نشریه پژوهش های تجربی در مهندسی عمران
سال چهارم شماره 1 (پیاپی 7، بهار و تابستان 1396)

Kahgel is one of the oldest traditional mortars in Iran, which it’s capabilities and performance in throughout history to conserve earthen buildings, show that it can be used as a covering for conservation of earthen architectural structures, but low durability and the need for renewal the plaster due to erosion of rainfall suggest that Kahgel plaster is weak and unstable. It is very essential in finding appropriate scientific methods to enhance the durability and lifespan of Kahgel plaster. The effect of micronized Kaolin and Bentonite additives used to build the different samples of Kahgel plaster on physical and mechanical properties to enhance the durability of Kahgel plaster, showed that micronized Kaolin, reduced saturated hydraulic conductivity of the Kahgel plaster at 82 % level and micronized Bentonite, is decreased by 121 %. In addition micronized Kaolin and Bentonite, increased uniaxial compression strength of the Kahgel plaster at 39 % and 33 %, respectively. Evaluation of water erosion of  the samples during rainfall by  rainfall simulator showed that use ofKaolin 3% (by weight of Khahgel), the minimum sample’s total dry material loss of the Kahgel plaster reduced to 16/7% and the maximum decrease to 31/4%  and increase durability of the Kahgel plaster against water erosion. Experimental results indicated that with decreasing the dimensions of the additive particles, its influence is improved due to the increased surface area of materials.

roller-compacted concrete is a type of concrete with a slump of zero and is transported, spread and compacted by machinery used in soil compaction operations operations. Application of this type of concrete in the construction of dams and the role of permeability in the design of dams has increased the importance of identifying the factors affecting the permeability of roller-compacted concrete. In this research, the effect of cement content, maximum aggregate size and the application of microsilica and the role of wet curing of joints on the permeability of roller-compacted concrete were considered. Therefore, by making laboratory samples and conducting permeability tests, the optimum amount of the replacement of cement with microsilica and also the effect of maximum aggregate size were investigated. The results showed that optimum cement content was 110 kg / m3, and as the maximum size of aggregates increased, permeability increased, too. In addition, the optimum amount of microsilica replacement with cement was 20% of the cement content. Also, the permeability of joints can be reduced by observing proper operating conditions and wet curing.

(An experimental study on durability of concrete with recycled glasses (fine) and silica fume)AbstractRecently, there has been an increasing trend toward the use of sustainable materials. Sustainability helps the environment by reducing the consumption of non-renewable natural resources. Concrete – the second most consumed material in the world after water – uses a significant amount of non-renewable resources. As a result, an experimental investigation was conducted to study the durability of concrete constructed with 5% and 10% recycled glass aggregate (fine) as well as 6% silica fume. This experimental program consisted of six mix designs. The electrical resistivity and chloride ion penetration of recycled concrete mixes were compared with the conventional concrete. Results of this study show that the mixes including both recycled glass aggregate and silica fume show superior durability (both electrical resistivity and chloride ion penetration) compared with conventional concrete.KEY WORDS: Durability, Recycled cconcrete, Silica fume, Recycled glass aggregate

By studying the behavior of concrete structures, several factors such as design and calculation mistakes, and the lack of proper implementation and changes in building regulations and changes in structural structures, etc., will result in the evaluation and re-evaluation of the design and construction, in order to improve it if necessary. In this paper, using experimental studies, GFRP has been studied to determine the criteria for determining the design of seismic rehabilitation and improvement of existing structures as well as new constructions. In this study rectangular Concrete has been tested. The results show that the sample with 1 layer of GFRP was 27% stronger than the control sample, and the sample with 2 layers of GFRP had a 46% increase in strength to the control sample, and the specimen strength with 3 layers of GFRP increased by 59% with respect to the control sample and also specimen with 4 layers of GFRP have a 69% increase in strength to the control sample, and with increasing number of layers , the ductility of the specimen increases.

Pervious concrete being a particular type of high porosity concrete, is mainly used for pavement purposes. Pervious concrete is usually free of fine aggregates and the coarse aggregates are only coated by the cement matrix. The use of additives including superplasticizer and the consequent effects on engineering characteristics of pervious concrete is outlined in this study. The pervious concrete should be designed in such a way to resist against deterioration during the freezing and thawing cycles, while keeping the permeability index within reasonable limits. In this study, six sets of pervious concrete samples including three granular aggregates in both water to cement (W/C) and aggregate to cement (G/C) of typical pervious concrete samples containing lubricating additives and antifreeze. It was produced by measuring the efficiency, density, porosity and compressive strength in two main characteristics of this concrete, namely compressive strength and porosity, to the following results. According to the results of the study, the compressive strength of the pervious concrete was increased by about 9 MPa, and the porosity decreased at most by 15%.

Concrete is one of the most used building materials. In recent decades, achieving high compressive strength in concrete has been the main objective of concrete workers. One of these produced concrete is high-strength concrete which its use is being developed due to the increasing demand for faster utilization of under construction buildings and facilities. High-strength concrete was used in 1965 in Chicago for the first time. High compressive strength , high tensile strength , greater modulus of elasticity , lower permeability , longer durability due to less porosity and high bonding strength between bars and reinforced concrete are benefits of these concrete products . In this paper, our attempt is to investigate the mechanical properties of high-strength concrete with the equations of conventional concrete of the five United states of America , Europe , Canada , Australia and Japan Codes and suggest a suitable relationship by comparing the results of previous investigations .