. The phase transition process and microstructure of PPCM with the best adsorption quantity were characterized by DSC and SEM. The results shown that the internal micropores of expanded perlite particles were almost completely filled with paraffin and the expanded perlite particles became close-grained particles. The phase change temperature of PPCM was basically similar with that of paraffin and its phase change latent heat was corresponded with that of paraffin in the PPCM.

Study on Production of Concrete Small Hollow Block with Recycled Aggregate

The construction waste was processed into recycled aggregate and was used to substitute for natural aggregate to produce concrete small hollow block with grade of MU7.5. The effect of grain composition, replacement ratios and chemical activator of recycled aggregate on compressive strength of concrete small hollow block was studied. The results shows that through optimized grain composition of recycled aggregate and mixed with appropriate chemical activator, the compressive strength of concrete small hollow block with 100% recycled aggregate can be satisfied with the requirement of MU7.5 concrete small hollow block.

Study of Fluorgypsum Modification

Physical modification and chemical modification were used to modify fluorgypsum. Effect of physical modification and chemical modification on the performance of fluorgypsum was studied, and the mechanism of modification was discussed by testing the phase composition and microstructure of modified fluorgypsum, using XRD and SEM. The results showed that fluorgypsum activity was excited effectively by physical modification and chemical modification. Physical modification decreased CaSO4 grain size and structure regularity, and increased fluorgypsum specific surface area, and the optimum specific surface area was 4600-4900cm2/g. Chemical modification accelerated fluorgypsum hydration and CaSO4•2H2O growth, and increased CaSO4•2H2O grain size and slenderness ratio. The strength of fluorgypsum was exerted effectively by chemical modification.

Effect of Straw Fiber Modification on Performance of Gypsum Composite

Straw fibers were modified by acrylic acid coating treatment, and mechanical properties of straw fibers reinforced gypsum composite were investigated. Wax emulsion was added in order to improve waterproof properties of gypsum composite. Surface modification effect of straw fibers and micro-morphology of gypsum composite were analyzed by scanning electron microscope, infrared spectrometer and mercury porosimeter. The mechanism of modified straw fibers and wax emulsion in improving performances of gypsum composite was discussed.

Study on the Microstructure of RFA Cement Mortar after Modification

The microstructures of fine recycled concrete aggregate (FRCA) after modifications in cement mortar were studied. The result indicated that the modification of RFA could strengthen the enhancement effect on microstructure when modified by 20wt% silica fume (SF) grout, 10wt% Polyvinyl alcohol (PVA) solution. After modification by SF grout and PVA solution, the thickness of interfacial transition zone (ITZ) of RFA cement mortar was decreased by 50% compared with the unmodified samples. The ITZ between RFA and cement paste was studied and the surface microstructure and sectional morphology of RFA was observed by scanning electron microscopy (SEM). Analyzing the modification mechanism and Building the superficial micro-structure model of RFA in cement mortar was carried out.

Study on the Preparation and Properties of Desulfurization Gypsum-Based Self-Leveling Material

In this paper self-leveling floor material with flue gas desulfurization (FGD) gypsum was studied. Gypsum-based self-leveling materials was prepared with desulfurization gypsum as binder and added fly ashadmixture Aadmixture B and four kinds of water reducing agents. The result indicated that HC multi-carboxylic acid based super plasticizer demonstrates excellent workability and better compatibility with gypsum, when its content was 1.0%, the fluidity of slurry met the demands of 145mm±5mm. Adding re-dispersible polymer powder to enhance the strength of desulfurization gypsum, the results showed that when its content was 3%, the adhesive strength of sample was increased to 1.21MPa that could meet the performance requirements of self-leveling floor material.

Preparation and Study on the Performance of Polymer-Modified Cement-Based Composite Insulation Materials

In the experiment, the influence of water-cement ratio on the strength of composite material was studied, and the optimal water-cement ratio was 0.45. The influence of different dosages of foam stabilizer on the mechanical properties of composite material was studied, and the optimal dosage of foam stabilizer was 3%. And the influence of different dosages of polymer on the strength and water absorption of composite material was studied, and the optimal dosage of polymer was 1.5%. In this ratio, the compressive strength is 0.53 MPa, flexural strength is 0.39 MPa, 2h water absorption is 41.1%, 24h water absorption is 43.1% and thermal conductivity is 0.048 W/(m·K). Meanwhile, scanning electron microscopy is used to observe the internal morphology of the samples, and the related action mechanism is explored.

Influence of Sintering Temperature on Performance of Red Mud Lightweight Ceramsite

The red mud lightweight ceramsite was made by using red mud, fly ash and bentonite, mixed with a certain amount of pore-forming agent and cosolvent, through the roasting process. Influence of sintering temperature to red mud ceramsite was studied. The microscopic morphology of red mud lightweight ceramsite damage fracture was analyzed by using scanning electron microscope and the roasting mechanism was investigated preliminarily. The results show that for the best sample, its apparent density is 724kg/m3, its bulk density is 574kg/m3; its cylinder compressive strength is 5.5Mpa, the water absorption is 8.6%.

Influences of Different Waterproofing Agents on Water Resistance of Foamed Cement

The rapid hardening sulphoaluminate cement was used to prepare foamed cement by the chemical foaming method. The impact of organic and inorganic waterproofing agent on the water absorption, mechanical strength and softening coefficient of foamed cement were studied. The results showed that adding waterproofing agent could improve its foam structure and reduce the water absorption, improve its mechanical strength and softening coefficient, thus improving its water resistance; Organic waterproof agents had a better performance than inorganic waterproof agents. The mechanisms of action of different waterproofing agent were explored.

Preparation of Cementitious Material with High Dosage of Low-Alkalinity Steel Slag

Low-alkalinity steel slag was mixed with FGD gypsum to make the gypsum based cementing material of low-alkalinity steel slag, by adding some appropriate activators. Mechanism of each component was discussed. Results show that, when steel slag-to-FGD gypsum is 1, the initial setting time is greatly shortened to 6min and the final to 9min. Flexural strengths of 2h, 1d and 7d are followed with 2.21MPa, 2.03MPa and 3.59MPa, while the compressive of 2h, 1d and 7d are 5.06MPa, 4.70MPa and 12.55MPa.