Received date: 17 June, 2017; Accepted date: 22 August, 2017
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Partial replacements of constituents of concrete have been the recent developments in the field of Civil Engineering and materials research. Neem Seed Husk Ash is partially replaced with the cementing material and the strength criteria are monitored and compared with the conventional ones to prove the effectiveness of the utilization of the replacement material. The properties of the M30 grade of concrete partially replaced with Neem Seed Husk Ash (NSHA) are studied experimentally, and the variations in strength are monitored. The compressive strength of the NSHA concrete increased with age but decreases with the increase in the proportion in the ash to cement. The setting time and workability of the NSHA concrete decreased as the replacement level of the Neem seed husk ash to cement increased with the different percentage of NSHA and combination of NSHA with suitable proportions of superplasticizers. Even though NSHA in concrete shows an increase in strength in the previous studies, and the results obtained from the NSHA concrete in this experimental investigation indicated a reduced compressive strength.
Neem seed husk ash, Super plasticizers, Compressive strength, Silica fume
In recent advancements in civil engineering, many researches has been conducted to incorporate an alternative material in replacing the cement. Due to increase in global emission of CO2 rate, the introduction of environmentally friendly alternative materials satisfying the strength criteria will be more efficient compared to the full usage of cement. The utilization of waste by-products in concrete has garnered positive regarding the cost saving and conservation of natural resources. Some of the resources currently being employed for manufacturing concrete are likely to negative effects on the environment besides being non-renewable, and this has resulted in an increase in research to develop alternative feed (Kanadasan and Razak, 2015). The use of replacement material offers cost reduction, energy saving, arguably superior products and fewer hazards in the environment (Raval, et al., 2012). The Neem Seed Husk Ash is a by-product which is obtained by processing the neem seed while extracting oil and the workability of the same was found to be increased when 5% to 10%added in concrete. TheNSHAwas also used in mortar as a replacement for cement in which one part of binder material have been mixed with three part of the sand(1:3). The flexural strength of the specimen decreased with the cement replacement by NSHA (Musa, 2014). Thermal analysis has been done for the specimen partially replacing the cement paste with NSHA (Musa, and Ejeh, 2012). Split tensile strength up to 10% replacement produced a positive result (Musa, 2013). Application of silica fume in cement concrete will give positive results when it is mixed in the proper proposition. 5 to 10%replacement of silica fume added in replacement for cement in concrete produced an increased strength (Ajileye, 2012). Silica fume, rice husk ash, fly ash, met kaolin and ground granulated blast furnace slag are well-established wastes because of high silica content in their chemical compositions (Abdulkadir, et al., 2014). The idea of using waste materials like kiln-dust, rice-husk, and groundnut shell ash as an alternative to cement have been in the experimental stage from a long time. Apart from saving the cost of disposal, their use in construction protects the environment from pollution (Agbo and Ayegba, 2013). The effect of ground shell ash on concrete has been studied, and the usage of ground shell ash was not meeting the required compressive strength, but the 10% replacement can be applied for the nonload bearing structures (Ndefo, 2013). Based on the previous research work in NSHA, this research work was undertaken to actually study the properties of NSHA as shown in (Fig. 1) This was carried out with and without the inclusion of admixture and superplasticizers. The design and mix proportion are shown in section 2.1 and results are presented in the Table 1.
|Components||Percentage of cement||Percentage of Neem seed husk ash|
|Iron oxide Fe2o3||3.05||8.68|
|Magnesium oxide MgO||1.5||2|
|Sulphur trioxide So3||2||4.42|
Table 1. Chemical properties of cement and neem seed husk ash (NSHA)
The research work is aimed at studying the exact behavior of the concrete in which the cement has been replaced by the neem seed husk ash (NSHA). River sand has been used as a fine aggregate having the size of 4.75mm, and the local quarry stone has been used as a coarse aggregate of size 20mm. The specific gravity of the fine aggregate and the coarse aggregate was found to be 2.62 and 2.75 respectively. Neem Seed Husk Ash (NSHA) is a by-product which is obtained from the neem processing industrial unit. It was dried until it lost its oil content and burned in open air.
A mix M30 grade was found to be 1:1.42:2.02, with w/c 0.40 as per Indian standard method and the same was used to prepare the test samples. Conventional concrete has been cast and it is compared with the specimen in which cement has been replaced with 5% NSHA, 2.5%NSHA, 2.5%NSHA with 10% of Silica Fume, 2.5%NSHA with addition of 10% Silica Fume and 1%Superplasticizer and 0.05%NSHA with 10%Silica Fume and 1.5% superplasticizer. Totally nine cubes and nine cylinder specimens were cast to study the results on 3,14 and 28 days after curing.
The conventional concrete took 24 hours to attain initial setting time whereas the NSHA replaced concrete took 48 hours to attain the same. The strength was observed to be decreasing with the increase in the percent of NSHA in replacement of cement with its all combination of admixture and superplasticizers. The observed mechanical properties of NSHA concrete are shown in (Fig. 1 and 2). The maximum compressive strength is 25 N/ mm2 after 28 days of curing.
Even though the application of NSHA in partial replacement with cement produced a positive result in previous research work (Musa, 2013; Muhammad, 2016). The observed values in this research work gave a negative result. As a result of the detailed study done to determine the reason for the negative result, it is determined as even after drying and burning NSHA cake; it has some slight oil mixture content in which subsequently increased the final setting time and drop with the binding property. The thermal analysis carried out with NSHA concrete has increased amount of calcium hydroxide concentration (Musa and Ejeh, 2012). NSHA has less fibrous structure after curing period of 28 days. As a result of these influence, this research work concludes that NSHA is not a suitable material for cement replacement in concrete.