Materials Technical Analysis - Report Example

MATERIALS TECHNICAL REPORT Student Course Date Executive Summary Currently, Self-Compacting concrete (SCC) and flowing concrete (FC) are produced with enough amount of super-plasticiser. Despite this, it is important to be aware that the FC, not need to have the capability of the SCC. In addition to that, FC is produced by adding excess water in the mixture without any super-plasticiser. This type of mix is normally prone to high segregation and bleeding. Thus, this paper is discussing on the results of the experimental study into the properties of the SCC and FC concrete under the influence of different levels of high performance Super-plasticiser. Here, the properties investigated are the slump flow workability, drying and compressive strengths of the concretes produced. In this analysis, the FC had a density of while the SCC of 350kg cement and 135 kg pulverised fly ash in 1. Also, the workability of concrete was tested using the slump flow test, V-funnel and L-box test. In this case, the strength of the concrete was increased with increase in the level of vibrations applied to it. From this experiment, the shrinkage of the mix composition during the drying period was greatly influenced by super-plasticiser level added to the mixture. Table of Contents Executive Summary 2 LIST OF TABLES AND FIGURE 4 Introduction 5 Experimental Method 6 Materials 6 Testing of the Workability of the self-compacting concrete 7 Slump Flow Test 7 V-funnel Test 7 L-box 7 Testing of Hardened Concrete 8 RESULTS AND DISCUSSION 9 WORKS CITED 11 LIST OF TABLES AND FIGURE Table 1: SCC and FC Concrete mixes 5 With an ever increasing complexity of constructed structures and lack of skilled workers in the complex reinforcement of the modern day structures, there is need to improve the compaction of the concrete structures. Lack of compaction of concrete leads not only to the reduction of the workability strength of a structure but also it increases the permeability of the concrete under investigation. As a result of increased permeability the durability of the concrete get reduced. Also, this property, permeability, is the major course of the reduction in durability in reinforced concrete such as that of the steel due to the presence of carbon IV oxide and chlorides. Therefore, the use of the special type of concrete, self-compacted concrete (SCC), has improved in the durability of the concrete structures in the construction industry (Ghorab, Kenawi & All 2011). Thus, the world wide’s interest in the development of this type of special material to help in the construction of the concrete structures in the modern day with higher compatibility of concrete as compared to cement alone. Hence, with this technology of using admixtures, concrete producers can achieve their target mix with ease. In addition to the above, quality of concrete structures is improved and the cost of construction is reduced despite the reduction of the effort of compaction and the time of construction (Spencer 1983). The prospects of SCC have been reported by Gibbs. In this case, the SCC concrete structures differs from the ordinary concrete structures in three different properties. Thus, in order to obtain the right mix in the design of the concrete structure, three parameters are considered. This report shows the study into the properties of flowing concrete and SCC by using a super-plasticisers on the effect on compaction of the concrete produced by testing the produced Experimental Method Materials The CEM1 class 52.5 cement and Pulverised Fly Ash were used as the binding materials in the construction of the required concrete mixes to be tested. In addition to that, gravel 10 mm was used as course sand while the fine sand of a maximum size that could pass through a 600 sieve was used in equal proportion to that of the course sand. In this case, the fine sand represented 32% and 46% of the aggregates used in the flowing concrete mix and the SCC mixes respectively. Thus, with increase in the content of the fine aggregate in the mix increased the cohesiveness of the SCC. The fine fraction of the particles in the aggregate below 0.60mm was 13% and 8% in the SCC and flowing concrete respectively. In addition to that, Glenium 51 was used as the high-performance Super-Plasticiser (Global Construction: Ultimate Concrete Opportunities, DHIR, and Hewlett & Newlands 2005). Table 1 shows the SCC and flowing concrete mix compositions used in the experiment. Table 1: SCC and FC Concrete mixes Mix Water Cement Pulverised Fly Ash Fine Aggregate Course Aggregate Super-plasticiser SCC 195 465 134 545 1155 Variable FC 175 350 0 852 934 Variable From the preliminary results of the concrete mixes of the two concretes under investigation, the mix compositions of table 1 was selected in the production of the self-compacting and flowing concretes. The difference between the two mixes was the level of compositions of the components of the mixes where the FC did not contain any Pulverised Fly Ash while SCC contents some proportion of Pulverised Fly Ash. In order to achieve the required results, following procedure was followed; fine and course aggregates were placed in a motorized free fall laboratory concrete mixer. As the dry mixing was taking place, some water was added into the mixing machine to wet the aggregate and the ash (if need) and the cement were added and then the level of water was increased to 80% of the required amount. Then the ingredients were left to wet for 2 minutes and then the a mixer of balanced super-plasticiser and water was added. This was followed by the mixing of the mixture for another half a minute and then then it was mixed in another 2 minutes. After this, it was left to settle for 2 minutes. Testing of the Workability of the self-compacting concrete Slump Flow Test The fresh mixed concrete was tested by using both non-standard and standard tests in accordance to the BS EN 12350-8:2010 in order to assess workability of the freshly mixed concrete and its segregation potential. In this case, the slump cone was used in which the concrete was filled into it and then it was poured out in order to determine the diameter of the concrete after lifting it. V-funnel Test The SCC mix was tested for the viscosity by use of the V-funnel test according to the BS EN 12350-9:2010 standards. Here, the v-funnel was filled with the freshly produced and then it was allowed to pour out through this v-funnel and then the time of flow was recorded L-box In the L-box, the SCC mixture was tested for its viscosity according to the BS EN 12350-10:2010 standards. In this case, the freshly prepared concrete was filled into the vertical of the box and then it was allowed to flow out of this to the horizontal section of the box and the time for the flow to move to the horizontal section was recorded (New Zealand Concrete Research Association. 1987). Testing of Hardened Concrete In this case, hardened concrete from cylinders and cube casted from fresh concrete were de-moulded and then placed in a water bath at 2 C after 24 hours. Then the tensile strength of the cylinders was carried at the 28th day. In addition to that, the drying shrinkage was carried out. RESULTS AND DISCUSSION From the experiment, it was found that the super-plasticiser dosage affected the performance of the concrete in SCC as follows in figure 1 below. Figure 1: A graph showing the effect of slump flow with time on different levels of PFA From the graph, was found that the range of flow in mm between 500 mm and 700 mm in the SCC was between 39 % to 53% while that of the FC was 20% and 30%. This was due to the binder material types used and the level of excess water. For example, in this case, the free water in FC was 195 kg/m3 while that of free SCC was 175 kg/m3. CONCLUSION From the results, the use of super-plasticiser in the hardening of concrete improves the performance of the concrete used in the construction industry. Despite it is positive effects to the performance of the concrete compaction, it has a limit of the amount it should be added into the mixture in order to obtain the required mix design (Ali 1996). Thus, super-plasticisers if used can solve the problem of flowing concrete. WORKS CITED Ali, A. 1996. Super-plasticisers in concrete: a review. Garston, Watford, Building Research Establishment. Ghorab, H. Y., Kenawi, I. M., & All, Z. G. A. 2011. The compatibility between the super-plasticizers and Portland cements: Super-plasticer-Cement Interaction. Saarbrücken, LAP Lambert Academic Publishing. Global Construction: Ultimate Concrete Opportunities, DHIR, R. K., Hewlett, P. C., & Newlands, M. D. 2005. Admixtures -- enhancing concrete performance: proceedings of the International Conference held at the University of Dundee, Scotland, UK on 6 July 2005. London, Thomas Telford. Guirguis, S. 1980. Super-plasticisers in concrete. [North Sydney, N.S.W.], Cement and Concrete Association of Australia. Kiesler, R., & George, W. 1980. Applications of super-plasticisers worldwide. 184-192. Lynsdale, C. J. 1989. The influence of super-plasticisers on the engineering properties and performance of concrete. Univ., Ph. D. Thesis—Leeds. New Zealand Concrete Research Association. 1987. Super-plasticisers. Porirua [N.Z.], New Zealand Concrete Research Association. Spencer, D. 1983. The use of super-plasticisers in concrete. Read More