Influence of Rock Block Content on Compaction Characteristics of Graded Coarse-Grained Fillers

The bearing capacity, stability, and durability of subgrade are affected by the compaction quality of fillers to a large extent. In this study, samples of graded coarse-grained fillers with different rock block contents were designed and prepared with the aid of an improved continuous gradation equation for coarse-grained soils. Then standard compaction tests of these samples with different water content conditions were conducted to understand the influence of rock block content on the compaction characteristics of graded coarse-grained fillers. Results show that the compaction curve peaks of graded coarse-grained fillers always increase with the rock block content. The maximum dry density of graded coarse-grained fillers increases linearly with the rock block content in approximation, while the optimal water content is the opposite. The optimal water content of graded coarse-grained fillers decreases in nonlinearity with characteristics of rapidly first and then slowly. Two empirical formulas about the rock block content were summarized for predicting the maximum dry density and optimal water content of graded coarse-grained fillers. The results of this study can provide a reference for the engineering application of graded coarse-grained fillers.

Some regularities of change in density in the lithosphere of Northern Eurasia

A method is proposed for calculating the normal compaction curve of rocks for the deep parts of the lithosphere. It is based on the analysis of petrophysical characteristics and interpretation of gravitational anomalies. The main regularities of density changes in the lithosphere of Northern Eurasia are investigated. It has been shown that the density section of the region’s lithosphere is characterized by alternation of paragenetically connected decompacted-compacted (relative to normal compaction) rock complexes at all levels of the lithosphere from the surface layers of bottom sediments to the mantle. These zones of decompacted-compacted rocks complexes have a global distribution.

Compaction Model for Shale in Differences of Geological Ages Using A 3D Empirical Relationship in Northeastern Thailand

Shales are well known for their strong anisotrophic properties. The classical Athy’s model on the exponential porosity reduction with the depth commonly uses based on localities only. Shale compaction curve affects the results of the basin modeling as it is important input data, thus the standard compaction curve of shales needs to be established. This study provided a new data and complies available data of Thailand shales to propose the new empirical relationship among porosity, burial depth, and geological age. The numerical data of the geological time were estimated by the application from the relationship of velocity and depth in each geological ages. The variation of the Thailand shale data due to the different geological ages was found in this study. Finally, the standard curve of shale compaction proposed by Puttiwongrak et al. [9] was examined and confirmed by this research findings.

Energy transfer and influencing factors in soil during compaction

In China, large-area excavation and filling engineering has increased rapidly with the expansion of construction land. The quality of filling engineering is the most important guarantee for the stability of building structures. Among all research on fill soil, the compaction characteristics are significant for indicating the strength and stability of filling engineering. In this paper, two layers of loess fill soil were compacted by a self-manufactured test system with three different compaction energies. Based on the variation in the soil bottom pressure obtained in the tests, the influence of the compaction parameters on the soil bottom pressure was investigated. The results show that the compaction curve can be used instead of the curve of the change in soil bottom pressure with water content; as the soil density increases, the soil bottom pressure increases to the maximum. The relation of the energy consumption ratio of the soil bottom (σ/σz) and the number of soil layers is exponential and reveals the stability of the soil skeleton formed during compaction. This paper describes the compaction characteristics of loess fill soil from the perspective of energy transfer, and the conclusions provide a theoretical basis for soil filling engineering.

Compaction behaviour of lime-treated metakaolin

Metakaolin has been widely used as pozzolanic additive to improve the pozzolanic activity of lime-based products. In this study, normal standard Proctor compaction test was performed on metakaolin with (5% lime) and without (0% lime) lime addition. The changes in stiffness, suction and microstructure with remoulding water content were investigated on statically compacted samples. Results show that lime-treated metakaolin exhibits one and half-peak compaction curve, while untreated metakaolin exhibits common one-peak compaction curve. The uncommon shape of the compaction curve of the treated metakaolin can be explained by the non-fully developed soil suction when water is not continuous. Treated and untreated samples compacted at both dry and wet of optimum show uni-modal pore size distribution characteristics, indicating the absence of aggregates. This is related to the specific thermal treatment, forming separate metakaolin platelets and leading to a modified uniform structure with diffuse platelets. The soil stiffness is rather dominated by the number of particle contacts or soil dry density, the effect of suction being insignificant. For the suction changes, on the dry side, the effect of pore size distribution prevails facing the effect of water content, while on wet side it is the effect of water content that becomes prevailing.

Effect of Reclaimed Asphalt Pavement Heating Temperature on the Compactability of Recycled Hot Mix Asphalt

The compactability of an asphalt mixture is related to the heating temperature of the materials, but the heating temperature of reclaimed asphalt pavement (RAP) is limited by the production process of hot-in-plant recycled mixtures. To choose a reasonable heating temperature for RAP according to the compactability, the compaction energy ratio (CER) obtained from the Superpave gyratory compactor compaction curve was developed. The CERs of fourteen kinds of asphalt mixtures made with different RAPs were compared, all of which were different in type, content, and heating temperature. The results indicated that CER is an effective energy index to evaluate the workability of a bituminous mixture, and it considers both the accumulated energy after each gyration and the number of gyrations. It was also found that increasing the heating temperature of the RAP cannot always improve the workability of the recycled mixture, because the higher heating temperature caused more hard-aged bitumen to be blended with soft virgin bitumen during the mixing process. At the same RAP heating temperature, increasing the RAP content made it more difficult to compact the mixture, especially for RAPs with styrene–butadiene–styrene (SBS) modified bitumen, and the recycled mixtures with SBS-modified bitumen were more difficult to compact than those with nonmodified bitumen.

A novel approach to evaluating the compaction control of soils

Soil compaction is an important operation during the construction of road embankments, railway subgrade, earth dams and compacted clay liners for waste disposal. Soil compaction is usually controlled based on the ratio of the dry density of the soil to the soil water content. However, this relationship presents problems in both the laboratory and in the field when using excess compaction energy levels in cohesive soils with a high natural water content, including differences in the compaction energy levels and a reduction in strength as a result of over-compaction. The compaction curve, which considered the compaction energy levels, is usually unknown in the field and the main factors influencing the stiffness and strength of compacted soils are the dry density and the degree of saturation. We show here compaction results for soils in terms of the dry density and degree of saturation and introduce the concept of an optimum compaction line.