Assessment of Cement-Lime as Stabilizer on Mud Bricks

The aim of this study was to evaluate the compressive strength of clay bricks and their stability to water absorption by inserting stabilizers such as lime and cement of 0%, 4%, 6%, 8%, 10%, 12% to 14%. Spectrometric analysis was used to characterize the various stabilizers and the clay used, and tests of resistance and water absorption were also carried out. The clay was found to be an aluminosilicate (15.55% to 17.17% Al2O3 and 42.12% to 44.15% SiO2). The lime contains 90.84% CaO and the cement has 17.80% SiO2, 3.46% Al2O3, 2.43% Fe2O3 and 58.47% CaO in the combined form of tricalcium silicate, dicalcium silicate, tricalcium aluminate and ferro-tetra calcium aluminate. The results showed that the insertion of locally available stabilizers (lime and cement) improved the strength of the material by almost 80% when the lime was increased from 0% to 14% for 14 days. For compressed cement, a 65% increase in strength was observed under the same conditions. Strength increases with drying time, with a 52% increase in strength at 28 days compared to 14 days. Furthermore, compressed cement bricks have a more compact structure, absorbing very little water (32%). In view of all these results, cement appears to be the best stabilizer, and compression improves compressive strength and reduces water absorption.

Hydrophilic and strength-softening characteristics of calcareous shale in deep mines

To better understand the mechanism of the strength weakening process of soft rocks in deep mines after interacting with water, a self-developed experimental system, Intelligent Testing System for Water Absorption in Deep Soft Rocks （ITSWADSR）, is employed to analyze the hydrophilic behavior of deep calcareous shale sampled from Daqiang coal mine. Experimental results demonstrate that the relation between water absorption and time can be expressed by power functions, and the soakage rate decreases while the soakage increases with time. In order to quantitatively calculate the weight coefficients of the influential factors for water absorbing capacity of rocks, a series of testing methods are adopted, including scanning electron microscope （SEM）, X-ray diffraction and mercury injection test. It is demonstrated that the effective porosity has a positive correlation with the water absorbing capacity of rocks and the contents of illite and illite/smectite. The initial water content presents a negative correlation with the water absorption capacity of rocks. According to the absolute value of weight coefficients of various influential factors, the order of magnitude from high to low is captured： initial water content, illite, illite/smectite formation （S=5%）, and the effective porosity. After water absorption tests, uniaxial compressive strength （UCS） tests were performed on rock specimens allowing a linear relationship between the UCS and the water content of rock to be established, indicating that the strength of calcareous shale decreases linearly with the increasing water content.

Experimental research on hydrophilic characteristics of natural soft rock at high stress state

In order to study features of rock–water interaction, a self-developed experimental system called Intelligent Testing System for Water Absorption in Deep Soft Rocks(ITSWADSR) was utilized to analyze the hydrophilic behaviors of natural soft rock at high stress state. Combining X-ray diffraction and mercury injection test, main influencing factors on hydrophilic characteristics were studied. According to the results, it could be concluded as the following:(1) the effective porosity, and the content of illite, illite/smectite formation(S = 5%) and kaolinite have positive correlation with the water absorption capacity of rock; meanwhile, the initial moisture content, fractal dimension of effective pores, illite/smectite formation(S = 30%) and chlorite present negative correlation;(2) among the positive factors, the ascending order is kaolinite, illite/smectite formation(S = 5%) and illite;(3) the descending order among the negative factors are chlorite, illite/smectite formation(S = 30%) and fractal dimension of the effective pores;(4) influence of effective porosity on the pressurized water absorbing capacity of rock is minimal, while it is maximal in the process of no pressurized water absorption.

Hydrophilic characteristics of soft rock in deep mines

A series of water absorption tests on dried soft rock have been conducted by the intelligent testing system for water absorption tests in deep soft rock, including tests of water absorption with and without pres- sure. The results show that the water absorbing capacity of rock with a certain pressure is larger than that of rock without pressure： however, the relationship between the water absorbing percentage and the time can be expressed by w（t） = a（l - e^-bt）. In hi-logarithmic coordinates, the hydrophilic relationship with time in tests with pressure could be characterized by linearity, while they present concave or convex in tests without pressure. Based on the hypothesis that each influential factor is irrelevant and they have a linear correlation with the water absorbing capacity, we calculated the weight coefficient of each factor according to experimental results under different conditions. The calculations demonstrate that the effec- tive porosity, content of smectite and kaolinite are all positively correlated with the water absorption capacity of rock; meanwhile, the fractal dimension of the effective pores presents a negative correlation with the water absorption capacity of rock. The water absorption capacity with pressure increases with increasing illite, chlorite and chlorite/smectite formation and a decrease in illite/smectite formation and the fractal dimension of the effective pores, while it is opposite in tests without pressure. The weight coefficient of smectite is smallest among positive factors, and the fractal dimension of the effective pores is the smallest amongst the negative factors.

提高日用细瓷产品质量的试验

针对我厂日用细瓷产吕白度下降、吸水率偏高．热稳定性能不良等质量问题，通过引入优质高岭土．调整坯料配方的研究。

Energy absorption potential of concrete floors containing secondary （shrinkage and temperature） reinforcements

This paper experimentally investigates the namely, normal density concrete and structural low-density energy absorption potential of two types of concrete floors, concrete, containing secondary （shrinkage and temperature） reinforcements. The test program considered the following secondary reinforcements： 1） traditional welded-wire steel mesh, 2） steel fiber and 3） poly composite fiber. To estimate the extent to which crushing of floor slab materials would help absorb energy, a series of concrete penetration tests employing patch loading was undertaken on scaled down model slabs. Each concrete-secondary reinforcement combination considered slabs of 50 mm in depth with square plan dimensions ranging from 50 to 500 mm, resulting in a total of 30 test specimens. The first part of the paper discusses the test specimens, the test setup, and the test procedure. The second part of the paper presents the experimental results and establishes the energy absorption of different concrete- secondary reinforcement combinations. Sieve analysis results of the crushed specimens were used to derive a ＂work index＂ value that relates the pulverized particle size distributions to energy inputs. The work index values of concrete-secondary reinforcement systems can be used to assess the energy dissipation potential associated with such floor slabs in buildings undergoing progressive collapse. The results indicate that floors with secondary reinforcements could play an important role in helping arrest global progressive collapse.