# Introduction he increasing world population is increasing the amount and type of the waste generated by human activities. Many wastes produced today will remain in the environment for hundreds and perhaps thousands of years. One solution to this crisis lies in recycling wastes into useful products [1]. The production of cement has diminished the limestone reserves in the world and requires a great consumption of energy. River sand has been the most popular choice for the fine aggregate component of concrete in the past, but overusing the material has led to the depletion of river-sand deposits and to a concomitant cost increase of the material. Therefore, it is desirable to obtain cheap, environmentally friendly substitutes for cement and river sand that are preferably by products [2]. Sukesh et al. [3] found that replacing sand with quarry powder improves concrete strength in compression, but the greater the replacement ratio, the lesser the workability of concrete, because of water absorption by the powder itself. The main objective in using very fine red clay in concrete and mortar production is the reduction of the amount of cement, thanks to the pozzolanic activity of red clay [4]. Using red clay in concrete and mortars brings in, therefore, at least three benefits: less energy consumption, less environmental impact and more recycling of waste materials, as red clay is partly a waste material. Kunavat and Sonawane [5] studied the use of brick waste as a replacement of cement and sand in cement mortar. The results indicated that richer mixes gives lower value of bulk density and higher values of compressive strength for sand replacement with brick waste up to 40%. When the building materials are exposed to fire, some deterioration takes place. This deterioration can often reach a level at which the structure may have to be thoroughly renovated or completely replaced. Cement has been used for the immobilization of low and intermediate level radioactive wastes. Compared to other materials, which are used to stabilization of radioactive wastes, cement is a rather cheap raw material [6]. The Portland Cement containing 20 -30 wt. % fly ash thus possesses good fire resistance and dimensional stability when exposed to high temperature and then high humidity or wetting [7]. The replacement of OPC by 20 wt. % of thermally activated kaolinite in cement paste increases its thermal stability against temperature up to 600 o C [8]. The compressive strength increases with the addition of homra up to 400 o C then decreases. The higher compressive strength of pozzolanic cement pastes containing 10 and 20 wt. % homra than OPC cement pastes at 300 o C is due to the pozzolanic reaction of homra with the free lime to produce additional amounts of calcium silicate and aluminosilicate hydrates [6]. The cracking of cementitious materials that exposed to a high temperature develops during the post cooling period as a result of rehydration of CaO associated with a significant increase in volume by about 44 % [9]. The enhancement of the thermal stability of concrete and the reduction of post cooling cracking have been achieved by the addition of pozzolana that consumes (Ca(OH) 2 ) liberated from the hydration of OPC forming additional calcium silicate hydrates [10]. The replacement of OPC by silica fume, fly ash, metakaolin and homra [11] was found to improve the physico mechanical properties, microstructure, and thermal stability of cementitious materials as well as reduce the extend of cracking when exposed to high temperatures. # II. # Research Significance The main objective of this study is to determine the suitable ratio of homra as a partial replacement of cement and sand to increase fire resistance. As well as the treatment type (quenched in water or cooled in air) will be studied. # III. # Experimental Program In this investigation, 108 cubes (100 x 100 x100 mm), 108 cylinders (100 mm in diameter and 200 mm in length), and 108 prisms (100 x 100 x 400 mm) as shown in Fig. 1 were tested using 2500 KN capacity testing machine to investigate concrete compressive strength, tensile strength by splitting tensile test and flexural strength, respectively. The main variables taken into consideration in this study were the replacement ratio of cement and sand with homra, where homra was used at ratios 15 %, 20 %, 25 % and 30 % as a partial replacement of cement then homra was used as a partial replacement of sand at the same ratios in addition to control specimens without homra. Furthermore, part of specimens were exposed to the fire for halfan-hour and the other part for one-hour as shown in Fig. 2. Then some specimens were allowed to cool down to room temperature in air and some specimens were quenched in water. # Properties of Materials a) Cement The cement used in this investigation was Ordinary Portland (OPC) that has been partially replaced by homra at ratios of 15 %, 20 %, 25 % and replaced by homra at ratios of 15 %, 20 %, 25 % and physical properties according Egyptian code of Practice [12]. # b) Aggregates Dolomite with 10 mm nominal maximum size was used as coarse aggregate and the fine Year aggregate was the natural sand free from impurities that has been partially replaced by homra at ratios of 15 %, 20 %, 25 % and 30 wt. %. # c) Red Clay (Homra) Homra is a solid waste material produced from the manufacture of clay bricks and consists mainly of quartz, aluminosilicate, anhydrite, and hematite. Therefore, it acts as a pozzolanic material. These crushed portions of homra are not for commercial use and may be considered as a solid waste to the environment. Homra was collected from brick plant sites and was obtained by grinding the solid shards to produce fine material as shown in Fig. 3. In this study, a super plasticizer Sikament NN, was used to improve the workability of concrete. V. # Mix Proportions and Casting Procedure For this study, the same cement content was adopted for all specimens ( i.e. 400 kg / m 3 ). Homra blended with cement and sand was prepared by a partial replacement of OPC ( Type I mixes, i.e. only a share of OPC was replaced with homra ) and sand ( Type II mixes, i.e. only a share of sand was replaced with homra) with previous mentioned ratios of homra to obtain eight mix proportions more over the control mix without any homra as shown in Table 1. The composition of the control mix is shown in Table 2, the remain mix compositions were adopted by replacement of cement and sand with homra by percentage as shown in Table 1. For each mix proportion, 12 cubes, 12 cylinders and 12 prisms were cast to obtain 324 total specimens. Cement, coarse and fine aggregates were weighed and placed into the concrete mixer for one minute then the mixing water containing super plasticizer was added. The slump test was carried on the fresh concrete as shown in Fig. 4. Fresh concrete was cast in molds then these molds were vibrated for one minute to remove any air bubbles and voids. After 24 hrs, specimens were demolded and cured under water until the desired curing time. After 28 days of curing under water, the hardened specimens were dried and some were exposed to fire for half-anhour and some for one-hour. After heating, the specimens were partly left to cool in air and partly were quenched in water. Table (1): The replacement ratios (by mass) of the cement and of the sand with red clay (homra). # Test Results and Disscusion a) Concrete Compressive Strength The values of concrete compressive strength according to different replacement of cement and sand with homra are shown in Figs. 5 and 6, respectively. These figures indicate that, in Type I mixes, the highest value of concrete compressive strength was obtained from replacement of cement by 15 % of homra. One may note ( Fig. 5(a)) that replacing 15 % of cement (by weight) with homra brings an increase in concrete compressive strength equal to 16.8 % and 20.14 % with respect to the control specimen, after quenching the specimens in water or cooling them in air, respectively (half-an-hour of fire exposure). However, after one-hour fire exposure the increase in the compressive strength was lower ( equal to 12.33 % and 15.18 %, after quenching in water or cooling in air, respectively ). The compressive strength of pozzolanic cement pastes containing wt. 15 % homra was higher than that of OPC pastes at high temperature due to the pozzolanic reaction of homra with the liberated lime to produce additional amounts of calcium silicate and aluminosilicate hydrates. These hydrates deposit within the pore system as shown from scanning electron microscopy (SEM) micrographs (Fig. 7). The decrease of the compressive strength with higher percentage of homra is due to the decrease of the clinker content. In Type II mixes, the higher the percentage of homra the higher the values of compressive strength up to 25 %, after that the increase in the percentage of homra leads to decrease in values of concrete compressive strength. It can be notice that specimens of Type I mixes with 15 % of homra as a replacement of cement give higher values of concrete compressive strength than those of Type II mixes with 25 % of homra as a replacement of sand. Fig. 8 (a) and (b) gives the effect of fire duration on concrete compressive strength in case of Type I and Type II mixes, respectively. The more prolonged the fire, the lower the values of the compressive strength whether specimens quenched in water or cooled in air after fire. The cement pastes made with pozzolanic materials as a partial replacement of Portland cement are more sensitive when exposed to fire. In case of Type I mixes with 15 % homra, the value of compressive strength decreased by 14.13 % when cooled in air and by 15.16 % when quenched in water. However, these values for Type II mixes with 25 % homra were estimated by 10.27 % when cooled in air and 12.92 % when quenched in water. Also, These figures demonstrate, therefore, that the specimens cooled in air exhibit a residual compressive strength greater than that exhibited by the specimens quenched in water, for both Type I and Type II mixes containing homra. # Global # Conclusions An experimental campaign is presented in this paper about effect of fire on a number of concretes, whose cement and sand have been partially replaced with red clay (homra). The focus is on concrete strength in compression, tension and bending. The following main conclusions can be drawn: 1![Figure 1: The test specimens](image-2.png "Figure 1 :") 2![Figure 2: Fire effect](image-3.png "Figure 2 :") ![. %. The tests were carried out to determine its Fire Effect on Concrete Containing Red Clay (Homra ) as a Partial Replacement of Both Cement and Sand](image-4.png "") 3![Figure 3: Homra d) AdmixtureIn this study, a super plasticizer Sikament NN, was used to improve the workability of concrete.](image-5.png "Figure 3 :") 5672017891011121314![Figure 5: Compressive strength for Type I mixes: (a) fire duration = half-an-hour ; (b) fire duration = one-hour.](image-6.png "FireFigure 5 :Figure 6 :Figure 7 : 2017 EFireFigure 8 :Figure 9 :FireFigure 10 :Figure 11 :Figure 12 :Figure 13 :Figure 14 :") ![Effect on Concrete Containing Red Clay (Homra ) As A Partial Replacement of Both Cement and Sand](image-7.png "Fire") (MixType I mixesType II mixesNo. *(homra / cement) %(homra / sand) %1--215 / 85-320 / 80-425 / 75-530 / 70-6-15 / 857-20 / 808-25 / 759-30 / 70* For each mix, 12 cubes, 12 cylinders and 12 prisms were castFigure 4: The slump test VI. © 2017 Global Journals Inc. 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