Advanced Materials Research Vols. 602-604

Abstract: In the case of construction with high volume blast-furnace slag(BFS) concrete during winter season, the setting and hardening are drastically delayed, so it has a high risk of initial frost. Assuming that the concrete incorporating a high volume of BFS is affected by freezing at the early age during the winter conditions, then this study is to investigate the effect of curing method on the strength development and the resistance to freezing-thawing action. As a result, the concrete performing water curing at 5°C after subjected to initial frost damage improve the long-term strength and the freezing-thawing durability. The concrete implementing water curing at 30°C enhance the long-term strength and the resistance to freezing-thawing action as well as the early strength. However, the concrete with sealed curing at 30°C exhibits the improvement in the early strength, but not in the long-term strength and the freezing-thawing durability.

Abstract: Red mud used in cement stabilized macadam, can be used as cementing materials and auxiliary cementation of cement, and be regard as fine aggregate, which has dual role. Aiming at optimum content of red mud which used in the cement stabilized macadam road base, the grey system theory was used and a new grey situation decision model was established. In this model, variation coefficient was used to decide index weighting. Based on the model for optimum mixture ratio of cement and red mud stabilized graded crushed stone, the calculation of the conclusion is consistent with the actual engineering, which shows that grey situation decision-making is the effective method of optimum content of red mud optimization.

Abstract: Quartz powder with different fineness were added into alkali activated slag cement to reduce the drying shringkage of the hardened cement paste. Experimental results showed that partially replacing the slag powder with quartz powder will reduce the water requirement of normal consistency, dry shrinkage and early age compressive and flexural strength of alkali-activated slag cement (AASC), however, the flexural/compressive strength ratio and the fracture toughness will be increased and so does the later strength. The fracture section of specimen of quartz powder modified alkali-activates slag cement paste has a rougher texture than that of pure alkali-activates slag cement paste.

Abstract: The cold recycled materials have temperature sensitivity; both the modules and the strength will decrease with the increase of temperature, which will change the mechanical state of pavement structure. The temperature sensitivity of cold recycling materials may produce failure. Two typical pavement structures, which have been used in practical project, were selected in the analysis. The result shows that the mechanical state of cold recycling pavement without semi-rigid base will be improved in hot summer, while the mechanical state of the cold recycling pavement without semi-rigid base will be deteriorated in hot summer which may produce adverse state.

Abstract: At present, cement stabilization and sand are mainly used as Chinese road bases. Portland cement which causes shrinkage crack of road base can’t be suitable for construction requirements. One kind of new type cementitious materials of road base was developed to substitute for Portland cement by the construction requirements that the fly ash is the main raw materials. This product is not only suitable for construction requirements, but also reduces crack of road base for its suitable strength and micro expansive.

Abstract: Abstract. Laying the road, a lot of asphalt mixing plants use recycled asphalt concrete instead of fresh asphalt concrete. The main reason is that the plants don’t need to provide the viscosity inspection when testing because it is not mentioned in the contract. Even if the value of bitumen viscosity is high in the test report, it is difficult to prove effectively whether to join the asphalt recycled materials or not. This study is to explore the relationship between their extraction of bitumen and coarse aggregate cleanliness by Soxhlet extraction from asphalt recycled materials and fresh asphalt concrete. Besides, we look for the differences after washing asphalt. The research focuses on the method to view the number of the cleanliness on the coarse aggregate surface. The coarse aggregates will be divided into four kinds of sieve (3/4 ", 1/2", 3/8 ", # 4) in process. The selected range is by the built-in program of Photoshop_CS3. We determined the percentage of asphalt area on the aggregates in line with the RGB values. We further used the image processing techniques (Matlab program of image analysis) to assess the relationship of the above mention and compared the basic properties of the asphalt.

Abstract: The k-means algorithm was used to divide the acoustic emission signals collected during the three-point bending test into two types. Combining with the analysis of AE parameters can we distinguish the micro-damage pattern recognition of the refractory materials. The bending test equipment is HMOR/STRAIN, and the AE acquisition device is DISP from PAC. Amplitude, counts, risetime, duration and centroid frequency were selected as the AE parameters .The microscopic damage modes of the refractory materials were recognized.

Abstract: This paper focused on the evaluation of burning performance of the traditional organic insulation materials, such as XPS, PU and phenolic foam. Cone calorimeter test indicated that PU showed a well flammability. After the combustion process, most of the XPS was melted, and most of the phenolic foam was burned. SBI test showed that the burning grade of XPS, PU and phenolic foam insulation board are in the region of grade B to Grade D, can not achieve grade A. All XPS samples can reach to level ZA3, however, some PU and phenolic foam samples can not reach to level ZA3.

Abstract: This paper focused on the evaluation of burning performance of the traditional organic insulation materials for external wall of building, such as XPS, EPS and PU foam. Results of full-scale fire testing showed that if the LOI of organic materials reach Class B2 requirements, and the organic insulating layer has been protected by thin plastering, then the fire will not spread during the full-scale practical fire testing.

Abstract: Using XRD and SEM analysis, the types and morphology of autoclaved aerated concrete (AAC) hydration products in different water-to-binder ratio (w/b) and different autoclaved system were studied. Strength test shows that, Using w/b=0.25 and autoclaved curing 190°C for 8h, AAC with dry density 765kg/m3 and compressive strength 7.5MPa was made. XRD and SEM analysis indicate that, the higher the autoclaved temperature is, the smaller the size of hydration products (most of them are tobermorite and hydrogamet) is, and the crystallinity has a little increase; with the extension of autoclaved time, the size of products is smaller, the crystallinity is first increased and then decreased, the crystal form of tobermorite turns 1.1nm into 1.4nm; the less the w/b is, the smaller the size of products is, and the higher the crystallinity is, and tobermorite turns 1.1nm into 1.4nm.