Properties Of Reactive Powder Concrete Research Articles

The effect of Silica Fume and Fly Ash on the Properties of Reactive Powder Concrete and its comparison with High Strength Concrete

The effect of Silica Fume and Fly Ash on the Properties of Reactive Powder Concrete and its comparison with High Strength Concrete

Effects of Multi-Walled Carbon Nanotubes and Recycled Fine Aggregates on the Multi-Generational Cycle Properties of Reactive Powder Concrete

In order to investigate the effect of multi-walled carbon nanotubes (MWCNTs) on the recyclable properties of multi-generation recycled concrete, the physical properties of multi-generation recycled fine aggregate and the mechanical properties of multi-generation recycled concrete with different dosages of MWCNTs were tested, and the enhancement mechanism was analyzed by scanning electron microscopy (SEM). The results showed that the apparent density of multi-generation recycled fine aggregate with 0.05 wt% MWCNTs was increased by 1.04~2.03%, the crushing value was decreased by 38.21~49.45%, the compressive strength of the concrete prepared by it was increased by 11.11~18.96%, the splitting tensile strength was increased by 10~43.94%, the flexural strength was increased by 13.62~22.23%, and the mechanical properties were analyzed by scanning electron microscopy (SEM). Combined with the scanning electron microscope image analysis, the MWCNTs can fill the pores inside the specimen, bridge the cracks, and retard the decrease in concrete strength after multi-generation recycling.

Effect of Steel Fiber Type and Curing Regimen on the Mechanical Properties of Reactive Powder Concrete

Reactive powder concrete (RPC) can provide enhanced mechanical properties and durability compared to conventional concrete. RPC has been developed in this study using locally available materials. Six types of steel fibers and three curing regimens were considered to examine their effect on the mechanical properties of RPC. Steel fibers were incorporated by 1% and 2% of the total volume of mixtures. Generally, the experimental results showed that 1% steel fibers enhanced the compressive, flexural, and splitting tensile strengths by 23.6%, 65.1%, and 72.7%, respectively, compared to control mixtures (no fibers). On the other hand, the 2% of fibers improved the compressive, flexural, and tensile strengths by 39.2 %, 155.0%, and 191.7%, respectively. The curing regimen, which consisted of 2 days at 60°C and 3 days at 90°C, followed by 21 days of moist curing at 21°C, indicated the ultimate enhancement of the mechanical properties of RPC. Also, hooked fibers appeared to enhance flexural strength and tensile strength compared to other types of fibers.

Mechanical Properties and High Temperature Performance of Sustainable Reactive Powder Concrete Containing Waste Glass

At present, it is a challenge to produce a high performance reactive powder concrete (RPC) from local available materials due to the least costly components of a conventional concrete are eliminated by more expensive elements such as the silica fume and steel fibers. In the other hand, million tons of glass is being dumped every year all over the world. More than 75% of glass composition is basically silica and reported to having a pozzolanic reaction. Thus, glass is potentially suitable material as replacement materials for the RPC mixture. In our work, waste glass powder (WGP) was used to completely replace silica fume. Compressive strength, splitting tensile strength, flexural strength and elastic modulus measurements were reported along with the density and colour of the RPC produced. The highlight of this study is on the assessment of the RPC at high temperature tested by direct burning at 600˚C. This had addressed to a very limited reported finding on the high temperature performance of RPC utilizing waste materials. It was found that, RPC containing waste glass powder changes the colour of RPC from darkish grey to light grey. Adding waste glass powder had reduced the density of RPC by (0.05) gm/cm3. Using waste glass powder instead of silica fume had also improves the mechanical properties of RPC. However, there is no effect of adding waste glass powder in solving the spalling problem of RPC at high temperature up to 600˚C. This paper reports finding on the mechanical properties and high temperature performance of sustainable RPC that utilize waste glass powder in total replacement for the silica fume. This is carried out as an effort to address the high cost of the material used in the ordinary RPC and to enhance the recycling of local waste glass.

Study on properties of basalt fiber reinforcing reactive powder concrete under different curing conditions

The influence of basalt fiber (BF) on the mechanical properties of reactive powder concrete (RPC) under different curing systems was studied. Three curing systems were adopted: natural curing (NC), standard curing (SC) and combined curing (CC). The design formulas for compressive and splitting tensile strength of basalt fiber reactive powder concrete (BFRPC) were established. The hydration process and strength changes of BFRPC under different systems were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The test results showed that the CC was better than the SC and slightly better than the NC, while the hydration of the CC was insufficient in the later stage, and the growth rate was significantly lower than the SC or NC. BF showed good compatibility with the matrix and was closely bonded. BF with proper content and the matrix were pressed together to improve the mechanical properties of BFRPC, while an excess of BF content would cause weakened areas and reduce strength. In comparison to plain RPC (with BF content of 0 %), the maximum increase rates of 28-day compressive strength of BFRPC under NC, SC and CC systems were 22.8 %, 18.4 % and 8.9 %, respectively. As for 28-day splitting tensile strength, the maximum increase rates became 74.5 %, 66.5 % and 49.67 %, respectively. Considering the economy and practicability of the actual project, the strength prediction formula of BFRPC was put forward to facilitate its popularization and application.

The Effects of Silica Fume and Superplasticizer Type on the Properties and Microstructure of Reactive Powder Concrete.

This paper deals with the optimization of reactive powder concrete mixtures with respect to the addition of silica fume and the type of polycarboxylate superplasticizer used. First, the properties of reactive powder concrete with eight different commercial polycarboxylate superplasticizers were tested in terms of workability, specific weight, and mechanical properties. It was found that different commercially available superplasticizers had significant effects on the slump flow, specific weight, and compressive and flexural strengths. The optimal superplasticizer (BASF ACE430) was selected for further experiments in order to evaluate the influences of silica fume and superplasticizer content on the same material properties. The results showed that the silica fume and superplasticizer content had considerable effects on the mini-cone slump flow value, specific weight, flexural and compressive strengths, and microstructure. There were clearly visible trends and local minima and maxima of the measured properties. The optimal reactive powder concrete mixture had a composition of 3.5-4.0% superplasticizer and 15-25% silica fume.

Experimental Study on The Effect of Size, Type, and Replacement Ratio of Recycled Aggregate on The Mechanical Properties of Reactive Powder Concrete

This paper presents an experimental investigation of the mechanical characteristics of Reactive Powder Concrete (RPC) and Recycled Aggregate Reactive Powder Concrete (RPC-RA), utilizing two types of recycled aggregate (RA), recycled concrete aggregate (RCA), and recycled concrete brick aggregate (RCBA) as alternative aggregates. A series of sixteen RPC and RPC-RA mixes were prepared and tested. A reference RPC mix without RA was tested to determine the maximum compressive strength of 128.17 MPa, the tensile strength of 15.56 MPa, and the flexural strength of 25.90 MPa. Then, the study examines twelve different mixes of RPC-RA, each with RCA with maximum particle sizes of 0.6, 1.18, 2.36, and 4.75 mm and replacement ratios of 20%, 40%, and 60%, to study the effects of varying replacement ratios of the RCA and various maximum particle sizes. Additionally, three mixes of RPC-RA are investigated using RCBA with a maximum particle size of 0.6 mm and replacement ratios of 20%, 40%, and 60%. The use of RA resulted in various percentages of reduction in compressive, splitting, and flexural strength, as shown in the results of the study.

The Effect of Secondary Aluminum Ash on the Properties of Reactive Powder Concrete.

Secondary aluminum ash is a kind of common solid waste which will pollute the environment without any treatment. In this study, the influence of secondary aluminum ash on the rheological properties and the initial setting time of fresh reactive powder concrete (RPC) are researched. Meanwhile, the mechanical properties and the drying shrinkage rates of RPC with the secondary aluminum ash are determined. The electrical parameters of RPC with the secondary aluminum ash are measured. Scanning electron microscopy is obtained to reflect the internal structure of RPC. Results show that the addition of secondary aluminum ash can lead to decreasing the fluidity and increase the yield shear stress of fresh RPC paste by varying rates of 16.1% and 58.3%, respectively. The addition of secondary aluminum ash can decrease the flexural and compressive strengths of RPC cured for 1 day by the decreasing rates of 0~18.7% and 0~19.3%. When the curing age is 28 days, the flexural and compressive strengths of RPC are increased by 0~9.1% and 0~19.1% with adding the secondary aluminum ash. The secondary aluminum ash can promote the condensation of RPC. The addition of the secondary aluminum ash can decrease the electrical resistance of RPC by an order of magnitude. The relationship between the electrical resistance and the electrical reactance fits the quadratic function equation. The electrical resistance of the pore solution increases in the form of a quadratic function with the mass ratio of the secondary aluminum ash. The dry shrinkage rates of RPC cured for 1 day and 28 days are decreased by 0~36.4% and 0~41.3% with the increasing dosages of secondary aluminum ash. As obtained from the microscopic testing results, the secondary aluminum ash can improve the compactness of hydration products.

Investigation of the effect of different grading on the mechanical properties of reactive powder concrete

In this study, 11 designs with sand-to-cement ratios of 4.5, 4.75, 5, 5.25, 5.5, 5.75, 6, 6.25, 6.5, 6.75, and 7 were used to investigate the impact of increasing the sand-to-cement ratio in reactive powder concrete. Laboratory results indicate a decrease in compressive and bending strength, following an increase in the ratio of sand to cement. Sample S7 with the highest ratio of sand to cement has the lowest bending strength and compressive strength at the ages of 1, 7, 14, 28, 42 and 56 days.In the second process, 1 % polymer resin was added to the sand-to-cement ratio from the first step. By analyzing the results, it was observed that the addition of 1 % of polymer resin causes a decrease of 40.8 % in compressive strength at the age of 1 day. The biggest one-day pressure drop is S6.75 with a drop of 68.1 %. As the samples age, adding 1 % of polymer resin increases the compressive strength at 11 sand-cement ratios, so that the 90-day compressive strength of the S4.75 sample reaches 59.7 MPa. The addition of 1 % polymer resin also increased the bending strength by 9.1 %. After examining the results of the first and second steps of the study, the sand to cement ratios of 5.5, 6, 6.25, 6.5 and 7 were selected as optimal and suitable samples. In the third step of the study, coarse aggregate with percentages of 10, 20, 30, 40 and 50 was added to the selected samples. The results showed that the addition of coarse aggregate caused a decrease of 41.1 % in the compressive strength of reactive powder concrete at the age of 1 day, compared to the control sample. In the third step, the maximum compressive strength at the ages of 28, 42, 56 and 90 days for sand-cement ratios of 5.5, 6, 6.25, 6.5 and 7 corresponds to the sample containing 50 % of coarse aggregate. The best samples of the third step in flexural strength are those with 50 % gravel, which increases flexural strength with increasing sand-cement ratio. On the other hand, with the addition of coarse aggregate, an increase in flexural strength was observed compared to the control sample of reactive powder concrete. In the fourth step of the study, 1 % of polymer resin was added to the samples of the third step. The results of this step show that, like the third step, the maximum compressive strength of the ages of 28, 42, 56 and 90 days for the sand-cement ratios of 5.5, 6, 6.25, 6.5 and 7 for the sample with 50 % coarse aggregate. In the fourth step, by increasing the ratio of sand to cement, samples with a lower percentage of sand have higher bending strength.

Effect of incorporating fibers in reactive powder concrete – A review

Modified form of High-Performance Concrete is a Reactive- Powder Concrete(RPC) which was first found by PierreRichard and Marcel Cheyrezy, they successfully built France laboratory using RPC. High compressive strength of over 200 MPa has been achieved, with flexural strength up to 40 MPa, and in certain cases crushing strengthup to 800 MPa with the introduction of hybrid fibre reinforcement. Cement OPC grade, silica fume, quartz sand, crushed quartz flour, water, a superplasticizer, and fibre reinforcement all contribute to making RPC.These materials have high durability characteristics as a result of their extremely low porosity, low permeability, limited shrinkage, and higher corrosion resistance. To increase package density, the powder combination of RPC should have a variety of granular particle classes. By dense packaging theory and grading optimization technique, the absence of coarse aggregate increased compactness. Because of its compactness, it reaches high strength. The rapid hydration of cement and silica fume at a high curing temperature of 100 °C as compete to 27 °C is something that causes the higher early strength. This paper discusses about the hybrid fibers incorporation in RPC under various curing conditions and its enhancement in strength than single fibers. Using micro and macro fibers dramatically improves the properties of RPC and thermal properties with various types of fiber. The mechanical characteristics of the RPC beam without the hybrid fiber, on the other end, are the lowest of all the mixtures. Apart from these characteristics, RPC can be utilized for industrial and nuclear waste storage facilities due to its ultra-dense microstructure, which provides ultra-high strength even at elevated temperature and water resistance. This paper infers that the addition of hybrid fiber in RPC considerably reduces the spalling of concrete at elevated temperatures and it exhibits superior strength and durability.

Effect of Dune Sand on the Properties of Reactive Powder Concrete Reinforced with Metal Fibers

Effect of Dune Sand on the Properties of Reactive Powder Concrete Reinforced with Metal Fibers

UTILIZATION OF SLAG POWDER AND RECYCLED CONCRETE WASTES IN REACTIVE POWDER CONCRETE

Using recycled wastes and industrial by-products in construction materials has become mandatory to conserve the natural resources and manage waste-disposal environmental problems. This experimental work investigates the workability and strength properties of reactive powder concrete (RPC), utilizing slag powder and finely ground recycled concrete waste as the partial substitutes for cement and quartz sand, respectively. The results for the slump flow, flexural strength, compressive strength, split-tensile strength were analysed for varying contents of the recycled concrete waste in RPC, i.e., (0, 5, 10, 15, 20, 25 and 30) % and a constant slag-powder addition of 20 %. Furthermore, water absorption of the hardened specimens of 28 d of curing was also examined. The results indicated a rise in the water absorption and reduced workability with the increase in the content of recycled concrete in RPC. This was due to porous inter-particle voids in recycled concrete wastes. The strength properties of RPC exhibited superior performance for the substitution of 15 % of quartz sand with recycled concrete waste. A low water-cement ratio and a steel-fibre addition to RPC play an important role in the strength development and durability properties of RPC.

Basic physical, mechanical, thermal and hygric properties of reactive powder concrete with basalt and polypropylene fibers after high-temperature exposure

Spalling is a well-known phenomenon that seriously limits application possibilities of concrete, the high performance- or reactive powder ones in particular. The dense structure of theirs, that under common circumstances provides excellent mechanical properties, is prone to easily trap molecules of water or water vapor in pores which can subsequently lead to inner pressure increase when exposed to an extensive heat source such as fire. There are several measures that are supposed to reduce or eliminate spalling risks, mostly based on an adjustment of the mixture composition by means of addition of various fibers. This paper aims at investigation of effects of basalt and propylene fibers on spalling of reactive powder concrete. Even if it might be sidelined by more frequently mentioned steel or glass fibers, the proposed combination has a large potential as it exploits excellent mechanical properties of basalt in wide temperature ranges to maintain the concrete integrity and, at the same time, polypropylene fibers can release the inner pressure by creation of water vapor escape paths when burned out. The complex determination of basic physical, mechanical, thermal and hygric properties as presented in this paper enables to assess the impact of polypropylene fibers on the concrete performance. It was shown, the mechanical properties are not negatively affected in a significant way. The highest decrease of compressive strength was found to be smaller than 9%. On the other hand, the moisture transport parameters were improved to allow a faster water vapor transfer through the body by up to 46.8%. This might represent the key factor in the spalling elimination efforts. The complex data presented in this paper are also highly valuable as input parameters for computational modelling whose lack is frequently mentioned in the scientific community.

Performance of polypropelene and polyester fibres-reinforced reactive powder concretes at elevated temperatures

Reactive Powder Concrete (RPC) is an emerging class of special concrete that falls under the category of ultra-high-performance concrete. RPC offers very superior mechanical properties as compared to conventional concretes. The application of RPC is limited to some of the restricted applications such as, construction of nuclear power plants, precast bridges and girders. The generalized application of RPC is restricted due to the unknown behavior of RPC, when it is exposed to fire load. The dense and fine microstructure of RPC is prone to spalling under elevated temperatures. To combat spalling, RPC is produced with suitable fibres. In this study RPC is prepared with addition of polypropelene and polyester fibres with different fibre dosages like 0.1, 0.5 and 0.9% by weight of cement. The residual mechanical and durability properties of fibre-based RPC are evaluated at elevated temperatures ranging from 200 to 800 °C. Results indicate that the combined effect of polypropelene and polyester fibre-based RPC, possess good spalling resistance with 0.1% fibre content. Fibre dosage of 0.5% has shown superior residual mechanical and durability properties of RPC at elevated temperatures. Formation of pores, cracks and evaporation of fibres due to elevated temperatures is also investigated based on microstructure examination for all RPC mixes.

The Influence of Assembly Unit of Fibers on the Mechanical and Long-Term Properties of Reactive Powder Concrete

The corrosion of concrete structures by chloride salt is very significant in coastal environments. In order to improve the durability of marine concrete structures, cement-based materials with high durability need to be developed. In this investigation, the influence of NaCl freeze–thaw cycles (FT-C) and NaCl dry-wet alternations (DW-A) on the flexural and compressive strengths of reactive powder concrete (RPC) with an assembly unit of basalt fibers and steel fibers is studied. Additionally, the mass loss rate, the relative dynamic modulus of elasticity (RDEM), the chloride ion migration coefficient (CMC) and the impact toughness are measured after the NaCl FT-C and DW-A action. Our findings show that the RDEM, mass loss, and mechanical strength loss of RPC are increased by the ascending NaCl FT-C and DW-A. Meanwhile, the RDEM and the impact toughness are decreased by the NaCl FT-C and DW-A. The RPC with 0.5% basalt fibers and 1.5% steel fibers by volume of RPC shows the optimum mechanical performance and resistance to NaCl FT-C and DW-A. However, RPC with 3% steel fibers shows the worst resistance to NaCl erosion. The maximum mass loss rates, RDEM, flexural strength loss rate, compressive strength loss rate, CMC and impact toughness of all specimens after 300 NaCl FT-C and 30 NaCl DW-A are 4.5%, 91.7%, 28.1%, 29.3%, 3.2 × 10−12 (m2/s) and 2471 J. Meanwhile, the corresponding minimum values are 1.62%, 83.2%, 20.4%, 15.7%, 1.1 × 10−12 (m2/s) and 625 J. The researching findings will provide an optimum mix ratio of RPC with an assembly unit of basalt fibers and steel fibers, which can be applied in the marine engineering environment.

Mechanical properties of ultra-high performance concrete based on reactive powder concrete: Effect of sand-to-cement ratio, adding glass fiber and calcium carbonate

Reactive Powder Concrete (RPC) contains high amounts of cement. This high ratio increases causing issues such as a high hydration temperature and concrete shrinkage. The present investigation is an attempt to study the effect of Sand-Cement ratio, substitution of calcium carbonate with part of Silica sand and adding glass fiber, on the properties of RPC. The study also deals with the microstructure investigation and Thermo-Gravimetric Analysis of RPC. Results indicate that increasing the S/C ratio up to 1.2 can improved the properties of RPC by reducing the amount of cement used. On the other hand, substitution 40%-50% of the silica sand with calcium carbonate can improved the microstructure of RPC. Moreover, the tensile behavior of RPC must be improved using another material due to the limit on the largest grain size in it. Adding glass fibers equivalent to 8%-10% of the cement weight to the mix design of RPC (containing 40%-50% silica sand that was replaced with calcium carbonate) improves the mechanical and durability behavior of RPC.

Investigating mechanical properties and microstructure of reactive powder concrete blended with sulfoaluminate cement

Super absorbent polymers, expansion agents, and shrinkage reduction agents have been used to improve the self-shrinkage of ultra-high-performance concrete (UHPC), but they may degrade the mechanical properties of concrete. Sulfoaluminate cement (SAC) has been proven to improve the compressive strength and self-shrinkage of UHPC. However, few studies have focused on the role of SAC in the tensile strength and pore structure of reactive powder concrete (RPC), a type of UHPC. In our study, we used compressive strength and splitting tensile strength tests, isothermal calorimetry, X-ray diffraction (XRD), thermogravimetric analysis (TG-DTA), mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM) to determine the mechanical properties and microstructure of RPC modified by SAC. The results showed that the addition of SAC effectively enhanced the strength of RPC, especially the early strength. Specifically, using an 8 wt% SAC caused an 871.4 % increase in compressive strength and 600% improvement in tensile strength after 8 h of curing. The tensile strength exhibited a strong positive linear correlation with the compressive strength. The rapid hydration of SAC promoted the generation of ettringite in RPC, which significantly increased the cumulative heat release and improved the strength of RPC at an early age; however, its effect was not significant on the later strength. The key reasons for the improvement in the mechanical properties of RPC by SAC modification were pore refinement and aggregate-paste interface improvement. Thus, incorporating SAC into RPC significantly enhance its early-age compressive and tensile strengths, which contributes to accelerate the formwork turnover of RPC components and operational efficiency of the stacking area.

Some properties of Reactive Powder Concrete Contain Recycled Glass Powder

Every year, millions of tons of waste glass are created across the globe. It is disposed of in landfills, which is unsustainable since it does not disintegrate into the environment. This study aims to produce reactive powder concrete by using recycled glass powder and determine the influence on the mechanical properties. This study investigated the effect of partial replacement of cement with recycled glass powder at two percentages (0, 20) % by weight of cement on some mechanical properties (Fresh density, Splitting tensile strength, Impact Strength, and voids%) of reactive powder concrete containing 1 % micro steel (MSRPC). Furthermore, using steam curing for (5 hours) at 90 degrees celsius after hardening the sample directly, RPC was produced using local cement, silica fume, and a super plasticizer, with a w/c (0.2). It was found the Fresh density increased by about (7.27%), splitting tensile strength increased by about (23.5%) at age 28day, energy that causes 1-st crack increased by about (77.7%), energy that causes ultimate failure increased by about (54.9%) at age 60 days, and a reduction in the voids % by about (12.5)% at age 28 day compared with the reference mixture.

Optimization of mixture parameter for physical and mechanical properties of reactive powder concrete under external sulfate attack using Taguchi method

• Taguchi analysis has been used to determine optimum mix design parapeter of RPC exposed to different Na 2 SO 4 solutions and exposure conditions. • Optimized level for RPC mixture with different water to binder ratio, steel fiber contents, and silica fume contents depends on different external sulfate attack exposure conditions. • RPC appears to be sustainable and durable material under different external sulfate attack exposure conditions. Reactive powder concrete (RPC) is defined as a cementitious composite material with an optimized size of granular constituents, very low water-to-binder ratio (w/b), pozzolanic materials like silica fume (SF), and discontinuous fiber reinforcement. RPC applications include bridge decks and girders, seismic columns, wind turbine towers, and pile foundations. Especially, a durable and robust RPC pile foundation with long service life is essential in building construction because continuous maintenance is impossible. Moreover, natural in-situ conditions such as water table, temperature, and sulfate concentration in soil to which the pile foundation is exposed are critical and related to deteriorating the pile foundation. Therefore, the Taguchi design of experiments (DOE) was used in this research to determine the optimal RPC mixture with beneficial characteristics against external sulfate attack (ESA). Mixture design parameters included steel fiber content (0, 1 and 2 %), w/b (0.16, 20 and 0.24), and SF content (15, 20 and 25 %). In contrast, environmental conditions of ESA exposure contained three different sodium sulfate (Na 2 SO 4 ) concentrations (0.35, 1.05, and 3.15 M), cyclic and continuous exposure at normal temperature (20 °C), and continuous exposure at elevated temperatures (40 °C and 60 °C). The analytical and statistical investigation evaluated mass change, compressive strength, and modulus of rupture in RPC mixtures exposed to these conditions for 52 weeks. Test results show that cyclic exposure and increased solution temperature in ESA facilitate RPC damage. If measured after air drying, RPC mixtures subjected to cyclic ESA are especially susceptible to failure. Taguchi analysis indicated the optimum parameters’ level for mass change as: 0 % steel fiber, w/b = 0.16, and 20 % SF content; for the compressive strength: 2 % steel fiber, w/b = 0.24, and 20 % SF content; and, for modulus of rupture: 2 % steel fiber, w/b = 0.20, and 25 % SF content. In conclusion, RPC appears to be sustainable and durable material under different ESA exposure conditions.

Triaxial compression test study on the influence of single crack on the mechanical properties of reactive powder concrete

AbstractTo investigate the influence of crack‐type defect and confining pressure on the mechanical properties of brittle materials, conventional triaxial compression tests were conducted on five types of prismatic samples with the same size of 41 mm × 70.7 mm × 175 mm at six confining pressures of 0, 5, 10, 20, 40, and 70 MPa, respectively. Among the five types of samples, one is intact, with uniaxial compressive strength of 140 MPa, and the other four are all defective and contain a single prefabricated crack with the length of 10 mm and the inclination angles of 0°, 30°, 60°, and 90°, respectively. All samples are made of reactive powder concrete with the same mix proportion. According to the test results, the following conclusions are obtained. (1) For any kind of defective sample and any confining pressure, relative values of the strength deviation that the defective samples deviating from the intact sample are all less than relative values of the strength range (max–min) of the five samples. (2) There exist two critical values p1 and p2 of the confining pressure p, the inclination angle of the prefabricated crack has significantly different impact on the compressive strength in the interval of 0 ≤ p < p1, p1 ≤ p < p2, and p ≥ p2, respectively.