An Experiment and Study of M30 Grade of Concrete by Partially Replacing Fine Aggregate with Marble Dust Powder and Phosphogypsum in Rigid Pavement

The Project is to study about M30 grade of concrete by adding waste materials. Marble dust powder and phosphogypsum which is easily available marble which are standard among the most imperative materials, utilized as a part of the development business. Marble dust is a waste material from the construction site is mixed with concrete as a replacement material. Marble dust powder is acquired from sawing and moulding of marble rock. Phosphogypsum is produced as an outgrowth of the production of fertilizer from phosphate rock. There is a high gypsum content and gypsum is a widely used material in constructions. It is weakly radioactive in nature because it is a by-product of phosphate fertilizers. In the M30 grade of concrete fine aggregate is partially replaced by marble dust powder and phosphosgypsum in some proportions. The fine aggregate is replaced by 10%, 20% and 30% in which marble dust powder and phosphogypsum and are added in an equal proportion. Keywords: Marble dust powder, phosphogypsum, grade of concrete, rigid pavement, green concrete.

Analysis of Shear Characteristics of Deep, Anchored Rock Mass under Creep Fatigue Loading

To study the influence of earthquakes and engineering disturbances on the deformation of deeply buried rock masses, shear tests were carried out on anchored sandstone rock masses, anchored marble rock masses, and anchored granite rock masses under creep fatigue loading, and a new creep fatigue model was established to characterize the deformation characteristics of anchored rock masses under creep fatigue loading. The creep fatigue curves of different lithologies clearly show three stages: creep attenuation, steady-state creep, and accelerated creep. Fatigue loading can increase the creep of anchored specimens, and the lower the rock strength is, the higher the creep variable under fatigue loading is. However, for the same rock strength, with the increase in load level, the creep variable produced by creep fatigue load presents a linear downward trend. Considering the changes in the mechanical properties of the anchored rock mass under creep fatigue loading, the creep fatigue model of anchored rock masses is established by introducing a function of the fatigue shear modulus, and the accuracy and applicability of the model are verified by laboratory creep fatigue test data. The model provides a theoretical basis for the study of anchored rock mass support under low-frequency earthquakes or blasting loads.

Fast and localized temperature measurements during simulated earthquakes in carbonate rocks

<p>The understanding of earthquake physics is hindered by the poor knowledge of fault strength and temperature evolution during seismic slip. Experiments reproducing seismic velocity (~1 m/s) allow us to measure both the evolution of fault strength and the associated temperature increase due to frictional heating. However, temperature measurements were performed with techniques having insufficient spatial and temporal resolution. Here we conduct high velocity friction experiments on Carrara marble rock samples sheared at 20 MPa normal stress, velocity of 0.3 and 6 m/s, and 20 m of total displacement. We measure the temperature evolution of the fault surface at the acquisition rate of 1 kHz and over a spatial resolution of ~40 µm<sup></sup>with optical fibers conveying the infrared radiation to a two-color pyrometer. Temperatures up to 1250 °C and low coseismic fault shear strength are compatible with the activation of grain size dependent viscous creep.</p>

Identification of Nonlinear Rheological Parameters of Medium-Strength Marble Rock

The rheological behavior of rocks has been more and more important to predict the long-term deformation of rock engineering. We select a typical medium-strength marble rock as a research object to study the long-term stability of large-scale underground caverns. Some dry and water-saturated rock specimens are used to perform the uniaxial compressive test and the uniaxial compressive creep test. Then a non-constant-parameter damage rheological constitutive model for this medium-strength marble rock is put forward based on the in-situ geological data and uniaxial compressive rheological test results. The least square method based on search mode is utilized to perform the identifications of the rheological parameters. According to the test curves, the related rheological parameters are obtained through inversion analysis on a basis of the non-constant-parameter damage rheological constitutive model, which can provide more accurate rheological parameters for long-term stability analysis of actual projects.