LABORATORY AND STATISTICAL EVALUATION OF CEMENT AND LIME ON THE PROPERTIES OF TROPICAL BLACK CLAY – IRON ORE TAILINGS MIXTURES

The need for cheaper and more economical soil improvement methods is of great significance in order to reduce the construction cost of flexible pavements. Also, major problems caused by industrial waste in Nigeria can be minimised by recycling or re-using of such wastes for soil improvement. The application of cement and lime along for such purpose has proven to increase the construction cost. Thus the use of industrial waste such as iron ore tailings (IOT) could aid in reducing the construction cost. Series of laboratory and statistical investigations were performed to compare the effect of cement and lime on the properties of tropical black clay (i.e. black cotton soil, BCS). Soil samples were admixed with up to 10 % IOT content and modified with up to 4 % each of cement and lime by dry weight of soil to evaluate their plasticity and compaction characteristics. Compaction was done with British Standard light (BSL) energy. Statistical tests for regression and correlation was achieved using Mini-tab R15 and Microsoft Excel software correspondingly. Results disclosed decreased in liquid limit and plastic limit. Liquid limit values of 56, 54.8, 54.5, 52.5, 52 and 51% were noted for 0, 2, 4, 6, 8 and 10% IOT content. Similar trend was noted for 1, 2, 3 and 4% lime and cement concentrations. A rise in maximum dry density (MDD) and drop in optimum moisture content (OMC) with greater concentration of IOT for all the lime and cement contents under study was noted. Statistical analysis revealed that soil-lime-IOT mixtures gave higher predicted values than soil-cement-IOT mixture for determining plasticity and compaction characteristics of BCS – IOT mixtures. Thus, 4 % lime – 6 % IOT mixture met the criteria for flexible pavement purpose as proposed by Nigerian General Specifications and is recommended for used as pavement material for roads that are lightly trafficked. While the soil – cement - IOT mixes fell to meet the criteria for used as pavement material.

Changes in availability and uptake of soil phosphorus influenced by management practices and crop growth stages under peanut cultivation in medium black clay soil of Saurashtra region, Gujarat

Aim: To investigate efficient utilization of soil phosphorus for peanut nutrition through integration of management practices in medium black clay soils of Saurashtra region in Gujarat. Methodology: Soil phosphorus availability and uptake by peanut plants were assessed at five plant growth stages under six different management practices in Kharif season. The availability of soil P was estimated by Olsen P and Resin P extraction methods. The biomass production and phosphorus uptake at each growth stages were observed in order to draw the relationship between these parameters.? Results: The management practices like raised bed with polythene mulch, integrated and organic nutrient management was consistently found promising for enhanced availability and uptake of soil phosphorus under peanut cultivation. The Olsen P decreased with plant growth under all the management options, except organic and integrated nutrient management practices.? In contrary, the resin P generally increased with plant growth, especially under inorganic and organic nutrient management and raised bed with polythene mulch practices. Irrespective of growth stages, the phosphorus uptake by peanut plants was significantly and strongly correlated with biomass production (r=0.85, p<0.01) and Olsen P (r=0.41, P<0.05).? Interpretation: The results indicate that phosphorus requirement of peanut plants can be efficiently met by integrating land and nutrient management practices in these medium black clay soils.

Color control in industrial clay calcination

The combined use of calcined clays and limestone in the ternary system LC3 enables up to 50% of clinker substitution without affecting the performance. Low grade calcined clays are rich in iron. If calcined in an oxygen rich atmosphere, they turn to red. Cement producers avoid selling cement with a color different to the traditional. This paper proposes a method to modify color during calcination by controlling the atmosphere during the cooling. At calcination, the high temperature favors the formation of magnetite even at oxidizing conditions. However, during the cooling phase, magnetite can convert back to hematite if oxygen is available and the calcined material will have a reddish color. The procedure to control color consists of injecting liquid fuel at the carcass of the kiln while the calcined material exits, so that it combusts and exhausts the oxygen available during the cooling process. The procedure was successfully implemented at a pilot kiln in India. Controlling the calcination atmosphere enabled the production of a black calcined clay, instead of a red material. The reactivity and properties of both red and black clay are very similar, and no side effects have impacted properties of LC3 cements produced with the treated clay.

Impacts of the black clay soil moisture on the corrosion and cathodic protection performance of the API X70 Pipeline

The impact of the black clay soil moisture of Skikda (East of Algeria), on the corrosion cathodic protection performance of the API X70 pipeline was studied in this paper. To achieve this objective, first, electrochemical analysis has been carried out. Then, in order the show impact of the black clay soil moisture of Skikda on the cathodic protection of the API X70 Pipeline, the corrosion parameters of the API X70 steel pipeline obtained by electrochemical measurements such as Tafel slopes, corrosion current densities, and corrosion potentials were used as boundary conditions in the elaborated cathodic protection model. The obtained results show that the corrosion current I corr is directly proportional to the moisture content up to 50 wt. %, with a potential shift towards the more electronegative values. The cathodic protection perfermance has been well proven in black soil at 100 wt. % moisture contents.

How to Recover Lost Traditions?

The aim of the project was to engage the community into the recovery and revitalization of some traditional trades and crafts that are at risk of disappearing. At the same time we intended to make students aware of the lost traditions from previous generations that with time are going to be lost. When visiting the place where the black clay of Bisalhães is produced(Intangible Cultural Heritage of Humanity by UNESCO) we realized that there are not enough potters. We went to explore the pottery extraction and production processes and we organized a traditional fair where we exposed all the pottery pieces made by students, so all the community could be aware of Bisalhães pottery. With our enthusiasm we awake the community curiosity for the beauty of traditions.