Self-compacted concrete (SCC) is cast in the formwork without compaction and it fulfills the formwork due to its own weight. SCC is considered to have many advantages in comparison with conventional concrete like improved construction quality, faster construction activity, reduced cost etc. SCC is produced with the same ingredients of normal concrete. However, cementitious materials are also adopted to replace the cement content in SCC in order to use waste materials from industries and agricultural products. To further enhance the performance of SCC, different types of fibers are tried in order to produce fiber reinforced SCC. The fibers in the concrete bridge the cracks and diffuse the crack propagation which improves mechanical properties. In developed countries SCC has reasonable acceptance in construction industry but in developing countries like Pakistan has not gained acceptance. This paper is focused on undertaking a review of SCC with cement replacement and fiber reinforcement materials. The main objective of this paper is to compile the literature in order to understand the various properties of SCC in fresh and hardened state when these cement replacement materials and fibers are used.

No abstract

Due to high cost of aggregates, cement and steel in plain regions of Pakistan, low income people are unable to get their houses constructed using Reinforced Cement Concrete (RCC). In this study, potential of baked clay as an economical material of building construction is investigated in order to replace normal concrete. For this purpose, compressive strength and tensile strength of baked clay fired at 1000˚C were determined. The results show that the compressive strength and tensile strength of baked clay are about 65%, and 80% more than those of corresponding values of normal concrete, respectively. This implies that by utilizing reinforced baked clay instead of RCC, saving of cement aggregates and reinforcing steel could be achieved.

This paper presents behaviour of Reinforced Baked Clay (RBC) beams under drop weight impact loading. The beams were made of two different grades of baked clay with cube crushing strength of 20 MPa and 30 MPa, respectively. The RBC beams were subjected to repeated drop weight loading by a hammer of weight equal to that of the specimen being tested. The results showed that the impact resistance of the RBC beams was governed by the compressive strength of the baked clay. Failure of grade 20 beams occurred due to irregular cracks and the beams of grade 30 failed by opening of a single crack at mid span. It was observed that the beams of grade 30 had sustained about 1.5 times more number of impacts until steel in tension zone yielded and failed completely after necking.

Coal is used as a traditional fuel for firing of clay bricks in kilns. The cost of coal is high and is increasing continuously. This paper describes the effect of alternate fuels on compressive strength, water absorption and density of fired clay bricks. The alternate fuels used in this study were 1) rapeseed husk (Type I), 2) combination of sugarcane-bagasse, rice husk and used clothes (Type II) and 3) coal (Type III). The results show that compressive strength of bricks fired using Type I and Type II fuels was decreased to 11% and 7%, respectively, compared to those fired with coal. However, the values of water absorption and density of bricks fired with Type I and Type II fuels were almost same as exhibited by those baked with coal. This study shows that a saving of 25%, and 18% could be achieved when the bricks were fired using Type I and Type II fuels, respectively, compared to those fired with coal.

Construction of Reinforced Cement Concrete (RCC) houses is unaffordable for low income people living in plains of Pakistan because of high cost of cement and aggregates. In such regions, use ofReinforced Baked Clay (RBC) is considered to be a cheaper alternative for RCC. This paper presents structural behaviour of RBC beams. The results of RBC beams were compared with a control RCC beam of same size and reinforcement. Both types of the beams showed similar load deflection behaviour in pre-yield stage. Whereas, in post yield stage, the RBC beams showed comparatively more deflection as compared to the RCC beam. The ultimate load carrying capacity of the RBC beams was almost similar to that of the RCC beam. This study suggests that the RBC beams can be used economically instead of RCC beams without losing strength and safety of a building.

Uncontrolled evaporation of moisture from compressed clay beams can cause surface cracks, resulting in reduction of strength. This paper presents various treatments applied to clay beams during the process of casting, compacting and drying in order to curtail the possibility of cracking and to decrease percentage of drying shrinkage. Following treatments were applied to the beams during casting and drying: (i) a steel plate and double layer of plastic sheet was provided between the beam and the plank, (ii) the beam was enveloped with a propylene fabric sheet during casting and (iii) beams were covered with plastic sheet during drying. Using these treatments, the clay beams were cast and compacted at various intensities of compaction. The results show that the drying shrinkage was reduced to minimum and the cracks were curtailed. The rate of drying shrinkage was decreased depending upon the level of compaction. Thus at the higher degree of compaction, more density of clay beams was achieved, which resulted in higher degree of compressive strength in baked and unbaked state.

Concrete’s self-weight is a major aspect of a structure’s overall weight. Recently, the use of lightweight concrete (no-fines, foamed and cellular concrete) has been increased. Normally no-fines concrete is produced with crushed coarse aggregate of uniform gradation. This study aims to investigate experimentally the effects of the use of uncrushed coarse aggregates on unit weight, compressive and tensile strength of the no-fines (NFC) as well as conventional concrete (CC). In addition, the effects of coarse aggregate size on the mechanical properties were also studied. Four gradations of uncrushed coarse aggregates ranging between (5.5-4.75) mm, (10-4.75) mm, (20-4.75) mm and (25-4.75) mm were used for preparing the concretes. The fixed cement-aggregate ratios of 1:6 (with w/c ratio=0.4) and 1:2:4 (with w/c ratio=0.5) were adopted for NFC and CC respectively. It was found that the gradation of uncrushed coarse aggregate has a significant effect on the mechanical properties of NFC. A maximum of 16% reduction in self-weight of the concrete without fines was obtained, as compared to that with fines. Moreover, the compressive strength of no-fines concrete significantly improved by replacing crushed with uncrushed coarse aggregate. The compressive strength increased by 16% for the batch of (25-4.75) mm.