China
Africa
Explore chapters and articles related to this topic
Prevention of Alkali-Silica Reaction
Published in Ian Sims, Alan Poole, Alkali-Aggregate Reaction in Concrete: A World Review, 2017
Michael D.A. Thomas, R. Doug Hooton, Kevin Folliard
Figure 4.17 shows an empirical relationship between the expansion of concrete at 2 years and a “chemical index” derived from the chemical composition of the total cementing materials to produce 132 different concrete mixes, which were tested in accordance with ASTM C1293 (2008) (Thomas & Shehata, 2004). The cementing materials used to produce these concretes were the same as those used for the pore solution study discussed above. The reactive coarse aggregate was siliceous limestone (Spratt’s). The best fit between expansion and chemical composition was found to be with the following index: [(Na2Oe)0.33 x CaO]/(SiO2)2. This relationship is not intended as a method for predicting expansion based on the chemical composition of the binder phase, but merely to examine what constituents of the binder tend to influence ASR expansion the most. The relationship is likely quite different if a different reactive aggregate or, even, a different test method is used. However, the relationship does indicate that expansion is likely to increase as the alkali and calcium content of the binder increase or as the silica content decreases, and this is somewhat intuitive.
A case study on one shot raise driving using multi-spherical charges in an open pit mine
Published in Charlie C. Li, Xing Li, Zong-Xian Zhang, Rock Dynamics – Experiments, Theories and Applications, 2018
Q.Y. Li, D.Y. Luo, W.H. Wang, Z.Y. Wu, D.H. Sun
The aim of the study is to excavate a raise in the mined-out area. The laser scanning results show that the dimensions of the mined-out area is 35.5 m × 34.7 m (length × width), and 13 m high. The rock in the blasting area is mainly siliceous limestone and skarn. The siliceous limestone is hard, f = 19, as well as having a high toughness; the skarn has slightly less strength, f = 14–16, but both rock types are difficult to blast. There are no faults in the test area.
Groundwater level and temperature changes following the great Tangshan earthquake of 1976 near the epicenter
Published in Geomatics, Natural Hazards and Risk, 2023
Yuchuan Ma, Guangcai Wang, Zheming Shi, Rui Yan, Huaizhong Yu
The SW1 and SW2 wells are located in Tangshan Hydrogeological Observation Station. The SW1 well has a depth of 185 m and is cased from the wellhead to 140.56 m. The screened section of the well is between 140.56 and 185 m, and the lithology of the screened section is Sinian siliceous limestone. The SW2 well has a depth of 71 m and is cased from the wellhead to the bottom. The screened section is not clear. The lithology from the wellhead to the bottom is Quaternary sediments. The water level of the SW1 well was monitored by a self-recording gauge between 1975 and 1979. The water levels of the SW1 and SW2 wells had similar annual variations. The water level observations were continuous before and after the Tangshan earthquake. Following the Tangshan earthquake, the depth of water level in the SW1 well increased from 30.3 m to 22.01 m, and the depth of water level in the SW2 well increased from 11 m to 9.17 m. The water level in the SW1 well decreased rapidly in the first 80 days after the earthquake, and it gradually recovered to the pre-seismic level in the following three years (Figure 3c). The recovery of water level in the SW2 well is difficult to distinguish because it was submerged in the background fluctuations (Figure 3d).
Multi-source information fusion technology for risk assessment of water inrush from coal floor karst aquifer
Published in Geomatics, Natural Hazards and Risk, 2022
Bo Li, Wenping Zhang, Jie Long, Juan Fan, Mengyu Chen, Tao Li, Pu Liu
The atmospheric precipitation is an important source of regional underground water. The deep underground water mainly exists in the form of confined water, and the flow direction of underground water is mainly controlled by stratum and structure, which is consistent with the trend of the stratum. The aquifuge of the coal seam floor consists of mudstone, silty mudstone, fine sandstone, and siliceous limestone. According to the hydrogeological investigation data of the coal mine, the distance between the karst fracture aquifer in the Maokou formation of the Permian Middle System and the 11th coal seam is 14.06∼29.25m and the mean distance is 19.76 m. It is the direct aquifer of the 11th coal seam. The grey to light grey powder limestones with thickness above 60 m can be found in the Maokou formation of the Permian Middle System. The aquifer in Maokou formation is featured with developed karst fractures and channels, the non-uniform height of water-rich stratum, static water level elevation 1076.799∼1151.883m, specific capacity 0.0054192 ∼ 0.017010 L/s.m, and hydraulic conductivity 0.0000004 m∼0.04153 m/d. Figure 2 shows the hydrogeological structure.
Effect of the use of Marpol waste as a partial replacement of the binder for the manufacture of more sustainable bituminous mixtures
Published in International Journal of Pavement Engineering, 2022
Teresa López-Montero, Rodrigo Miró, Adriana Martínez
To verify that the high wheel tracking values are not due to the binder, the wheel tracking tests were repeated using the same mixture (AC16surf D) but manufactured with a different type of aggregate, a porphyry aggregate. Figure 7 shows the laboratory results. In this case, the values obtained are lower than those for the mixture with siliceous-limestone aggregate, regardless of the binder type. Table 7 includes the average values of the main parameters obtained from the laboratory wheel tracking test. For this type of aggregate, no differences are seen in the results obtained for binders REF and TEC1. These results confirm the theory that the critical plastic deformation values obtained for the mixture manufactured with siliceous-limestone aggregate are due to the morphology of the aggregate.