No abstract

The increasing cost and scarcity of portland cement has impacted negatively on the delivery of affordable housing and infrastructural development in many parts in Sudan, especially in Darfur. This paper focused on the evaluation of the pozzolanic characteristics of the volcanic ash obtained from Jebel Marra (mountains) west of Sudan as potential Supplementary Cementitious Materials for use in blended cement and concrete. The study investigated the chemical, physical, and mineralogical characteristics of the volcanic ash and its reactivity toward lime and cement, in addition , the compressive strengths of blended mortar containing volcanic ash in percentage addition were tested at 7, 28, and 90 days. X-Ray Fluorescence and X-ray diffraction techniques were used for chemical and mineralogical analysis respectively. The results of the chemical analysis showed that the sum oxides of Silica, Alumina and Iron were 83.75%. The strength reactivity with lime was 4.2Mpa, while the 28-days compressive strengths for the replacement level with cement 10%, 20%, 30%, 40%, and 50% were 38.9, 35, 29.33, 28.64, and 25 Mpa respectively, against 41.33Mpa., for the control mix. These results indicated that the Jebel Marra Volcanic Ash possesses pozzolanic characteristics and is thus potential cementitious material for use in blended cement.

This paper aims to assess the pozzolanic characteristics of the volcanic ash obtained from Jebal Tagabo (Tagabo Mountains) in western Sudan (North Darfur State) as potential Supplementary Cementitious Materials for use in blended cement and concrete. Four natural Pozzolanic materials samples have been obtained; the first is volcanic ash from the Garma region (TG1VA), the second from the Mabo region (TG2VA), the third from the Mawo region (TG3VA) and the last from the Daim Sanosi region (TG4VA). This study has investigated the chemical and physical characteristics of the samples and their pozzolanic activities with Ordinary Portland cement (OPC) at different substitution levels of cement by weights, which are 10, 20, 30, 40, and 50%. And the results of chemical analysis show that all samples can be classified as Class N according to the American standard ASTM C618. The strength activity indices of the four samples at 20% level were found to be 75, 84, 89, and 83% respectively. These results indicate that the Jebal Tagabo Pozzolans are potential supplementary cementitious materials for use in blended cement.

Rice husk ash (RHA) is an agricultural waste product which is a pozzolanic material. It is blended with the cement for manufacturing concrete. It reduces the environmental impact of the cement industry. Blending of cement with supplementary cementitious materials like fly ash and rice husk ash makes concrete more durable. This paper studies effect of a partial replacement of cement with various ratios of rice husk ash (RHA) on physical and mechanical properties of concrete. Three mixtures were prepared with proportions of 4, 8, and 16% RHA by weight of cement in addition to 15% fly ash (FA) by weight of cement to be compared with a reference mixture with 100% Portland cement. Compressive strength test, tensile strength test, flexural strength test and rate of water absorption test were performed at different ages of curing. Test results have reflected that the compressive strength, tensile strength and flexural strength achieved with 16% replacement of cement with RHA maximum increase. Compressive strength increased with 16% RHA by 12.5% at 56 days age compared to compressive strength of control mix. Flexural strength increased with 16% RHA by 17.33% at 56 days age compared to flexural strength of control mix. There is significant development in mechanical properties compared to control mix. The mixture with 16% RHA showed the lowest ratios of water absorption by about 2.8% and 2% at 28 and 56 days of cuing, respectively.

This study aims to appraisal the qualification of (NALCO 23214) which is used as added substance to Cooling Water Tower in General Company for Chemical Fertilizers Industry / North Region-Baiji. Already the results which we are obtained show the corrosion rates in (C.W.) system, and measuring this substance efficiency in corrosion inhibition. The results showed the substance qualification in reduction of corrosion rates when control on the special conditions in system, so the inhibitor qualification and corrosion rate were calculated.