Papers by Keyword: Gravel

Abstract: The work concerns the use of polyvinyl chloride joints as a modern method of stabilizing the trenches in military construction built on unstable water-saturated slopes by combining it with a transverse drainage. Employment of the method will reduce the hydrostatic pressure on the trench walls, excluding the possibility of collapse, and will increase the efficiency of service at military bases. Polyvinyl chloride joints are used in hydraulic engineering in a number of countries, in the construction of artificial canals, swimming pools and flood protection. The novelty of this method is its usage in flooded areas, which at the same time prevents landslides by organizing drainage.

Abstract: The need for porous concrete has become increased due its ability to control surface water, increase the rate of recharging groundwater, and reduce pollution of the ecosystem. Granite is a coarse aggregate that is quite expensive when compared with gravel in Nigeria. Therefore, this research is aimed at optimizing blended granite and gravel in the production of porous concrete. Samples of blended granite-gravel porous concrete of varying mix proportions were produced using cement to aggregate mix ratio of 1:4. The samples were tested for their porosity, workability and compressive strengths. The data collected were analyzed with the aid of Design Expert 10.0. It was observed that the optimal combination for the granite-gravel blended porous concrete is 12% granite, 88% gravel, and a water-cement ratio of 0.66%. This combination gave a porous concrete with a compressive strength of 48.4 N/mm², percentage porosity of 6% and a compacting factor of 0.91. These values when compared to that of the control specimen revealed that the optimal mix gave a porous concrete with higher porosity, higher workability and a better compressive strength.

Abstract: The non-linear finite element program Ls-DYNA/ANSYS is applied to simulate numerically the capacity for the geo-materials to dissipate the energy induced by the falling objects. The calculation results for the crushed stone coincide well with those recommended by the current Code of《DNV-rp-f107_2010》, which is on the basis of experiment data, implying the feasibility of using this program to estimate the energy dissipating capacity of the geo-materials. Because little research has been performed with clay soil, the program Ls-DYNA/ANSYS is used to predict the energy dissipating capacity of clay layers.

Abstract: This paper discusses the perception of gravel suppliers in the six states situated in South-western Nigeria. It reported findings from a research on gravel supply studies in the study area. Major gravel pits, together with their perceived technical characteristics in the states were identified through a structured questionnaire designed to solicit response from truck drivers and association of gravel suppliers. Based on this, factors affecting gravel supply and usage were measured by random variables devised for the purpose. The observed outcomes of the variables from the survey carried out constituted the research data. The collated data was analyzed based on quantitative method through the use of simple percentage method of data analysis. The paper posits that geological location of Lagos state is responsible for the absence of any gravel pit in the state, hence the prohibitive cost of gravel in the state when compared to other states in the zone. In all the states, more than 99% of gravel suppliers attribute transport as a major factor affecting the cost of gravels. The technical characteristics of gravels from South-western Nigeria are also perceived to be good in construction, though these assertions need to be empirically proved.

Abstract: This research carried out field tests on nine vertical anchors to investigate their behavior in gravel of Taichung Basin. An anchor can be categorized as a deep anchor when the free length Z exceeds 8D (D is the diameter of the anchor). The shape of the heave on the ground surface of a shallow anchor is similar to a normal distribution curve. The extended diameter of the heave was between 170 and 300 cm, which could be divided into two zones, primary and secondary, based on the failure mode of the ground. As the fixed length of a shallow anchor increased, the extended diameter also increased. The ultimate load of an anchor increased with the free length and, to a greater degree, with the fixed length of an anchor: a fixed length of only 3 m (D = 0.12 m) generated an ultimate load of over 1100 kN.

Abstract: The non-linear finite element program Ls-DYNA/ANSYS is applied to simulate numerically the capacity for the geo-materials to dissipate the energy induced by the falling objects. The calculation results for the crushed stone coincide well with those recommended by the current Code of《DNV-rp-f107_2010》, which is on the basis of experiment data, implying the feasibility of using this program to estimate the energy dissipating capacity of the geo-materials. Because little research has been performed with clay soil, the program Ls-DYNA/ANSYS is used to predict the energy dissipating capacity of clay layers.

Abstract: To the old cement concrete pavement which lost the overall loading capacity and large areas are damaged, by using rubblization technology to shocks, crushing and compaction it, pouring the warm-mix asphalt sealing, formed less than 60mm size of flexible base of gravel and paved with warm-mix asphalt pavement on this base. This article is about analysis of interlinear stresses of pavement structure and production cost analysis of mixture on this combination structure. Proved that the structure could in-place recycling, solving the environmental issues of dropped cement pieces garbage. Mix in mixture, spreading process of reducing harmful gas emissions, can save more than 30% of construction costs.

Abstract: The direct roof of B132 coal seam is conglomerate layer in a coal mine, which is cemented with gravels and sandstones and has brought great difficulty for tunnel supporting. It is necessary to study the grain size and strength characteristics of gravel in conglomerate layer for the mining of B132 coal seam safely and efficiently. The statistics and analysis of grain-size characteristics of gravel was carried out in this paper, including of the quantity and volume percent of gravel. Uniaxial compressive strength of gravel was tested with point load method. The test results show that uniaxial compressive strength of gravel is very high, especially the black gravels, whose compressive strength is commonly above 200 MPa and the highest even can reach more than 300 MPa.

Abstract: Different amount of pumice were used to replace gravel to make mixed aggregate concrete, the fast freeze-thaw cycle test were conducted and the influence of pumice rate substitution to the frost resistance properties of concrete were studied.The mass loss rate, strength loss and relative dynamic elastic modulus were regarded as the evaluation index of frost resistance properties of concrete. Results showed that the mass loss rate and strength loss rate gradually decreased and the relative dynamic elastic modulus gradually increased with the increase of pumice rate, the mass loss rate, strength loss rate and the relative dynamic elastic modulus gradually decreased with the increase of freeze-thaw cycles. Polypropylene fibers could reduce the strength loss rate, improved the relative dynamic elastic modulus, but had little effect to improve the mass loss. Through the frost resistance, the frost resistance of concrete improved with the increase of pumice content, at the same time, polypropylene fiber also could improve the frost resistance of concrete.

Abstract: In Xinjiang area, the resources of the pebble aggregate is very abundant, which are widely distributed, are the main source of the coarse aggregate for the ready-mixed concrete industry. The aggregate, which accounts for 80% of the quality, have a great effect on the performance of the concrete, not only play a great role in filling, but also in the workability, strength and durability part. Many technicians have lack knowledge of the ready-mixed concrete industry and pay insufficient attention to the aggregate quality, so it’s necessary to research the pebble concrete performance to provide ready-mixed concrete industry with technical guidance in Xinjiang area.