EFFECT OF RICE HUSK ASH IN THE PRODUCTION OF HOLLOW SANDCRETE BLOCK

The effect of rice husk ash as a component of hollow sandcrete blocks was investigated. The objective was to reduce the present high cost of building construction. The rice hush ash used was derived from rice husk which is a bye-product of milling rice. Batching of the material was done by weight and a nominal mix proportion of 1:6 of cement and sand respectively was used. One hundred and twenty samples of hollow sandcrete blocks were produced in two different sizes 226x225x450 (mm) and 150x225x450(mm). Various proportions of rice husks ash i.e. 0%,4%,10%,20%, and 30% were used as replacement of cement in the mix. The compressive strength of the samples were determined after 28days using the universal testing machine and the average values obtained were 2.8, 2.2, 2.5, 2.0, and 1.7(N/mm2) respectively. It was concluded that rice husk ash blocks have relatively lower strength compared to blocks without rice husk ash. At 10% ash replacement however, the hollow block developed compressive value of 2.5N/mm2 which met the minimum standard required for building construction. Cost analysis showed that a saving of 5.3% per block can be achieved through the use of rice husk ash blocks. It was therefore recommended the rice block ash blocks with up to 10% replacement can be used in building construction for non-load bearing walls such as fence walls and partitions

Assessment of activity moduli and acidic resistance of slag-based geopolymer concrete incorporating pozzolan

The environmental impact of Portland cement production and utilization in the construction sector has led to the global call for the use of eco-friendly construction materials for the production of cleaner and sustainable products. Therefore, this study explored agro-industrial wastes, slag and corncob ash, for the production of geopolymer concrete (GPC). Corncob was dehydroxylated at 600 �C for 3 h and partially used as a replacement for slag at 0%, 20 %, 40 %, 60 %, 80 %, and 100 %. A 12 M, 14 M, and 16 M of both sodium silicate (SS) and sodium hydroxide (SH) were used as activators. The chemical moduli of each and mixed binder were quantified and evaluated based on the major reactive oxides, hence leading to the evaluation of reactivity indexes (RIs). Moreover, the RIs and mix design properties (MDPs) of concrete were used for the prediction of flexural strength while the chemical resistance of each concrete sample was investigated. Compared with the experimental results, the predictive flexural strengths based on the RIs and the MDPs yielded a high precision with R2 ranging from 88–92 % at 7–90 days, respectively. Moreover, the GPC, unlike Portland cement concrete (PCC), resisted the more acidic attack. Therefore, the use of GGBFS�CCA blended concrete would be more advantageous in a highly acidic environment than PCC. Ultimately, the models proposed by this study can be useful in the concrete mix design procedure for the flexural strength development of GPC incorporating agro-industrial provided the oxide compositions of each and mixed material were obtained

Evaluation of reactivity indexes and durability properties of slag-based eopolymer concrete incorporating corn cob ash

The method of determining the quantities of geopolymer concrete (GPC) ingredients to attain the required and specifiable characteristics is complex owing to the involvement of more variables compared with Portland cement concrete (PCC) systems. Therefore, this study evaluated the hydraulic responses and chemical resistance of GPC produced with supplementary cementitious materials (SCMs), ground granulated blast furnace slag (GGBFS) and corn cob ash (CCA) at ambient curing conditions. Corn cob was dehydroxylated at 600 �C and used as a partial replacement for GGBFS at 0, 20, 40, 60, 80, and 100%. The activators used were 12, 14 and 16 M concentration (M) of both sodium silicate (SS) and sodium hydroxide (SH). The chemical compositions of individual and mixed binders were analyzed, while the chemical moduli of each and blended binder were examined and evaluated based on the significant reactive oxides, hence resulting in the evaluation of reactivity indexes (RIs). Moreover, the compressive strength was predicted based on the RIs and mix design proportions (MDPs) of the blended concrete, while the durability properties of each concrete sample were investigated. The results indicated that the oxide compositions of GGBFS and CCA influenced the compressive strength of GPC produced. Compared with the experimental results, the predictive compressive strengths based on the RIs and the MDPs yielded a high precision with 95% ‘‘R2”. Furthermore, the incorporation of both GGBFS and CCA increased the durability of GPC produced against sulfate attacks. Ultimately, the model equations developed by this study can be beneficial in the refinement of mix designs of both GPC and conventional concrete incorporating SCMs provided the oxide compositions of the elements are obtained

BUILDING A SUSTAINABLE WORLD: ECONOMY INDEX OF GEOPOLYMER CONCRETE

Geopolymer concrete offers a considerable solution not only to the environmental problem but also to the structural deterioration confronting the world. But, limited or no study is found on its cost implications. Consequently, this study evaluates the production cost and the economy index of geopolymer concrete (GPC) and compares it with the Portland cement concrete (PCC). Corncob ash (CCA) and ground granulated blast furnace slag (GGBFS) were used as source materials in the production of geopolymer concrete. Alkaline liquids were prepared to obtain 12 molar concentrations. The concentration was used to activate the source materials. Grade 30 concrete (M30) was adopted as a mix design proportion. GGBFS was replaced by CCA in varying percentages as 0%, 20%, 40%, 60%, 80%, and 100%. The research findings reveal that GPC is 27.71% lesser than the PCC in terms of production cost while the economy index of GPC is higher than the PCC for the same grade of concrete. The results infer that GPC is cheaper and more viable than the PCC. Thus, geopolymer concrete proves to be an innovative product and appears to be a feasible solution not only to the environmental and structural deteriorating problems but also to the problem of high cost of Portland cement in the construction industr

Effect of Coarse Aggregate Size and Gradation on Workability and Compressive Strength of Plain Concrete

In this study effect of coarse aggregate size and gradation on workability and compressive strength of concrete was investigated. A mix ratio of 1:2:4 with a target strength of 20/25MPa, was adopted with a water-cement ratio of 0.6. Concrete cubes were produced with uniform coarse aggregate size of 4.75, 6.7, 9.5, 13.2 and 19mm respectively, with another set of samples produced with all the coarse aggregate sizes. Slump tests were carried out for all mixes and all sets of samples were tested for compressive strength after, 7, 14 and 28 days of curing. It was observed that workability was similar for all mixes with no well-defined pattern of relationship with size of coarse aggregate used. Compressive strength was observed to increase with increase in coarse aggregate size. Authors attributed this to the less quantity of water absorbed by larger size coarse aggregate during mixing which results in lesser quantity of capillary pores after curing. Maximum compressive strength was recorded for samples with 9.5mm coarse aggregate size. These show that quality concrete can still be produced with single-sized coarse aggregate as long as the optimum size can be determined for the particular mix.&nbsp

Quality Management in Construction Project: Empirical Study of Covenant University Sports Complex

The acceptable level of quality in construction projects has long been a problem. Significant resources are wasted on construction projects because of inefficient or non-existent quality management procedures. Therefore, this study evaluates the quality management and the quality grading practices in the construction project with emphasis on the Covenant University Sports Complex. The quantitative research strategy and questionnaire survey were used as the main data collection instrument for soliciting information from the project participants in order to determine the best key for quality management practice. Moreover, an ultrasonic pulse velocity tester was engaged to assess and evaluate the conditions of concrete structural members. It was found out that management commitment to quality is the most key for effective quality management practices in the construction project. In addition, the ultrasonic pulse velocity (UPV) test carried out on the randomly selected structural members varied in the range 4.2km/sec to 4.6km/sec. From this, it is inferred that the quality grading and homogeneity of concrete in the tested reinforced concrete columns, beams and slabs fall in the range of “good to excellent concrete”. The findings would assist project participants in implementing an efficient quality grading and management while executing construction projects