Advanced Materials Research Vols. 250-253

Abstract: As reinforced material, basalt fiber is added into cement-based material. In this paper, the influence of basalt fiber on the performance of cement-based material is made experiment to look for the more appropriate. The content and length of basalt fiber is the important factors affecting the fluidity, flexural strength and compressive strength.

Abstract: In order to study the shrinkage characteristics of cement paste, environmental scanning electron microscope was used to observe the microstructure shrinkage of cement paste and cement mortar under different humidity. The results showed that : with the relative humidity decreased from 80% to 10%, the shrinkage cracking of paste microstructure appeared in different degree and increased continuously,also the regression analysis showed the relative humidity and shrinkage was conical relationship.

Abstract: Durability of dry-mixing self-compacting concrete was evaluated through carbonation testing, freeze-thaw testing and chloride ions diffusion testing. The results indicate that carbonation resistance, frost resistance and chloride ions diffusion of durability of dry-mixing self-compacting concrete are excellent, compared with normally vibrated concrete (NVC). Durability of dry-mixing self-compacting concrete shows a better pore structure. Furthermore, the more the content of coarse aggregates is, the poorer the pore structure becomes.

Abstract: The early age cracking of concrete is concerned with its thermal expansion properties, which is mainly reflected by the thermal expansion coefficient. Reasonably controlling the coefficient is an effective way of reducing cracks in the early age of concrete. While thermal expansion properties are related to the micro-pore texture characteristics of the concrete. Micro-pore textures of concretes of different mixing ratios and curing time were measured via mercury intrusion porosimetry (MIP), and the thermal expansion coefficient was determined by the comparator. The analysis of test results indicates the correlation between the parameters of micro-pore texture and thermal expansion properties, and also shows a highly positive correlation between the pore area and the thermal expansion coefficient. The results provide a solution for reducing the thermal expansion coefficient, thus controlling the early age cracking.

Abstract: In recent years, many buildings went up in flames one after another. It is thought-provoking. So the fire-proof property should be considered into one of the most important performance of the building thermal insulation materials. As a result, the study on the expanded perlite lightweight porous inorganic material heated up fast although its application still has some problems to be solved. In this paper, we take the expanded perlite as raw material to make thermal insulation board, and then study on the effect of volume weight on the coefficient of thermal conductivity and tensile strength. What is more important, we find that a new binding agent of Na2O-B2O₃-SiO₂ syetem sol contributes to improving its water resistance.

Abstract: Aerogel is regarded as one kind of super thermal insulation materials which could be large-scalely used as building materials. However, the aerogel’s production cost and poor mechanical property limit the its applications. In this paper, we put forward a new low cost way to produce a novel building thermal insulation material: synthesized the aerogel within the expanded perlite’s pores, and using sodium silicate as precursor without adopting supercritical fluid drying and surface modification. The thermal conductivity of expanded perlite was successfully decreased after modified by aerogel.

Abstract: Since modern architectural technology has set a new standard for toughness of mortar, expensive polymer admixture has been used to modify dry-mixed mortar currently. But high cost critically restricted popularization of dry-mixed mortar. A new expanded Perlite powder- redispersible Polymer powder Compound dry-mixed mortar Admixture (PPCA) was researched in this paper. The research has indicated that PPCA showed synergistically optimized effect. There was the best modification effect when expanded perlite powder/redispersible polymer powder rate was 2 and admixture/cement rate was 0.15. The Ratio of Compressive strength to Flexural strength (RCF) declined to less than 3 when compressive strength of mortar staying above 10MPa. Moreover, cost of this compound admixture only was 1/3 of redispersible polymer powder admixture of the same performance. Meanwhile, this PPCA can improve water retention and increase softening coefficient of mortar to above 1.

Abstract: The representative aeolian sand taken from Horqin desert freeway is used as Subgrade Material. In this paper, California Bearing Ratio (CBR) and rebound modulus E₀ are analyzed by experiments which are based on different aeolian samples with different compaction degree, different dry density and different moisture capacity. Simultaneously, the relation of stress and strain is studied to summarize the mechanical strength characteristic of aeolian sand under different compaction criterion. According to carrying capacity of aeolian sand, statics properties are analyzed. Experiment results show that aeolian sand is compacted under the natural moisture capacity in subgrade engineering, which is feasible and effective. The CBR of the compacted aeolian sand should be controlled less than 10% during construction.

Abstract: The foamable phenolic resin was prepared by gradual copolymerization of formaldehyde, paraformaldehyde and phenol using sodium hydroxide (NaOH) as catalyst, by way of adding NaOH, paraformaldehyde in different steps. The environmental protection vesicant, foam stabilizer and mixed acid curing agent were mixed with the foamable phenolic resin to prepare flame-retardant insulation phenolic foam. The influence of the formaldehyde/phenol molar ratio on the activity, toxic residue of foamable phenolic resin was investigated. Besides, the foam cell structure, insulation and flame-retardant properties of the phenolic foam were also studied. The results showed that as the molar ratio of formaldehyde to phenol was 2.0, the free phenol content was 2.3% and hydroxymethyl content was 34.83%, the thermal conductivity was 0.046w/mk, oxygen index was 54.3% and carbon monoxide (CO) peak production was as high as 1.8584 kg/kg, which was suitable to be used as insulation and flame-retardant materials in buildings.

Abstract: The microstructure of alkali-activated granulated blast furnace slag-based geopolymer was studied by means of field emission scanning electron microscope (FESEM) coupled with energy dispersive X-ray analysis (EDXA). FESEM images showed that the geopolymer material has worm-like microstructure in the nanoscale with an average particle size of 20 nm. EDXA results demonstrated that the Na-based and Ca-based geopolymers were produced via the disintegration of amorphous phases and some minerals in GBFS and polycondensation reaction of oxygen-silicon and oxygen-aluminum tetrahedrons under alkaline condition.