Jiesheng Liu

Research on Connection between Essential Properties and Micromechanism of Organic Silicon–Modified Cement Mortar

This article aimed to research the effect of organic silicon on the density, mechanical strength, water absorption, porosity, and crack resistance of cementitious construction materials. Modified cement mortar was prepared by adding different amounts of organic silicon into control cement mortar. Mechanical strength was evaluated using bending and compressive strength tests. Porosity was evaluated to assess the inner structure of cement mortar. Furthermore, the micromechanism of modified cement mortar and control cement mortar was explored using the nitrogen-absorption test and a Scanning Electron Microscope (SEM). Experimental results showed that for the organic silicon and mix design used in this article, the incorporation of organic silicon generally reduced the mechanical strength and density and increased the water absorption, porosity, and crack resistance. In addition, the analysis of the nitrogen-absorption test and SEM test revealed the modified mechanism and the connection between the macroscopic properties and micromechanism of modified cement mortar.

Experimental Study in the Modification of Mortar Samples with Incorporated Rice Husk

The aim of this work is to investigate the influence of rice husk (RH) on the properties of mortar. Two different RH were used as integral additives in the mortar samples: direct natural RH addition to the mortar and the use of pretreated RH. The results of such modification are described, taking into consideration the interaction between the RH and mortar. In addition, the physical properties, visual observation and microstructure of mortar prepared with different amount of modified RH were experimentally studied. The test results indicated that modification of RH enhanced the interaction between the RH and mortar because of the impurities removal and rougher surface. Comparing with the natural RH, the modification of RH increases the density and the mechanical properties. The addition of RH can increase the pore number of the mortar mixture, resulting in decrease in the density and mechanical properties of mortar. Morphology characterization results showed that the modification of RH results in an improvement in the interaction between the RH and mortar and further increase in RH content increases the number of pores in the mortar structure.

Investigation of Structural, Morphological, and Dynamic Mechanical Properties of Unvulcanized PDMS/Silica Compound

In this study, the interaction between the silica filler and polydimethylsiloxanes (PDMS) was investigated from the aspects of the bound rubber and morphological characterization. With special attention to the dynamic properties, the dynamic test was conducted by dynamic shear rheometer. The results show that the modified filler disperses uniformly within the PDMS matrix without aggregation and connects closely with the matrix compared to that of the unmodified fillers. Surface modification of the filler increases the bound-rubber content. The increase in silica loading leads to an increase in the silica–silica interaction and a decrease in filler–rubber interaction, which results in the aggregation of fillers and the increase of the bound-rubber content. It was apparent that storage modulus, loss modulus, and tanδ of unvulcanized PDMS/filler compounds filled with treated silica filler were lower than that of the untreated silica system. Moreover, the tanδ decreases with increasing silica loading.

Experimental Research of Cement Mortar With Incorporated Lauric Acid/Expanded Perlite Phase-Change Materials

The study presented in this paper focuses on an experimental investigation of cement mortar incorporated lauric acid/expanded perlite phase-change materials (PCMs). The physical properties of mortar incorporated shape-stable PCMs (SSPCMs) were evaluated. The results showed that the addition of SSPCM increased the water absorption of mortar, reduced the bulk density, and thermal conductivity coefficient of SSPCM mortar. Microstructure was studied for SSPCM composite in mortar. Scanning electron microscope (SEM) imaging indicated that most SSPCM granular particles were evenly distributed into the cement matrix after the mechanical strength test, and the SSPCM are in good bond with the cement binder. The temperature-control test revealed that the temperature adjustment properties of samples incorporating SSPCM was significantly greater than that of the reference mortar, and SSPCM-integrated mortar is thermally reliable because of the fact that the SSPCM mortars showed no degradation in thermal performance after multiple thermal cycles.

Study in Physical Properties of Rice Husk Mortar

Rice husk cement composites (RHPC) were prepared in this study. The bulk density, compressive strength, thermal coefficient and water absorption property of the RHPC composites were characterized. The results can provide technical support for the application of rice husk application in practical engineering.

Investigation of Interaction between the Silicone Rubber Sealant and Concrete Substrate

This investigation aimed to study the interaction between concrete substrate and silicone rubber sealant. Several surface treatments were applied in order to obtain different levels of surface roughness in concrete substrates. The bond tensile test showed that abrasion and solvent cleaning methods improved the bond strength relative to that of untreated substrates. The effects of silane coupling agents on the bond strength was studied via two methods of application of the coupling agent, namely, (a) pre-treatment of concrete substrate in an aqueous solution of silane, and (b) adding silane to the silicone rubber sealant as an integral blend additive. No significant differences in bonding values were noted between the two methods. An increase in the amount of silane coupling agent increased the bond strength of the silicone rubber sealant, but beyond a certain point, further increases in the amount of silane lowered the bond strength. As the amount of silanes increased, the failure mode of the samples changed from adhesive failure to cohesive failure. Scanning electron microscopy and contact angle methods were employed to investigate the interface. The results strongly suggest that interface adhesion and treatments are crucial factors in creating a durable bond interface between substrate and sealant.